In fact, the parasite was missing a critical organelle all together. 10.
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After that, a special organelle creates a barrier to keep other sperm out.
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A Golgi (an organelle found in most eukaryotic cells) is shown in green, and a cell membrane appears in red.
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But if the model can figure out where organelle A is based on the presence and shape of membrane B, tagging isn't necessary.
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Remarkably, the researchers were able to observe melanosomes—a cellular organelle that synthesizes melanin pigment—inside the feathers, suggesting these creatures had a ginger-brown coloring.
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Click here to view original GIFImage: Ryan F. Mandelbaum/YouTube/DataBase Center for Life Science/Wikimedia CommonsMitochondria are the only cellular organelle you probably remember—they're the powerhouse of the cell, after all.
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"[The study authors'] breakthrough opens up wide-ranging opportunities for exploring the molecular mechanisms that underpin the organelle community's dance," Sang-Hee Shim, assistant chemistry professor at Korea University wrote in commentary for Nature.
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They then act as GPS devices to cross the crowded terrain of a cell or a human body and, like finding a mailbox across the universe, penetrate precisely the right worksite organelle for each protein's assigned task.
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They proposed that appendages like those of Prometheoarchaeum entangled a passing bacterium, which was then engulfed and eventually evolved into an organelle - internal structure - called a mitochondrion that is the powerhouse of a cell and crucial for respiration and energy production.
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Further tests confirmed it — there was no mitochondrial genome at all, and hence no chance of the organism functioning the way researchers had expected, although there did seem to be a loose sac that might once have been the organelle.
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Giardia, a parasite that causes gut troubles in people, and Trichomonas vaginalis, a parasite that drives the sexually transmitted infection trichomoniasis, have just a vestige of the original organelle, a sac that does not perform the traditional energy-producing role.
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Several processes are known to have developed for organelle biogenesis. These can range from de novo synthesis to the copying of a template organelle; the formation of an organelle 'from scratch' and using a preexisting organelle as a template to manufacture an organelle, respectively. The distinct structures of each organelle are thought to be caused by the different mechanisms of the processes which create them and the proteins that they are made up of. Organelles may also be 'split' between two cells during the process of cellular division (known as organelle inheritance), where the organelle of the parent cell doubles in size and then splits with each half being delivered to their respective daughter cells.
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Organelle biogenesis is the biogenesis, or creation, of cellular organelles in cells. Organelle biogenesis includes the process by which cellular organelles are split between daughter cells during mitosis; this process is called organelle inheritance.
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A human may have between 1000 and 10000 magnetic particles arranged in a cluster within an organelle with only one cell in 5000 having said organelle. Finally, the human magnetosomic organelle has an unknown function that does not involve detecting the earth's magnetic field.
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However, organelle genes in heteroplasmic cells can segregate because they each have several copies of their genome. This may result in daughter cells with differential proportions of organelle genotypes. # Mendel states that nuclear alleles always segregate during meiosis. However, organelle alleles may or may not do this.
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Eubacterial flagellum is a multifunctional organelle. It’s also one of a range of motility systems in bacteria. The structure of the organelle appears like a motor, shaft and a propeller.Young, Matt & Edis, Taner (2004).
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The cytostome has also been found to associate with the flagellum of Trypanosoma cruzi. So far, this is the only known example of an endocytotic organelle being associated with an organelle that is used for locomotion.
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Formation of Magnetosome Chain. These magnetite crystals are contained within an organelle envelope. This envelope is referred to as a magnetosome. Within the organelle there can either ferrimagnetic crystals of magnetite (Fe3O4) or the iron sulfide greigite (Fe3S4).
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Only by this initial chemical exchange can the parasite enter into the erythrocyte via actin-myosin motor complex. It has been posited that this organelle works cooperatively with its counterpart organelle, the rhoptry, which also is a secretory organelle. It is possible that, while the microneme initiates erythrocyte-binding, the rhoptry secretes proteins to create the PVM, or the parasitophorous vacuole membrane, in which the parasite can survive and reproduce.
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Small membrane bound vesicles responsible for transporting proteins from one organelle to another are commonly found in endocytic and secretory pathways. Vesicles bud from their donor organelle and release the contents of their vesicle by a fusion event in a particular target organelle. The net movement of proteins from the endoplasmic reticulum (ER) to the golgi apparatus represents one form of intracellular transport through this mode of vesicle budding. Since the ER is the site of protein synthesis, it would serve as the parent organelle, and the cis face of the golgi, where proteins and signals are received, would be the acceptor.
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For mammals, cortical granule migration is considered an indication of oocyte maturity and organelle organization.
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The mitochondrion-like organelle of Trimastix pyriformis contains the complete glycine cleavage system. PLoS One, 8(3). Current research indicates that despite there being no strong evidence that the organelle can produce ATP, there are many mitochondrial functions that it appears to have maintained .
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FERMT3 functions as a stabilizer of the cytoskeleton and regulates its dynamics in cell and organelle motility.
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The mutations alter myelin composition, thickness and integrity. Endoplasmic reticulum (ER) is the main organelle for lipid synthesis.
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In 1975, Carpenter discovered and published a paper on the recombination nodule, an organelle that mediates meiotic recombination.
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Autolysis of individual cell organelles can be lessened if the organelle is stored in warm isotonic buffer after cell fractionation.
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Endosymbiotic theory for the origin of mitochondria suggests that the proto- eukaryote engulfed a protomitochondria, and this endosymbiont became an organelle.
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This is also an example of cell organelle stealing, the concept called kleptoplasty, and endosymbiosis. Dinophysis acuminata reproduces sexually and asexually.
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The interactions with cytoskeletal proteins and a kinase substrate suggest a role for this protein in vesicular trafficking or organelle transport.
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In 1909, while studying chloroplast genomes, Erwin Baur made the first observations about organelle inheritance patterns. Organelle genome inheritance differs from nuclear genome, and this is illustrated by four violations of Mendel's laws. # During asexual reproduction, nuclear genes never segregate during cellular divisions. This is to ensure that each daughter cell gets a copy of every gene.
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Retrieved 2008-07-26 a relatively small protrusion of the cell membrane that looks like a stick or a finger under the electron microscope. Primary cilium is typically used by the cell as a sensory organelle, or antenna.Singla V (2006). The primary cilium as the cell's antenna: signaling at a sensory organelle. Science. 313(5787):629-33.
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A hydrogenosome is a membrane bound, redox active organelle. They produce hydrogen gas from the oxidation of pyruvate, and function in anaerobic environments.
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Crithidia luciliae is a haemoflagellate protist with an organelle known as the kinetoplast. This organelle contains a high concentration of circular DNA with no recognisable nuclear antigens, allowing for the reliable detection of anti-dsDNA antibodies. The kinetoplast fluoresces if serum contains high avidity anti- dsDNA antibodies. This test has a higher specificity than EIA because it uses unprocessed DNA.
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It is very rare for organelle genes from different lineages to recombine. These genomes are usually inherited uniparentally, which does not provide a recombination opportunity. If they are inherited biparentally, it is unlikely that the organelles from the parents will fuse, meaning they will not share genomes. However, it is possible for organelle genes from the same lineage to recombine.
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Each cnidocyte contains an organelle called a cnida, cnidocyst, nematocyst, ptychocyst or spirocyst. This organelle consists of a bulb-shaped capsule containing a coiled hollow tubule structure attached to it. An immature cnidocyte is referred to as a cnidoblast or nematoblast. The externally oriented side of the cell has a hair-like trigger called a cnidocil, which is a mechano- and chemo-receptor.
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Underground orchids do not possess chloroplasts but they retain plastid genes, although R. gardneri possesses the smallest organelle genome yet described in land plants.
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The rough endoplasm reticulum cisternae and organelle was very well developed and the cellular membranes of oocyte and granulosa cells were in close connection.
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Peter Michaelis's work contributed largely to the development and understanding of organelle inheritance in Epilobium and other plants with two or more chloroplasts per cell.
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They possess an organelle known as the kinetoplast which is a large mitochondrion with a network of interlocking circular dsDNA molecules. After incubation with serum containing anti-dsDNA antibodies and fluorescent-labelled anti-human antibodies, the kinetoplast will fluoresce. The lack of other nuclear antigens in this organelle means that using C.luciliae as a substrate allows for the specific detection of anti-dsDNA antibodies.
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In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name organelle comes from the idea that these structures are parts of cells, as organs are to the body, hence organelle, the suffix -elle being a diminutive. Organelles are either separately enclosed within their own lipid bilayers (also called membrane- bound organelles) or are spatially distinct functional units without a surrounding lipid bilayer (non-membrane bound organelles). Although most organelles are functional units within cells, some functional units that extend outside of cells are often termed organelles, such as cilia, the flagellum and archaellum, and the trichocyst.
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The process of organelle biogenesis is known to be regulated by specialized transcription networks that modulate the expression of the genes that code for specific organellar proteins. In order for organelle biogenesis to be carried out properly, the specific genes coding for the organellar proteins must be transcribed properly and the translation of the resulting mRNA must be successful. In addition to this, the process requires the transfer of polypeptides to their site of function, guided by signaling peptides. If proteins are not directed to their respective sites of subcellular function, a defective organelle that fails to fulfill its tasks within the cell properly may result.
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Granules are one of the non-living cell organelle of plant cell (the others-vacuole and nucleoplasm). It serves as small container of starch in plant cell.
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A model called the cell state splitter involves alternating cell contraction and expansion, initiated by a bistable organelle at the apical end of each cell. The organelle consists of microtubules and microfilaments in mechanical opposition. It responds to local mechanical perturbations caused by morphogenetic movements. These then trigger traveling embryonic differentiation waves of contraction or expansion over presumptive tissues that determine cell type and is followed by cell differentiation.
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The presence of floridean starch-like storage in some apicomplexan parasites is one piece of evidence supporting a red alga ancestry for the apicoplast, a non-photosynthetic organelle.
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Because the E. cuniculi genome contains genes related to some mitochondrial functions (for example, Fe-S cluster assembly), it is possible that microsporidia have retained a mitochondrion-derived organelle.
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Michael Syvanen, Clarence I. Kado Horizontal Gene Transfer Academic Press, p. 405 The host cell and organelle need to develop a transport mechanism that enables the return of the protein products needed by the organelle but now manufactured by the cell. Cyanobacteria and α-proteobacteria are the most closely related free-living organisms to plastids and mitochondria respectively. Both cyanobacteria and α-proteobacteria maintain a large (>6Mb) genome encoding thousands of proteins.
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Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. Numerous circular vesicles can be seen in proximity to the organelle. The Golgi apparatus, also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane- bound vesicles inside the cell before the vesicles are sent to their destination.
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Ribbon synapses are a type of synapse often found in sensory neurons and are of a unique structure that specially equips them to respond dynamically to inputs from electrotonic potentials. They are so named for an organelle they contain, the synaptic ribbon. This organelle can hold thousands of synaptic vesicles close to the presynaptic membrane, enabling neurotransmitter release that can quickly react to a wide range of changes in the membrane potential.
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This view is supported by how the tension-compression interactions of tensegrity minimize material needed to maintain stability and achieve structural resiliency. Therefore, natural selection pressures would likely favor biological systems organized in a tensegrity manner. As Ingber explains: In embryology, Richard Gordon proposed that Embryonic differentiation waves are propagated by an 'organelle of differentiation'Gordon, N.K. and Gordon, R. The organelle of differentiation in embryos: the cell state splitter [invited review.] Theor. Biol. Med. Model.
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In the search for magnetite receptors, a large iron containing organelle (the cuticulosome) in the inner ear of pigeons was discovered. This organelle might represent part of an alternative magnetosensitive system. Taken together the receptor responsible for magnetosensitivity in homing pigeons remains uncertain. Aside from the sensory receptor for magnetic reception in homing pigeons there has been work on neural regions that are possibly involved in the processing of magnetic information within the brain.
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The Thraustochytrium mitochondrial code (translation table 23) is a genetic code found in the mitochondria of labyrinthulid Thraustochytrium aureum. The mitochondrial genome was sequenced by the Organelle Genome Megasequencing Program.
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Coleochaetophyceae are a class of charophyte algae that includes some of the closest multicellular relatives of land plants. Their mitogenome is the most intron rich organelle among the streptophyte algae.
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Several metabolic diseases are known to be caused by a fault in the process of organelle biogenesis. These may include mitochondrial biogenesis defects, peroxisome biogenesis disorders, and lysosomal storage disorders.
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Recombination of organelle DNA is very limited, meaning that any traits that are encoded by the oDNA are likely to remain the same as they are passed from generation to generation.
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The cells group around the nanopillars because of its small size and recognize it as an organelle. The nanopillars simply hold the cells in place while the cells are being observed.
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Giezen in Birmingham, 2015 Mark van der Giezen is Professor of Biological Chemistry, Centre for Organelle Research, University of Stavanger, Norway. He holds Dutch nationality and is married with three children .
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It is also possible to isolate these polar organelles from the bacterial cells and study them in face view in negatively stained preparations. The polar organelle bears a fine array of attached particles in hexagonal close packing and these have been shown to possess ATPase activity. The polar organelle is found in close juxtaposition to the points of insertion of the bacterial flagella into the plasma membrane, especially where multiple flagella bases are grouped in a region of the cell membrane. It may thus be inferred that the polar organelle could be of importance in the supply and transfer of energy to the bidirectional molecular rotational motor situated at the base of each individual bacterial flagellum (see also electrochemical gradient).
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Adherence of M. pneumoniae to a host cell (usually a respiratory tract cell, but occasionally an erythrocyte or urogenital lining cell) is the initiating event for pneumonic disease and related symptoms. The specialized attachment organelle is a polar, electron dense and elongated cell extension that facilitates motility and adherence to host cells. It is composed of a central filament surrounded by an intracytoplasmic space, along with a number of adhesins and structural and accessory proteins localized at the tip of the organelle. A variety of proteins are known to contribute to the formation and functionality of the attachment organelle, including the accessory proteins HMW1–HMW5, P30, P56, and P90 that confer structure and adhesin support, and P1, P30 and P116 which are involved directly in attachment.
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The possible presence of organelle DNA inside the nuclear genome was suggested after finding of homologous structure to the mitochondrial DNA, which was shortly after the discovery of the presence of an independent DNA within the organelles in 1967. This topic stayed untouched until the 1980s. Initial evidence that DNA could move among cell compartments came when fragments of chloroplast DNA were found in the maize mitochondrial genome with the help of cross-hybridization, between chloroplast and mitochondrial DNA, and physical mapping of homologous regions. After this initial observation, Ellis coined the name "promiscuous DNA" in order to signify the transfer of DNA intracellularly from one organelle to the other and is the presence of organelle DNA in multiple cellular compartments.
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Hermansky–Pudlak syndrome 4 protein is a protein that in humans is encoded by the HPS4 gene. Hermansky–Pudlak syndrome is a disorder of organelle biogenesis in which oculocutaneous albinism, bleeding, and pulmonary fibrosis result from defects of melanosomes, platelet dense granules, and lysosomes. Mutations in this gene as well as several others can cause this syndrome. The protein encoded by this gene appears to be important in organelle biogenesis and is similar to the mouse 'light ear' protein.
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A vesiculo-vacuolar organelle (VVO) is an organelle that contributes to endothelial cell permeability. VVOs are found in the endothelium of normal blood vessels and vessels associated with tumors or allergic inflammation. VVOs actively transport fluid and macromolecules from the cytoplasm of endothelial cells into the blood vessel lumen, contributing to the increase in vascular permeability that occurs during the process of inflammation. This kind of transport is mediated by VEGF, one of the chemical mediators of inflammation.
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Saccharomyces cerevisiae was the first eukaryotic organism to have its complete genome sequence determined. This list of "sequenced" eukaryotic genomes contains all the eukaryotes known to have publicly available complete nuclear and organelle genome sequences that have been sequenced, assembled, annotated and published; draft genomes are not included, nor are organelle- only sequences. DNA was first sequenced in 1977. The first free-living organism to have its genome completely sequenced was the bacterium Haemophilus influenzae, in 1995.
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The biofilm needs bacterial cells to move in a certain manner, while flagella is the organelle which has locomotive function. Mutant strains lacking flagella can still form pellicle, albeit much less rapidly.
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Vegetative segregation, the random partitioning of cytoplasm, is a distinguishable characteristic of organelle heredity. During cell division, the organelles are divided equally, providing each daughter cell with a random selection of plasmid genotypes.
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It has an elongated shape and its cells possess two internal compartments, one packed with granules, the other filled with coarse granules (consistent with ribosomal structures). The organism has properties of adherence through a specific organelle called the tip organelle. M. Penetrans has a coding sequence (MYPE1570) similar to that of MYPE470 in Mycoplasma pneumoniae which codes for an accessory protein that aids in cytadherence, the adherence to respiratory epithelium. This similarity suggests M. penetrans could attach to host cells through cytadherence.
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Mycoplasma pneumoniae grows exclusively by parasitizing mammals. Reproduction, therefore, is dependent upon attachment to a host cell. According to Waite and Talkington, specialized reproduction occurs by “binary fission, temporally linked with duplication of its attachment organelle, which migrates to the opposite pole of the cell during replication and before nucleoid separation”. Mutations that affect the formation of the attachment organelle not only hinder motility and cell division, but also reduce the ability of M. pneumoniae cells to adhere to the host cell.
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Similar to most positive (+) ssRNA viruses, flaviviruses generate organelle-like structures in the endoplasmic reticulum (ER) of the host organism for replication. Since the ER is involved in de novo biogenesis of some cell organelles, viruses take advantage of the replication location to take over some of the organelle functions for its own replication cycle. Viral genome replication in the ER occurs in structures called virus replication organelles. The organelles include two distinct subdomains, vesicle packets (VP) and convoluted membranes (CMs).
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While PSF I derives members from gram-negative bacteria primarily one family of eukaryotic mitochondrial porins, PSF II and V porins are derived from Actinobacteria. PSF III and V are derived from eukaryotic organelle.
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A selfish cytoplasmic gene is a gene located in an organelle, plasmid or intracellular parasite that modifies reproduction to cause its own increase at the expense of the cell or organism that carries it.
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Notable characteristics of trypanosomatids are the ability to perform trans- splicing of RNA and possession of glycosomes, where much of their glycolysis is confined to. The acidocalcisome, another organelle, was first identified in trypanosomes.
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This list of sequenced animal genomes contains animal species for which complete genome sequences have been assembled, annotated and published. Substantially complete draft genomes are included, but not partial genome sequences or organelle-only sequences.
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This list of sequenced protist genomes contains all the protist species known to have publicly available complete genome sequences that have been assembled, annotated and published; draft genomes aren't included, nor are organelle only sequences.
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Cyanidioschyzon merolae is a small (2μm), club-shaped, unicellular haploid red alga adapted to high sulfur acidic hot spring environments (pH 1.5, 45 °C). The cellular architecture of C. merolae is extremely simple, containing only a single chloroplast and a single mitochondrion and lacking a vacuole and cell wall. In addition, the cellular and organelle divisions can be synchronized. For these reasons, C. merolae is considered an excellent model system for study of cellular and organelle division processes, as well as biochemistry and structural biology.
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Durinskia is a genus of dinoflagellate that can be found in freshwater and marine environments. This genus was created to accommodate its type species, Durinskia baltica, after major classification discrepancies were found. While Durinskia species appear to be typical dinoflagellates that are armored with cellulose plates called theca, the presence of a pennate diatom-derived tertiary endosymbiont is their most defining characteristic. This genus is significant to the study of endosymbiotic events and organelle integration since structures and organelle genomes in the tertiary plastids are not reduced.
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This list of sequenced fungi genomes contains all the fungal species known to have publicly available complete genome sequences that have been assembled, annotated and published; draft genomes are not included, nor are organelle only sequences.
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Meta-algae are organisms with photosynthetic organelles of secondary or tertiary endosymbiotic origin, and their close non-photosynthetic, plastid- bearing, relatives. Apicomplexans are a secondarily non-photosynthetic group of chromalveoates which retain a reduced plastid organelle.
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A single Golgi body with swelled cisternae lies beneath the flagellum, and each cell has an ejectile organelle that putatively releases a cylindrical structure. A vacuole, or cluster of vacuoles, contains the putative carbohydrate storage product.
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Major vault protein is a protein that in humans is encoded by the MVP gene. 78 copies of the protein assemble into the large compartments called vaults, illustrated and discussed in the article on Vault (organelle).
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The cytosol is extremely reduced in these genera and the vacuole can occupy between 40–98% of the cell. The vacuole contains high concentrations of nitrate ions and is therefore thought to be a storage organelle.
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Like most signal peptides, mitochondrial targeting signals and plastid specific transit peptides are cleaved once targeting is complete. Some plant proteins have an N-terminal transport signal that targets both organelles often referred to as dual-targeted transit peptide. Approximately 5% of total organelle proteins are predicted to be dual-targeted however the specific number could be higher considering the variable degree of accumulation of passenger proteins in both organelles. The targeting specificity of these transit peptides depends on many factors including net charge and affinity between transit peptides and organelle transport machinery.
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He was the first to establish the type of liver tumour, now known in his honour as "Novikoff hepatoma". In 1961 with Sidney Goldfischer, Novikoff developed a staining method for the Golgi body using the enzyme nucleosidediphosphatase, by which they described the enzymatic property of the organelle for the first time. In 1969 they developed a staining technique (alkaline diaminobenzidine, or DAB) by which they studied the structure of another new organelle, peroxisome, for the first time. In 1969 he gave the first clear-cut distinction between lysosomes and peroxisomes.
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The glycosome is a membrane-enclosed organelle that contains the glycolytic enzymes. The term was first used by Scott and Still in 1968 after they realized that the glycogen in the cell was not static but rather a dynamic molecule. It is found in a few species of protozoa including the Kinetoplastida which include the suborders Trypanosomatida and Bodonina, most notably in the human pathogenic trypanosomes, which can cause sleeping sickness, Chagas's disease, and leishmaniasis. The organelle is bounded by a single membrane and contains a dense proteinaceous matrix.
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Plant cell structure Animal cell structure A vacuole () is a membrane-bound organelle which is present in plant and fungal cells and some protist, animal and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution, though in certain cases they may contain solids which have been engulfed. Vacuoles are formed by the fusion of multiple membrane vesicles and are effectively just larger forms of these. The organelle has no basic shape or size; its structure varies according to the requirements of the cell.
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Small Cajal body-specific RNAs (scaRNAs) are a class of small nucleolar RNAs (snoRNAs) that specifically localise to the Cajal body, a nuclear organelle (cellular sub-organelle) involved in the biogenesis of small nuclear ribonucleoproteins (snRNPs or snurps). ScaRNAs guide the modification (methylation and pseudouridylation) of RNA polymerase II transcribed spliceosomal RNAs U1, U2, U4, U5 and U12. The first scaRNA identified was U85. It is unlike typical snoRNAs in that it is a composite C/D box and H/ACA box snoRNAs and can guide both pseudouridylation and 2′-O-methylation.
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Protist Paramecium aurelia with contractile vacuoles A contractile vacuole (CV) is a sub-cellular structure (organelle) involved in osmoregulation. It is found predominantly in protists and in unicellular algae. It was previously known as pulsatile or pulsating vacuole.
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HPS6 is a protein that may play a role in organelle biogenesis, and KCNIP2 is a voltage-gated potassium channel interacting protein. The same pattern is observed in the orthologous locus in mice, as well as most other vertebrates.
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It is usually found in a marine environments rich in algae and sea grass. It is capable of movement by use of this organelle. They are generally decomposers. They are cultivated for their active production of Omega-3 fatty acids.
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Two types of blebs are recognized in apoptosis. Initially, small surface blebs are formed. During later stages, larger so-called dynamic blebs may appear, which may carry larger organelle fragments such as larger parts of the fragmented apoptotic cell nucleus.
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Proteins that are to be targeted to a particular organelle or for secretion have an N-terminal signal peptide that directs the protein to its final destination. This signal peptide is removed by proteolysis after their transport through a membrane.
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S/MAR-Element), which allows for autonomous replication in the recipient cell. Minicircles are small (~4kb) circular replicons. They occur naturally in some eukaryotic organelle genomes. In the mitochondria-derived kinetoplast of trypanosomes, minicircles encode guide RNAs for RNA editing.
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One of its arms is embedded in the inner membrane of the mitochondria, and the other is embedded in the organelle. The two arms are arranged in an L-shaped configuration. The total molecular weight of the complex is 1MDa.
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Sketch of a longitudinal ultrathin section through a typical motile bacterium bearing a flagellum and surrounding polar organelle at one end of the cell. A polar organelle is a structure at a specialised region of the bacterial polar membrane that is associated with the flagellar apparatus. This flagellum- associated structure can easily be distinguished from the other membrane regions in ultrathin sections of embedded bacteria by electron microscopy when the cell membrane is orientated perpendicular to the viewing direction. There, the membrane appears slightly thickened with a finely frilled layer facing the inside of the cell.
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Magnetotactic bacteria (MTB), which are utilized for the applications of magnetogenetics, are typically found in aquatic environments and uniquely contain an organelle called a magnetosome. Microbes used to be thought as randomly spaced throughout an environment, research has been showing that magnetism of the earth and nearby magnet field may impact the locations of microbes. Now there is a significant amount of data found that can correlate the magnetic fields of objects and the earth, there is still more data required in order to make this correlation connected to causation. This membraned organelle contains a microscopic crystalline structure of a magnetic iron mineral.
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P30 is not involved in the localization of P1 in the tip structure since P1 is trafficked to the attachment organelle in P30 mutants, but rather it may function as a receptor-binding accessory adhesin. P30 mutants also display distinct morphological features such as multiple lobes and a rounded shape as opposed to elongated, which suggests P30 may interact with the cytoskeleton during formation of the attachment organelle. A number of eukaryotic cell surface components have been implicated in the adherence of M. pneumoniae cells to the respiratory tract epithelium. Among them are sialoglycoconjugates, sulfated glycolipids, glycoproteins, fibronectin, and neuraminic acid receptors.
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In eukaryotes, the processing of pre-mRNA and RNA editing take place at sites determined by the base pairing between the target RNA and RNA constituents of small nuclear ribonucleoproteins (snRNPs). Such enzyme targeting is also responsible for gene down regulation though RNA interference (RNAi), where an enzyme-associated guide RNA targets specific mRNA for selective destruction. Likewise, in eukaryotes the maintenance of telomeres involves copying of an RNA template that is a constituent part of the telomerase ribonucleoprotein enzyme. Another cellular organelle, the vault, includes a ribonucleoprotein component, although the function of this organelle remains to be elucidated.
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This list of sequenced plant genomes contains plant species known to have publicly available complete genome sequences that have been assembled, annotated and published. Unassembled genomes are not included, nor are organelle only sequences. For all kingdoms, see the list of sequenced genomes.
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The erythrocyte is differentiated for such function to predominantly express hemoglobin and remove all the organelle including protein synthesis machinery. Our traditional review of erythrocyte function is solely for gaseous exchange. Nevertheless, several previously undetected physiologic functions of erythrocyte are largely neglected.
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For this reason, organelle DNA, including mtDNA, is inherited from the mother. Mutations in mtDNA or other cytoplasmic DNA will also be inherited from the mother. This uniparental inheritance is an example of non-Mendelian inheritance. Plants also show uniparental mtDNA inheritance.
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A microbody (or cytosome) is a type of organelle that is found in the cells of plants, protozoa, and animals. Organelles in the microbody family include peroxisomes, glyoxysomes, glycosomes and hydrogenosomes. In vertebrates, microbodies are especially prevalent in the liver and kidney.
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Dendritic spines can develop directly from dendritic shafts or from dendritic filopodia. During synaptogenesis, dendrites rapidly sprout and retract filopodia, small membrane organelle-lacking membranous protrusions. Recently, I-BAR protein MIM was found to contribute to the initiation process.Saarikangas, Juha, et al.
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Subsequently, the host's methane forming capability was lost. Thus, the origins of the heterotrophic organelle (symbiont) are identical to the origins of the eukaryotic lineage. In this hypothesis, the presence of H2 represents the selective force that forged eukaryotes out of prokaryotes.
