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Cellular compartment

About: Cellular compartment is a research topic. Over the lifetime, 1082 publications have been published within this topic receiving 53794 citations. The topic is also known as: cell compartmentation.


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Journal ArticleDOI
TL;DR: The kinetics of the fusion process upon simultaneous generation of the pH gradient across the vesicle bilayer and initiation of the Fusion reaction show that the inward movement of oleic acid in response to the pHgradient is extremely fast, occurring well within 1 s.
Abstract: The influence of a transmembrane pH gradient on the Ca2+-induced fusion of phospholipid vesicles, containing free fatty acids, has been investigated. Large unilamellar vesicles composed of an equimolar mixture of cardiolipin, dioleoylphosphatidylcholine, and cholesterol, containing 20 mol 7% oleic acid, were employed. Fusion was measured using a kinetic assay for lipid mixing, based on fluorescence resonance energy transfer. At pH 7.5, but not at pH 6.0, in the absence of a pH gradient, oleic acid stimulates the fusion of the vesicles by shifting the Ca2+ threshold concentration required for aggregation and fusion of the vesicles from about 13 mM to 10 mM. In the presence of a pH gradient (at an external pH of 7.5 and a vesicle interior pH of 10.5), the vesicles exhibit fusion characteristics similar to vesicles that do not contain oleic acid at all, consistent with an effective sequestration of the fatty acid to the inner monolayer of the vesicle bilayer induced by the imposed pH gradient. The kinetics of the fusion process upon simultaneous generation of the pH gradient across the vesicle bilayer and initiation of the fusion reaction show that the inward movement of oleic acid in response to the pH gradient is extremely fast, occurring well within 1 s. Conversely, dissipation of an imposed pH gradient, by addition of a proton ionophore during the course of the fusion process, results in a rapid enhancement of the rate of fusion due to reequilibration of the oleic acid between the two bilayers leaflets. Membrane fusion is a fundamental process in cell biology. It plays a key role in cell-cell fusion phenomena such as fertilization and myogenesis. It is also the basis of intracellular trafficking and sorting processes, involving fusion of shuttle vesicles derived from one cellular compartment with the lim- iting membrane of another compartment or, as in the process of exocytosis, with the plasma membrane of the cell. Obvi- ously, these membrane fusion processes must be highly specific and strictly controlled, at the level of the initial recognition and attachment of the interacting membranes as well as that of the actual fusion reaction. However, very little is known about the molecular mechanisms involved. Much of our current knowledge of the molecular mecha- nisms of membrane fusion has been derived from investigation of fusion in lipid vesicle (liposome) systems (for reviews, see

19 citations

Journal ArticleDOI
TL;DR: X-ray microanalysis revealed that calcium was a constituent of the electron-opaque deposits of Emiliania huxleyi and the most extensive deposits occurred in the Golgi apparatus, the “peripheral space”, the multivesicular bodies, and the cell vacuole.
Abstract: Emiliania huxleyi is a coccolithophorid with a life cycle including a stage characterized by the occurrence of a scale-bearing cell type. The scales are composed of organic material and are produced in the cisternae of the Golgi apparatus. The present report deals with the ultrastructural calcium localization in scale-bearing cells using cation-precipitating agents. Cations were precipitated either with potassium pyroantimonate alone or according to a combined procedure in which cells are treated first with potassium oxalate, or potassium carbonate, or potassium phosphate, and then with potassium pyroantimonate. The distribution of electron-opaque deposits was the same when visualized by all four techniques. The most extensive deposits occurred in the Golgi apparatus, the “peripheral space” (a cellular compartment totally encompassing the protoplast), the multivesicular bodies, and the cell vacuole. X-ray microanalysis revealed that calcium was a constituent of the electron-opaque deposits. The uptake and transport of calcium, as universal functions of the Golgi apparatus, are discussed.

19 citations

Journal ArticleDOI
TL;DR: It is suggested that the endoplasmic reticulum serves both physiological and structural roles during chronic salt stress by providing the driving force behind increased synthetic/Golgi apparatus activities of the cells, and by providing a type of ‘cellular scaffolding’ to limit the degree of cell contraction in the face of long-term salt stress.
Abstract: The ultrastructural changes taking place in Dunaliella bioculata after chronic exposure to a sodium chloride-induced stress were examined. Hyperosmotic shock was induced by raising the sodium chloride concentration of the culture medium from 0·3 to 1·3 M, which affected a number of cellular organelles during the initial stages of the stress period, i.e. 24, 48 and 72 h. Changes in whole-cell volume were recorded, as well as alterations in the size of the following components: starch grains and sheath, lipid and plastoglobuli, chloroplast, pyrenoid, nucleus, mitochondria, cytoplasm, Golgi apparatus and endoplasmic reticulum. Cells were examined using transmission electron microscopy and changes to their fine structure quantified via image analysis of the electron micrographs. The image analysis program was designed to measure various geometric parameters for all the cell components within individual algal cells. Quantitative image analysis of cells subjected to a chronic salt stress revealed marked increases in the cross-sectional areas of the Golgi apparatus and the endoplasmic reticulum. The enhanced production of the Golgi apparatus within the algal cells was thought to be the direct result of a salt-stress-induced endoplasmic reticulum production within the cells. The increase in the endoplasmic reticulum was manifested as extensive networks of cortical endoplasmic reticulum. It is suggested that the endoplasmic reticulum serves both physiological and structural roles during chronic salt stress by providing the driving force behind increased synthetic/Golgi apparatus activities of the cells, and by providing a type of ‘cellular scaffolding’ to limit the degree of cell contraction in the face of long-term salt stress.

19 citations

Journal ArticleDOI
TL;DR: ToF‐SIMS analysis proved the uptake of the particles into the cell body, provided images of their distribution around the cell nucleus and indications that the cell membranes are undulated by the µm‐sized particles beneath the membrane.
Abstract: Label-free characterization of cellular compartments and molecular structures in single cells has become possible by means of ToF-SIMS 3D analysis [1, 2]. Major molecular building blocks, such as amino acid fragments and phophatidylcholine fragments could be detected successfully. A correlation between the distribution of these components and the intracellular architecture (golgi, nucleus, nucleoli) was possible and the respective results were in line with the expectations derived from cell biology textbooks.

19 citations

Journal ArticleDOI
TL;DR: It is demonstrated that the cytoplasmic facing membrane of the endoplasmic reticulum (ER) and the nucleus are relatively BR-enriched spaces and mitochondrial intermembrane space and the ER lumen are relativelyBR-depleted spaces, demonstrating a relationship between such asymmetrical BR distribution in the ER membrane and the BR metabolic pathway.
Abstract: Bilirubin (BR) is a de novo synthesized metabolite of human cells. However, subcellular localization of BR in the different organelles of human cells has been largely unknown. Here, utilizing UnaG as a genetically encoded fluorescent BR sensor, we report the existence of relatively BR-enriched and BR-depleted microspaces in various cellular organelles of live cells. Our studies indicate that (i) the cytoplasmic facing membrane of the endoplasmic reticulum (ER) and the nucleus are relatively BR-enriched spaces and (ii) mitochondrial intermembrane space and the ER lumen are relatively BR-depleted spaces. Thus, we demonstrate a relationship between such asymmetrical BR distribution in the ER membrane and the BR metabolic pathway. Furthermore, our results suggest plausible BR-transport and BR-regulating machineries in other cellular compartments, including the nucleus and mitochondria.

19 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
202225
202133
202040
201933
201829