Prevention of microvesiculation by adhesion of buds to the mother cell membrane — A possible anticoagulant effect of healthy donor plasma

AbstractIn the process of asymmetric cell division, the mother cell induces polarity in both the membrane and the cytosol by distributing substrates and components asymmetrically. Such polarity formation results from the harmonization of the upstream and downstream polarities between the cell membrane and the cytosol. MEX-5/6 is a well-investigated downstream cytoplasmic protein, which is deeply involved in the membrane polarity of the upstream transmembrane protein PAR in the Caenorhabditis elegans embryo. In contrast to the extensive exploration of membrane PAR polarity, cytoplasmic polarity is poorly understood, and the precise contribution of cytoplasmic polarity to the membrane PAR polarity remains largely unknown. In this study, we explored the interplay between the cytoplasmic MEX-5/6 polarity and the membrane PAR polarity by developing a mathematical model that integrates the dynamics of PAR and MEX-5/6 and reflects the cell geometry. Our investigations show that the downstream cytoplasmic protein MEX-5/6 plays an indispensable role in causing a robust upstream PAR polarity, and the integrated understanding of their interplay, including the effect of the cell geometry, is essential for the study of polarity formation in asymmetric cell division.

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Anti-SARS-CoV-2 antibodies in healthy donor plasma pools and IVIG products

The Lancet Infectious Diseases ◽

10.1016/s1473-3099(21)00059-1 ◽

2021 ◽

Author(s):

Carolina Romero ◽

José María Díez ◽

Rodrigo Gajardo

Keyword(s):

Healthy Donor ◽

Donor Plasma

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Energy-dependence of calcium accumulation during sporulation of Bacillus megaterium KM

Biochemical Journal ◽

10.1042/bj1780627 ◽

1979 ◽

Vol 178 (3) ◽

pp. 627-632 ◽

Cited By ~ 5

Author(s):

C Hogarth ◽

D J Ellar

Keyword(s):

Cell Membrane ◽

Active Transport ◽

Bacillus Megaterium ◽

Mother Cell ◽

Adenosine Triphosphatase ◽

Nadh Oxidase ◽

Endogenous Respiration ◽

Facilitated Diffusion ◽

Carbonyl Cyanide ◽

Active Transport Process

Ca2+ accumulation and endogenous respiration of sporulating Bacillus megaterium are inhibited to the same extent by electron-transport of inhibitors and the uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone, suggesting that Ca2+ is accumulated by an active transport process. Forespores isolated in stage V of sporulation demonstrated Ca2+-specific carrier-mediated Ca2+ uptake, consistent with downhill transfer [Hogarth & Ellar (1978) Biochem. J. 176, 197-203]. In the present studies forespore Ca2+ uptake was unaffected by carbonyl cyanide p-trifluoromethoxyphenylhydrazone and by concentrations of respiratory inhibitor that inhibited forespore endogenous respiration by 85%. These data suggest that Ca2+ enters the isolated forespore by facilitated diffusion. Ca2+ uptake into sporulating protoplasts was completely inhibited by concentrations of respiratory inhibitors that had no effect on either Ca2+ uptake or respiration of stage-V forespores, but which resulted in inhibition of mother-cell membrane NADH oxidase. These results indicate that the mother-cell membrane is a site for active transport of Ca2+ into the sporulating cell. The effects of the adenosine triphosphatase inhibitor dicyclohexylcarbodi-imide on mother-cell membrane adenosine triphosphatase, NADH oxidase and protoplast Ca2+ uptake were examined.

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Circulating Proteasomes Are Functional and Have a Subtype Pattern Distinct from 20S Proteasomes in Major Blood Cells

Clinical Chemistry ◽

10.1373/clinchem.2006.072496 ◽

2006 ◽

Vol 52 (11) ◽

pp. 2079-2086 ◽

Cited By ~ 58

Author(s):

Annette Zoeger ◽

Michael Blau ◽

Karl Egerer ◽

Eugen Feist ◽

Burkhardt Dahlmann

Keyword(s):

Autoimmune Disease ◽

Human Plasma ◽

Lupus Erythematosus ◽

Blood Cells ◽

Healthy Donor ◽

Intracellular Protein ◽

Disease Markers ◽

Apparent Homogeneity ◽

Healthy Donors ◽

Donor Plasma

Abstract Background: 20S proteasomes, the proteolytic core particles of the major intracellular protein degradative pathway, are potential disease markers because they are detectable in human plasma as circulating proteasomes and their concentrations are increased in patients suffering from various diseases. To investigate the origin of circulating proteasomes, we compared some of their features with those of proteasomes isolated from major blood cells. Methods: We isolated circulating proteasomes from the plasma of 2 patients with rheumatoid arthritis and 2 with systemic lupus erythematosus and from human plasma from healthy donors. We purified the proteasomes to apparent homogeneity and then used electron microscopy for imaging and chromatography for subtype spectrum analysis. We compared subtype results with those from 20S proteasomes purified from 4 major blood cell populations. We also tested proteasomes for enzymatic activity and immunosubunit content. Results: Circulating proteasomes from plasma of healthy donors and from patients with autoimmune disease were found to have the same size and shape as erythrocyte proteasomes, be proteolytically active, and contain standard- and immunosubunits. Chromatography revealed 6 circulating proteasome subtype peaks in healthy donor plasma and 7 in patient donor plasma. Proteasomes from erythrocytes had 3 subtype peaks and those of monocytes, T-lymphocytes, and thrombocytes each had 5 different subtype peaks. Conclusion: Circulating proteasomes were intact and enzymatically active in plasma from healthy donors and from patients with autoimmune disease. Because the subtype patterns of circulating proteasomes clearly differ from those of proteasomes from blood cells, these cells cannot be regarded as a major source of circulating proteasomes.