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The transition from mastigote to coccoid stage in Symbiodinium occurs rapidly, but details about cellular changes are unknown. Mucocysts (an ejectile organelle) located beneath the plasmalemma are found in S. pilosum and their function is unknown, but may be involved in heterotrophic feeding.
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Most excavates are unicellular, heterotrophic flagellates. Only the Euglenozoa are photosynthetic. In some (particularly anaerobic intestinal parasites), the mitochondria have been greatly reduced. Some excavates lack "classical" mitochondria, and are called "amitochondriate", although most retain a mitochondrial organelle in greatly modified form (e.g.
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The translocation of proteins into the mitochondrial matrix involves the interactions of both GTP and ATP. The importing of these proteins plays an important role in several pathways regulated within the mitochondria organelle, such as converting oxaloacetate to phosphoenolpyruvate (PEP) in gluconeogenesis.
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Briefly, the CoRR hypothesis states that endosymbiotic organelles such as mitochondria and chloroplasts retain genomes to provide for regulation of gene expression by electron transport and the redox state of the organelle. In addition, Allen works on mitochondrial ageing in relation to sex.
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This intronless gene encodes a protein that may play a role in organelle biogenesis associated with melanosomes, platelet dense granules, and lysosomes. HPS6 along with HPS3 and HPS5 form a stable protein complex named Biogenesis of Lysosome-related Organelles Complex-2 (BLOC-2).
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The above reactions are inhibited by bisphosphonates (used for osteoporosis). Statin-induced rhabdomyolysis is due to the depletion of farnesyl-PPi, which leads to a depletion of CoQ in the electron transport chain of mitochondria, an organelle that is found in great numbers in myocytes.
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No differences were found between cv. Danvers and D. capillifolius plastid DNA patterns when examined using eight different restriction enzymes. The data indicate that specific isoenzyme and organelle DNA restriction fragment patterns will be useful markers for precise identification of genomes of different Daucus species.
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If the synthesized proteins "belong" in a different organelle, they can be transported there in either of two ways depending on the protein: Co-translational translocation (translocation during the process of translation), and post-translational translocation (translocation after the process of translation is complete).
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Glycosomes are composed of glycogen and proteins. The proteins are the enzymes that are associated with the metabolism of glycogen. These proteins and glycogen form a complex to make a distinct and separate organelle. The proteins for glycosomes are imported from free cytosolic ribosomes.
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Approximate pHs of various organelles within a cell. The pH within a particular organelle is tailored for its specific function. For example, lysosomes have a relatively low pH of 4.5. Additionally, fluorescence microscopy techniques have indicated that phagocytes also have a relatively low internal pH.
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The MAM is enriched in enzymes involved in lipid biosynthesis, such as phosphatidylserine synthase on the ER face and phosphatidylserine decarboxylase on the mitochondrial face. Because mitochondria are dynamic organelles constantly undergoing fission and fusion events, they require a constant and well-regulated supply of phospholipids for membrane integrity. But mitochondria are not only a destination for the phospholipids they finish synthesis of; rather, this organelle also plays a role in inter-organelle trafficking of the intermediates and products of phospholipid biosynthetic pathways, ceramide and cholesterol metabolism, and glycosphingolipid anabolism. Such trafficking capacity depends on the MAM, which has been shown to facilitate transfer of lipid intermediates between organelles.
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GetOrganelle is a toolkit that assembles organellar genomes uses genome skimming reads. Organelle-associated reads are recruited using a modified “baiting and iterative mapping” approach. The reads aligning to the target genome, using Bowtie2, are referred to as “seed reads”. The seed reads are used as “baits” to recruit more organelle-associated reads via multiple iterations of extension. The read extension algorithm uses a hashing approach, where the reads are cut into substrings of certain lengths, referred to as “words”. At each extension iteration, these “words” are added to a hash table, referred to as a “baits pool”, which dynamically increases in size with each iteration.
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Although sterol transfer is proposed to occur at regions where organelle membranes are closely apposed, disruption of endoplasmic reticulum-plasma membrane contact sites do not have major effects on sterol transfer, though phospholipid homeostasis is perturbed. Various ORPs confine at membrane contacts sites (MCS), where endoplasmic reticulum (ER) is apposed with other organelle limiting membranes. Yeast ORPs also participate in vesicular trafficking, in which they affect Sec14-dependent Golgi vesicle biogenesis and, later in post-Golgi exocytosis, they affect exocyst complex-dependent vesicle tethering to the plasma membrane. In mammalian cells, some ORPs function as sterol sensors that regulate the assembly of protein complexes in response to changes in cholesterol levels.
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Asticcacaulis biprosthecum is a stalked bacterial species phylogenetically closely related to the species Caulobacter crescentus. However, instead of a single polar organelle called the stalk, Asticcacaulis biprosthecum possesses two stalks that are laterally positioned along the cylindrical cell body. The ecological significance of this arrangement is unknown.
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A preproenzyme is an enzyme with two additional characteristics: "pre" refers to a signal sequence (signal peptide) which directs the enzyme to a specific organelle or subcellular localization; "pro" indicates that the enzyme is present in an inactive form and requires modification (e.g. cleavage) for activation.
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The authors reasoned this was due to the low rate of chromosomal rearrangements of sex chromosomes. Open chromatin regions are active regions. It is more likely that genes will be transferred to these regions. Genes from organelle and virus genome are inserted more often in these regions.
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Paulinella has a similar organelle which does not belong to the plastids discussed in this text. It is a chromatophore, which is a more recently acquired endosymbiotic β-Cyanobacteria. This endosymbiosis event occurred much more recent, and is only the second known primary endosymbiosis event of cyanobacteria.
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Ribosomes are sometimes referred to as organelles, but the use of the term organelle is often restricted to describing sub-cellular components that include a phospholipid membrane, which ribosomes, being entirely particulate, do not. For this reason, ribosomes may sometimes be described as "non-membranous organelles".
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Bee orchid is controlled by a specialized organelle in plant cells called a chromoplast. Chromoplasts are plastids, heterogeneous organelles responsible for pigment synthesis and storage in specific photosynthetic eukaryotes. It is thought that like all other plastids including chloroplasts and leucoplasts they are descended from symbiotic prokaryotes.
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This method seems to be most effective when applied to each cellular organelle separately. Mitochondrial proteins, for example, which are more effective at transporting electrons across its membrane, can be specifically targeted effectively in order to match their electron-transporting ability to their amino acid sequence.
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It is thought that it takes part in protein-protein interactions, but it is not known for certain. In some proteins, it also contributes to the localization of each protein to a membrane contact site (zone of close contact between the endoplasmic reticulum and a second organelle).
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Kinesin family member 6 is a protein that in humans is encoded by the KIF6 gene. This gene encodes a member of the kinesin family of proteins. Members of this family are part of a multisubunit complex that functions as a microtubule motor in intracellular organelle transport.
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Tachyzoites of Toxoplasma gondii, transmission electron microscopy. Rhoptries: ro (click to enlarge) A rhoptry is a specialized secretory organelle. They are club-shaped organelles connected by thin necks to the extreme apical pole of the parasite. These organelles, like micronemes, are characteristic of the motile stages of Apicomplexa protozoans.
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The first scientific publication about identification of the function of a hitherto unknown gene utilizing knockout moss appeared 1998 and was authored by Ralf Reski and coworkers. They deleted the ftsZ-gene and thus functionally identified the first gene pivotal for the division of an organelle in any eukaryote.
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The Rickettsiaceae are a family of bacteria. The genus Rickettsia is the most prominent genus within the family. From this family, the bacteria that eventually formed the mitochondrion (an organelle in eukaryotic cells) is believed to have originated. Most human pathogens in this family are in genus Rickettsia.
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In 1999, the structure of FimH was resolved via x-ray crystallography. FimH is folded into two domains. The N terminal adhesive domain plays the main role in surface recognition while the C-terminal domain is responsible for organelle integration. A tetra-peptide loop links the two domains.
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The rest of the aminoacids of the mature protein (584 AA) are distributed in this way: from AA 1 to 415 they are located at the lumen of the ER, from 416 to 434 are anchored at the membrane of the organelle, and the others in the cytoplasm.
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The Stieda body is an organelle located at the polar region of the sporocyst of some coccidia visible with electron microscopy. It appears as a knob like structure and is a plug occluding a hole in the sporocyst. The breakdown of this body allows excystation of the sporozoites.
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Like other agents of this class, it either slows or kills bacteria by inhibiting protein production. It kills malaria by targeting a plastid organelle, the apicoplast. Doxycycline was patented in 1957 and came into commercial use in 1967. It is on the World Health Organization's List of Essential Medicines.
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Plant cells with visible chloroplasts.The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle found in the cells of plants, algae, and some other eukaryotic organisms. They are considered endosymbiotic Cyanobacteria, related to the Gloeomargarita. The event to permanent endosymbiosis probably occurred with a cyanobiont.
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Under stress condition, the production of reactive oxygen species (ROS) increases, causing damages in the photosynthesis and the PCD. TOP enzymes mediate the response to this unfavorable condition. TOP1 regulates the importation of antioxidant enzymes to the chloroplast. These antioxidant enzymes reduce the ROS levels within the organelle.
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An isolate of Erythropsidinium. The arrow indicates the piston; the double arrowhead indicates the ocelloid. Scale bar 20 µm. A piston (also known as a dart, prod, or tentacle) is a complex contractile organelle found in some dinoflagellates, namely the Erythropsidinium and Greuetodinium genera of the family Warnowiaceae.
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This network of proteins participates not only in the initiation of attachment organelle formation and adhesion but also in motility. The P1 adhesin (trypsin-sensitive protein) is a 120 kDa protein highly clustered on the surface of the attachment organelle tip in virulent mycoplasmas. Both the presence of P1 and its concentration on the cell surface are required for the attachment of M. pneumoniae to the host cell. M. pneumoniae cells treated with monoclonal antibodies specific to the immunogenic C-terminus of the P1 adhesin have been shown to be inhibited in their ability to attach to the host cell surface by approximately 75%, suggesting P1 is a major component in adherence.
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The Apicomplexa, a phylum of obligate parasitic protozoa including the causative agents of malaria (Plasmodium spp.), toxoplasmosis (Toxoplasma gondii), and many other human or animal diseases also harbor a complex plastid (although this organelle has been lost in some apicomplexans, such as Cryptosporidium parvum, which causes cryptosporidiosis). The 'apicoplast' is no longer capable of photosynthesis, but is an essential organelle, and a promising target for antiparasitic drug development. Some dinoflagellates and sea slugs, in particular of the genus Elysia, take up algae as food and keep the plastid of the digested alga to profit from the photosynthesis; after a while, the plastids are also digested. This process is known as kleptoplasty, from the Greek, kleptes, thief.
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This gene encodes a protein with six coiled-coil domains. The protein is localized to the centrosome, a non-membraneous organelle that functions as the major microtubule-organizing center in animal cells. Recent computational analysis revealed pathogenic property of L61P point mutation in CEP63 protein that affected its native structural conformation.
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This can be done using machine learning approaches that can reach an accuracy at genus-level of about 80%. Other popular analysis packages provide support for taxonomic classification using exact matches to reference databases and should provide greater specificity, but poor sensitivity. Unclassified microorganism should be further checked for organelle sequences.
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170 px Pearson syndrome is a mitochondrial disease caused by a deletion in mitochondrial DNA (mtDNA). An mtDNA is genetic material contained in the cellular organelle called the mitochondria. Depending on the tissue type, each cell contains hundreds to thousands of mitochondria. There are 2–10 mtDNA molecules in each mitochondrion.
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The stalk will finish growing in several hours. The stalk is made up of the spasmoneme, a contractile organelle, with rigid rod filaments, batonnets, surrounding it. The coiled spasmoneme and batonnets serve as a molecular spring, so that Vorticella can contract. The cell body can move hundreds of micrometers in milliseconds.
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LACTB shares sequence similarity to the beta-lactamase/penicillin-binding protein family of serine proteases that are involved in bacterial cell wall metabolism. The N-terminal 97 amino acid segment of LACTB does not form part of the conserved penicillin-binding protein domain and may therefore be responsible for organelle targeting.
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This gene encodes a protein that belongs to the centrosome-associated family of proteins. The centrosome is a subcellular organelle in the animal cell that functions as a microtubule organizing center and is involved in cell-cycle progression. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Jul 2013].
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Uniparental inheritance refers to the fact that, in most organisms, many offspring inherit organelle genes from only one parent. However, this is not a general law. Many organisms that have the ability to differentiate maternal and paternal sexes will produce offspring with a mixture of maternal, paternal, and biparental mitochondrial DNA.
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The nucleolus forms around rDNA genes from different chromosomes. However, only a subset of rDNA genes is transcribed at a time and do so by looping into the interior of the nucleolus. The rest of the genes lay on the periphery of the sub-nuclear organelle in silenced heterochromatin state.
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Most of them – the glycolytic enzymes – are involved in the glycolytic pathway, i.e., the conversion of stored energy into muscle power. The two most abundant myofibrillar proteins, myosin and actin, are responsible for the muscle's overall structure. The remaining protein mass consists of connective tissue (collagen and elastin) as well as organelle tissue.
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Sagenista is a group of heterokonts containing the labyrinthulids and Eogyrea, a class of yet uncultured protists. Originally, it contained the Labyrinthulids and bicosoecids. However at present the bicosoecids have been removed, and Eogyrea were added, in order to make the group monophyletic. Some have a special organelle called a bothrosome (or sagenogenetosome).
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Importantly, the process in the organelle has no net ATP synthesis. This ATP comes later from processes outside of the glycosome. Inside of the glycosome does need NAD+ for functioning and its regeneration. Fructose 1,6-biphosphate is used in the glycosome as a way to help obtain oxidizing agents to help start glycolysis.
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Traditionally, they were thought to be cytoskeletal elements and to consist primarily of vimentin. However, more recent research suggested that that was incorrect and that they may be composed of lipids arranged into bilayer membranes. They were also once thought to be related to centrioles, an organelle involved in cell division in eukaryotes.
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This gene encodes a protein that may play a role in organelle biogenesis associated with melanosomes, platelet dense granules, and lysosomes. The encoded protein is part of the heterotetrameric AP-3 protein complex which interacts with the scaffolding protein clathrin. Mutations in this gene are associated with Hermansky–Pudlak syndrome type 2.
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That same year, Alex B. Novikoff from the University of Vermont visited de Duve's laboratory, and, using electron microscopy, successfully produced the first visual evidence of the lysosome organelle. Using a staining method for acid phosphatase, de Duve and Novikoff further confirmed the location of the hydrolytic enzymes (acid hydrolases) of lysosomes.
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These polymers may be administered in the liquid form through a macroscopic injection and solidify or gel in situ because of the difference in pH or temperature. Nanoparticle and liposome preparations are also routinely used for material encapsulation and delivery. A major advantage of liposomes is their ability to fuse to cell and organelle membranes.
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The cilium (;Mosby’s Medical, Nursing and Allied Health Dictionary, Fourth Edition, Mosby-Year Book Inc., 1994, p. 336 the plural is cilia) is an organelle found on eukaryotic cells in the shape of a slender protuberance that projects from the much larger cell body. There are two types of cilia: motile and non-motile cilia.
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Raphidophytes contain numerous ellipsoid chloroplasts, which contain chlorophylls a, c1 and c2. They also make use of accessory pigments including β-carotene and diadinoxanthin. Unlike other heterokontophytes, raphidophytes do not possess the photoreceptive organelle (or eyespot) typical of this group. In terms of ecology, raphidophytes occur as photosynthetic autotrophs across a range of aquatic systems.
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Pathogenicity of Mycoplasma pneumoniae in vasculitic/thrombotic disorders Mycoplasma pneumoniae parasitizes the respiratory tract epithelium of humans. Adherence to the respiratory epithelial cells is thought to occur via the attachment organelle, followed by evasion of host immune system by intracellular localization and adjustment of the cell membrane composition to mimic the host cell membrane.
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Hyphae grow at their tips. During tip growth, cell walls are extended by the external assembly and polymerization of cell wall components, and the internal production of new cell membrane. The spitzenkörper is an intracellular organelle associated with tip growth. It is composed of an aggregation of membrane-bound vesicles containing cell wall components.
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It provides the sensory component of the Golgi tendon reflex. The Golgi organ is not to be confused with the Golgi apparatus, which is an organelle in the eukaryotic cell, or the Golgi stain, which is a histologic stain for neuron cell bodies. All of these are named after the Italian physician Camillo Golgi.
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Photosynthetic eukaryotes originated following a primary endosymbiotic event, where a heterotrophic eukaryotic cell engulfed a photosynthetic cyanobacterium-like prokaryote that became stably integrated and eventually evolved into a membrane-bound organelle: the plastid. This primary endosymbiosis event gave rise to three autotrophic clades with primary plastids: the green plants, the red algae and the glaucophytes.
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MtDNA is DNA located in mitochondria, an organelle that is found in human cells. The mitochondria is maternally inherited by all persons, and analysis of the mtDNA can provide information about maternal ancestry. MtDNA genomes are classified into different haplogroups based on a shared common ancestor. These distinct haplogroups provide information about ancient migration patterns.
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The outer mitochondrial membrane, which encloses the entire organelle, is 60 to 75 angstroms (Å) thick. It has a protein-to-phospholipid ratio similar to that of the cell membrane (about 1:1 by weight). It contains large numbers of integral membrane proteins called porins. A major trafficking protein is the pore-forming voltage-dependent anion channel (VDAC).
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Some cationic drugs, such as chloroquine and sertraline, are known as lysosomotropic drugs. These drugs are weak bases that become protonated in the acidic environment of the lysosome. This traps the otherwise non- protonated compound within the lysosome, as protonation prevents its passage back across the lipid membrane of the organelle. This phenomenon is known as ion trapping.
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Centrosomal protein of 72 kDa is a protein that in humans is encoded by the CEP72 gene. The product of this gene is a member of the Leucine-rich repeat (LRR) superfamily of proteins. The protein is localized to the centrosome, a non-membraneous organelle that functions as the major microtubule-organizing center in animal cells.
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The 156 kb plastome gene map of Nicotiana tabacum. The 154 kb plastid genome map of a model flowering plant (Arabidopsis thaliana: Brassicaceae). The highly reduced, 27 kb plastome map of the parasitic Hydnora visseri. A plastome is the genome of a plastid, a type of organelle found in plants and in a variety of protoctists.
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Oldest known depiction of cells and their nuclei by Antonie van Leeuwenhoek, 1719 Drawing of a Chironomus salivary gland cell published by Walther Flemming in 1882. The nucleus contains polytene chromosomes. The nucleus was the first organelle to be discovered. What is most likely the oldest preserved drawing dates back to the early microscopist Antonie van Leeuwenhoek (1632–1723).
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Kinesin heavy chain isoform 5A is a protein that in humans is encoded by the KIF5A gene. This gene encodes a member of the kinesin family of proteins. Members of this family are part of a multisubunit complex that functions as a microtubule motor in intracellular organelle transport. Mutations in this gene cause autosomal dominant spastic paraplegia 10.
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Because of its ubiquitous expression, the intracellular localisation and function of VAPA may vary between cell types. It is however mainly located in the ER, Golgi apparatus and the Vesicular Tubular Compartment or ER-Golgi Intermediate Compartment, an organelle of eukaryotic cells consisting in fused ER-derived vesicles that transports proteins from the ER to the Golgi apparatus.
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The protein it encodes is an organelle intron maturase, a protein that splices Group II introns. It is essential for in vivo splicing of Group II introns. Amongst other maturases, this protein retains only a well conserved domain X and remnants of a reverse transcriptase domain. Universal matK primers can be used for DNA barcoding of angiosperms.
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The food vacuole, or digestive vacuole, is an organelle found in parasites that cause malaria. During the stage of the parasites' lifecycle where it resides within a human (or other mammalian) red blood cell, it is the site of haemoglobin digestion and the formation of the large haemozoin crystals that can be seen under a light microscope.
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Dipolomonads used to be defined as Fornicata, but their characteristics remain the same despite their renaming. They are microaerophilic protists. Diplomonads were previously defined by the lack of a mitochondria, but recent studies have found that they have a nonfunctional, mitochondrial remnant organelle called a mitosome. Most are harmless except for Giardia, Hexamita salmonis, and Histomonas meleagridis.
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16S and 23S rRNA is found only in prokaryotes by definition. Chloroplasts and mitochondria also replicate semi-autonomously outside of the cell cycle replication system via binary fission. Consistent with the theory, decreased genome size within the organelle and gene integration into the nucleus occurred. Chloroplasts genomes encode 50-200 proteins, compared to the thousands in cyanobacterium.
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It is a regularly updated online resource that contains >13,000 entries from ~1,000 distinct references. Examples of data include transcription and translation rates, organism and organelle sizes, metabolites concentrations and growth rates. Entries are provided with full reference and details such as measurement method and comments. BioNumbers also publishes a monthly review of a problem in quantitative biology.
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Oxymonas have two pairs of flagella which originate from pairs of basal bodies, which are located at the base of the rostellum. These basal body pairs are connected to the preaxostyle, which is a paracrystalline structure. In addition to the preaxostyle, there is an axostyle. This organelle moves the Oxymonas by undulating and changing shape in a sinusoidal fashion.
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Most living things that are visible to the naked eye in their adult form are eukaryotes, including humans. However, many eukaryotes are also microorganisms. Unlike bacteria and archaea, eukaryotes contain organelles such as the cell nucleus, the Golgi apparatus and mitochondria in their cells. The nucleus is an organelle that houses the DNA that makes up a cell's genome.
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Lysosomes also use their hydrolytic enzymes to recycle the cell's obsolete organelles in a process called autophagy. The lysosome engulfs another organelle and uses its enzymes to take apart the ingested material. The resulting organic monomers are then returned to the cytosol for reuse. The last function of a lysosome is to digest the cell itself through autolysis.
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Cross-section of a centriole showing its microtubule triplets. In cell biology a centriole is a cylindrical organelle composed mainly of a protein called tubulin. Centrioles are found in most eukaryotic cells. A bound pair of centrioles, surrounded by a highly ordered mass of dense material, called the pericentriolar material (PCM), makes up a structure called a centrosome.
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Starch is stored in the amyloplasts, a specialized organelle found within plant cells, as starch grains. The starch grain is specifically important for study due to the fact that it is commonly found in most plants, its long-lasting nature, as well as the diverse forms and structures that they can take based on which taxa they belong to.
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There has been a variety of evidence found biochemically to give evidence that glycosomes are present in cells. In the organelle that is assumed to be a glycosome, numerous proteins are found. These include glycogen synthase, phosphorylase, and branching and debranching enzymes for glycogen. All of these are regulatory enzymes that are needed in glycogen synthesis.
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The main tissues that make up an organ tend to have common embryologic origins, such as arising from the same germ layer. Functionally related organs often cooperate to form whole organ systems. Organs exist in most multicellular organisms. In single-celled organisms such as bacteria, the functional analogue of an organ is known as an organelle.
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Purines, however, are first synthesized from the sugar template onto which the ring synthesis occurs. For reference, the syntheses of the purine and pyrimidine nucleotides are carried out by several enzymes in the cytoplasm of the cell, not within a specific organelle. Nucleotides undergo breakdown such that useful parts can be reused in synthesis reactions to create new nucleotides.
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If all genes disappear from the primary subset, CoRR predicts that there is no function for genes in the secondary subset, and such organelles will then, eventually, lose their genomes completely. However, if even only one gene remains under redox control, then an organelle genetic system is required for the synthesis of its single gene product.
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A nematocyst is a subcellular structure or organelle containing extrusive filaments found in two families of athecate dinoflagellates (a group of unicellular eukaryotes), the Warnowiaceae and Polykrikaceae. It is distinct from the similar subcellular structures found in the cnidocyte cells of cnidarians, a group of multicellular organisms including jellyfish and corals; such structures are also often called nematocysts (alternatively, cnidocysts or cnidae), and cnidocytes are sometimes referred to as nematocytes. It is unclear whether the relationship between dinoflagellate and cnidarian nematocysts is a case of convergent evolution or common descent, although molecular evidence has been interpreted as supporting an endosymbiotic origin for cnidarian nematocysts. In polykrikoids the nematocyst is found associated with another extrusive organelle called the taeniocyst, a complex that has been described as synapomorphic for the genus Polykrikos.
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The number of mitochondria in a cell can vary widely by organism, tissue, and cell type. For instance, red blood cells have no mitochondria, whereas liver cells can have more than 2000. The organelle is composed of compartments that carry out specialized functions. These compartments or regions include the outer membrane, the intermembrane space, the inner membrane, and the cristae and matrix.
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The time delay involved in signalling the nucleus and transporting a cytosolic protein to the organelle results in the production of damaging reactive oxygen species. The final hypothesis states that the assembly of membrane proteins, particularly those involved in redox reactions, requires coordinated synthesis and assembly of subunits; however, translation and protein transport coordination is more difficult to control in the cytoplasm.
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Peripheral vesicles are responsible both for taking up extracellular nutrients, and expelling waste outside the cell. Each cell also contains a pair of rigid structures called median bodies which make up part of the G. lamblia cytoskeleton. Trophozoites adhere to host epithelial cells via a specialized disk-shaped organelle called the ventral disk. Cysts are oval-shaped cells slightly smaller than trophozoites.
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Receptor desensitization is mediated through a combination phosphorylation, β-arr binding, and endocytosis as described above. Downregulation occurs when endocytosed receptor is embedded in an endosome that is trafficked to merge with an organelle called a lysosome. Because lysosomal membranes are rich in proton pumps, their interiors have low pH (≈4.8 vs. the pH≈7.2 cytosol), which acts to denature the GPCRs.
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Chloroplasts are a special type of a plant cell organelle called a plastid, though the two terms are sometimes used interchangeably. There are many other types of plastids, which carry out various functions. All chloroplasts in a plant are descended from undifferentiated proplastids found in the zygote, or fertilized egg. Proplastids are commonly found in an adult plant's apical meristems.
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Proteasome endopeptidase complex (, ingensin, macropain, multicatalytic endopeptidase complex, prosome, multicatalytic proteinase (complex), MCP, proteasome, large multicatalytic protease, proteasome organelle, alkaline protease, 26S protease, tricorn proteinase, tricorn protease) is an enzyme. This enzyme catalyses the following chemical reaction : Cleavage of peptide bonds with very broad specificity This 20-S protein is composed of 28 subunits arranged in four rings of seven.
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PMID 18558658 Silene flowers are frequently visited by flies, such as Rhingia campestris. Silene species have also been used to study speciation, host-pathogen interactions, biological species invasions, adaptation to heavy-metal-contaminated soils, metapopulation genetics, and organelle genome evolution. Notably, some members of the genus Silene hold the distinction of harboring the largest mitochondrial genomes ever identified.Sloan DB et al. 2012.
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The two met at Central Park in New York City to discuss their results. In 1955, now confident that the membranous particles were cell organelles, de Duve gave a hypothetical name "lysosomes" to reflect their digestive properties. That same year, after visiting de Duve's laboratory, using his own histochemical protocol Novikoff successfully produced the first real images (electron micrographs) of the new organelle.
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Nucleolar protein 6 is a protein that in humans is encoded by the NOL6 gene. The nucleolus is a dense subnuclear membraneless organelle that assembles around clusters of rRNA genes and functions in ribosome biogenesis. This gene encodes a nucleolar RNA-associated protein that is highly conserved between species. RNase treatment of permeabilized cells indicates that the nucleolar localization is RNA dependent.
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Although uniparental inheritance is the most common form of inheritance in organelles, there is increased evidence of diversity. Some studies found doubly uniparental inheritance (DUI) and biparental transmission to exist in cells. Evidence suggests that even when there is biparental inheritance, crossing- over doesn't always occur. Furthermore, there is evidence that the form of organelle inheritance varied frequently over time.
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S. roeselii is found in still or slow-moving bodies of water, where it feeds on bacteria, flagellates, algae, and other ciliates. When feeding, the cell is fixed in place (sessile), attached by a posterior "holdfast" organelle to a firm surface such as plant stem or submerged detritus. Attached specimens are trumpet-shaped, and very contractile. When swimming freely, cells are compactly ovoid.
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Minteer worked at Saint Louis University for eleven years before joining the University of Utah in 2011. She studies the interface between biocatalysts and electrode surfaces for bioelectrocatalysis. She works on enzyme cascades for bioelectrocatalysis as well as organelle bioelectrocatalysis for detection of microscopic events. She also works on the production of biofuels, using synthetic biology and nanotechnology to improve the production.
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Clathrin-coated vesicles bud from immature Weibel–Palade bodies, reducing their volumes, condensing their contents, and removing select membrane proteins. Maturing Weibel–Palade bodies may also fuse with each other. The only parallel organelle in physiology is the alpha granule of platelets, which also contains vWF. Weibel–Palade bodies are the main source of vWF, while α-granules probably play a minor role.
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Post-translational modifications occurring at the N-terminus of the amino acid chain play an important role in translocation across biological membranes. These include secretory proteins in prokaryotes and eukaryotes and also proteins that are intended to be incorporated in various cellular and organelle membranes such as lysosomes, chloroplast, mitochondria and plasma membrane. Expression of posttranslated proteins is important in several diseases.
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Edouard Van Beneden made the first observation of centrosomes (which are composed of two orthogonal centrioles) in 1883. In 1895, Theodor Boveri named the organelle a "centrosome".Boveri, T. Ueber das Verhalten der Centrosomen bei der Befruchtung des Seeigel-Eies nebst allgemeinen Bemerkungen über Centrosomen und Verwandtes. Verh. d. Phys.-Med. Ges. zu Würzburg, N. F., Bd. XXIX, 1895. link.
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The BCKD enzyme complex catalyzes one step in breaking down amino acids. Those amino acids being leucine, isoleucine, and valine. The BCKD enzyme complex can be found in the mitochondria, an organelle known as the powerhouse of the cell. All three amino acids can be found in protein-rich foods and when broken down, they can be used for energy.
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Centrosome-associated protein 350 is a protein that in humans is encoded by the CEP350 gene. CEP350 is a large protein with a CAP-Gly domain typically found in cytoskeleton-associated proteins. It primarily localizes to the centrosome, a non-membraneous organelle that functions as the major microtubule-organizing center in animal cells. CEP350 is required to anchor microtubules at the centrosome.
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The exclusion of certain lipids in particular regions drive to processes such as membrane binding or signaling. 3-They work as lipid sensors altering interactions with other proteins due to binding or releasing lipid ligands. It occurs mainly at inally organelle contact sites. 4-The access of other lipid-binding proteins to the membrane is regulated by ORPs in two ways.
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Polka discovered that carboxysome, a protein organelle in cyanobacteria, grows like a crystal until it is coated by a layer of shell proteins. Negatively stained electron micrograph of purified R bodies in their extended (low pH) state, taken by Polka. Polka was co-chair of the American Society for Cell Biology's COMPASS (Committee for Postdocs and Students) during 2013 and 2014.
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Although non- motile or primary cilia were first described in 1898, they were largely ignored by biologists. However, microscopists continued to document their presence in the cells of most vertebrate organisms. The primary cilium was long considered—with few exceptions—to be a largely useless evolutionary vestige, a vestigial organelle. Recent research has revealed that cilia are essential to many of the body's organs.
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Crystallization of DECR with 2,4 Hexadienoyl-CoA and NADPH (not shown). Key residues in the enzyme active site orient the substrate for hydride transfer through a network of hydrogen bonds. Eukaryotic DECR exists in both the mitochondria (mDECR) and the peroxisome (pDECR, coded by gene DECR2). The enzymes from each organelle are homologous and part of the short-chain dehydrogenase/reductase SDR super-family.
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Cavalier-Smith was born on 21 October 1942 in London. His parents were Alan Hailes Spencer and Mary Maude Cavalier-Smith. He was educated at Norwich School, Gonville and Caius College, Cambridge (MA) and King's College London (PhD). He was under the supervision of Sir John Randall for his PhD thesis between 1964 and 1967; his thesis was entitled "Organelle Development in Chlamydomonas reinhardii".
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In fact, the presence of oxygen over 2 μM inhibits the anammox pathway, which is why members of the proposed genus Scalindua respire anaerobically. These reactions occur in a large membrane-bound cellular organelle called the anammoxosome, which contains an electron transport chain and an ATPase that pumps protons back into the cytoplasm from the anammoxosome lumen. It functions much like a mitochondrion in eukaryotic cells.
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There are two fundamental classifications of cells: prokaryotic and eukaryotic. Prokaryotic cells are distinguished from eukaryotic cells by the absence of a cell nucleus or other membrane bound organelle. Prokaryotic cells are much smaller than eukaryotic cells, making them the smallest form of life. The study of eukaryotic cells is typically the main focus of cytologists, whereas prokaryotic cells are the focus of microbiologists.
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Ribosomes, the organelle for protein translation takes place, are made out of rRNA and proteins. Ribosomes may be the best and most abundant example of nucleic acid quaternary structure. The specifics of ribosome structure varies among different kingdoms and species, but all ribosomes are made of a large subunit and a small unit. Different classes of organisms have ribosomal subunits of different characteristic sizes.
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Nuclear rotation implicated in cellular reorganization before mitosis in mouse breast cancer cells. The nucleus is the largest organelle in animal cells. In mammalian cells, the average diameter of the nucleus is approximately 6 micrometres (µm), which occupies about 10% of the total cell volume. The contents of the nucleus are held in the nucleoplasm similar to the cytoplasm in the rest of the cell.
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The extracellular domain just externally from the cell or organelle. If the polypeptide chain crosses the bilayer several times, the external domain comprises loops entwined through the membrane. By definition, a receptor's main function is to recognize and respond to a type of ligand. For example, a neurotransmitter, hormone, or atomic ions may each bind to the extracellular domain as a ligand coupled to receptor.
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Rhodopsin transport in the membrane of the connecting cilium of mammalian photoreceptor cells. Cell Motility and the Cytoskeleton, 46(2), 95–107. Although the primary cilium was discovered in 1898, it was largely ignored for a century and considered a vestigial organelle without important function. Recent findings regarding its physiological roles in chemosensation, signal transduction, and cell growth control, have revealed its importance in cell function.
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The designation of CPVL is a true serine carboxypeptidase. Although the primary sequence displays the expected serine carboxypeptidase active site, the enzymatic activity remains to be demonstrated. The primary sequence of CPVL contains a putative signal sequence, four potential N-linked glycosylation sites and four myristoylation sites, but no transmembrane domain, suggesting that it may be luminal in an organelle and/or involved in the secretory pathway.
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While most eukaryotes contain 10 or so copies of the dynamins required for pinching membranes to separate dividing compartments, C. merolae only contains two, a fact that researchers have taken advantage of when studying organelle division. Although possessing a small genome, the chloroplast genome of C. merolae contains many genes not present in the chloroplast genomes of other algae and plants. Most of its genes are intronless.
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Organelle movement is facilitated through the cytoskeleton, which consists of actin and microtubules. Organelles are attached to the microtubules of the cytoskeleton and movement is due to the sliding of microtubules along each other in both directions. This giant freshwater foraminferan contains many haploid nuclei, approximately 5 μm in diameter. Small section of the Reticulopodial Network of Reticulomyxa filosa: Fine reticulopods alter with small Lamellipodial sections.
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Numerous genes considered essential for life seem to be missing, suggesting that the species may have achieved organelle-like status. At the time of its sequencing, C. ruddii was thought to have the smallest genome of any characterized bacterial species. Nasuia deltocephalinicola is now considered to have the known smallest bacterial genome (112kb). C. ruddii and related species appear to be actively undergoing gene loss.
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LOV domains have been found to control gene expression through DNA binding and to be involved in redox-dependent regulation, like e.g. in the bacterium Rhodobacter sphaeroides. Notably, LOV- based optogenetic tools have been gaining wide popularity in recent years to control a myriad of cellular events, including cell motility, subcellular organelle distribution, formation of membrane contact sites, microtubule dynamics, transcription, and protein degradation.
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The best characterized bacterial adhesin is the type 1 fimbrial FimH adhesin. This adhesin is responsible for D-mannose sensitive adhesion. The bacterium synthesizes a precursor protein consisting of 300 amino acids then processes the protein by removing several signal peptides ultimately leaving a 279 amino acid protein. Mature FimH is displayed on the bacterial surface as a component of the type 1 fimbrial organelle.
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The bacteria are released as injection drops into the host root nodule cells where the plasma membrane encloses them in the organelle-like structure of the symbiosome. In most plants a symbiosome encloses a single endosymbiont bacterium but some types may contain more than one. A negative feedback loop called the autoregulation of nodulation works to balance the need for nitrogen and thus the formation of nodules.
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An ejectosome is a cellular organelle responsible for ejecting their contents from the cell. Two unrelated types of ejectosomes are described in the literature: # Cryptomonads have two types of characteristic ejectosomes known as extrusomes. # Intracellular pathogens, such as Mycobacterium tuberculosis, escape from their host cells using an actin-based structure, also called an ejectosome. Cryptomonad ejectosomes contain two connected spiral ribbon-like structures, held under tension.
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Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds, or joined together to form macromolecules. This process often consists of metabolic pathways. Some of these biosynthetic pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles.
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In 1970, Günter Blobel conducted experiments on the translocation of proteins across membranes. He was awarded the 1999 Nobel prize for his findings. He discovered that many proteins have a signal sequence, that is, a short amino acid sequence at one end that functions like a postal code for the target organelle. The translation of mRNA into protein by a ribosome takes place within the cytosol.
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An overview of endosymbiosis. Symbiogenesis explains the origins of eukaryotes, whose cells contain two major kinds of organelle: mitochondria and chloroplasts. The theory proposes that these organelles evolved from certain types of bacteria that eukaryotic cells engulfed through phagocytosis. These cells and the bacteria trapped inside them entered an endosymbiotic relationship, meaning that the bacteria took up residence and began living exclusively within the eukaryotic cells.
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Lysosomes are organelles that contain hydrolytic enzymes that are used for intracellular digestion. The main functions of a lysosome are to process molecules taken in by the cell and to recycle worn out cell parts. The enzymes inside of lysosomes are acid hydrolases which require an acidic environment for optimal performance. Lysosomes provide such an environment by maintaining a pH of 5.0 inside of the organelle.
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The initiation of synthesis of glycogen requires glycogenin, found in glycosomes, a protein primer. Glycogen synthase as mentioned helps in glycogen elongation and the removal of the glucose from glycogen is aided by debranching enzymes and phosphorylase. All of these enzymes are found in the glycosome, showing that this organelle complete with glycogen as well is responsible for storing glycogen and separate from the cytosol.
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In fact, DNA analysis of these two types of domains have shown that many sequences overlap, indicating that certain regions may switch between lamina-binding and nucleolus-binding. NADs are associated with nucleolus function. The nucleolus is the largest sub-organelle within the nucleus and is the principal site for rRNA transcription. It also acts in signal recognition particle biosynthesis, protein sequestration, and viral replication.
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Early on, STED was thought to be a useful technique for working with living cells. Unfortunately, the only way for cells to be studied was to label the plasma membrane with organic dyes. Combining STED with fluorescence correlation spectroscopy showed that cholesterol- mediated molecular complexes trap sphingolipids, but only transiently. However, only fluorescent proteins provide the ability to visualize any organelle or protein in a living cell.
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The principal cytoplasmic proteins are myosin and actin (also known as "thick" and "thin" filaments, respectively) which are arranged in a repeating unit called a sarcomere. The interaction of myosin and actin is responsible for muscle contraction. Every single organelle and macromolecule of a muscle fiber is arranged to ensure form meets function. The cell membrane is called the sarcolemma with the cytoplasm known as the sarcoplasm.
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It is not uncommon for drugs to damage muscle fibers. Particular families of drugs are known to induce myopathies on the molecular level, thus altering organelle function such as the mitochondria. Use of multiple drugs from these families in conjunction with one another can increase the risk of developing a myopathy. Many of the drugs associated with inducing myopathies in patients are found in rheumatology practice.
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Sulfatases are found in lower and higher organisms. In higher organisms they are found in intracellular and extracellular spaces. Steroid sulfatase is distributed in a wide range of tissues throughout the body, enabling sulfated steroids synthesized in the adrenals and gonads to be desulfated following distribution through the circulation system. Many sulfatases are localized in the lysosome, an acidic digestive organelle found within the cell.
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A mitosome is an organelle found in some unicellular eukaryotic organisms, like in members of the supergroup Excavata. The mitosome was found and named in 1999, and its function has not yet been well characterized. It was termed a crypton by one group, but that name is no longer in use. The mitosome has been detected only in anaerobic or microaerophilic organisms that do not have mitochondria.
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During periods of rapid growth and aging, trout display high levels of metabolic activity. High metabolic activity has been correlated with increased levels of oxidative stress and decreased machinery repair in rainbow trout. During high oxidative stress, the mitochondria are the most important organelle contributing to tissue damage because of their role in metabolism and production of reactive oxygen species. In a study done by Almaida-Pagàn et al.
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Viral mRNAs and proteins are produced and the virions or complete viral particles gather in the cytoplasm of the cell. A retrieval signal from the cell's endoplasmic reticulum brings Env from the virion to the organelle. Without Env and GAG proteins, there is no foamy virus budding that occurs. Before budding occurs, later reverse transcription can take place, which results in 20% of the virions containing infectious DNA.
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The loss of autonomy and integration of the endosymbiont with its host can be primarily attributed to nuclear gene transfer. As organelle genomes have been greatly reduced over evolutionary time, nuclear genes have expanded and become more complex. As a result, many plastid and mitochondrial processes are driven by nuclear encoded gene products. In addition, many nuclear genes originating from endosymbionts have acquired novel functions unrelated to their organelles.
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Diagram of endomembrane system in eukaryotic cell Modern eukaryotic cells use the endomembrane system to transport products and wastes in, within, and out of cells. The membrane of nuclear envelope and endomembrane vesicles are composed of similar membrane proteins. These vesicles also share similar membrane proteins with the organelle they originated from or are traveling towards. This suggests that what formed the nuclear membrane also formed the endomembrane system.
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In enterobacterium; Serratia sp. strain ATCC39006, gas vesicle is produced only when there is sufficient concentration of a signalling molecule, N-acyl homoserine lactone. In this case, the quorum sensing molecule, N-acyl homoserine lactone acts as a morphogen initiating organelle development. This is advantageous to the organism as resources for gas vesicle production are utilized only when there is oxygen limitation caused by an increase in bacterial population.
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Hermansky–Pudlak syndrome 5 protein is a protein that in humans is encoded by the HPS5 gene. This gene encodes a protein that may play a role in organelle biogenesis associated with melanosomes, platelet dense granules, and lysosomes. This protein interacts with Hermansky–Pudlak syndrome 6 protein and may interact with the cytoplasmic domain of integrin, alpha-3. Mutations in this gene are associated with Hermansky–Pudlak syndrome type 5.
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The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ALD subfamily, which is involved in peroxisomal import of fatty acids and/or fatty acyl-CoAs in the organelle.
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As a result any changes observed after a stimulus is applied can be statistically correlated and it could be decided if these changes are reactions to the stimulus or just merely coincidental. In this moment BY-2 cells are relatively well understood and often used in research. This model plant system is especially useful for studies of cell division, cytoskeletons, plant hormone signaling, intracellular trafficking, and organelle differentiation.
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INPP5E is a phosphatidylinositol (3,4,5)-trisphosphate (PtdInsP3) and phosphatidylinositol 4,5-bisphosphate 5-phosphatase. Its intracellular localization is the primary cilium, a small organelle involved in signal transduction. INPP5E plays a role in hydrolyzing PtdInsP3 produced in response to various growth factors such as PDGF. Inactivation of the mouse INPP5E gene decreases primary cilia stability, leading to a multiorgan disorder, including absence of eyes, polydactyly, exencephaly and renal cysts.
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Although it is not well characterized, selection can occur for organelle genomes in heteroplasmic cells. Intracellular ("within cells") selection occurs within individual cells. It refers to the selective segregation of certain genotypes in mitochondrial DNA that allows the favoured genotype to thrive. Intercellular ("between cells") selection occurs on a larger scale, and refers to the preferential growth of cells that have greater numbers of a certain mitochondrial genotype.
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HSAN ID is caused by heterozygous missense mutations in the ATL1 gene which encodes atlastin-1. Atlastin-1 is a member of the dynamin/Mx/guanylate-binding protein superfamily of large GTPases. The enzyme contains an endoplasmic reticulum (ER) retention moiety, indicating that it functions predominantly in the organelle. It is highly expressed in the mammalian central nervous system and is enriched in the hippocampus and pyramidal neurons.
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A rare form of phagocytosis known as coiling phagocytosis has been described for L. pneumophila, but this is not dependent on the Dot/Icm (intracellular multiplication/defect in organelle trafficking genes) bacterial secretion system and has been observed for other pathogens. Once internalized, the bacteria surround themselves in a membrane-bound vacuole that does not fuse with lysosomes that would otherwise degrade the bacteria. In this protected compartment, the bacteria multiply.
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Microtubules have a major structural role in eukaryotic cilia and flagella. Cilia and flagella always extend directly from a MTOC, in this case termed the basal body. The action of the dynein motor proteins on the various microtubule strands that run along a cilium or flagellum allows the organelle to bend and generate force for swimming, moving extracellular material, and other roles. Prokaryotes possess tubulin-like proteins including FtsZ.
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When a symbiont reaches this stage, it begins to resemble a cellular organelle, similar to mitochondria or chloroplasts. Many instances of endosymbiosis are obligate; that is, either the endosymbiont or the host cannot survive without the other, such as the gutless marine worms of the genus Riftia, which get nutrition from their endosymbiotic bacteria. The most common examples of obligate endosymbioses are mitochondria and chloroplasts. Some human parasites, e.g.
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Wuchereria bancrofti and Mansonella perstans, thrive in their intermediate insect hosts because of an obligate endosymbiosis with Wolbachia spp. They can both be eliminated from said hosts by treatments that target this bacterium. However, not all endosymbioses are obligate and some endosymbioses can be harmful to either of the organisms involved. Two major types of organelle in eukaryotic cells, mitochondria and plastids such as chloroplasts, are considered to be bacterial endosymbionts.
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Archaea are prokaryotic unicellular organisms, and form the first domain of life, in Carl Woese's three-domain system. A prokaryote is defined as having no cell nucleus or other membrane bound-organelle. Archaea share this defining feature with the bacteria with which they were once grouped. In 1990 the microbiologist Woese proposed the three-domain system that divided living things into bacteria, archaea and eukaryotes, and thereby split the prokaryote domain.
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Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. Numerous circular vesicles can be seen in proximity to the organelle The Golgi apparatus (also known as the Golgi body and the Golgi complex) is composed of separate sacs called cisternae. Its shape is similar to a stack of pancakes. The number of these stacks varies with the specific function of the cell.
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The proteins imported into the organelle have a specific sequence, a PTS1 ending sequence to make sure they go to the right place. They are similar to alpha- granules in the cytosol of a cell that are filled with glycogen. Glycosomes are typically round-to-oval shape with size varying in each cell. Although glycogen is found in the cytoplasm, that in the glycosome is separate, surrounded by membrane.
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It has 3 cofactors: iron, Sulfur, and Nickel. Ferredoxin hydrogenase found in the green algae Chlamydomonas reinhardtii use supplied electrons from photosystem I to reduce protons into hydrogen gas. This electron supply transfer is possible through photosystem I interactions with photosynthetic electron transfer ferredoxin (PetF). The inter-conversion of protons and electrons with hydrogen gas allow organisms to modulate energy input and output, adjust organelle redox potential, and transduce chemical signals.
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A simplified illustration of energy production in a mitochondrion. The third major proposed cause of cell death in Parkinson's disease involves the energy- generating mitochondrion organelle. In Parkinson's disease, mitochondrial function is disrupted, inhibiting energy production and resulting in death. The mechanism behind mitochondrial dysfunction in Parkinson's disease is hypothesized to be the PINK1 and Parkin complex, having been shown to drive autophagy of mitochondria (also known as mitophagy).
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The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ALD subfamily, which is involved in peroxisomal import of fatty acids and/or fatty acyl-CoAs in the organelle.
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In molecular biology, Duffy binding proteins are found in plasmodia. Plasmodium vivax and Plasmodium knowlesi merozoites invade Homo sapiens erythrocytes that express Duffy blood group surface determinants. The Duffy receptor family is localised in micronemes, an organelle found in all organisms of the phylum Apicomplexa. The presence of duffy-binding-like domains defines the family of erythrocyte binding-like proteins (EBL), a family of cell invasion proteins universal among Plasmodium.
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The membrane bilayer is not always flat. Local curvature of the membrane can be caused by the asymmetry and non-bilayer organization of lipids as discussed above. More dramatic and functional curvature is achieved through BAR domains, which bind to phosphatidylinositol on the membrane surface, assisting in vesicle formation, organelle formation and cell division. Curvature development is in constant flux and contributes to the dynamic nature of biological membranes.
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In filamentous fungi, peroxisomes move on microtubules by 'hitchhiking,' a process involving contact with rapidly moving early endosomes. Physical contact between organelles is often mediated by membrane contact sites, where membranes of two organelles are physically tethered to enable rapid transfer of small molecules, enable organelle communication and are crucial for coordination of cellular functions and hence human health. Alterations of membrane contacts have been observed in various diseases.
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The N-terminus is the first part of the protein that exits the ribosome during protein biosynthesis. It often contains signal peptide sequences, "intracellular postal codes" that direct delivery of the protein to the proper organelle. The signal peptide is typically removed at the destination by a signal peptidase. The N-terminal amino acid of a protein is an important determinant of its half-life (likelihood of being degraded).
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Paramecium tetraurelia, a ciliate, with discharged trichocysts (artificially colored in blue). A trichocyst is an organelle found in certain ciliates and dinoflagellates. A trichocyst can be found in tetrahymena and along cila pathways of several metabolic systems. It is also a structure in the cortex of certain ciliate and flagellate protozoans consisting of a cavity and long, thin threads that can be ejected in response to certain stimuli.
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Amazingly, hydrazine ( – rocket fuel) is produced as an intermediate during anammox metabolism. To deal with the high toxicity of hydrazine, anammox bacteria contain a hydrazine-containing intracellular organelle called the anammoxasome, surrounded by highly compact (and unusual) ladderane lipid membrane. These lipids are unique in nature, as is the use of hydrazine as a metabolic intermediate. Anammox organisms are autotrophs although the mechanism for carbon dioxide fixation is unclear.
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Modeling the processes involved in converting sunlight into chemical energy meant representing 100 million atoms, 16,000 lipids, and 101 proteins, the contents of a tiny sphere-shaped organelle occupying just one percent of the cell's total volume. The team used the Titan supercomputer at the Oak Ridge National Laboratory in Tennessee. At his death Schulten was already planning simulations for the exa-scale Summit computer, expected to be built by 2018.
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Eukaryotic undulipodium. 1-axoneme, 2-cell membrane, 3-IFT (intraflagellar transport), 4-basal body, 5-cross section of axoneme, 6-triplets of microtubules of basal body. An undulipodium (a Greek word meaning "swinging foot") or a 9+2 organelle is a motile filamentous extracellular projection of eukaryotic cells. It is basically synonymous to flagella and cilia which are differing terms for similar molecular structures used on different types of cells.
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This arginine-hydroxylase is involved in the assembly of mitochondrial NADH:ubiquinone oxidoreductase complex (complex I, MT-ND1) at early stages. Complex I is composed of 45 evolutionally conserved core subunits, including both mitochondrial DNA and nuclear encoded subunits. One of its arms is embedded in the inner membrane of the mitochondria, and the other is embedded in the organelle. The two arms are arranged in an L-shaped manner.
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Furthermore, these over-expressing mice show no decrease in age-dependent number of pups per litter. Overexpression of catalase targeted to mitochondria extends the lifespan of mice. Catalase is usually located in a cellular organelle called the peroxisome. Peroxisomes in plant cells are involved in photorespiration (the use of oxygen and production of carbon dioxide) and symbiotic nitrogen fixation (the breaking apart of diatomic nitrogen (N2) to reactive nitrogen atoms).
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Although SP-deficient mature mice both lack the spine apparatus and display impaired LTP, the relationship between SP, the spine apparatus, and plasticity is complicated by the following three findings: (1) In addition to being associated with the spine apparatus, SP is also located in the cisternal organelle, which is structurally similar to the spine apparatus. (2) The spine apparatus is generally found in mushroom spines of mature neurons, but ample levels of SP and expression of LTP have been detected in juvenile rats just 15 days old. (3) Unlike SP, the spine apparatus has not been found in cultured neurons. These findings have led some to the conclusion that the spine apparatus is implicated in plasticity only because this organelle is associated with SP. Direct evidence for an essential function of the spine apparatus in mGluR-dependent long-term depression (LTD) has been provided by comparing plasticity of synapses on spines with or without spine apparatus.
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The MAM is a critical signaling, metabolic, and trafficking hub in the cell that allows for the integration of ER and mitochondrial physiology. Coupling between these organelles is not simply structural but functional as well and critical for overall cellular physiology and homeostasis. The MAM thus offers a perspective on mitochondria that diverges from the traditional view of this organelle as a static, isolated unit appropriated for its metabolic capacity by the cell.Csordás et al.
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Oil Bodies are the organelle that has evolved to hold triglycerides in plant cells. They are therefore the principal store of chemical energy in oleaginous seeds. The structure and composition of plant seed oil bodies has been the subject of research from at least as far back as the 1980s, with several papers published in the 80s and 90s. Recent work, using updated techniques, has given a detailed molecular profile of oil bodies.
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The mechanisms of gene transfer are not fully known; however, multiple hypotheses exist to explain this phenomenon. The cDNA hypothesis involves the use of messenger RNA (mRNAs) to transport genes from organelles to the nucleus where they are converted to cDNA and incorporated into the genome. The cDNA hypothesis is based on studies of the genomes of flowering plants. Protein coding RNAs in mitochondria are spliced and edited using organelle-specific splice and editing sites.
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A chloroplast is a type of organelle known as a plastid, characterized by its two membranes and a high concentration of chlorophyll. Other plastid types, such as the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photosynthesis. Chloroplasts are highly dynamic—they circulate and are moved around within plant cells, and occasionally pinch in two to reproduce. Their behavior is strongly influenced by environmental factors like light color and intensity.
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Miro functions to tether the complex to the mitochondrion while the complex transports the mitochondrion via microtubules within cells. Though Miro has been predominantly studied in neurons, the protein has also been observed to participate in the transport of mitochondria in lymphocytes toward inflamed endothelia. The motor/adaptor complex is regulated by calcium ion levels. At high concentrations, calcium ions arrest mitochondrial transport by binding Miro, causing the complex to detach from the organelle.
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The vault or vault cytoplasmic ribonucleoprotein is a eukaryotic organelle whose function is not fully understood. Discovered and isolated by Nancy Kedersha and Leonard Rome in 1986, vaults are cytoplasmic organelles which when negative-stained and viewed under an electron microscope resemble the arches of a cathedral vaulted ceiling, with 39-fold (Or D39d) symmetry. They are present in many types of eukaryotic cells and appear to be highly conserved amongst eukaryotes.
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In plants, ABC transporters are often found within cell and organelle membranes, such as the mitochondria, chloroplast, and plasma membrane. There is evidence to support that plant ABC transporters play a direct role in pathogen response, phytohormone transport, and detoxification. Furthermore, certain plant ABC transporters may function in actively exporting volatile compounds and antimicrobial metabolites. In petunia flowers (Petunia hybrida), the ABC transporter PhABCG1 is involved in the active transport of volatile organic compounds.
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In prokaryotes, nonviral extrachromosomal DNA are primarily found in plasmids whereas in eukaryotes extrachromosomal DNA are primarily found in organelles. Mitochondrial DNA are a main source of this extrachromosomal DNA in eukaryotes. The fact that this organelle contains its own DNA supports the hypothesis that mitochondria originated as bacterial cells engulfed by ancestral eukaryotic cells. Extrachromosomal DNA are often used in research of replication because they are easy to identify and isolate.
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A lysosome () is a membrane-bound organelle found in many animal cells.By convention similar cells in plants are called vacuoles, see #Controversy in botany They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane proteins, and its lumenal proteins. The lumen's pH (~4.5–5.0) is optimal for the enzymes involved in hydrolysis, analogous to the activity of the stomach.
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Hermansky–Pudlak syndrome 3 protein is a protein that in humans is encoded by the HPS3 gene. This gene encodes a protein containing a potential clathrin- binding motif, consensus dileucine signals, and tyrosine-based sorting signals for targeting to vesicles of lysosomal lineage. The encoded protein may play a role in organelle biogenesis associated with melanosomes, platelet dense granules, and lysosomes. Mutations in this gene are associated with Hermansky–Pudlak syndrome type 3.
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The stages of ultrastructural changes of organelles in developing erythroid cells are similar to the developmental changes in other vertebrate groups. The greatest difference is the periodical transverse alignment of hemoglobin molecules in the organelle matrix of the hemosomes. The transformation of the erythroid cell organelles for hemoglobin biosynthesis occurs slowly. This is due to the low metabolic rate of A. alba which is a result of the hypoxic environment where it lives.
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In addition to the nuclear genome, endosymbiont organelles contain their own genetic material typically as circular plasmids. Mitochondrial and chloroplast DNA varies across taxa, but membrane-bound proteins, especially electron transport chain constituents are most often encoded in the organelle. Chloroplasts and mitochondria are maternally inherited in most species, as the organelles must pass through the egg. In a rare departure, some species of mussels are known to inherit mitochondria from father to son.
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A topogenic sequence is a collective term used for a peptide sequence present at nascent proteins essential for their insertion and orienting in cellular membranes. The sequences are also used to translocate proteins across various intracellular membranes, and ensure they are transported to the correct organelle after synthesis. The position of the sequence may be at the end, e.g. N-terminal signal sequence, or in mid parts of the nascent protein, e.g.
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Fulvio Reggiori, Chao-Wen Wang, Usha Nair, Takahiro Shintani, Hagai Abeliovich, and Daniel J. Klionsky, Early Stages of the Secretory Pathway, but Not Endosomes, Are Required for Cvt Vesicle and Autophagosome Assembly in Saccharomyces cerevisiae, from Molecular Biology of the Cell Vol. 15, 2189–2204, May 2004. The organelle consists of two enclosed membranes forming an enclosed lumen, which contains cytoplasm. It is formed by vesicles budding off the Golgi apparatus or the endoplasmic reticulum.
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The shells of testate amoebae may be composed of various substances, including calcium, silica, chitin, or agglutinations of found materials like small grains of sand and the frustules of diatoms. testate amoeba Difflugia acuminata. To regulate osmotic pressure, most freshwater amoebae have a contractile vacuole which expels excess water from the cell. This organelle is necessary because freshwater has a lower concentration of solutes (such as salt) than the amoeba's own internal fluids (cytosol).
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Miro functions to tether the complex to the mitochondrion while the complex transports the mitochondrion via microtubules within cells. Though Miro has been predominantly studied in neurons, the protein has also been observed to participate in the transport of mitochondria in lymphocytes toward inflamed endothelia. The motor/adaptor complex is regulated by calcium ion levels. At high concentrations, calcium ions arrest mitochondrial transport by binding Miro, causing the complex to detach from the organelle.
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The mitochondria then generates energy for the protist to keep up with cellular life functions. Photosynthetic protists produce energy through the use of their mitochondria and chloroplasts. Finally, anaerobic chemoorganotrophs produce energy through the use of hydrogenosomes, which is a membrane enclosed organelle that releases molecular hydrogen (H2). Encystment is when a protist becomes a dormant cyst with a cell wall; during encystment, the cyst has decreased complexity and metabolic activity relative to the protist.
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Trypanosoma cruzi is able to repair nucleotides in its genomic or kinetoplast DNA that have been damaged by reactive oxygen species produced by the parasite’s host during infection. DNA polymerase beta expressed in T. cruzi is employed in the removal of oxidative DNA damages by the process of base excision repair. It appears that DNA polymerase beta acts during kinetoplast DNA replication to repair oxidative DNA damages induced by genotoxic stress in this organelle.
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A plastid is a membrane-bound organelle found in plants, algae and other eukaryotic organisms that contribute to the production of pigment molecules. Most plastids are photosynthetic, thus leading to color production and energy storage or production. There are many types of plastids in plants alone, but all plastids can be separated based on the number of times they have undergone endosymbiotic events. Currently there are three types of plastids; primary, secondary and tertiary.
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At the Marine Biological Laboratory, Vale and Sheetz teamed up with Bruce Schnapp and Thomas J. Reese. They found that membrane organelle transport occurred bidirectionally on a microtubule, and not actin filament as Vale had originally thought. Vale further demonstrated that purified organelles by themselves rarely moved on microtubules, but movement was observed after adding the cytosol of the axon. He then discovered serendipitously that cytosol caused microtubules to translocate along a glass surface.
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The bundle of cilia that projects from the surface of the hair cell is the organelle which participates in mechanosensation. Each of these bundles are approximately 4-10 μm high and have 30-300 stereocilia and one kinocilium, which has motile characteristics. Along the axis of symmetry, each successive row of stereocilia is approximately 0.5-1.0 μm taller, with the kinocilium next to the tallest row. Extracellular structures connect the stereocilia together.
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A symbiosome is formed as a result of a complex, and coordinated interaction between the symbiont host and the endosymbiont. At the point of entry into a symbiont host cell part of the cell's membrane envelopes the endosymbiont and breaks off into the cytoplasm as a discrete unit, an organelle-like vacuole called the symbiosome. This is an endocytosis- like process that forms a symbiosome rather than an endosome. In plants this process is unique.
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The ability for a mitochondrion to self-replicate is rooted in its evolutionary history. It is commonly thought that mitochondria descend from cells that formed endosymbiotic relationships with α-protobacteria, they have their own genome for replication. However, recent evidence suggests that mitochondria may have evolved without symbiosis. The mitochondrion is a key regulator of the metabolic activity of the cell, and is also an important organelle in both production and degradation of free radicals.
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Centrioles produce the spindle during nuclear division. The significance of cytoskeletal structures is underlined in the determination of shape of the cells, as well as their being essential components of migratory responses like chemotaxis and chemokinesis. Some protists have various other microtubule-supported organelles. These include the radiolaria and heliozoa, which produce axopodia used in flotation or to capture prey, and the haptophytes, which have a peculiar flagellum-like organelle called the haptonema.
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From the beginning of the process, STED has allowed fluorescence microscopy to perform tasks that had been only possible using electron microscopy. As an example, STED was used for the elucidation of protein structure analysis at a sub-organelle level. The common proof of this level of study is the observation of cytoskeletal filaments. In addition, neurofilaments, actin, and tubulin are often used to compare the resolving power of STED and confocal microscopes.
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Basic structure of a peroxisome Distribution of peroxisomes (white) in HEK 293 cells during mitosis Peroxisome in rat neonatal cardiomyocyte A peroxisome () is a membrane-bound organelle (formerly known as a microbody), found in the cytoplasm of virtually all eukaryotic cells. Peroxisomes are oxidative organelles. Frequently, molecular oxygen serves as a co-substrate, from which hydrogen peroxide (H2O2) is then formed. Peroxisomes owe their name to hydrogen peroxide generating and scavenging activities.
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PEX genes encode the protein machinery ("peroxins") required for proper peroxisome assembly, as described above. Membrane assembly and maintenance requires three of these (peroxins 3, 16, and 19) and may occur without the import of the matrix (lumen) enzymes. Proliferation of the organelle is regulated by Pex11p. Genes that encode peroxin proteins include: PEX1, PEX2 (PXMP3), PEX3, PEX5, PEX6, PEX7, PEX9 , PEX10, PEX11A, PEX11B, PEX11G, PEX12, PEX13, PEX14, PEX16, PEX19, PEX26, PEX28, PEX30, and PEX31.
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First the phagophore engulfs the material that needs to be degraded, which forms a double membrane known as an autophagosome, around the organelle marked for destruction. The autophagosome then travels through the cytoplasm of the cell to a lysosome, and the two organelles fuse. Within the lysosome, the contents of the autophagosome are degraded via acidic lysosomal hydrolase. Microautophagy, on the other hand, involves the direct engulfment of cytoplasmic material into the lysosome.
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The isopropyl radical formed as a result of the metabolism of iproniazid, is able to covalently bind to proteins and other macromolecules in the liver. These interactions are the reason for the hepatotoxicity of iproniazid. Covalent binding results in liver necrosis by presumably changing protein function leading to organelle stress and acute toxicity. However, the exact mechanism of how the binding of iproniazid derivatives to liver proteins would induce liver necrosis remains unclear.
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Phase separation, endometriosis, vesicle formation, organelle trafficking Either the substrate of the enzyme can move. Movement is typically the disruption of palmitate mediated localization. For proteins that are both palmitoylated and bind PIP2, increasing the concentration of PIP2 favors trafficking of the enzyme out of lipid rafts to PIP2. PIP2 is primarily polyunsaturated which causes the lipid to localize away from lipid rafts and allows the PIP2 to oppose palmitate mediated localization.
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Large vacuoles are found in three genera of filamentous sulfur bacteria, the Thioploca, Beggiatoa and Thiomargarita. The cytosol is extremely reduced in these genera and the vacuole can occupy between 40–98% of the cell. The vacuole contains high concentrations of nitrate ions and is therefore thought to be a storage organelle. Gas vesicles, also known as gas vacuoles, are nanocompartments which are freely permeable to gas, and are present in some species of Cyanobacteria.
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The peroxisome biogenesis disorders (PBDs; MIM 601539) are a group of genetically heterogeneous diseases that are usually lethal in early infancy. Although the clinical features of PBD patients vary, cells from all PBD patients exhibit a defect in the import of one or more classes of peroxisomal matrix proteins into the organelle. This cellular phenotype is shared by yeast 'pex' mutants, and human orthologs of yeast PEX genes defective in some PBD complementation groups (CGs).
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The human gene ATP6AP1 encodes the S1 subunit of the enzyme V-type proton ATPase. This gene encodes a component of a multisubunit enzyme (1 mDa MW) that mediates acidification of eukaryotic intracellular organelles. Vacuolar ATPase (V-ATPase) is composed of a cytosolic, V1, (site of the ATP catalytic site) and a transmembrane, V0, domain. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, and receptor-mediated endocytosis.
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The endosymbiont not only acts as feeding apparatus, but also as an eye spot, by which it probably helps the protist for directional movements towards light (phototaxis). H. arenicola cannot divide without containing the endosymbiont. But, unlike a fully integrated organelle, the Nephroselmis alga does not divide along with the host cell. When the host cell divides, one of the daughter cells receives the Nephroselmis cell and the other daughter returns to a heterotrophic lifestyle.
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Hermansky–Pudlak syndrome 1 protein is a protein that in humans is encoded by the HPS1 gene. This gene encodes a protein that may play a role in organelle biogenesis associated with melanosomes, platelet dense granules, and lysosomes. The encoded protein is a component of three different protein complexes termed biogenesis of lysosome-related organelles complex (BLOC)-3, BLOC4, and BLOC5. Mutations in this gene are associated with Hermansky–Pudlak syndrome type 1.
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In yeast, where organelle membranes are closely apposed it has been proposed that ORPs work as sterol transporters, though only a few ORPs actually bind sterols and collectively yeast ORPs are dispensable for sterol transfer in vivo. They are also part of Golgi-to-plasma membrane vesicular trafficking, but their role is not clear yet. In mammalian, ORPs participate as sterol sensors.This sensors regulate the assembly of protein complexes when cholesterol levels fluctuate.
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A more recent study (October 2010) published in PLoS ONE contradicts the conclusion of Kaye and supports Schweitzer's original conclusion. Evidence for the extraction of short segments of ancient DNA from dinosaur fossils has been reported on two separate occasions. The extraction of protein, soft tissue, remnant cells and organelle-like structures from dinosaur fossils has been confirmed. Blood- derived porphyrin proteins have also been discovered in a mid Eocene mosquito fossil.
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J D Robertson."The molecular structure and contact relationships of cell membranes." Progress Biophysics and Biophysical Chemistry, (1960) 10, 343-418.J D Robertson."The ultrastructure of cell membranes and their derivatives." Biochemical Society Symposia, (1959) 16. 3-43. In this body of work, Robertson put forward the concept of the “unit membrane.” This was the first time the bilayer structure had been universally assigned to all cell membranes as well as organelle membranes.
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Although they are outside the cells, the filaments of Labyrinthulomycetes are surrounded by a membrane. They are formed and connected with the cytoplasm by a unique organelle called a sagenogen or bothrosome. The cells are uninucleated and typically ovoid, and move back and forth along the amorphous network at speeds varying from 5-150 μm per minute. Among the labyrinthulids, the cells are enclosed within the tubes, and among the thraustochytrids, they are attached to their sides.
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Actin participates in many important cellular processes, including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, and the establishment and maintenance of cell junctions and cell shape. Many of these processes are mediated by extensive and intimate interactions of actin with cellular membranes. In vertebrates, three main groups of actin isoforms, alpha, beta, and gamma have been identified. The alpha actins, found in muscle tissues, are a major constituent of the contractile apparatus.
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Protein cappuccino homolog is a protein that in humans is encoded by the CNO gene. This intronless gene encodes a protein that may play a role in organelle biogenesis associated with melanosomes, platelet dense granules, and lysosomes. A similar protein in mouse is a component of a protein complex termed biogenesis of lysosome-related organelles complex 1 (BLOC-1), and is a model for Hermansky–Pudlak syndrome. The encoded protein may play a role in intracellular vesicular trafficking.
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For a peptide spectra library, to reach a maximal coverage is a long-term goal, even with the support of scientific community and ever-growing proteomic technologies. However, the optimization for a particular module of the peptide spectra library is a more manageable goal, e.g. the proteins in a particular organelle or relevant to a particular biological phenotype. For example, a researcher studying mitochondrial proteome, will likely focus his/her analyses within protein modules within the mitochondria.
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The nucleus provides a site for genetic transcription that is segregated from the location of translation in the cytoplasm, allowing levels of gene regulation that are not available to prokaryotes. The main function of the cell nucleus is to control gene expression and mediate the replication of DNA during the cell cycle. The nucleus is an organelle found in eukaryotic cells. Inside its fully enclosed nuclear membrane, it contains the majority of the cell's genetic material.
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The lysosome is shown in purple, as an endpoint in endocytotic sorting. AP2 is necessary for vesicle formation, whereas the mannose-6-receptor is necessary for sorting hydrolase into the lysosome's lumen. Many components of animal cells are recycled by transferring them inside or embedded in sections of membrane. For instance, in endocytosis (more specifically, macropinocytosis), a portion of the cell's plasma membrane pinches off to form vesicles that will eventually fuse with an organelle within the cell.
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In all vascular plants studied so far, tannins are manufactured by a chloroplast-derived organelle, the tannosome. Tannins are mainly physically located in the vacuoles or surface wax of plants. These storage sites keep tannins active against plant predators, but also keep some tannins from affecting plant metabolism while the plant tissue is alive; it is only after cell breakdown and death that the tannins are active in metabolic effects. Tannins are classified as ergastic substances, i.e.
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Probably the most important feature of a biomembrane is that it is a selectively permeable structure. This means that the size, charge, and other chemical properties of the atoms and molecules attempting to cross it will determine whether they succeed in doing so. Selective permeability is essential for effective separation of a cell or organelle from its surroundings. Biological membranes also have certain mechanical or elastic properties that allow them to change shape and move as required.
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V-type proton ATPase 21 kDa proteolipid subunit is an enzyme that in humans is encoded by the ATP6V0B gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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V-type proton ATPase subunit e 1 is an enzyme that in humans is encoded by the ATP6V0E1 gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor- mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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Hepatocytes have the ability to metabolize, detoxify, and inactivate exogenous compounds such as drugs (see drug metabolism), insecticides, and endogenous compounds such as steroids. The drainage of the intestinal venous blood into the liver requires efficient detoxification of miscellaneous absorbed substances to maintain homeostasis and protect the body against ingested toxins. One of the detoxifying functions of hepatocytes is to modify ammonia into urea for excretion. The most abundant organelle in liver cells is the smooth endoplasmic reticulum.
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Two flagella emanate from the anterior papilla of the cell, and cells have two contractile vacuoles at the flagellar base. Polytoma possesses a leukoplast in place of a chloroplast, in which many starch grains are concentrated; there is no pyrenoid. Since they lack photosynthetic capability, Polytoma species are entirely saprotrophic, obtaining nutrients from decaying organic matter. Some species possess an eyespot apparatus (stigma) in the anterior portion of the leucoplast, but in others this organelle is absent.
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The species is an endosymbiont that is present in all species of phloem sap-feeding insects known as psyllids. The endosymbionts occurs in a specialised structure known as the bacteriome. C. ruddii is not completely parasitic in its relationship with its host insect; it supplies the host with some essential amino acids. It is therefore probably in the evolutionary process of becoming an organelle, similar to the mitochondria of eukaryotic cells that also evolved from an endosymbiont.
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The TIGER domain is a minor membraneless organelle in which messenger RNA (mRNA) encodes certain types of proteins to find the appropriate environment for growth. It is closely associated with the endoplasmic reticulum during protein synthesis. The TIGER domain was first documented by cell biologists Christine Mayr and Weirui Ma at the Gerstner Sloan Kettering Graduate School of Biomedical Sciences in 2018. The letters TIG stand for TIS granules and letters ER stands for the endoplasmic reticulum.
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Trichomonas vaginalis lacks mitochondria and therefore necessary enzymes and cytochromes to conduct oxidative phosphorylation. T. vaginalis obtains nutrients by transport through the cell membrane and by phagocytosis. The organism is able to maintain energy requirements by the use of a small amount of enzymes to provide energy via glycolysis of glucose to glycerol and succinate in the cytoplasm, followed by further conversion of pyruvate and malate to hydrogen and acetate in an organelle called the hydrogenosome.
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Cyanobacteria, which are prokaryotic organisms which carry out oxygenic photosynthesis, occupy many environmental conditions, including fresh water, seas, soil, and lichen. Cyanobacteria carry out plant-like photosynthesis because the organelle in plants that carries out photosynthesis is derived from anHill, Malcolm S. "Production Possibility Frontiers in Phototroph:heterotroph Symbioses: Trade- Offs in Allocating Fixed Carbon Pools and the Challenges These Alternatives Present for Understanding the Acquisition of Intracellular Habitats." Frontiers in Microbiology 5 (2014): 357. PMC. Web. 11 March 2016.
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V-type proton ATPase subunit C 2 is an enzyme that in humans is encoded by the ATP6V1C2 gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor- mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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There is no evidence this mitochondria-like organelle produces ATP, but there is evidence that the glycolytic pathway is intact within it. The mitosome also still appears to be targeted by proteins involved in amino acid metabolism, transport and maturation of proteins and transport of metabolites so it likely retains some mitochondrial function relating to those areas. Trimastix have one anterior pear-shaped nucleus that contains a large nucleolus, with the exception of Trimastix marina which has two nuclei.
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TRP channels are composed of 6 membrane-spanning helices (S1-S6) with intracellular N- and C-termini. Mammalian TRP channels are activated and regulated by a wide variety of stimuli including many post- transcriptional mechanisms like phosphorylation, G-protein receptor coupling, ligand-gating, and ubiquitination. The receptors are found in almost all cell types and are largely localized in cell and organelle membranes, modulating ion entry. Most TRP channels form homo- or heterotetramers when completely functional.
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The pellicles forms a shell around the cytoskeleton covering the whole cell and fuses together around the microtubule reinforced-pocket (MTR). This pocket acts as a sort of cytostome or ingestion organelle, allowing the organism to feed when bacteria enter inside. The microtubules are arranged in a peculiar doublet and triplet pattern in the upper canal. In certain species of Phacus, the MTR is a microtubule organizing center and is connected to a reservoir membrane by a striated fiber.
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Like many other protists, species of Amoeba control osmotic pressures with the help of a membrane-bound organelle called the contractile vacuole. Amoeba proteus has one contractile vacuole which slowly fills with water from the cytoplasm (diastole), then, while fusing with the cell membrane, quickly contracts (systole), releasing water to the outside by exocytosis. This process regulates the amount of water present in the cytoplasm of the amoeba. Immediately after the contractile vacuole (CV) expels water, its membrane crumples.
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When examining closely related species, or branching within species, recombination creates a large number of 'irrelevant SNPs' for cladistic analysis. MtDNA, through the process of organelle division, became clonal over time; very little, or often none, of that paternal mtDNA is passed. While recombination may occur in mtDNA, there is little risk that it will be passed to the next generation. As a result, mtDNA become clonal copies of each other, except when a new mutation arises.
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In healthy mammalian cells, the majority of BAX is found in the cytosol, but upon initiation of apoptotic signaling, Bax undergoes a conformational shift. Upon induction of apoptosis, BAX becomes organelle membrane-associated, and in particular, mitochondrial membrane associated. BAX is believed to interact with, and induce the opening of the mitochondrial voltage-dependent anion channel, VDAC. Alternatively, growing evidence also suggests that activated BAX and/or Bak form an oligomeric pore, MAC in the MOM.
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Offspring of the females with the trait always inherit the trait (independently from their own gender). Nuclear DNA has two copies per cell (except for sperm and egg cells), one copy being inherited from the father and the other from the mother. Mitochondrial DNA, however, is inherited from the mother only (with some exceptions) and each mitochondrial organelle typically contains between 2 and 10 mtDNA copies. During cell division the mitochondria segregate randomly between the two new cells.
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Most Oxymonads are around 50 μm in size and have a single nucleus, associated with four flagella. Their basal bodies give rise to several long sheets of microtubules, which form an organelle called an axostyle, but different in structure from the axostyles of parabasalids. The cell may use the axostyle to swim, as the sheets slide past one another and cause it to undulate. An associated fiber called the preaxostyle separates the flagella into two pairs.
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The human gene SPAST codes for the microtubule-severing protein of the same name, commonly known as spastin. This gene encodes a member of the AAA (ATPases associated with a variety of cellular activities) protein family. Members of this protein family share an ATPase domain and have roles in diverse cellular processes including membrane trafficking, intracellular motility, organelle biogenesis, protein folding, and proteolysis. The encoded ATPase may be involved in the assembly or function of nuclear protein complexes.
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This technique is commonly used in conjunction with green fluorescent protein (GFP) fusion proteins, where the studied protein is fused to a GFP. When excited by a specific wavelength of light, the protein will fluoresce. When the protein that is being studied is produced with the GFP, then the fluorescence can be tracked. Photodestroying the GFP, and then watching the repopulation into the bleached area can reveal information about protein interaction partners, organelle continuity and protein trafficking.
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There is a clear connection between ROS and autophagy and a correlation seen between excessive amounts of ROS leading to apoptosis. The depolarization of the mitochondrial membrane is also characteristic of the initiation of autophagy. When mitochondria are damaged and begin to release ROS, autophagy is initiated to dispose of the damaging organelle. If a drug targets mitochondria and creates ROS, autophagy may dispose of so many mitochondria and other damaged organelles that the cell is no longer viable.
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The location of expression of the BEST1 gene is essential for protein functioning and mislocalization is often connected to a variety of retinal degenerative diseases. The BEST1 gene expresses the Best1 protein primarily in the cytosol of the retinal pigment epithelium. The protein is typically contained in vesicles near the cellular membrane. There is also research to support that the Best1 protein is localized and produced in the endoplasmic reticulum (intracellular organelle involved in protein and lipid synthesis).
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The partitioning ability of the lipid bilayer is based on the fact that hydrophilic molecules cannot easily cross the hydrophobic bilayer core, as discussed in Transport across the bilayer below. The nucleus, mitochondria and chloroplasts have two lipid bilayers, while other sub-cellular structures are surrounded by a single lipid bilayer (such as the plasma membrane, endoplasmic reticula, Golgi apparatus and lysosomes). See Organelle. Prokaryotes have only one lipid bilayer - the cell membrane (also known as the plasma membrane).
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Tubulin inhibitors are chemotherapy drugs that interfere directly with the tubulin system, which is in contrast to those chemotherapy drugs acting on DNA. Microtubules play an important role in eukaryotic cells. Alpha- and beta- tubulin, the main components of microtubules, have gained considerable interest because of their function and biophysical properties and has become the subject of intense study. The addition of tubulin ligands can affect microtubule stability and function, including mitosis, cell motion and intracellular organelle transport.
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Glucosylceramides (GluCer) are the most widely distributed glycosphingolipids in cells serving as precursors for the formation of over 200 known glycosphingolipids. GluCer is formed by the glycosylation of ceramide in an organelle called Golgi via enzymes called glucosylceramide synthase (GCS) or by the breakdown of complex glycosphingolipids (GSLs) through the action of specific hydrolase enzymes. In turn, certain β-glucosidases hydrolyze these lipids to regenerate ceramide. GluCer appears to be synthesized in the inner leaflet of the Golgi.
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V-type proton ATPase subunit E 1 is an enzyme that in humans is encoded by the ATP6V1E1 gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor- mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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V-type proton ATPase subunit B, kidney isoform is an enzyme that in humans is encoded by the ATP6V1B1 gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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V-type proton ATPase subunit D is an enzyme that in humans is encoded by the ATP6V1D gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor- mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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V-type proton ATPase subunit G 1 is an enzyme that in humans is encoded by the ATP6V1G1 gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor- mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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V-type proton ATPase subunit F is an enzyme that in humans is encoded by the ATP6V1F gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor- mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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V-type proton ATPase catalytic subunit A is an enzyme that in humans is encoded by the ATP6V1A gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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V-type proton ATPase subunit B, brain isoform is an enzyme that in humans is encoded by the ATP6V1B2 gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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V-type proton ATPase subunit d 1 is an enzyme that in humans is encoded by the ATP6V0D1 gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor- mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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The shapes of mitochondria in cells are continually changing via a combination of fission, fusion, and motility. Specifically, fusion assists in modifying stress by integrating the contents of slightly damaged mitochondria as a form of complementation. By enabling genetic complementation, fusion of the mitochondria allows for two mitochondrial genomes with different defects within the same organelle to individually encode what the other lacks. In doing so, these mitochondrial genomes generate all of the necessary components for a functional mitochondrion.
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The acrosome is an organelle that develops over the anterior half of the head in the spermatozoa (sperm cells) of many animals including humans. It is a cap-like structure derived from the Golgi apparatus. In Eutherian mammals the acrosome contains digestive enzymes (including hyaluronidase and acrosin). These enzymes break down the outer membrane of the ovum, called the zona pellucida, allowing the haploid nucleus in the sperm cell to join with the haploid nucleus in the ovum.
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Additionally, Lippincott-Schwartz's laboratory demonstrated that Golgi enzymes constitutively recycle back to the endoplasmic reticulum and that such recycling plays a central role in the maintenance, biogenesis, and inheritance of the Golgi apparatus in mammalian cells. Within Lippincott-Schwartz lab, current projects include several cell biological areas. For example, protein transport and cytoskeleton interaction, organelle assembly and disassembly, and cell polarity generation. There are also projects analyzing the dynamics of proteins that have been fluorescently labeled.
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The samples must also be very thin (below 100 nm) in order for the electrons to pass through it. Cross-sections of cells stained with osmium and heavy metals reveal clear organelle membranes and proteins such as ribosomes. With a 0.1 nm level of resolution, detailed views of viruses (20 – 300 nm) and a strand of DNA (2 nm in width) can be obtained. In contrast, the SEM has raster coils to scan the surface of bulk objects with a fine electron beam.
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Nuclear copies of some mitochondrial genes, however, do not contain organelle-specific splice sites, suggesting a processed mRNA intermediate. The cDNA hypothesis has since been revised as edited mitochondrial cDNAs are unlikely to recombine with the nuclear genome and are more likely to recombine with their native mitochondrial genome. If the edited mitochondrial sequence recombines with the mitochondrial genome, mitochondrial splice sites would no longer exist in the mitochondrial genome. Any subsequent nuclear gene transfer would therefore also lack mitochondrial splice sites.
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P. conicum, a large feeding veil — a pseudopod called the pallium — is extruded to capture prey which is subsequently digested extracellularly (= pallium- feeding). Oblea, Zygabikodinium, and Diplopsalis are the only other dinoflagellate genera known to use this particular feeding mechanism. Katodinium (Gymnodinium) fungiforme, commonly found as a contaminant in algal or ciliate cultures, feeds by attaching to its prey and ingesting prey cytoplasm through an extensible peduncle. Two related species, polykrikos kofoidii and neatodinium, shoots out a harpoon-like organelle to capture prey.
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This protein is a member of the ALD subfamily, which is involved in peroxisomal import of fatty acids and/or fatty acyl-CoAs in the organelle. All known peroxisomal ABC transporters are half transporters which require a partner half transporter molecule to form a functional homodimeric or heterodimeric transporter. The function of this peroxisomal membrane protein is unknown. However, it is speculated that it may function as a heterodimer for another peroxisomal ABC transporter and, therefore, may modify the adrenoleukodystrophy phenotype.
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Both chlorophyll and singlet oxygen then remove hydrogen ions from the unsaturated lipids present in de cells and the organelle membranes, forming lipid radicals. These radicals will oxidize other lipids and proteins, eventually resulting in loss of the membrane integrity of the cells and organelles. This will result in a loss of chlorophyll, leakage of cellular contents, cell death, and eventually death of the plant. Woody plants first show yellowing of the leaves before they start to defoliate, eventually they will die.
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The theory states that in plant endosymbioses, the micro-symbiont and the macro- symbiont generally share their lytic vacuolar compartments. This stems from Mellor's earlier 1988 symbiosome (or "symbiosome is a lysosome") theory, which states that the organelle that microsymbionts inhabit partially takes over the lysosomal functions in these plant cells. These plant cells are analogous to the role of protein bodies in seeds, in particular that the rhizobial symbiosome is an organ-specific form of lysosome or vacuole in legume root nodules.
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A flagellum (; plural: flagella) is a lash-like appendage that protrudes from the cell body of certain bacteria and eukaryotic cells termed as flagellates. A flagellate can have one or several flagella. The primary function of a flagellum is that of locomotion, but it also often functions as a sensory organelle, being sensitive to chemicals and temperatures outside the cell. The similar structure in the archaea functions in the same way but is structurally different and has been termed the archaellum.
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The defining characteristic of the genera Labyrinthula is the formation of an ectoplasmic net around the cells and embedding the whole colony. The ectoplasmic net is secreted and attached to the cell by specialized organelles called segenetosome or bothrosomes. A bothrosome is an electron-opaque organelle, which prevents the leaking of the organelles into the net. The etymology of "bothrosome" and "sagenetosome" originated from bothros: hole and soma: body, as well as from sagena: net, genetes: ancestor and soma: body respectively.
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This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain. The V1 domain consists of three A and three B subunits, two G subunits plus the C, D, E, F, and H subunits.
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Berkeley bodies are organelles unique to the yeast cell Saccharomyces cerevisiae, with a secretory mutation in the genes sec7 and sec14. The function of the organelle lies in the CTV (cytoplasm to vacuole targeting) pathway, which is a transport pathway for certain vacuolar hydrolases to be degenerated. The Berkeley body acts as the transport medium from the cytoplasm to the vacuole within this pathway. Studies have shown that Berkeley bodies share structural similarities with autophagosomes, which are involved in autophagy.
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A motile sperm organelle morphology examination (MSOME) is a particular morphologic investigation wherein an inverted light microscope equipped with high-power optics and enhanced by digital imaging is used to achieve a magnification above x6000, which is much higher than the magnification used habitually by embryologists in spermatozoa selection for intracytoplasmic sperm injection (x200 to x400). A potential finding on MSOME is the presence of sperm vacuoles, which are associated with sperm chromatin immaturity, particularly in the case of large vacuoles.
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Unlike the atrial cells, SA node cells contain fewer mitochondria (the power plant of the cell), fewer myofibers (the contractile machinery of the cell), and a smaller sarcoplasmic reticulum (a calcium storage organelle that releases calcium for contraction). This means that the SA node cells are less equipped to contract compared to the atrial and ventricular cells. Action potentials pass from one cardiac cell to the next through pores known as gap junctions. These gap junctions are made of proteins called connexins.
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Formation and examples of membraneless organelles Biomolecular condensates are a class of non-membrane bound organelles and organelle subdomains. As with other organelles, biomolecular condensates are specialized subunits of the cell. However, unlike many organelles, biomolecular condensate composition is not controlled by a bounding membrane. Instead they can form through a range of different processes, the most well-known of which is phase separation of proteins, RNA and other biopolymers into either colloidal emulsions, liquid crystals, solid crystals or aggregates within cells.
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Bordetella pertussis, the causative agent of whooping cough, secretes the pertussis toxin partly through the type IV system. Legionella pneumophila, the causing agent of legionellosis (Legionnaires' disease) utilizes a type IVB secretion system, known as the icm/dot (intracellular multiplication / defect in organelle trafficking genes) system, to translocate numerous effector proteins into its eukaryotic host. The prototypic Type IVA secretion system is the VirB complex of Agrobacterium tumefaciens. Protein members of this family are components of the type IV secretion system.
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While in the rod, these discs lack any direct connection to the surface membrane (with the exception of a few recently formed basal discs that remain in continuity with the surface), the cone's photosensitive membrane is continuous with the surface membrane. The outer segment (OS) discs are densely packed with rhodopsin for high- sensitivity light detection.Chuang, J., Zhao, Y., & Sung, C. (2007). "SARA- regulated vesicular targeting underlies formation of the light sensing organelle in mammalian rods", Cell, 130, 535-547.
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Staphylococcus aureus bacteria magnified about 10,000x Bacteria like archaea are prokaryotic – unicellular, and having no cell nucleus or other membrane- bound organelle. Bacteria are microscopic, with a few extremely rare exceptions, such as Thiomargarita namibiensis. Bacteria function and reproduce as individual cells, but they can often aggregate in multicellular colonies. Some species such as myxobacteria can aggregate into complex swarming structures, operating as multicellular groups as part of their life cycle, or form clusters in bacterial colonies such as E.coli.
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Importantly, the endomembrane system does not include the membranes of chloroplasts or mitochondria, but might have evolved from the latter (see below: Evolution). The nuclear membrane contains a lipid bilayer that encompass the contents of the nucleus. The endoplasmic reticulum (ER) is a synthesis and transport organelle that branches into the cytoplasm in plant and animal cells. The Golgi apparatus is a series of multiple compartments where molecules are packaged for delivery to other cell components or for secretion from the cell.
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Cells without glycosomes are deficient in these enzymes as without the compartmentalization of the glycosome the enzymes are degraded in the cell in the cytosol. The organelle keeps metabolism of the enzymes from occurring. For parasites, ether-lipid synthesis is vital to be able to complete its life cycle, making the enzymes protected by the glycosome also vital. In their life cycle, glycolysis partly through the glycosome is very high in the blood stream form comparatively to the pro-cyclic form.
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Yet, extremely large fragments of organelle DNA are found in some the plant genomes. As the genome evolves and alters over time by mutation, the number of NUMT in the genome differs over the course of evolution. NUMT enters the nucleus and inserts in the nDNA at different stages of the time. Due to constant mutation and instability of NUMT, the resemblance of this genome stretch to the mtDNA varies widely across the kingdom Animalia and even within the certain genome.
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IUPAC code letters and circles indicate conserved nucleotides and positions with variable nucleotide identity, respectively. Conserved and covariant substitutions in canonical (Watson-Crick) base-pairs are shaded. Translation machineries of mitochondria and plastids (organelles of endosymbiotic bacterial origin), and their bacterial relatives share many features but also display marked differences. Organelle genomes encode SSU and LSU rRNAs without exception, yet the distribution of 5S rRNA genes (rrn5) is most uneven. Rrn5 is easily identified and common in genomes of most plastids.
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Lipid droplet biology, Mathias Beller page, Max-Planck- Institut für biophysikalische Chemie websiteOhsaki1 Y, Suzuki1 M, Fujimoto1 T, Open Questions in Lipid Droplet Biology, Chemistry & Biology, 2014 (January 16), 21(1):86–96, DOI: 10.1016/j.chembiol.2013.08.009 His group extensively studied proteins required to adjust lipid droplet size and composition according to the cellular state. Additionally, his research focused on organelle biogenesis and membrane biology. At Yale, Walther also oversaw the High Throughput Cell Biology Center at Yale's West Campus.
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This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain. The V1 domain consists of three A and three B subunits, two G subunits plus the C, D, E, F, and H subunits.
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The organelle of differentiation in embryos: the cell state splitter Theoretical Biology and Medical Modelling, 13(11) 2016 specific points: # In order to maintain a gradient at steady state there has to be a sink i.e. a way in which diffusing molecules are destroyed or removed along the way and/or at some boundaries. Sinks are rarely, if ever, even considered when the gradient model is invoked. # Diffusion must occur in a confined space if a gradient is to be established.
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Melkonian has research interests that range from cell biology, Melkonian, M., Robenek, H. (1980): Eyespot membranes of Chlamydomonas reinhardii: a freeze-fracture study. J. Ultrastruct. Res. 72, 90-102Salisbury, J.L., Baron, A., Surek, B., Melkonian, M. (1984): Striated flagellar roots: isolation and partial characterization of a calcium-modulated contractile organelle. J. Cell Biol. 99, 962-970 Melkonian, M., Reize, I.B., Preisig, H.R. (1987): Maturation of a flagellum/basal body requires more than one cell cycle in algal flagellates: Studies on Nephroselmis olivacea (Prasinophyceae).
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V-type proton ATPase 116 kDa subunit a isoform 1 is an enzyme that in humans is encoded by the ATP6V0A1 gene. This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain.
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This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain. The V1 domain consists of three A and three B subunits, two G subunits plus the C, D, E, F, and H subunits.
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Colponema is a colorless biflagellate with a pronounced ventral feeding groove. Cell size ranges from 4-14 µm in width and 8-17 µm in length and they have an oval shape that narrows at the anterior end. The cells have 1 µm long toxicysts, a type of organelle that is extruded from the cell and are used to immobilize prey. Species of Colponema vary in the presence of a contractile vacuoles, degree of dorsoventral flattening, and the length of flagella.
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Cytoplasmic male sterility genes, usually found in the mitochondrial genome, show up and are established when female fertility is just slightly more than the hermaphroditic fertility. The female only needs to make slightly more or better seeds than hermaphrodites since the mitochondrial genome is maternally inherited. Research done on plants has shown that hermaphroditic plants are in constant battles against organelle genes trying to kill their male parts. In over 140 plant species, these “male killer” genes have been observed.
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A. nasoniae exhibits the son-killer trait which causes lethality of approximately 80% of male embryos produced by infected female wasps. A. nasoniae causes inhibition of the formation of the maternal centrosome in male N. vitripennis embryos. The maternal centrosome is an organelle which is specifically required for early male embryonic development. The action of the killer-son trait by A. nasoniae results in unorganized mitotic spindles and developmental arrest prior to the establishment of somatic sexual identity of the host wasps' offspring.
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Modern endosymbiotic theory posits that simple life forms merged, forming cell organelles, like mitochondria. Kwang Jeon's experiment: [I] Amoebae infected by x-bacteria [II] Many amoebae become sick and die [III] Survivors have x-bacteria living in their cytoplasm [IV] Antibiotics kill x-bacteria: host amoebae die as now dependent on x-bacteria. According to Keeling and Archibald, biologists usually distinguish organelles from endosymbionts by their reduced genome sizes. As an endosymbiont evolves into an organelle, most of its genes are transferred to the host cell genome.
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All the same, the dinoflagellate cell consists of the more common organelles such as rough and smooth endoplasmic reticulum, Golgi apparatus, mitochondria, lipid and starch grains, and food vacuoles. Some have even been found with a light-sensitive organelle, the eyespot or stigma, or a larger nucleus containing a prominent nucleolus. The dinoflagellate Erythropsidium has the smallest known eye. Some athecate species have an internal skeleton consisting of two star-like siliceous elements that has an unknown function, and can be found as microfossils.
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The development of plastids among the alveolates is intriguing. Cavalier-Smith proposed the alveolates developed from a chloroplast-containing ancestor, which also gave rise to the Chromista (the chromalveolate hypothesis). Other researchers have speculated that the alveolates originally lacked plastids and possibly the dinoflagellates and Apicomplexa acquired them separately. However, it now appears that the alveolates, the dinoflagellates, the Chromerida and the heterokont algae acquired their plastids from a red alga with evidence of a common origin of this organelle in all these four clades.
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In enzymology, a peroxisome-assembly ATPase () is an enzyme that catalyzes the chemical reaction :ATP + H2O \rightleftharpoons ADP + phosphate Thus, the two substrates of this enzyme are ATP and H2O, whereas its two products are ADP and phosphate. Its function is to transport components of the peroxisome in and out of the organelle. This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides to facilitate cellular and subcellular movement. The systematic name of this enzyme class is ATP phosphohydrolase (peroxisome-assembling).
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The presence of these tags allow for binding to mannose 6-phosphate receptors in the Golgi apparatus, a phenomenon that is crucial for proper packaging into vesicles destined for the lysosomal system. Upon leaving the Golgi apparatus, the lysosomal enzyme-filled vesicle fuses with a late endosome, a relatively acidic organelle with an approximate pH of 5.5. This acidic environment causes dissociation of the lysosomal enzymes from the mannose 6-phosphate receptors. The enzymes are packed into vesicles for further transport to established lysosomes.
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"Apicoplast" is a specialised word, derived from the word "plastid". Initially the word plastid was more suitable than "chloroplast" when describing organelles of apparent algal descent in any protist, but that lack any chlorophyll or light absorbing pigment. Those found in apicomplexan parasites are a prominent example. The majority of members of the apicomplexan lineage still contain a genome in the plastid, indicating the organelle of the lineage's ancestors was once photosynthetic, but these plastids have no light absorbing pigments or light reaction machinery.
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CAP-Gly domain-containing linker protein 2 is a protein that in humans is encoded by the CLIP2 gene. The protein encoded by this gene belongs to the family of cytoplasmic linker proteins, which have been proposed to mediate the interaction between specific membranous organelles and microtubules. This protein was found to associate with both microtubules and an organelle called the dendritic lamellar body. This gene is hemizygously deleted in Williams syndrome, a multisystem developmental disorder caused by the deletion of contiguous genes at 7q11.23.
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At EMBL Sharon Tooze studied transport of a viral glycoprotein from a SARS virus and showed that O-linked glycosylation starts in the ER-Golgi intermediate compartment. Later she became interested in organelle biogenesis and in how immature secretory granules form from the trans-Golgi network in neuroendocrine cells. In 2006, Tooze developed interest in autophagy and the biogenesis of autophagosomes. Since then her lab has identified several mammalian Atg proteins and continues to contribute to understanding of autophagy at the molecular cell biology level.
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If the gene for proteorhodopsin is inserted into E. coli and retinal is given to these modified bacteria, then they will incorporate the pigment into their cell membrane and will pump H+ in the presence of light. A deep purple is representative of clearly transformed colonies, due to light absorption. Proton gradients can be used to power other membrane protein structures or used to acidify a vesicle type organelle. It was further demonstrated that the proton gradient generated by proteorhodopsin could be used to generate ATP.
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In 1989 the concept was applied to the similar structure found in the nitrogen-fixing root nodules of certain plants. The symbiosome in the root nodules has been much more successfully researched due in part to the complexity of isolating the symbiosome membrane in animal hosts. The symbiosome in a root nodule cell in a plant is an organelle-like structure that has formed in a symbiotic relationship with nitrogen-fixing bacteria. The plant symbiosome is unique to those plants that produce root nodules.
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The advent of these technologies resulted in a rapid intensification in the scope and speed of completion of genome sequencing projects. The first complete genome sequence of a eukaryotic organelle, the human mitochondrion (16,568 bp, about 16.6 kb [kilobase]), was reported in 1981, and the first chloroplast genomes followed in 1986. In 1992, the first eukaryotic chromosome, chromosome III of brewer's yeast Saccharomyces cerevisiae (315 kb) was sequenced. The first free-living organism to be sequenced was that of Haemophilus influenzae (1.8 Mb [megabase]) in 1995.
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Nomarski micrograph of a ruthenium red-stained nematocyst from Aiptasia pallida, the pale anemone. The red dye stains the polyanionic venom proteins found inside the capsule of this partially-discharged nematocyst. A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one giant secretory organelle called a cnidocyst (also known as a cnida (plural cnidae) or nematocyst) that can deliver a sting to other organisms. The presence of this cell defines the phylum Cnidaria (corals, sea anemones, hydrae, jellyfish, etc.).
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Vacuoles, which are found in both plant and animal cells (though much bigger in plant cells), are responsible for maintaining the shape and structure of the cell as well as storing waste products. A vesicle is a relatively small, membrane-enclosed sac that stores or transports substances. The cell membrane is a protective barrier that regulates what enters and leaves the cell. There is also an organelle known as the Spitzenkörper that is only found in fungi, and is connected with hyphal tip growth.
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Several major human diseases are caused by the obligate intracellular protozoan parasites in the phylum Apicomplexa. The apicoplast organelle in these organisms is believed to have come from an endosymbiotic event in which an ancestral protozoan engulfed an algal cell. These apicoplasts contain plant-like FNRs that the protozoan uses to generate reduced ferredoxin, which is then used as a reductant in essential biosynthetic pathways. FNRs from two major parasites affecting humans, Plasmodium falciparum, which causes malaria, and Toxoplasma gondii, which causes toxoplasmosis, have been sequenced.
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An organelle in eukaryotice cells now known as Golgi apparatus or Golgi complex, or sometimes simply as Golgi, was discovered by Camillo Golgi. Golgi modified his black reaction using osmium dichromate solution with which he stained the nerve cells (Purkinje cells) of the cerebellum of an owl. He noticed thread-like networks inside the cells and named them apparato reticolare interno (internal reticular apparatus). Recognising them to be unique cellular components, he presented his discovery before the Medical- Surgical Society of Pavia in April 1898.
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Like other cyclophilins, PPIB forms a β-barrel structure with a hydrophobic core. This β-barrel is composed of eight anti-parallel β-strands and capped by two α-helices at the top and bottom. In addition, the β-turns and loops in the strands contribute to the flexibility of the barrel. In particular, PPIB is a 21 kDa protein which contains a C-terminal ER retention motif that directs the protein to the ER organelle, while its N-terminal extension attaches it to its substrates.
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HOOK is a family of evolutionarily related proteins. This family consists of several HOOK1, 2 and 3 proteins from different eukaryotic organisms. The different members of the human gene family are HOOK1, HOOK2 and HOOK3. Different domains have been identified in the three human HOOK proteins, and it was demonstrated that the highly conserved N-terminal domain mediates attachment to microtubules, whereas the central coiled coil motif mediates homodimerisation and the more divergent C-terminal domains are involved in binding to specific organelles (organelle-binding domains).
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The Feulgen reaction is a semi-quantitative technique. If the only aldehydes remaining in the cell are those produced from the hydrolysis of DNA, then the technique is quantitative for DNA. It is possible to use an instrument known as a microdensitometer or microspectrophotometer to actually measure the intensity of the pink Feulgen reaction for a given organelle. Using this procedure, it was early determined that interphase cells were composed of two populations, those with diploid DNA and those with tetraploid DNA (two complete genomes).
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An unusual guide snoRNA U85 that functions in both 2'-O-ribose methylation and pseudouridylation of small nuclear RNA (snRNA) U5 has been identified. This composite snoRNA contains both C/D and H/ACA box domains and associates with the proteins specific to each class of snoRNA (fibrillarin and Gar1p, respectively). More composite snoRNAs have now been characterised. These composite snoRNAs have been found to accumulate in a subnuclear organelle called the Cajal body and are referred to as small Cajal body-specific RNAs.
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Crystal structure of Thermotoga maritima encapsulin. PDB entry Encapsulin nanocompartments, or encapsulin protein cages, are spherical bacterial organelle-like compartments roughly 25-30 nm in diameter that are involved in various aspects of metabolism, in particular protecting bacteria from oxidative stress. Encapsulin nanocompartments are structurally similar to the HK97 bacteriophage and their function depends on the proteins loaded into the nanocompartment. The sphere is formed from 60 (for a 25 nm sphere) or 180 (for a 30 nm sphere) copies of a single protomer, termed encapsulin.
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Over time, these GAGs collect in the cells, blood and connective tissues. The result is permanent, progressive cellular damage which affects appearance, physical abilities, organ and system functioning, and, in most cases, mental development. The mucopolysaccharidoses are part of the lysosomal storage disease family, a group of more than 40 genetic disorders that result when the lysosome organelle in animal cells malfunctions. The lysosome can be thought of as the cell's recycling center because it processes unwanted material into other substances that the cell can utilize.
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A descendant of this eukaryotic alga was then itself engulfed by a heterotrophic eukaryote with which it formed its own symbiotic relationship and was preserved as a plastid. The apicoplast evolved in its new role to preserve only those functions and genes necessary to beneficially contribute to the host-organelle relationship. The ancestral genome of more than 150 kb was reduced through deletions and rearrangements to its present 35 kb size. During the reorganization of the plastid the apicoplast lost its ability to photosynthesize.
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The SPG7 protein is a nuclear-encoded metalloprotease protein that is a member of the AAA protein family. Members of this protein family share an ATPase domain and have roles in diverse cellular processes including membrane trafficking, intracellular motility, organelle biogenesis, protein folding, and proteolysis. The SPG7 protein is a transmembrane protein that is located to the inner mitochondrial membrane, and is part of the m-AAA metalloproteinase complex, which constitutes one of the known intra-mitochondrial proteases that function in mitochondrial protein quality control.
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In an experimental setting if the left anterior descending coronary artery of the animal is ligated the downstream cardiac cellular mass is infarcted and will be injured and then die. If, on the other hand the tissue is subjected to IPC the downstream cellular mass will sustain only minimal to modest damage. IPC protects the tissue by initiating a cascade of biochemical events that allows for an up-regulation of the energetics of the tissue. The locus of this phenomenon is the intracellular organelle, the mitochondrion.
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Additionally, for a number of applications it is important to be able to acquire images in different colors at different exposure times. For example, to visualize exocytosis in TIRFM, very fast acquisition is necessary. However, to image a fluorescently labeled stationary organelle in the cell, low excitation is necessary to avoid photobleaching and as a result the acquisition has to be relatively slow. In this regard, the above implementation offers great flexibility, since different cameras can be used to acquire images in different channels.
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This research provided evidence for non-Mendelian uniparental inheritance; it also showed that there are multiple independent genetic systems in Chlamydomonas. She found further evidence when she mapped the streptomycin sensitivity/resistance trait and found a stable, nonchromosomal inheritance system that she proposed may have arisen before chromosomes. She was the first person to publish extensive genetic mapping of a cellular organelle. She joined Columbia University's zoology department as a research associate in 1955, supported by funding from the United States Public Health Service and the National Science Foundation.
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As the membrane of the phagosome is formed by the fusion of the plasma membrane, the basic composition of the phospholipid bilayer is the same. Endosomes and lysosomes then fuse with the phagosome to contribute to the membrane, especially when the engulfed particle is very big, such as a parasite. They also deliver various membrane proteins to the phagosome and modify the organelle structure. Phagosomes can engulf artificial low-density latex beads and then purified along a sucrose concentration gradient, allowing the structure and composition to be studied.
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According to the bulk flow hypothesis, genes are transferred to the nucleus following the disturbance of organelles. Disturbance was common in the early stages of endosymbiosis, however, once the host cell gained control of organelle division, eukaryotes could evolve to have only one plastid per cell. Having only one plastid severely limits gene transfer as the lysis of the single plastid would likely result in cell death. Consistent with this hypothesis, organisms with multiple plastids show an 80-fold increase in plastid-to-nucleus gene transfer compared with organisms with single plastids.
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It is important to understand the mechanisms and molecular contributors involved in genome organization, this is essential in order to fully comprehend the fundamental relationship between nuclear organization and genome function. Nuclear genes also play major roles in the expression of chloroplast genes. Vast amounts of nuclear genes are required for mRNA processing. The majority of proteins in a cell are the product of messenger RNA transcribed from nuclear genes, including most of the proteins of the organelles, which are produced in the cytoplasm like all nuclear gene products and then transported to the organelle.
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Adjacent to the nucleus, G. lamblia cells have an endoplasmic reticulum that extends through much of the cell. Trophozoites about to differentiate into cysts also contain prominent vesicles termed encystation-specific vesicles that disappear once cyst wall construction begins. Unlike most other eukaryotes, G. lamblia cells contain no visible mitochondria, but instead contains a substantially reduced metabolic organelle termed a mitosome. Additionally, cells appear to contain no Golgi bodies, and instead the secretory system consists entirely of the endoplasmic reticulum and numerous vesicles spread throughout the cell, termed peripheral vesicles.
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Chloroplasts alone make almost all of a plant cell's amino acids in their stroma except the sulfur-containing ones like cysteine and methionine. Cysteine is made in the chloroplast (the proplastid too) but it is also synthesized in the cytosol and mitochondria, probably because it has trouble crossing membranes to get to where it is needed. The chloroplast is known to make the precursors to methionine but it is unclear whether the organelle carries out the last leg of the pathway or if it happens in the cytosol.
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Some air conditioning systems use biomimicry in their fans to increase airflow while reducing power consumption. Technologists like Jas Johl have speculated that the functionality of vacuole cells could be used to design highly adaptable security systems. "The functionality of a vacuole, a biological structure that guards and promotes growth, illuminates the value of adaptability as a guiding principle for security." The functions and significance of vacuoles are fractal in nature, the organelle has no basic shape or size; its structure varies according to the requirements of the cell.
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The same year, Alex B. Novikoff from the University of Vermont visited de Duve's laboratory, and successfully obtained the first electron micrographs of the new organelle. Using a staining method for acid phosphatase, de Duve and Novikoff confirmed the location of the hydrolytic enzymes of lysosomes using light and electron microscopic studies. de Duve won the Nobel Prize in Physiology or Medicine in 1974 for this discovery. Originally, De Duve had termed the organelles the "suicide bags" or "suicide sacs" of the cells, for their hypothesized role in apoptosis.
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There is a fairly tight positive correlation between the presence of Cdc14 in a species and whether that species makes flagella or cilia. This may be related to the ancestral role of Cdc14. Whether flagella-anchoring basal bodies or centrioles involved in mitosis appeared first during evolution has been debated, but one theory is that flagella evolved first as a motility and sensory organelle, and the basal body was later co-opted into a mitotic role. The function of Cdc14 may have adapted to different functions during the evolution of those organelles.
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If both of these receptors have a high enough affinity to Listerias internalin A and B, then it will be able to invade the cell via an indirect zipper mechanism. Once phagocytosed, the bacterium is encapsulated by the host cell's acidic phagolysosome organelle. Listeria, however, escapes the phagolysosome by lysing the vacuole's entire membrane with secreted hemolysin, now characterized as the exotoxin listeriolysin O. The bacteria then replicate inside the host cell's cytoplasm. Listeria must then navigate to the cell's periphery to spread the infection to other cells.
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The discovery of Chromera velia and its unique plastid which is similar in origin to the apicoplasts, provides an important link in the evolutionary history of the apicomplexans. Previous to the description of C. velia, much speculation surrounded the idea of a photosynthetic ancestral lineage for apicomplexan parasites. For a step by step history of the characterization of the apicomplexan apicoplast organelle, see for example the web review by Vargas Parada (2010). It is hypothesized that apicomplexans, with their relic chloroplast, the apicoplast, were once able to synthesize energy via photosynthesis.
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TRP channels modulate ion entry driving forces and Ca2+ and Mg2+ transport machinery in the plasma membrane, where most of them are located. TRPs have important interactions with other proteins and often form signaling complexes, the exact pathways of which are unknown. TRP channels were initially discovered in the trp mutant strain of the fruit fly Drosophila which displayed transient elevation of potential in response to light stimuli and were so named transient receptor potential channels. TRPML channels function as intracellular calcium release channels and thus serve an important role in organelle regulation.
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This is extremely valuable to certain scientific disciplines, a dramatic example being the collection of meteorites that are left exposed in unparalleled numbers and excellent states of preservation. Sublimation is important in the preparation of certain classes of biological specimens for scanning electron microscopy. Typically the specimens are prepared by cryofixation and freeze-fracture, after which the broken surface is freeze-etched, being eroded by exposure to vacuum till it shows the required level of detail. This technique can display protein molecules, organelle structures and lipid bilayers with very low degrees of distortion.
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The process of mitochondrial fission is directed by Drp1, a member of the cytosolic dynamin family. This protein forms a spiral around mitochondria and constricts to break apart both the outer and inner membranes of the organelle. On the other hand, the process of fusion is directed by different membrane-anchored dynamin proteins at different levels of the mitochondria. Fusion at the level of the outer mitochondrial membrane is mediated by Mfn1 and Mfn2 (Mitofusins 1 and 2), and fusion at the level of the inner mitochondrial membrane is mediated by Opa1.
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Research has indicated the presence of magnetosome cells within human brain tissues. Biosynthesis of magnetite particles in vertebrates like mammals is implied to be similar to that observed in bacterial cells, although no evidence is provided. The difference between bacterial magnetosomes and human magnetosomes appears to be the number of magnetite particles synthesized per cell, the clustering of those particles within each respective organism, and the purpose of each magnetosome. A species of magnetosomic bacterial cell may have 20 magnetic particles arranged linearly in an organelle for each member of the species.
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The apical complex, which is actually a combination of organelles, is an important structure. It contains secretory organelles called rhoptries and micronemes, which are vital for mobility, adhesion, host cell invasion, and parasitophorous vacuole formation. As an apicomplexan, it harbours a plastid, an apicoplast, similar to plant chloroplasts, which they probably acquired by engulfing (or being invaded by) a eukaryotic alga and retaining the algal plastid as a distinctive organelle encased within four membranes. The apicoplast is involved in the synthesis of lipids and several other compounds and provides an attractive drug target.
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Skeletal muscle fiber, with sarcoplasmic reticulum colored in blue. The sarcoplasmic reticulum (SR), from the Greek σάρξ sarx ("flesh"), is smooth ER found in myocytes. The only structural difference between this organelle and the smooth endoplasmic reticulum is the medley of proteins they have, both bound to their membranes and drifting within the confines of their lumens. This fundamental difference is indicative of their functions: The endoplasmic reticulum synthesizes molecules, while the sarcoplasmic reticulum stores calcium ions and pumps them out into the sarcoplasm when the muscle fiber is stimulated.
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Many proteins are destined for other parts of the cell than the cytosol and a wide range of signalling sequences or (signal peptides) are used to direct proteins to where they are supposed to be. In prokaryotes this is normally a simple process due to limited compartmentalisation of the cell. However, in eukaryotes there is a great variety of different targeting processes to ensure the protein arrives at the correct organelle. Not all proteins remain within the cell and many are exported, for example, digestive enzymes, hormones and extracellular matrix proteins.
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Antibacterials can also affect the vaginal flora, and may lead to overgrowth of yeast species of the genus Candida in the vulvo-vaginal area. Additional side effects can result from interaction with other drugs, such as the possibility of tendon damage from the administration of a quinolone antibiotic with a systemic corticosteroid. Some antibiotics may also damage the mitochondrion, a bacteria-derived organelle found in eukaryotic, including human, cells. Mitochondrial damage cause oxidative stress in cells and has been suggested as a mechanism for side effects from fluoroquinolones.
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Most recently, Dr. Seenivasan working in conjunction with Professors Michael Melkonian (University of Cologne) and Linda Medlin (Marine Biological Association of the UK) formally described the picobiliphytes as the heterotrophic nanoflagellate phylum, Picozoa, and published thin sections of the cells. Several unique features in the cell, such as a feeding organelle, substantiate their unique phylogenetic position, an unusual movement, and heterotrophic mode of nutrition. No traces of viral or bacterial particles were found inside these heterotrophic cells, which prompted these authors to suggest that they feed on very small organic particles.
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Abnormal polypeptides that escape proteasome-dependent degradation and aggregate in cytosol can be transported via microtubules to an aggresome, a recently discovered organelle where aggregated proteins are stored or degraded by autophagy. Synphilin 1, a protein implicated in Parkinson disease, was used as a model to study mechanisms of aggresome formation. When expressed in naïve HEK293 cells, synphilin 1 forms multiple small highly mobile aggregates. However, proteasome or Hsp90 inhibition rapidly triggered their translocation into the aggresome, and surprisingly, this response was independent on the expression level of synphilin 1.
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PMEL is a 100 kDa type I transmembrane glycoprotein that is expressed primarily in pigment cells of the skin and eye. The transmembrane form of PMEL is modified in the secretory pathway by elaboration of N-linked oligosaccharides and addition and modification of O-linked oligosaccharides. It is then targeted to precursors of the pigment organelle, the melanosome, where it is proteolytically processed to several small fragments. Some of these fragments form non-pathological amyloid that assemble into sheets and form the striated pattern that underlies melanosomal ultrastructure.
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To date, the Freiburg Chair of Plant Biotechnology hosts an online database of Physcomitrella patens comprising the genomic sequence, annotated gene models and supplemental information.database cosmoss.org Due to its scientific and economic importance, the genome of Physcomitrella patens has been chosen as a "flagship plant genome" by the DOE JGI in 2010.Hudson Alpha Genome Sequencing Center on flagship plant genomes Also in 1998, Reski and coworkers generated a knockout moss by deleting an ftsZ gene and thus identified the first gene essential in the division of an organelle in any eukaryote.
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Mitochondria demonstrate kiss-and-run fusion in exchanging inner membrane materials. Studies using mitochondrial matrix-targeted green- photoactivated, red-fluorescent KFP and cyan-photoactivated, green- fluorescence PAGFP in rat cells have shown interactions where the KFP and PAGFP were transferred from one mitochondrion to another mitochondrion through transient fusion, suggesting a kiss-and-run mechanism. Unlike full fusion of mitochondria, which resulted in a single organelle, transient kiss-and-run fusion of two mitochondria resulted in two distinct membranes. Manipulation of the optic atrophy 1 (Opa1) gene had interesting effects on fusion between mitochondria.
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Peroxisomes can be derived from the endoplasmic reticulum under certain experimental conditions and replicate by membrane growth and division out of pre-existing organelles. Peroxisome matrix proteins are translated in the cytoplasm prior to import. Specific amino acid sequences (PTS or peroxisomal targeting signal) at the C-terminus (PTS1) or N-terminus (PTS2) of peroxisomal matrix proteins signals them to be imported into the organelle by a targeting factor. There are currently 36 known proteins involved in peroxisome biogenesis and maintenance, called peroxins , which participate in the process of peroxisome assembly in different organisms.
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The diverse functions of peroxisomes require dynamic interactions and cooperation with many organelles involved in cellular lipid metabolism such as the endoplasmic reticulum (ER), mitochondria, lipid droplets, and lysosomes. Peroxisomes interact with mitochondria in several metabolic pathways, including β-oxidation of fatty acids and the metabolism of reactive oxygen species. Both organelles are in close contact with the endoplasmic reticulum (ER) and share several proteins, including organelle fission factors. Peroxisomes also interact with the endoplasmic reticulum (ER) and cooperate in the synthesis of ether lipids (plasmalogens) which are important for nerve cells (see above).
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CoRR states that chloroplasts and mitochondria contain those genes whose expression is required to be under the direct, regulatory control of the redox state of their gene products, or of electron carriers with which those gene products interact. Such genes comprise a core, or primary subset, of organellar genes. The requirement for redox control of each gene in the primary subset then confers an advantage upon location of that gene within the organelle. Natural selection therefore anchors some genes in organelles, while favouring location of others in the cell nucleus.
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It is also noteworthy that the mitochondrion, the small membrane- bound intracellular organelle that is the site of eukaryotic oxygen-driven energy metabolism, arose from the endosymbiosis of a bacterium related to obligate intracellular Rickettsia, and also to plant-associated Rhizobium or Agrobacterium. Therefore, it is not surprising that all mitrochondriate eukaryotes share metabolic properties with these Proteobacteria. Most microbes respire (use an electron transport chain), although oxygen is not the only terminal electron acceptor that may be used. As discussed below, the use of terminal electron acceptors other than oxygen has important biogeochemical consequences.
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Current knowledge indicates mitosomes probably play a role in Fe-S cluster assembly, since they do not display any of the proteins involved in other major mitochondrial functions (aerobic respiration, haem biosynthesis) and they do display proteins required for Fe-S cluster biosynthesis (like frataxin, cysteine desulfurase, Isu1 and a mitochondrial Hsp70). Unlike mitochondria, mitosomes do not have genes within them. The genes for mitosomal components are contained in the nuclear genome. An early report suggested the presence of DNA in this organelle, but more recent research has shown this not to be the case.
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The fougaro system (Greek; Fougaro, chimney) is a sub-organelle system in the nucleus that may be a mechanism to recycle or remove molecules from the cell to the external medium. The molecules or peptides are ubiquitinated before being released from the nucleus of the cells. The ubiquitinated molecules are released independently or associated with endosomal proteins such as Beclin.Thomas S, Hoxha K, Alexander W, Gilligan J, Dilbarova R, Whittaker K, Kossenkov A, Prendergast GC, Mullin JM. Intestinal barrier tightening by a cell-penetrating antibody to Bin1, a candidate target for immunotherapy of ulcerative colitis.
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By that means, ORPs most likely affect organelle membrane lipid compositions, with impacts on signaling and vesicle transport, but also cellular lipid metabolism. Oxysterol is a cholesterol metabolite that can be produced through enzymatic or radical processes. Oxysterols, that are the 27-carbon products of cholesterol oxidation by both enzymic and non-enzymic mechanisms, constitute a large family of lipids involved in a plethora of physiological processes. Studies identifying the specific cellular targets of oxysterol indicate that several oxysterols may be regulators of cellular lipid metabolism via control of gene transcription.
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These inhibitory effects are seen most dramatically in actively proliferating cells such as in the gastrointestinal tract or the bone marrow. Protein synthesis occurs in both the cytoplasm of the cell as well as in the luminal space of mitochondria, the cytoplasmic organelle responsible for producing the cell's energy. This is done through an enzymatic pathway that generates highly oxidized molecules called reactive oxygen species, for example hydrogen peroxide. Reactive oxygen species can react with and cause damage to many critical parts of the cell including membranes, proteins, and DNA.
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Agrobacterium tumefaciens, from which it was originally discovered, uses this system to send the T-DNA portion of the Ti plasmid into plant cells, in which a crown gall (tumor) is produced as a result. Helicobacter pylori uses it for delivering CagA into gastric epithelial cells, to induce gastric cancer. Bordetella pertussis, the causative bacterium of whooping cough, secretes its pertussis toxin partly through T4SS. Legionella pneumophila that causes legionellosis (Legionnaires' disease) has a T4SS called icm/dot (intracellular multiplication/defect in organelle trafficking genes) that transport many bacterial proteins into its eukaryotic host.
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Protein accumulation in a Sec14p knockout is also accompanied by the formation of Berkeley bodies, an organelle unique to yeast consisting of cytoplasm enclosed by a double membrane. The presence of Berkeley bodies in Sec14p knockouts suggests Sec14p regulates or is involved in the uptake and reabsorption of certain vesicles by other organelles, such as the Golgi body, or the plasma membrane of the cell. The accumulation of both Berkeley bodies and proteins in the cytosol indicate that Sec14p is involved in the formation and degradation of anterograde vesicles of certain proteins.
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The MRC Mitochondrial Biology Unit (formerly the MRC Dunn Human Nutrition Unit) is a department of the School of Clinical Medicine at the University of Cambridge, funded through a strategic partnership between the Medical Research Council and the University. It is located at the Addenbrooke’s Hospital / Cambridge Biomedical Campus site in Cambridge, England. The unit is concerned with the study of the mitochondrion, as this organelle has a varied and critical role in many aspects of eukaryotic metabolism and is implicated in many metabolic, degenerative, and age-related human diseases.
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The phagosome moves along microtubules of the cytoskeleton, fusing with endosomes and lysosomes sequentially in a dynamic "kiss-and-run" manner. This intracellular transport depends on the size of the phagosomes. Larger organelles (with a diameter of about 3 µm) are transported very persistently from the cell periphery towards the perinuclear region whereas smaller organelles (with a diameter of about 1 µm) are transported more bidirectionally back and forth between cell center and cell periphery. Vacuolar proton pumps (v-ATPase) are delivered to the phagosome to acidify the organelle compartment, creating a more hostile environment for pathogens and facilitating protein degradation.
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Autophagosomes are different from phagosomes in that they are mainly used to selectively degrade damaged cytosolic organelles such as mitochondria (mitophagy). However, when the cell is starved or stressed, autophagosomes can also non-selectively degrade organelles to provide the cell with amino acids and other nutrients. Autophagy is not limited to professional phagocytes, it is first discovered in rat hepatocytes by cell biologist Christian de Duve. Autophagosomes have a double membrane, the inner one from the engulfed organelle, and the outer membrane is speculated to be formed from the endoplasmic reticulum or the ER-Golgi Intermediate Compartment (ERGIC).
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Although ciliopathies are usually considered to involve proteins that localize to motile and/or immotile (primary) cilia or centrosomes, it is possible for ciliopathies to be associated with unexpected proteins such as XPNPEP3, which localizes to mitochondria but is believed to affect ciliary function through proteolytic cleavage of ciliary proteins. Significant advances in understanding the importance of cilia were made in the mid-1990s. However, the physiological role that this organelle plays in most tissues remains elusive. Additional studies of how ciliary dysfunction can lead to such severe disease and developmental pathologies is still a subject of current research.
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Comparisons with their closest free living cyanobacteria of the genus Synechococcus (having a genome size 3 Mb, with 3300 genes) revealed that chromatophores underwent a drastic genome shrinkage. Chromatophores contained genes that were accountable for photosynthesis but were deficient in genes that could carry out other biosynthetic functions; this observation suggests that these endosymbiotic cells are highly dependent on their hosts for their survival and growth mechanisms. Thus, these chromatophores were found to be non-functional for organelle-specific purposes when compared with mitochondria and plastids. This distinction could have promoted the early evolution of photosynthetic organelles.
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Some of the endosymbionts lysed (burst), and high levels of DNA were incorporated into the nucleus. A similar mechanism is thought to occur in tobacco plants, which show a high rate of gene transfer and whose cells contain multiple chloroplasts. In addition, the bulk flow hypothesis is also supported by the presence of non- random clusters of organelle genes, suggesting the simultaneous movement of multiple genes. Molecular and biochemical evidence suggests that mitochondria are related to Rickettsiales proteobacteria (in particular, the SAR11 clade, or close relatives), and that chloroplasts are related to nitrogen-fixing filamentous cyanobacteria.
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Mitochondria of a mammal lung cell visualized using Transmission Electron Microscopy Mitochondria are organelles that synthesize ATP for the cell by metabolizing carbon-based macromolecules. The presence of deoxyribonucleic acid (DNA) in mitochondria and proteins, derived from mtDNA, suggest that this organelle may have been a prokaryote prior to its integration into the proto-eukaryote. Mitochondria are regarded as organelles rather than endosymbionts because mitochondria and the host cells share some parts of their genome, undergo mitosis simultaneously, and provide each other means to produce energy. Endomembrane system and nuclear membrane were hypothesized to have derived from the protomitochondria.
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Small GTPases of the RAB superfamily are recognized as key players of the protein machinery involved in vesicular transport and organelle dynamics in eukaryotic cells. RAB2B follows mainly exocytic pathways, from the endoplasmic reticulum to Golgi complex. RAB proteins are involved in docking and fusion of transport vesicles with their target membranes. These proteins associate with effector proteins (GARIL4 and GARIL5) to create complexes.left In order to do its biological function, RAB2B has to switch from the GDP form to the GTP form, and this is possible thanks to the catalysation of GEF proteins, which are guanine exchange factors.
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The fact that apicomplexans still keep their nonphotosynthetic chloroplast around demonstrates how the chloroplast carries out important functions other than photosynthesis. Plant chloroplasts provide plant cells with many important things besides sugar, and apicoplasts are no different—they synthesize fatty acids, isopentenyl pyrophosphate, iron-sulfur clusters, and carry out part of the heme pathway. This makes the apicoplast an attractive target for drugs to cure apicomplexan-related diseases. The most important apicoplast function is isopentenyl pyrophosphate synthesis—in fact, apicomplexans die when something interferes with this apicoplast function, and when apicomplexans are grown in an isopentenyl pyrophosphate-rich medium, they dump the organelle.
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In a large proportion (50–70%) of cases, the propensity for malignant hyperthermia is due to a mutation of the ryanodine receptor (type 1), located on the sarcoplasmic reticulum (SR), the organelle within skeletal muscle cells that stores calcium. RYR1 opens in response to increases in intracellular level mediated by L-type calcium channels, thereby resulting in a drastic increase in intracellular calcium levels and muscle contraction. RYR1 has two sites believed to be important for reacting to changing concentrations: the A-site and the I-site. The A-site is a high affinity binding site that mediates RYR1 opening.
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The extremely simple divisome, simple cell architecture, and ability to synchronize divisions in C. merolae makes it the perfect organism for studying mechanisms of eukaryotic cell and organelle division. Synchronization of the division of organelles in cultured cells can be very simple and usually involves the use of light and dark cycles. The chemical agent aphidicolin can be added to easily and effectively synchronize chloroplast division. The peroxisome division mechanism was first ascertained using C. merolae as a system, where peroxisome division can be synchronized using the microtubule-disrupting drug oryzalin in addition to light-dark cycles.
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The large, multinucleate foraminferan is characteristic for its lack of test and named for the network of connecting pseudopodia surrounding its central body mass. The organism has unique bidirectional cytoplasmic streaming throughout the anastomosing pseudopodia that is some of the fastest reported organelle transport observed. Reticulomyxa was first described in 1949 and is commonly used as a model organism for the unique transport of organelles throughout the cytoplasm of pseudopodia by cytoskeletal mechanisms. Only asexual reproduction of this genus has been observed in culture, but the genome possesses genes related to meiosis suggesting it is capable of sexually reproductive life stages.
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Axonemal dynein causes sliding of microtubules in the axonemes of cilia and flagella and is found only in cells that have those structures. Cytoplasmic dynein, found in all animal cells and possibly plant cells as well, performs functions necessary for cell survival such as organelle transport and centrosome assembly. Cytoplasmic dynein moves processively along the microtubule; that is, one or the other of its stalks is always attached to the microtubule so that the dynein can "walk" a considerable distance along a microtubule without detaching. Cytoplasmic dynein helps to position the Golgi complex and other organelles in the cell.
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The contraction of the contractile vacuole and the expulsion of water out of the cell is called systole. Water always flows first from outside the cell into the cytoplasm, and is only then moved from the cytoplasm into the contractile vacuole for expulsion. Species that possess a contractile vacuole typically always use the organelle, even at very hypertonic (high concentration of solutes) environments, since the cell tends to adjust its cytoplasm to become even more hyperosmotic than the environment. The amount of water expelled from the cell and the rate of contraction are related to the osmolarity of the environment.
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OSBP is the most extensively studied member of the oxysterol-binding protein (OSBP) related proteins family (ORP). It was first described as the cytoplasmic receptor for 25-hydroxycholesterol, and after more than 20 years it was shown that it's a cholesterol regulated protein in complex with ERK. Now, after the description of the structural basis for sterol sensing and transport, ORP protein family members are known to be essential for sterol signalling and sterol transport functions. Their peculiar structure is characterized by a conserved β-barrel sterol-binding fold with additional domains that can target multiple organelle membranes.
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Its meristematic activity is conveniently differentiated from the typical mechanism in that it is free of cross-walls, is not covered by mature laterals and its laterals all lie in the same plane, so new mass is added to the inner surface of the growing walls from transverse microfibrils (Green, 1960). The apical development and arrangement of transverse microfibrils play an important role in the lateral and longitudinal growth of the cell wall structure (Green, 1960). Chloroplasts and light-harvesting modulation The chloroplast is the largest organelle in the cell of Bryopsis (Lü et al., 2011).
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The ocelloid of warnowiids functions similarly to eyes found in much larger organisms, containing structures similar to a retina and lens. It is receptive only to the polarized light that is created as light passes through the thecal plates of other dinoflagellates. Because dinoflagellates are the main source of food for warnowiids, this trait is particularly useful for locating prey. A gene fragment that is expressed in the rhodopsin of the retinal body of the ocelloid has been shown to be most closely related to those of bacteria, suggesting a bacterial endosymbiont as the origin of the organelle.
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This protein complex is functionally similar to the TOM/TIM Complex located on the outer and inner membranes of the mitochondria, in the sense that it too transports proteins across multiple membranes and into the lumen of an organelle. Both complexes (TOC/TIC) are GTPases, that is, they must both hydrolyze GTP in order to power the translocation. The chloroplast also harnesses the power of an electrochemical gradient using protons. The gradient is only used to power transport across the thylakoid membrane, however, while the gradient in the mitochondria is used to power transport across its inner membrane.
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Recently there have been a few other magnetic compounds found but these are far less common and do not change the purpose of the organelle. Around twenty proteins have been found in magnetotactic bacteria that are specifically used for the creation of magnetosomes. These proteins are responsible for the control of vesicle formation, magnetosome ion transport, and the crystallization of the magnetites and their arrangement with in the particular vesicle. The arrangement of the magnetites is critical because individually they are not very strong, but when linked in an ordered chain they increase significantly in strength.
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The structure of the centrosome molecular components of a cell In cell biology, the centrosome (Latin centrum 'center' + Greek sōma 'body') is an organelle that serves as the main microtubule organizing center (MTOC) of the animal cell, as well as a regulator of cell-cycle progression. The centrosome is thought to have evolved only in the metazoan lineage of eukaryotic cells. Fungi and plants lack centrosomes and therefore use other structures to organize their microtubules. Although the centrosome has a key role in efficient mitosis in animal cells, it is not essential in certain fly and flatworm species.
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Golgi-derived vacuoles are shared by both organelles and supply each with molecules needed for its growth along with participating in NTC articulation. Organelles are located in proximity, but lie within different membranes and are separated by a passage, called “chute”. The nematocyst is a larger organelle and lies posterior to taeniocyst. Some recent research have shown that the work of two organelles is coupled, with the taeniocyst adhering to prey, followed by nematocyst discharge leading to prey puncturing and, lastly, retrieving the prey using a tow filament, located on the end of the nematocysts close to posterior vesicle.
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Microscopic techniques have revealed a lot about the glycosome in the cell and have indeed proven that there is a membrane-bound organelle in the cell for glycogen and its processes. Paul Erlich's findings as early as 1883 noted that from the microscope he could tell that glycogen in the cell was always found with what he called a carrier, later known to be protein. The glycogen itself was also always seen in the cell towards the lower pole in one group, fixed. When scientists tried to stain what was assumed was simple glycogen molecules, the staining had different outcomes.
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Tay–Sachs disease was the first of these disorders to be described, in 1881, followed by Gaucher disease in 1882. In the late 1950s and early 1960s, de Duve and colleagues, using cell fractionation techniques, cytological studies, and biochemical analyses, identified and characterized the lysosome as a cellular organelle responsible for intracellular digestion and recycling of macromolecules. This was the scientific breakthrough that would lead to the understanding of the physiological basis of the LSDs. Pompe disease was the first disease to be identified as an LSD in 1963, with L. Hers reporting the cause as a deficiency of α-glucosidase.
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This tool helped scientists to discover how the environment influences processes such as the orientation of the cell division axis, organelle positioning, cytoskeleton rearrangement cell differentiation and directionality of cell migration. Micropatterns can be made on a wide range of substrates, from glass to polyacrylamide and Polydimethylsiloxane (PDMS). The polyacrylamide and PDMS in particular come into handy because they let scientists specifically regulate the stiffness of the substrate, and they allow researchers to measure cellular forces (traction force microscopy). Advanced custom micropatterning allow precise and relatively rapid experiments controlling cell adhesion, cell migration, guidance, 3D confinement and microfabrication of microstructured chips.
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In 2006, she became a Howard Hughes Medical Institute professor. In 2011, she became a fellow of the American Society of Plant Biologists; in 2013, she became a fellow of the American Academy of Arts and Sciences; and in 2016 was elected a member of the National Academy of Sciences.2016 NAS Awards Announcement Bartel's research combines biochemical, cell biological, and genetic approaches to study plant signaling involving auxins and organelle homeostasis (primarily peroxisomes). While studying the enzymes that release auxin from precursor molecules, Bartel's laboratory discovered that the endoplasmic reticulum and peroxisomes compartmentalize auxin production pathways.
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Microscopic examination of retinal pigment epithelium and skin pigment cells (melanocytes) of people affected by ocular albinism type 1 reveal the presence of characteristic macromelanosomes, even though skin appears normal. Studies from Oa1 knock-out mice reveal that these giant melanosomes appear due to abnormal growth of a single melanosome and not due to aggregation or fusion of many melanosomes. These melanin macroglobules are probably formed due to failure of melanosomes to separate from the ER-golgi system with the accumulation of enzymes and other secretory proteins leading to an increase organelle size. However, Incerti, et al.
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Which cargo molecules are incorporated into a particular type of vesicle relies on specific interactions. Some of these interactions are directly with AP complexes and some are indirectly with "alternative adaptors", as shown in this diagram. As examples, membrane proteins can have direct interactions, while proteins that are soluble in the lumen of the donor organelle bind indirectly to AP complexes by binding to membrane proteins that traverse the membrane and bind at their lumenal end to the desired cargo molecule. Molecules that should not be included in the vesicle appear to be excluded by "molecular crowding".
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Ceramide-1-phosphate (C1P) is formed by the action of ceramide kinase (CK) enzymes on Cer. C1P carry ionic charge at neutral pH and contain two hydrophobic chains making it relatively insoluble in aqueous environment. Thus, C1P reside in the organelle where it was formed and is unlikely to spontaneously flip-flop across membrane bilayers. C1P activate phospholipase A2 and is found, along with CK, to be a mediator of arachidonic acid released in cells in response to a protein called interleukin-1β (IL-1β) and a lipid-soluble molecule that transports calcium ions (Ca2+) across the bilayer, also known as calcium ionophore.
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Ceramide can also be broken down by enzymes called ceramidases, leading to the formation of sphingosine, Moreover, a phosphate group can be attached to ceramide (phosphorylation) by the enzyme, ceramide kinase. It is also possible to regenerate sphingomyelin from ceramide by accepting a phosphocholine headgroup from phosphatidylcholine (PC) by the action of an enzyme called sphingomyelin synthase. The latter process results in the formation of diacylglycerol (DAG) from PC. Ceramide contains two hydrophobic ("water-fearing") chains and a neutral headgroup. Consequently, it has limited solubility in water and is restricted within the organelle where it was formed.
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Acidocalcisomes are rounded electron-dense acidic organelles, rich in calcium and polyphosphate and between 100 nm and 200 nm in diameter. Acidocalcisomes were originally discovered in Trypanosomes (the causing agents of sleeping sickness and Chagas disease) but have since been found in Toxoplasma gondii (causes toxoplasmosis), Plasmodium (malaria), Chlamydomonas reinhardtii (a green alga), Dictyostelium discoideum (a slime mould), bacteria and human platelets. Their membranes are 6 nm thick and contain a number of protein pumps and antiporters, including aquaporins, ATPases and Ca2+/H+ and Na+/H+ antiporters. They may be the only cellular organelle that has been conserved between prokaryotic and eukaryotic organisms.
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Transitional endoplasmic reticulum ATPase (TER ATPase) also known as valosin- containing protein (VCP) or p97 in mammals and CDC48 in S. cerevisiae, is an enzyme that in humans is encoded by the VCP gene. The TER ATPase is an ATPase enzyme present in all eukaryotes and archaebacteria. Its main function is to segregate protein molecules from large cellular structures such as protein assemblies, organelle membranes and chromatin, and thus facilitate the degradation of released polypeptides by the multi-subunit protease proteasome. p97/CDC48 is a member of the AAA+ (extended family of ATPases associated with various cellular activities) ATPase family.
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Stygiella /ˌstɪ.d͡ʒiˈɛ.lə/ is a genus of free-living marine flagellates belonging to the family Stygiellidae in the jakobids (excavata). The genus currently includes four species, all of which are secondary obligate anaerobes.. The species are all unicellular and crescent-shapedBernard, C, Simpson, A. G. B. & Patterson, D. J. (2000) Some free-living flagellates (protista) from anoxic habitats, Ophelia, 52:2, 113-142, DOI: 10.1080/00785236.1999.10409422.. All members possess hydrogenosomes, a type of acristate mitochondrion-derived organelle (MRO) that produces hydrogen gas as a metabolic productLeger, M. M., Eme, L., Hug, L. A., & Roger, A. J. (2016).
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The cloning method Campbell and Wilmut used to create Dolly constituted a breakthrough in scientific discovery. Known as somatic cell nuclear transfer, this process involves removing the nucleus of a regular body cell and implanting that nucleus into an egg cell that has had its cell nucleus removed. A nucleus is the organelle that holds a cell's genetic material (its DNA). Campbell and Wilmut found that if the donor, somatic cell is arrested in the stage of the cell cycle where it is dormant and non-replicating (the quiescent phase) prior to nuclear transfer, the resulting fused cell will develop into an embryo.
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The ERGIC lies between the rough endoplasmic reticulum (RER) and Golgi on the secretory pathway The vesicular-tubular cluster (VTC), also referred to as the endoplasmic-reticulum–Golgi intermediate compartment (ERGIC), is an organelle in eukaryotic cells. This compartment mediates trafficking between the endoplasmic reticulum (ER) and Golgi complex, facilitating the sorting of cargo. The cluster was first identified in 1988 using an antibody to the protein that has since been named ERGIC-53. In mammalian organisms, COPII vesicles that have budded from exit sites in the endoplasmic reticulum lose their coats and fuse to form the vesicular-tubular cluster (VTC).
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Willingham, M.C. and Pastan, I.: The visualization of fluorescent proteins in living cells by video intensification microscopy (VIM). Cell 13: 501-507, 1978Willingham, M.C. and Pastan, I.: The receptosome: An intermediate organelle or receptor-mediated endocytosis in cultured fibroblasts. Cell 21: 67-77, 1980 These studies identified the pathway by which growth factors enter cells and established a mechanism that helped explain down-regulation of receptors and the loss of growth factor responsiveness. Following the identification of the EGF receptor by Stanley Cohen, Pastan and colleagues made several seminal advances that identified the EGF receptor as a proto- oncogene.
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Two mitochondria from mammalian lung tissue displaying their matrix and membranes as shown by electron microscopy The mitochondrion (, plural mitochondria) is a semi autonomous double-membrane-bound organelle found in most eukaryotic organisms. Some cells in some multicellular organisms may, however, lack mitochondria (for example, mature mammalian red blood cells). A number of unicellular organisms, such as microsporidia, parabasalids, and diplomonads, have also reduced or transformed their mitochondria into other structures. To date, only one eukaryote, Monocercomonoides, is known to have completely lost its mitochondria, and one multicellular organism, Henneguya salminicola, is known to have retained mitochondrion-related organelles in association with a complete loss of their mitochondrial genome.
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His research in this field was often motivated by and tied to his work in microscopy and advancing the field of microcinematography. Investigating the dynamic properties of living cells demanded higher resolution light microscopy to record cellular structures in motion, which had to that point mainly been visible in static electron microscope photographs. These included pioneering work with the ultraviolet microscope in 1964 & 1987 introduction of video techniques to improve microscope resolution allowing the observation of the endoplasmic reticulum and organelle structure in living plant cells. This development of film techniques for dynamic cell processes led to an interest in science education and communication.
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Diagram of a human mitochondrion In genetics, a cytohet (or heteroplasmon) is a eukaryotic cell whose non-nuclear genome is heterozygous. The non-nucleic genome of eukaryotic cells exists in cytoplasmic organelles, namely the chloroplasts (only in plant cells) and the mitochondria (in all eukaryotic cells). Most of the genes in the mitochondria code for respiration-related proteins, and most of the genes in the chloroplasts code for photosynthesis- related proteins. The cytoplasmic genome, in contrast with the nucleic genome, exists in many copies in each cell: each cell contains numerous mitochondria and/or chloroplasts, and each such organelle contains multiple copies of its chromosome.
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The product of this gene is a component of the centrosome, a non-membraneous organelle that functions as the major microtubule-organizing center in animal cells. During interphase, the encoded protein localizes to the sub-distal appendages of mature centrioles, which are microtubule-based structures thought to help organize centrosomes. During mitosis, the protein associates with spindle microtubules near the centrosomes. The protein interacts with the intraflagellar transport protein 81 (IFT81), the SH3-domain containing protein PRAX-1, and is phosphorylated by cyclin dependent kinase 1 (Cdk1) and polo-like kinase 1 (PLK1), and functions in maintaining Microtubule organization, cell morphology and cilium stability.
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7x speed timelapse video of fish melanophores responding to 200uM adrenaline; the melanosomes retreat to the center of the star-shaped melanophore cells Fish and frog melanophores are cells that can change colour by dispersing or aggregating pigment-containing melanosomes. A melanosome is an organelle found in animal cells and is the site for synthesis, storage and transport of melanin, the most common light-absorbing pigment found in the animal kingdom. Melanosomes are responsible for color and photoprotection in animal cells and tissues. Melanosomes are synthesised in the skin in melanocyte cells, as well as the eye in choroidal melanocytes and retinal pigment epithelial (RPE) cells.
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As it forces its way into the host cell, the parasite forms a parasitophorous vacuole (PV) membrane from the membrane of the host cell. The PV encapsulates the parasite, and is both resistant to the activity of the endolysosomal system, and can take control of the host's mitochondria and endoplasmic reticulum. When first invading the cell, the parasite releases ROP proteins from the bulb of the rhoptry organelle. These proteins translocate to the nucleus and the surface of the PV membrane where they can activate STAT pathways to modulate the expression of cytokines at the transcriptional level, bind and inactivate PV membrane destroying IRG proteins, among other possible effects.
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The centriole, an organelle involved in cell division, is structurally inherited. Structural inheritance or cortical inheritance is the transmission of an epigenetic trait in a living organism by a self-perpetuating spatial structures. This is in contrast to the transmission of digital information such as is found in DNA sequences, which accounts for the vast majority of known genetic variation. Examples of structural inheritance include the propagation of prions, the infectious proteins of diseases such as scrapie (in sheep and goats), bovine spongiform encephalopathy ('mad cow disease') and Creutzfeldt–Jakob disease (although the protein-only hypothesis of prion transmission has been considered contentious until recently).
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There are several reasons why it is possible that the N-end rule functions in the chloroplast organelle of plant cells as well. The first piece of evidence comes from the endosymbiotic theory which encompasses the idea that chloroplasts are derived from cyanobacteria, photosynthetic organisms that can convert light into energy. It is thought that the chloroplast developed from an endosymbiosis between a eukaryotic cell and a cyanobacterium, because chloroplasts share several features with the bacterium, including photosynthetic capabilities. The bacterial N-end rule is already well documented; it involves the Clp protease system which consists of the adaptor protein ClpS and the ClpA/P chaperone and protease core.
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50px Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. Chloroplasts (from the Greek chloros for green, and plastes for "the one who forms") are organelles that conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules while freeing oxygen from water in plant and algal cells. They then use the stored energy to make organic molecules from carbon dioxide in a process known as the Calvin cycle. A chloroplast is a type of organelle known as a plastid, characterized by its two membranes and a high concentration of chlorophyll.
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Magnetotactic bacteria are widespread, motile, diverse prokaryotes that biomineralize a unique organelle called the magnetosome. A magnetosome consists of a nano-sized crystal of a magnetic iron mineral, which is enveloped by a lipid bilayer membrane. In the cells of most all magnetotactic bacteria, magnetosomes are organized as well-ordered chains. The magnetosome chain causes the cell to behave as a motile, miniature compass needle where the cell aligns and swims parallel to magnetic field lines. The magnetic dipole moment of the cell is often large enough that its interaction with Earth’s magnetic field overcomes the thermal forces that tend to randomize the orientation of the cell in its aqueous surroundings.
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The lack of a cell wall also calls for increased support of the cell membrane(reinforced with sterols), which includes a rigid cytoskeleton composed of an intricate protein network and, potentially, an extracellular capsule to facilitate adherence to the host cell. M. pneumoniae are the only bacterial cells that possess cholesterol in their cell membrane (obtained from the host) and possess more genes that encode for membrane lipoprotein variations than other mycoplasmas, which are thought to be associated with its parasitic lifestyle. M. pneumoniae cells also possess an attachment organelle, which is used in the gliding motility of the organism by an unknown mechanism.
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Some of the enzymes involved in these salvage pathways appear to be concentrated in the cell nucleus, which may compensate for the high level of reactions that consume NAD in this organelle. There are some reports that mammalian cells can take up extracellular NAD from their surroundings, and both nicotinamide and nicotinamide riboside can be absorbed from the gut. The salvage pathways used in microorganisms differ from those of mammals. Some pathogens, such as the yeast Candida glabrata and the bacterium Haemophilus influenzae are NAD auxotrophs – they cannot synthesize NAD – but possess salvage pathways and thus are dependent on external sources of NAD or its precursors.
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Consequently, many of the proteins found in the cisternal space of the endoplasmic reticulum lumen are there only temporarily as they pass on their way to other locations. Other proteins, however, constantly remain in the lumen and are known as endoplasmic reticulum resident proteins. These special proteins contain a specialized retention signal made up of a specific sequence of amino acids that enables them to be retained by the organelle. An example of an important endoplasmic reticulum resident protein is the chaperone protein known as BiP which identifies other proteins that have been improperly built or processed and keeps them from being sent to their final destinations.
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Kinetoplastida (or Kinetoplastea, as a class) is a group of flagellated protists belonging to the phylum Euglenozoa, and characterised by the presence of an organelle with a large massed DNA called kinetoplast (hence the name). The organisms are commonly referred to as "kinetoplastids" or "kinetoplasts" The group includes a number of parasites responsible for serious diseases in humans and other animals, as well as various forms found in soil and aquatic environments. Their distinguishing feature, the presence of a kinetoplast, is an unusual DNA-containing granule located within the single mitochondrion associated with the base of the cell's flagellum (the basal body). The kinetoplast contains many copies of the mitochondrial genome.
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Their integrity as a closed, bilayer structure, that could release its contents after detergent treatment (structure-linked latency) was established by Bangham, Standish and Weissmann in the next year. Weissmann - during a Cambridge pub discussion with Bangham - first named the structures "liposomes" after the lysosome, which his laboratory had been studying: a simple organelle the structure-linked latency of which could be disrupted by detergents and streptolysins. Liposomes can be easily distinguished from micelles and hexagonal lipid phases by negative staining transmission electron microscopy. Alec Douglas Bangham with colleagues Jeff Watkins and Malcolm Standish wrote the 1965 paper that effectively launched the liposome “industry”.
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She has described the emergence of shape and patterns in membranes and in multicomponent complex mixtures. She and her students and postdocs discovered that electrostatics leads to spontaneous symmetry breaking in ionic membranes such as viral capsids (for which they were awarded the 2007 Cozzarelli Prize) and in fibers. They also demonstrated the spontaneous emergence of various regular and irregular polyhedral geometries in closed membranes with non-homogeneous elastic properties such as bacterial microcompartments, including carboxysomes, via a mechanism that explains observed shapes in crystalline shells formed by more than one component such as archaea and organelle wall envelopes as well as in ionic vesicles.
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While most infections clear up spontaneously, treatment with tetracycline or doxycycline appears to reduce the symptomatic duration and reduce the likelihood of chronic infection. A combination of erythromycin and rifampin is highly effective in curing the disease, and vaccination with Q-VAX vaccine (CSL) is effective for prevention of it. The bacteria use a type IVB secretion system known as Icm/Dot (intracellular multiplication / defect in organelle trafficking genes) to inject over 100 effector proteins into the host. These effectors increase the bacteria's ability to survive and grow inside the host cell by modulating many host cell pathways, including blocking cell death, inhibiting immune reactions, and altering vesicle trafficking.
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The differences between the bacterial and eukaryotic ribosomes are exploited by pharmaceutical chemists to create antibiotics that can destroy a bacterial infection without harming the cells of the infected person. Due to the differences in their structures, the bacterial 70S ribosomes are vulnerable to these antibiotics while the eukaryotic 80S ribosomes are not. Even though mitochondria possess ribosomes similar to the bacterial ones, mitochondria are not affected by these antibiotics because they are surrounded by a double membrane that does not easily admit these antibiotics into the organelle. A noteworthy counterexample, however, includes the antineoplastic antibiotic chloramphenicol, which successfully inhibits bacterial 50S and mitochondrial 50S ribosomes.
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Eisosomes ('eis' meaning into or portal and 'soma', meaning body) are large, heterodimeric, immobile protein complexes at the plasma membrane which mark the site of endocytosis in some eukaryotes, and were discovered in the yeast Saccharomyces cerevisiae in 2006. Currently, seven genes: Pil1, Lsp1 and Sur7, Eis1, Seg1 and Ygr130C, Seg2,Seger S and Philippsen P (2010), Personal Communication to SGD are annotated to the formation of the proteins identified in eisosomes. These organelle-like structures have put to rest the idea that sites of endocytosis in cells are chosen at random. Eisosomes have a profound role in regulating plasma membrane architecture and organization in yeast.
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Semi-biotic systems are systems that incorporate biologically derived components/modules – which could range from multi-protein complexes through DNA constructs to multi-cellular assemblies – and integrate them with synthetic components (e.g. microfabricated systems) to produce hybrid devices. One of the potential attractions of these hybrid devices is the possibility that they can be designed to exhibit higher degrees of adaptability and autonomy than is possible with solid-state devices. Examples include: artificial organelle-like systems that could accomplish the synthesis of complex biomacromolecules, or synthetic multi-cellular structures that incorporate specific sensing and reporting functionalities, such that they could be used in hybrid devices for chemical or biological agent sensing.
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The dyadic space is the name for the volume of cytoplasm between pairs (dyads) of areas where the cell membrane and an organelle such as the endoplasmic reticulum (or sarcoplasmic reticulum) come into close contact (within 10-12 nanometers ) of each other, creating what are known as dyadic clefts. The space is important for ionic signalling. For example, the phenomenon of calcium-induced calcium release, when extracellular calcium enters the cell through ion channels in T-Tubules, leading to a rapidly increased calcium concentration in the dyadic space, triggering ryanodine receptors on the sarcoplasmic reticulum to release more calcium and trigger cardiac myocyte contraction - the heart beat.
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Its amorphous and fibrous structure occurred in drawings as early as in 1933 (Risley). Today, the nuage is accepted to represent a characteristic, electrondense germ plasm organelle encapsulating the cytoplasmic face of the nuclear envelope of the cells destined to the germline fate. The same granular material is also known under various synonyms: dense bodies, mitochondrial clouds, yolk nuclei, Balbiani bodies, perinuclear P granules in Caenorhabditis elegans, germinal granules in Xenopus laevis, chromatoid bodies in mice, and polar granules in Drosophila. Molecularly, the nuage is a tightly interwoven network of differentially localized RNA-binding proteins, which in turn localize specific mRNA species for differential storage, asymmetric segregation (as needed for asymmetric cell division), differential splicing and/or translational control.
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Starch granules are very common in chloroplasts, typically taking up 15% of the organelle's volume, though in some other plastids like amyloplasts, they can be big enough to distort the shape of the organelle. Starch granules are simply accumulations of starch in the stroma, and are not bounded by a membrane. Starch granules appear and grow throughout the day, as the chloroplast synthesizes sugars, and are consumed at night to fuel respiration and continue sugar export into the phloem, though in mature chloroplasts, it is rare for a starch granule to be completely consumed or for a new granule to accumulate. Starch granules vary in composition and location across different chloroplast lineages.
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A transporter protein on the cells of the small bowel, copper membrane transporter 1 (Ctr1; SLC31A1), carries copper inside the cells, where some is bound to metallothionein and part is carried by ATOX1 to an organelle known as the trans-Golgi network. Here, in response to rising concentrations of copper, an enzyme called ATP7A (Menkes' protein) releases copper into the portal vein to the liver. Liver cells also carry the CMT1 protein, and metallothionein and ATOX1 bind it inside the cell, but here it is ATP7B that links copper to ceruloplasmin and releases it into the bloodstream, as well as removing excess copper by secreting it into bile. Both functions of ATP7B are impaired in Wilson's disease.
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Oleosins are structural proteins found in vascular plant oil bodies and in plant cells. Oil bodies are not considered organelles because they have a single layer membrane and lack the pre-requisite double layer membrane in order to be considered an organelle. They are found in plant parts with high oil content that undergo extreme desiccation as part of their maturation process, and help stabilize the bodies. Oleosins are proteins of 16 kDa to 24 kDa and are composed of three domains: an N-terminal hydrophilic region of variable length (from 30 to 60 residues); a central hydrophobic domain of about 70 residues and a C-terminal amphipathic region of variable length (from 60 to 100 residues).
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Breviata anathema is a single-celled flagellate amoeboid eukaryote, previously studied under the name Mastigamoeba invertens. The cell lacks mitochondria but has remnant mitochondrial genes, and possesses an organelle believed to be a modified anaerobic mitochondrion, similar to the mitosomes and hydrogenosomes found in other eukaryotes that live in low-oxygen environments. Early molecular data placed Breviata in the Amoebozoa, but without obvious affinity to known amoebozoan groups. More recently, phylogenomic analysis has shown that the class Breviatea is a sister group to the Opisthokonta and Apusomonadida. Together, these three groups form the clade Obazoa (the term Obazoa is based on an acronym of Opisthokonta, Breviatea, and Apusomonadida, plus ‘zóa’ (pertaining to ‘life’ in Greek)).
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Near-field imaging techniques, such as Atomic Force Microscopy (AFM) could also provide with structural information, which however, is limited only to samples on the surface. FPM is capable of imaging orientations in dynamic samples at the time scale of seconds or milliseconds, thus it can serve as a complementary method for measurement of subcellular organelle structures. FPM has been evolving during past decades, from manual or mechanical switching of polarization detection or excitation to simultaneously detection and fast polarization modulation via electro-optic devices. With faster imaging speed and higher imaging quality, FPM has been incorporated with various imaging modalities, such as wide-field, confocal microscopy, two-photon confocal, total internal reflection fluorescence microscope, FRAP, etc.
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Cell division, growth & proliferation Cell growth refers to an increase in the total mass of a cell, including both cytoplasmic, nuclear and organelle volume. Cell growth occurs when the overall rate of cellular biosynthesis (production of biomolecules or anabolism) is greater than the overall rate of cellular degradation (the destruction of biomolecules via the proteasome, lysosome or autophagy, or catabolism). Cell growth is not to be confused with cell division or the cell cycle, which are distinct processes that can occur alongside cell growth during the process of cell proliferation, where a cell, known as the "mother cell", grows and divides to produce two "daughter cells". Importantly, cell growth and cell division can also occur independently of one another.
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TMEM143 expression in Humans and other primates; In humans, the heart and skeletal muscle exhibit high expression (18.8 and 16.4, respectively) Possible human expression of TMEM143 protein occurs in Jurkat cells (T lymphocyte). Organelle association puts TMEM143 in the mitochondria as an integral protein in the membrane, as well as the predicted of presence in the plasma membrane, endoplasmic reticulum, extracellular matrix and the Golgi apparatus. High expression has been found in the heart and skeletal muscle, as indicated through human expression profiling. Microarray expression of normal human tissues also predict expression in the heart and skeletal muscle, a 95-97 percentile rank (amongst other tissues tested for normal human expression of TMEM143).
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The analysis of this sub organelle organisation of the cell requires techniques conserving the native state of the protein complexes. In native polyacrylamide gel electrophoresis (native PAGE), proteins remain in their native state and are separated in the electric field following their mass and the mass of their complexes respectively. To obtain a separation by size and not by net charge, as in IEF, an additional charge is transferred to the proteins by the use of Coomassie Brilliant Blue or lithium dodecyl sulfate. After completion of the first dimension the complexes are destroyed by applying the denaturing SDS- PAGE in the second dimension, where the proteins of which the complexes are composed of are separated by their mass.
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Since the position of the large nucleus (dinokaryon), shape of the eye spot, and the number and shape of chloroplasts may vary among species, the most reliable method of identification is to observe tabulation pattern of thecal plate. The most interesting feature of Durinskia is the presence of its tertiary plastid which originated from a pennate diatom. Durinskia’s tertiary plastid is sometimes confused with the tertiary plastid in Peridiniopsis penardii, which originated from a centric diatom since both plastids have four membranes. As a reminder, a plastid is an endosymbiont that has been incorporated into the host as an essential organelle, and a pennate diatom is elongated in valve view whereas a centric diatom is circular.
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Even the most careful fixation does alter the sample and introduce artifacts that can interfere with interpretation of cellular ultrastructure. A prominent example is the bacterial mesosome, which was thought to be an organelle in gram-positive bacteria in the 1970s, but was later shown by new techniques developed for electron microscopy to be simply an artifact of chemical fixation. Standardization of fixation and other tissue processing procedures takes this introduction of artifacts into account, by establishing what procedures introduce which kinds of artifacts. Researchers who know what types of artifacts to expect with each tissue type and processing technique can accurately interpret sections with artifacts, or choose techniques that minimize artifacts in areas of interest.
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Cell scheme. 1-haptonema, 2-flagella, 3-mitochondrion, 4-Golgi apparatus, 5-nucleus, 6-scales, 7-chrysolaminarin vacuole, 8-plastid, 9-ribosomes, 10-stigma, 11-endoplasmic reticulum, 12-chloroplast endoplasmic reticulum, 13-pyrenoid, 14-thylakoids. The chloroplasts are pigmented similarly to those of the heterokonts, but the structure of the rest of the cell is different, so it may be that they are a separate line whose chloroplasts are derived from similar red algal endosymbionts. The cells typically have two slightly unequal flagella, both of which are smooth, and a unique organelle called a haptonema, which is superficially similar to a flagellum but differs in the arrangement of microtubules and in its use.
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For instance, the malaria parasite Plasmodium feeds by pinocytosis during its immature trophozoite stage of life (ring phase), but develops a dedicated feeding organelle (cytostome) as it matures within a host's red blood cell. Paramecium bursaria, a ciliate which derives some of its nutrients from algal endosymbionts in the genus Chlorella Protozoa may also live as mixotrophs, supplementing a heterotrophic diet with some form of autotrophy. Some protozoa form close associations with symbiotic photosynthetic algae, which live and grow within the membranes of the larger cell and provide nutrients to the host. Others practice kleptoplasty, stealing chloroplasts from prey organisms and maintaining them within their own cell bodies as they continue to produce nutrients through photosynthesis.
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While working on Nerve growth factor (NGF) receptors as a graduate student, Vale became interested in exploring the mechanism of how receptors and other molecules are transported in nerve axons. He then heard of the research of Michael Sheetz and James Spudich, who used a video camera on a microscope to film myosin-coated beads moving along actin filaments. In 1983, Vale and Sheetz decided to test whether the movement of myosin on actin was the source for organelle transport in axons, using the squid giant axon as a model. However, since no squid were caught that year at Stanford's Hopkins Marine Station, following Shooter's approval, they went to the Marine Biological Laboratory instead.
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The molecular mass of a diploid SPB, including microtubules and microtubule associated proteins, is estimated to be 1–1.5 GDa whereas a core SPB is 0.3–0.5 GDa. The SPB is a cylindrical multilayer organelle. These layers are: an outer plaque (OP), which connects to the cytoplasmic microtubules (cMT); a first intermediate layer (IL1) and an electrondense second intermediate layer (IL2); an electrondense central plaque (CP), which is at the level of the nuclear envelope and is connected to it by hook-like structures, an ill-defined inner plaque (IP); and a layer of the inner plaque that contains capped nuclear microtubules (nMT) ends. The central plaque and IL2 appeared as distinct but highly ordered layers.
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Similarly, the bacterial species involved in this eukaryogenesis retained its capacity to produce energy in the form of ATP while also passing much of its genetic information into this new virus-nucleus organelle. It is hypothesized that the modern cell cycle, whereby mitosis, meiosis, and sex occur in all eukaryotes, evolved because of the balances struck by viruses, which characteristically follow a pattern of tradeoff between infecting as many hosts as possible and killing an individual host through viral proliferation. Hypothetically, viral replication cycles may mirror those of plasmids and viral lysogens. However, this theory is controversial, and additional experimentation involving archaeal viruses is necessary, as they are probably the most evolutionarily similar to modern eukaryotic nuclei.
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General schema showing the relationships of the genome, transcriptome, proteome, and metabolome (lipidome). The metabolome refers to the complete set of small-molecule chemicals found within a biological sample. The biological sample can be a cell, a cellular organelle, an organ, a tissue, a tissue extract, a biofluid or an entire organism. The small molecule chemicals found in a given metabolome may include both endogenous metabolites that are naturally produced by an organism (such as amino acids, organic acids, nucleic acids, fatty acids, amines, sugars, vitamins, co-factors, pigments, antibiotics, etc.) as well as exogenous chemicals (such as drugs, environmental contaminants, food additives, toxins and other xenobiotics) that are not naturally produced by an organism.
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The process mainly depends on the time mtDNA transfers into the nucleus. As shown in figure 2b, direct integration of unedited mtDNA fragments into the nuclear genomes is the most plausible and the evidence both found in plants, Arabidopsis genome, and animals with the help of different methods, including BLAST-based analysis. In this case, mtDNA is transferred into the nucleus whereby editing and introns arise in the mitochondrion later. If a gene, for instance, was transferred to the nucleus in one lineage before mitochondrial editing evolved, but remained in the organelle in other lineages where editing arose, the nuclear copy would appear more similar to an edited transcript than to the remaining mitochondrial copies at the edited sites.
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Cell-penetrating peptides are of different sizes, amino acid sequences, and charges but all CPPs have one distinct characteristic, which is the ability to translocate the plasma membrane and facilitate the delivery of various molecular cargoes to the cytoplasm or an organelle. There has been no real consensus as to the mechanism of CPP translocation, but the theories of CPP translocation can be classified into three main entry mechanisms: direct penetration in the membrane, endocytosis- mediated entry, and translocation through the formation of a transitory structure. CPP transduction is an area of ongoing research. Cell-penetrating peptides (CPP) are able to transport different types of cargo molecules across plasma membrane; thus, they act as molecular delivery vehicles.
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She is also a pioneer in developing live cell imaging techniques to study the dynamic interactions of molecules in cells, including photobleaching and photoactivation techniques which allow investigation of subcellular localization, mobility, transport routes, and turnover of important cellular proteins related to membrane trafficking and compartmentalization. Lippincott-Schwartz's lab also tests mechanistic hypotheses related to protein and organelle functions and dynamics by utilizing quantitative measurements through kinetic modeling and simulation experiments. Along with Dr. Craig Blackstone, Lippincott-Schwartz utilized advanced imaging techniques to reveal a more accurate picture of how the peripheral endoplasmic reticulum is structured. Their findings may yield new insights for genetic diseases affecting proteins that help shape the endoplasmic reticulum.
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Other proteins implicated in scaffolding likewise have functions independent of structural tethering at the MAM; for example, ER-resident and mitochondrial-resident mitofusins form heterocomplexes that regulate the number of inter-organelle contact sites, although mitofusins were first identified for their role in fission and fusion events between individual mitochondria. Glucose-related protein 75 (grp75) is another dual-function protein. In addition to the matrix pool of grp75, a portion serves as a chaperone that physically links the mitochondrial and ER Ca2+ channels VDAC and IP3R for efficient Ca2+ transmission at the MAM. Another potential tether is Sigma-1R, a non-opioid receptor whose stabilization of ER-resident IP3R may preserve communication at the MAM during the metabolic stress response.
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The hydrophobicity hypothesis states that highly hydrophobic (water hating) proteins (such as the membrane bound proteins involved in redox reactions) are not easily transported through the cytosol and therefore these proteins must be encoded in their respective organelles. The code disparity hypothesis states that the limit on transfer is due to differing genetic codes and RNA editing between the organelle and the nucleus. The redox control hypothesis states that genes encoding redox reaction proteins are retained in order to effectively couple the need for repair and the synthesis of these proteins. For example, if one of the photosystems is lost from the plastid, the intermediate electron carriers may lose or gain too many electrons, signalling the need for repair of a photosystem.
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A nuclear gene is a gene located in the cell nucleus of a eukaryote. The term is used to distinguish nuclear genes from the genes of the endosymbiotic organelle, that is genes in the mitochondrion, and in case of plants and algae, the chloroplast, which host their own genetic system and can produce proteins from scratch. Eukaryotic genomes have distinct higher-order chromatin structures that are closely packaged and ultimately organized in a certain construct that functionally relates to gene expression. These cells function to package the genome "several thousand-fold into the confines of the cell nucleus," ensuring the maintenance of the gene accessibility along with chromatin structure, which accommodate highly dynamic processes such as: gene transcription, replication, and DNA repair.
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Antibodies to these specific antigens have been associated with a number of conditions:Berg PA, Klein R (1986) Mitochondrial antigens and autoantibodies: from anti-M1 to anti-M9. Klin Wochenschr 64(19):897-909 anti M2, M4, M8, and M9 are associated with primary biliary cirrhosis; M2 – autoimmune hepatitis; M1 – syphilis; M3 – drug-induced lupus erythematosus; M6 – drug-induced hepatitis; M7 – cardiomyopathy, myocarditis; M5 – systemic lupus erythematosus and undifferentiated collagenosis, autoimmune haemolytic anaemia.Labro MT, Andrieu MC, Weber M, Homberg JC (1976) A new pattern of non-organ- and non-species-specific anti- organelle antibody detected by immunofluorescence: the mitochondrial antibody number 5. Clin Exp Immunol 31(3):357-366 These associations are not completely specific and should not be relied upon solely for diagnosis.
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Schematic representation of a Euglena cell with red eyespot (9) Schematic representation of a Chlamydomonas cell with chloroplast eyespot (4) The eyespot apparatus (or stigma) is a photoreceptive organelle found in the flagellate or (motile) cells of green algae and other unicellular photosynthetic organisms such as euglenids. It allows the cells to sense light direction and intensity and respond to it, prompting the organism to either swim towards the light (positive phototaxis), or away from it (negative phototaxis). A related response ("photoshock" or photophobic response) occurs when cells are briefly exposed to high light intensity, causing the cell to stop, briefly swim backwards, then change swimming direction. Eyespot-mediated light perception helps the cells in finding an environment with optimal light conditions for photosynthesis.
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This mode of feeding could be unique in the animal kingdom: the particles, collected in a slime layer, are drawn through the intercellular gaps (cellular interstices) of the epitheloid by the fibre cells and then digested by phagocytosis ("cell-eating"). Such "collecting" of nutrient particles through an intact tegument is only possible because some "insulating" elements (specifically, a basal lamina under the epitheloid and certain types of cell-cell junctions) are not present in the Placozoa. Not all bacteria in the interior of Placozoa are digested as food: in the endoplasmic reticulum, an organelle of the fibre syncytium, bacteria are frequently found that appear to live in symbiosis with Trichoplax adhaerens. In particular it has been proposed that there is a rickettsial endosymbiont.
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Due to the permanent inhibition of the individual proton pump that each molecule of rabeprazole has bound to, acid secretion is effectively suppressed until new proton pumps are produced by the parietal cells. Rabeprazole, like other medications in the same class, cannot inhibit the H+/K+ ATPase pumps found in lysosomes, a cellular organelle that degrades biological molecules, because the pumps found in these organelles lack the cysteine residues involved in rabeprazole's mechanism of action. A unique feature of rabeprazole's mechanism of action in inhibiting acid secretion involves its activation. The pKa (the pH at which 50% of the drug becomes positively charged) of rabeprazole is around 5.0, meaning that it doesn't take a lot of acid to activate it.
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Small's research focus is organelle biogenesis and molecular regulation of lipid metabolism; she has published and lectured widely in this area. Previously, Small served on the faculty at the University of Florida (1988), where she led her own independent research program to study peroxisome biogenesis and the molecular regulation of lipid metabolism. In 1992, she became a faculty member at Mount Sinai School of Medicine in New York, where she directed a laboratory as well as served as Director of the Interdisciplinary Graduate Program in Molecular, Cellular, and Developmental Biology. At CUNY, Small was instrumental in redesigning doctoral education in the sciences and in enhancing the University’s scientific research infrastructure. She established CUNY’s first Postdoctoral Program for postdoctoral fellows across the University and the Technology Commercialization office.
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However, although it is clear that lipid transport is a central process in organelle biogenesis, the mechanisms by which lipids are transported through cells remain poorly understood. The first proposal that the membranes within cells form a single system that exchanges material between its components was by Morré and Mollenhauer in 1974. This proposal was made as a way of explaining how the various lipid membranes are assembled in the cell, with these membranes being assembled through lipid flow from the sites of lipid synthesis. The idea of lipid flow through a continuous system of membranes and vesicles was an alternative to the various membranes being independent entities that are formed from transport of free lipid components, such as fatty acids and sterols, through the cytosol.
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This leads to an increase in cytoplasmic calcium concentration, which improves cardiac contractility. Under normal physiological conditions, the cytoplasmic calcium used in cardiac contractions originates from the sarcoplasmic reticulum, an intracellular organelle that specializes in the storage of calcium. Human newborns, some animals, and patients with chronic heart failure lack well developed and fully functioning sarcoplasmic reticula and must rely on the Na/Ca exchanger to provide all or a majority of the cytoplasmic calcium required for cardiac contraction. For this to occur, cytoplasmic sodium must exceed its typical concentration to favor a reversal in potential, which naturally occurs in human newborns and some animals primarily through an elevated heart rate; in patients with chronic heart failure it occurs through the administration of digitalis.
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Genetic and ultrastructural evidence place the Phaeophyceae among the heterokonts (Stramenopiles), a large assemblage of organisms that includes both photosynthetic members with plastids (such as the diatoms) as well as non-photosynthetic groups (such as the slime nets and water molds). Although some heterokont relatives of the brown algae lack plastids in their cells, scientists believe this is a result of evolutionary loss of that organelle in those groups rather than independent acquisition by the several photosynthetic members. Thus, all heterokonts are believed to descend from a single heterotrophic ancestor that became photosynthetic when it acquired plastids through endosymbiosis of another unicellular eukaryote. The closest relatives of the brown algae include unicellular and filamentous species, but no unicellular species of brown algae are known.
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Specifically, it has been suggested that certain genes (such as the genes for cytochrome oxidase subunits I and II) within the organelle are necessary to regulate redox balance throughout membrane- associated electron transport chains. These parts of the mitochondrial genome have been reported to be the most frequently employed. Mitochondria is not the only location within which the cell mtDNA, mitochondrial DNA, can be found; sometimes transfer of mitochondrial DNA from organelles to the nucleus can occur; the evidence of such translocation has been seen through the comparison of mitochondrial DNA sequence with the genome sequence of the counterparts. The integration and recombination of cytoplasmic mtDNA into the nuclear DNA is called Nuclear Mitochondrial DNA, which is abbreviated as NUMT.
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Jennifer Lippincott-Schwartz is a Senior Group Leader at Howard Hughes Medical Institute's Janelia Research Campus and a founding member of the Neuronal Cell Biology Program at Janelia. Previously, she was the Chief of the Section on Organelle Biology in the Cell Biology and Metabolism Program, in the Division of Intramural Research in the Eunice Kennedy Shriver National Institute of Child Health and Human Development at the National Institutes of Health from 1993 to 2016. Lippincott-Schwartz received her Ph.D. from Johns Hopkins University, and performed post-doctoral training with Dr. Richard Klausner at the NICHD, NIH in Bethesda, Maryland. Lippincott-Schwartz's research revealed that the organelles of eukaryotic cells are dynamic, self-organized structures that constantly regenerate themselves through intracellular vesicle traffic, rather than static structures.
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A few chloroplast genes found new homes in the mitochondrial genome—most became nonfunctional pseudogenes, though a few tRNA genes still work in the mitochondrion. Some transferred chloroplast DNA protein products get directed to the secretory pathway, though many secondary plastids are bounded by an outermost membrane derived from the host's cell membrane, and therefore topologically outside of the cell because to reach the chloroplast from the cytosol, the cell membrane must be crossed, which signifies entrance into the extracellular space. In those cases, chloroplast- targeted proteins do initially travel along the secretory pathway. Because the cell acquiring a chloroplast already had mitochondria (and peroxisomes, and a cell membrane for secretion), the new chloroplast host had to develop a unique protein targeting system to avoid having chloroplast proteins being sent to the wrong organelle.
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Initially, Dr. Lodish's work focused on translational control of protein synthesis and on development of the cellular slime mold Dictyostelium discoideum. Beginning in 1973, his laboratory has concentrated on the biogenesis, structure, and function of several important secreted and plasma membrane glycoproteins. He defined the biosynthesis and maturation of the vesicular stomatitis virus and other plasma membrane glycoproteins, identified the intracellular organelles that mediate recycling of the asialoglycoprotein and transferrin receptors, and clarified the role of pH changes in delivery of iron to cells and recycling of the transferrin receptor. His group has elucidated steps in folding and oligomerization of several proteins within the endoplasmic reticulum, showed that exit of newly made proteins from this organelle requires that they be properly folded, and developed probes for measurement of the redox state within the endoplasmic reticulum.
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Kinesins were discovered as MT-based anterograde intracellular transport motors. The founding member of this superfamily, kinesin-1, was isolated as a heterotetrameric fast axonal organelle transport motor consisting of 2 identical motor subunits (KHC) and 2 "light chains" (KLC) via microtubule affinity purification from neuronal cell extracts. Subsequently, a different, heterotrimeric plus-end-directed MT-based motor named kinesin-2, consisting of 2 distinct KHC-related motor subunits and an accessory "KAP" subunit, was purified from echinoderm egg/embryo extracts and is best known for its role in transporting protein complexes (IFT particles) along axonemes during cilium biogenesis. Molecular genetic and genomic approaches have led to the recognition that the kinesins form a diverse superfamily of motors that are responsible for multiple intracellular motility events in eukaryotic cells.
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Karlodinium micrum, another dinolagelate, expresses a blue tuned proteorhodopsin (E109) which may be related to its deep water vertical migrations. O.Marina was originally believed to be a heterotroph, however the proteorhodopsin may well partake in a functionally significant manner, as it was the most abundantly expressed nuclear gene and, furthermore, is dispersed unevenly in the organism, suggesting some organelle membrane function. Previously the only eukaryotic solar energy transducing proteins were Photosystem I and Photosystem II. It has been hypothesized that lateral gene transfer is the method by which proteorhodopsin has made its way into numerous phyla. Bacteria, archea and eukarya all colonize the photic zone where they come to light; Proteorhodopsin has been able to disseminate through this zone, but not to other portions of the water column.
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As the building-blocks for the organelle, production of rRNA is ultimately the rate-limiting step in the synthesis of a ribosome. In the nucleolus, rRNA is synthesized by RNA polymerase I using the specialty genes (rDNA) that encode for it, which are found repeatedly throughout the genome. The genes coding for 18S, 28S and 5.8S rRNA are located in the nucleolus organizer region and are transcribed into large precursor rRNA (pre-rRNA) molecules by RNA polymerase I. These pre-rRNA molecules are separated by external and internal spacer sequences and then methylated, which is key for later assembly and folding. After separation and release as individual molecules, assembly proteins bind to each naked rRNA strand and fold it into its functional form using cooperative assembly and progressive addition of more folding proteins as needed.
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Also, because of its hydrophobic nature, ceramide readily flip-flops across membranes as supported by studies in membrane models and membranes from red blood cells (erythrocytes). However, ceramide can possibly interact with other lipids to form bigger regions called microdomains which restrict its flip-flopping abilities. This could have immense effects on the signaling functions of ceramide because it is known that ceramide generated by acidic SMase enzymes in the outer leaflet of an organelle membrane may have different roles compared to ceramide that is formed in the inner leaflet by the action of neutral SMase enzymes. Ceramide mediates many cell-stress responses, including the regulation of programmed cell death (apoptosis) Obeid, L. M., Linardic, C. M., Karolak, L. A. & Hannun, Y. A. (1993) Programmed cell death induced by ceramide. Science.
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Accepting that his children have achieved beyond his wildest expectations, Bean risks his life by docking with the ark's cargo hold to float down into the ecotat. Lying in the grass and basking in the artificial sunlight, Bean communes for three days with the formic males. Though the Formics think it is silly to believe the Queen would hide anything from them, Bean learns that workers could rebel against a Queen and regain their free will. After Bean has slept for a while, his children wake him, informing him that by studying how the Hive Queen suppresses her workers, Ender has devised and administered a virus that will develop an organelle to shut off their growth genome, leaving their intelligence intact but saving them from the giantism half of Anton's Key.
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Focusing on the cellular defects characterizing this type of leukemia, she then discovered the implication of a novel cellular organelle, the PML Nuclear Body, and clarified the mechanisms underlying the high efficiency of acute promyelocytic leukemia treatment by retinoic acid and arsenic which leeds to cure in more than 95% of the patients. Together, her studies led to the identification of the genetic and cellular mechanisms responsible for a human leukemia and to the understanding of the unique efficacy of this anti-tumor therapy targeted on the genetic defect. Her most recent work aims at eludicating the role of the post-translational modification by the SUMO protein in the epigenetic control of gene expression. Manipulation of experimental data supporting research articles published by Anne Dejean-Assémat has been reported in several cases.
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One of the first significant contributions of Maheswari was the discovery of RNA polymerase activity in chloroplasts which he accomplished during his early stint at California Institute of Technology while working with Robert S. Bandurski and their researches revealed the presence of DNA in organelle. In 1966, he, along with Sipra Guha Mukherjee, developed a new high- speed culture technique for producing homozygous pure lines of haploid plants which is now in practice for crop improvement and for commercial production of horticultural and ornamental plants. His researches on plant growth hormones returned new protocols for the isolation of cytokinins and gibberellins and elucidated the function of salicylic acid during the flowering period. His work assisted in genetic engineering of plants and in the phytochrome control of plant metabolism.
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However, if green pollen fertilized a white stigma, the progeny were white, but if the sexes of the donors were reversed (white pollen on a green stigma), the progeny were green. This non- mendelian inheritance pattern was later traced to a gene named iojap which codes for a small protein required for proper assembly of the chloroplast ribosome. Even though iojap assorts according to Mendel's rules, if the mother is homozygous recessive, then the protein is not produced, the chloroplast ribosomes fail to form, and the plasmid becomes non-functional because the ribosomes cannot be imported into the organelle. The progeny could have functional copies of iojap, but since the chloroplasts come exclusively from the mother in most angiosperms, they would have been inactivated in the previous generation, and so will give white plants.
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It has inherited normal mitochondrial DNA from wild-type parent, which is replicated in the offspring. Suppressive petites (rho–S): crosses between petite and wild-type, all offspring are petite, showing "dominant" behavior to suppress wild-type mitochondrial function. Most petite mutants of S. cerevisiae are of a suppressive type, and they differ from neutral petite by affecting the wild- type, although both are a mutation in mitochondrial DNA. Mitochondrial genome of yeast will be the first eukaryotic genome to be understood in terms of both structure and function and this should smooth the way to understand the evolution of organelle genomes and its relationship with nuclear genomes.It is evident that Ephrussi’s work not only opened the field of extrachromosomal genetics, but also provide a fantastic incentive for the investigations which followed up to this day.
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In July 2015 the full genome sequences of chromerids C.velia and V. brassicaformis were published, revealing the array of genes that were co-opted or adapted in the transition from a free living lifestyle to a parasitic lifestyle. The plastid genome of C. velia is unusual in that there is evidence it may be linear and contains split genes for key photosystem genes. The linear state of the C. velia plastid genome is a reminder that C. velia is not an ancestral organism, but is a derived form, which evolved from an ancestral photosynthetic alveolate that presumably had a circular plastid genome, just as the other known chromerid Vitrella brassicaformis does. Much research surrounds the flagellar apparatus of Chromera, Vitrella and apicomplexans, in relation to the morphological transition of this organelle during the origination of parasitism in apicomplexans.
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The nucleus, which is the largest and stiffer, compared to the surrounding cytoskeleton, organelle, is mechanically firmly stabilized by an extensive network of structural proteins, and, for this reason, its shape, most likely, often does not undergo significant changes. However, the amoeboid type of migration is characterized by the most pronounced nucleus deformation, caused by the lack of proteolytic degradation of the surrounding matrix. Since tumor cells have to move through narrow spaces and pores, the nucleus in this case also occurs in a maximum compressed state. It is assumed that, like the amoeboid movement of leukocytes, nuclei inside single migrating tumor cells move forward toward the leading edge. In contrast to the mesenchymal movement, amoeboid or a non-proteolytic model of migration prevails when the surrounding matrix is characterized by relatively low stiffness (“soft” matrix).
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A few chloroplast genes found new homes in the mitochondrial genome—most became nonfunctional pseudogenes, though a few tRNA genes still work in the mitochondrion. Some transferred chloroplast DNA protein products get directed to the secretory pathway (though many secondary plastids are bounded by an outermost membrane derived from the host's cell membrane, and therefore topologically outside of the cell, because to reach the chloroplast from the cytosol, you have to cross the cell membrane, just like if you were headed for the extracellular space. In those cases, chloroplast-targeted proteins do initially travel along the secretory pathway). Because the cell acquiring a chloroplast already had mitochondria (and peroxisomes, and a cell membrane for secretion), the new chloroplast host had to develop a unique protein targeting system to avoid having chloroplast proteins being sent to the wrong organelle.
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Akhmanova's team focuses mainly on dynein, the motor that moves toward the minus end of the microtubule, and how it is linked to the various organelles and vesicles it transfers. They also study how dynein coordinates with kinesin, the motor that moves toward the plus end of the microtubule, when they are attached to the same organelle or vesicle, and they study the different signaling pathways that affect these motors. As of 2016, they were examining the protein Bicaudal D and its role in dynein- dependent transport, as it has been found to be important for dynein-dependent transport of mRNA in flies and of exocytotic vesicles in mammals. Bicaudal D was also found to be important for the positioning of the centrosomes and nucleus during mitosis, as the positioning is facilitated by dynein and kinesin.
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The RealThiol (RT) probe is a second-generation reversible reaction-based GSH probe. A few key features of RealThiol: 1) it has a much faster forward and backward reaction kinetics compared to ThiolQuant Green, which enables real-time monitoring of GSH dynamics in live cells; 2) only micromolar to sub-micromolar RealThiol is needed for staining in cell-based experiments, which induces minimal perturbation to GSH level in cells; 3) a high-quantum-yield coumarin fluorophore was implemented so that background noise can be minimized; and 4) equilibrium constant of the reaction between RealThiol and GSH has been fine-tuned to respond to physiologically relevant concentration of GSH. RealThiol can be used to perform measurements of glutathione levels in single cells using a high-resolution confocal microscope, as well as be applied in flow cytometry to perform bulk measurements in high throughput manner. Organelle-targeted RT probe has also been developed.
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A) Filamentous Mycoplasma pneumoniae cells B) M. pneumoniae cells (M) attached to ciliated mucosal cells by the attachment organelle (indicated by arrow) Mycoplasmas, which are among the smallest self-replicating organisms, are parasitic species that lack a cell wall and periplasmic space, have reduced genomes, and limited metabolic activity. Mycoplasma pneumoniae cells have an elongated shape that is approximately 0.1–0.2 µm (100-200 nm) in width and 1-2 µm (1000-2000 nm) in length. The extremely small cell size means they are incapable of being examined by light microscopy; a stereomicroscope is required for viewing the morphology of M. pneumoniae colonies, which are usually less than 100 µm in length. The inability to synthesize a peptidoglycan cell wall is due to the absence of genes encoding its formation and results in an increased importance in maintenance of osmotic stability to avoid desiccation.
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Nucleus 2 Nuclear pore 3 Rough endoplasmic reticulum (RER) 4 Smooth endoplasmic reticulum (SER) 5 Ribosome on the rough ER 6 Proteins that are transported 7 Transport vesicle 8 Golgi apparatus 9 Cis face of the Golgi apparatus 10 Trans face of the Golgi apparatus 11 Cisternae of the Golgi apparatus The endoplasmic reticulum (ER) is a membranous synthesis and transport organelle that is an extension of the nuclear envelope. More than half the total membrane in eukaryotic cells is accounted for by the ER. The ER is made up of flattened sacs and branching tubules that are thought to interconnect, so that the ER membrane forms a continuous sheet enclosing a single internal space. This highly convoluted space is called the ER lumen and is also referred to as the ER cisternal space. The lumen takes up about ten percent of the entire cell volume.
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The SFV capsid is assembled in the cytoplasm as a result of multimerization of Gag molecules, but unlike other related viruses, SFV Gag lacks an N-terminal myristylation signal and capsids are not targeted to the plasma membrane (PM). They require expression of the envelope protein for budding of intracellular capsids from the cell, suggesting a specific interaction between the Gag and Env proteins. Evidence for this interaction was discovered in 2001 when a deliberate mutation for a conserved arginine (Arg) residue at position 50 to alanine of the SFVcpz inhibited proper capsid assembly and abolished viral budding even in the presence of the envelope glycoproteins. Analysis of the glycoproteins on the envelope of the viral particle indicate that it is localized to the endoplasmic reticulum (ER), and that once it buds from the organelle, the maturation process is finalized and can leave to infect additional cells.
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Although he did not publish the first electron microscopy study of lipid bilayers J. David Robertson was the first to assert that the two dark electron-dense bands were the headgroups and associated proteins of two apposed lipid monolayers. In this body of work, Robertson put forward the concept of the “unit membrane.” This was the first time the bilayer structure had been universally assigned to all cell membranes as well as organelle membranes. Around the same time, the development of model membranes confirmed that the lipid bilayer is a stable structure that can exist independent of proteins. By “painting” a solution of lipid in organic solvent across an aperture, Mueller and Rudin were able to create an artificial bilayer and determine that this exhibited lateral fluidity, high electrical resistance and self-healing in response to puncture, all of which are properties of a natural cell membrane.
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Nanotechnology has played a pivotal role in the field of genetic engineering and plant transformations, making it a desirable candidate in the optimization and manipulation of cultivated plants. In the past, most genetic modifications to plants have been done with Agrobacterium, or utilising tools such as the gene gun (biolistics); however, these older methods of gene implementation face roadblocks due to low species compatibility lack of versatility/compatibility with Chloroplastial/Mitochondrial gene transformations, and potential for cell or organelle damage (due to impact of biolistics). While biolistics and Agrobacterium are useful in specific species of plants- more refined approaches are being explored through the utilisation of nanomaterials- allowing for a less invasive and forced delivery approach. These methods utilise Carbon Nanotube (CNT) and various porous nanoparticle (NP) enabled delivery methods, which may allow for higher-throughput plant transformation- while also circumventing legal GMO restrictions.
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The term 'colloid' was coined by Wolfgang Ostwald and defined by Thomas Graham in 1861 to describe the behaviour of certain biological macromolecules (starch, albumin, gelatin, etc) and inorganic molecules as slowly diffusing components of cloudy liquid solution-suspensions that were blocked by semi-permeable membranes, while the physics of phase separation was described by Josiah Willard Gibbs in his landmark paper titled On the Equilibrium of Heterogeneous Substances, published in parts between 1875 and 1878. Influenced by Willard Gibbs, important contributions were also made by Johannes Diderik van der Waals, who in 1890 published a treatise on the Theory of Binary Solutions. Glycogen granules in Spermiogenesis in Pleurogenidae (Digenea) The concept of intracellular colloids as an organizing principle for the compartmentalization of living cells dates back to the end of the 19th century, beginning with William Bate Hardy and Edmund Beecher Wilson who described the cytoplasm (then called 'protoplasm') as a colloid. Around the same time, Thomas Harrison Montgomery Jr. described the morphology of the nucleolus, an organelle within the nucleus, which has subsequently been shown to form through intracellular phase separation.
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At pH 8, it can be seen that the unprotonated histidine residues are involved in a network of hydrogen bonds at the interface of the helices in the bundle that block substrate access to the active site and disruption of this interaction by protonation (at pH 6.3) or by replacement of the histidine residues by alanine causes a large molecular motion of the bundle, separating the helices by 11Å and opening the catalytic site. Logically, the histidine residues cannot be replaced by alanine in nature but this experimental replacement further confirms that the larger histidine residues block the active site. Additionally, three Gly-Gly sequences, one in the N-terminal helix and two in the helix-loop-helix motif, could serve as hinges about which the chains rotate in order to further open the pathway to the catalytic site and enlarge the active site. A dinoflagellate luciferase is capable of emitting light due to its interaction with its substrate (luciferin) and the luciferin-binding protein (LBP) in the scintillon organelle found in dinoflagellates.
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PKD results from defects in the primary cilium, an immotile, hair-like cellular organelle present on the surface of most cells in the body, anchored in the cell body by the basal body. In the kidney, primary cilia have been found to be present on most cells of the nephron, projecting from the apical surface of the renal epithelium into the tubule lumen. The cilia were believed to bend in the urine flow, leading to changes in signalling, however this has since been shown to be an experimental error (the bending of cilia was an artifact of focal plane compensation, and also the actual effect on micturition by severe hypertension and cardiac arrest) and that bending of cilia does not contribute to alterations in Ca flux. While it is not known how defects in the primary cilium lead to cyst development, it is thought to possibly be related to disruption of one of the many signaling pathways regulated by the primary cilium, including intracellular calcium, Wnt/β-catenin, cyclic adenosine monophosphate (cAMP), or planar cell polarity (PCP).
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His most seminal research accomplishments include the direct visualization in living cells of the recruitment of factors involved in gene expression to active genes; the development of a biochemical fractionation approach to purify a sub-nuclear domain (nuclear speckles) and characterize its protein constituents; the development of a live cell imaging system to visualize a stably integrated genetic locus and follow in real-time its mRNA and protein products; the elucidation of a rapid-response mechanism of regulating gene expression through RNA nuclear retention; identification of a mechanism by which a single genetic locus can produce a long nuclear retained non-coding RNA and a small cytoplasmic tRNA-like transcript, the identification and characterization of a long nuclear retained non-coding RNA that is involved in organizing a sub- nuclear organelle (paraspeckles), and determining that knockout or knockdown of the lncRNA Malat1 results in the differentiation of mammary tumors and a significant reduction in metastasis. In addition, Spector has co-edited numerous microscopy techniques manuals (i.e. Basic Methods in Microscopy, Live Cell Imaging: A Laboratory Manual), and a treatise of The Nucleus, that are used in laboratories throughout the world.
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