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Subcellular Localization of a Small Sporulation Protein in Bacillus subtilis

Journal of Bacteriology ◽

10.1128/jb.185.4.1391-1398.2003 ◽

2003 ◽

Vol 185 (4) ◽

pp. 1391-1398 ◽

Cited By ~ 47

Author(s):

Christiaan van Ooij ◽

Richard Losick

Keyword(s):

Bacillus Subtilis ◽

Cell Membrane ◽

Subcellular Localization ◽

Mother Cell ◽

Green Fluorescence Protein ◽

Protein S ◽

Anchoring Protein ◽

Unknown Gene ◽

Fluorescence Protein ◽

Α Helix

ABSTRACT SpoVM is an unusually small (26-residue-long) protein that is produced in the mother cell chamber of the sporangium during the process of sporulation in Bacillus subtilis. We investigated the subcellular localization of SpoVM, which is believed to be an amphipathic α-helix, by using a fusion of the sporulation protein to the green fluorescence protein (GFP). We found that SpoVM-GFP is recruited to the polar septum shortly after the sporangium undergoes asymmetric division and that the fusion protein localizes to the mother cell membrane that surrounds the forespore during the subsequent process of engulfment. We identified a patch of three residues near the N terminus of the proposed α-helix that is needed both for proper subcellular localization and for SpoVM function. We also identified a patch of residues on the opposite face of the helix and residues near both ends of the protein that are needed for SpoVM function but not for subcellular localization. Subcellular localization of SpoVM-GFP was found to require an unknown gene(s) under the control of the mother cell transcription factor σE. We propose that the N-terminal patch binds to an unknown anchoring protein that is produced under the control of σE and that other residues important in SpoVM function to recruit an unknown sporulation protein(s) to the mother cell membrane that surrounds the forespore. Our results provide evidence that SpoVM function depends on proper subcellular localization.

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The mother-cell-membrane adenosine triphosphatase of sporulating Clostridium pasteurianum

Biochemical Journal ◽

10.1042/bj1860191 ◽

1980 ◽

Vol 186 (1) ◽

pp. 191-199 ◽

Cited By ~ 2

Author(s):

David J. Clarke ◽

J. Gareth Morris

Keyword(s):

Cell Membrane ◽

Mother Cell ◽

Vegetative Cell ◽

Sodium Dodecyl ◽

Proton Channel ◽

Clostridium Pasteurianum ◽

Synthetase Activity ◽

Inhibitor Protein ◽

Protein Subunit ◽

Membrane Atpase

1. Sporulation of Clostridium pasteurianum effects several changes in its proton-translocating cell-membrane H+-ATPase. Notable among these are the acquisition of susceptibility to activation by trypsin and a changed protein subunit composition. 2. A protein was isolated from the mother-cell membrane that inhibited the ATP phosphohydrolase activity of purified vegetative-cell-membrane H+-ATPase [BF0F1 complex, which consists of soluble ATPase (BF1) and the proton-channel component (BF0)] and rendered it susceptible to trypsin activation. 3. This trypsin-sensitive inhibitor protein had a molecular weight of 10000 and on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis was indistinguishable from the novel protein subunit e of the mother-cell-membrane ATPase 4. In bacteriorhodopsin-containing everted membrane vesicles, the specific ATP synthetase activity of the mother-cell-membrane ATPase was significantly greater than that of the vegetative-cell-membrane ATPase. 5. Treatment with trypsin-sensitive inhibitor protein of artificial proteoliposomes containing bacteriorhodopsin and vegetative-cell-membrane H+-ATPase (BF0F1) significantly increased the specific ATP synthetase activity of this enzyme. 6. The ATP synthetase activity of crude cell-membrane preparations from cultures of Clostridium pasteurianum increased during that period in the course of sporulation when the membrane ATP phosphohydrolase was both most rapidly decreasing in specific activity and acquiring its susceptibility to activation by trypsin.

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Sarcolemmal permeability changes during early myocardial anoxia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100084089 ◽

1978 ◽

Vol 36 (2) ◽

pp. 642-643

Author(s):

M. Ashraf ◽

L. Landa ◽

L. Nimmo ◽

C. M. Bloor

Keyword(s):

Cell Membrane ◽

Membrane Permeability ◽

Coronary Artery Occlusion ◽

Artery Occlusion ◽

Cell Membrane Permeability ◽

Enzyme Release ◽

Sprague Dawley ◽

Sprague Dawley Rats ◽

Sarcolemmal Permeability ◽

Membrane Changes

Following coronary artery occlusion, the myocardial cells lose intracellular enzymes that appear in the serum 3 hrs later. By this time the cells in the ischemic zone have already undergone irreversible changes, and the cell membrane permeability is variably altered in the ischemic cells. At certain stages or intervals the cell membrane changes, allowing release of cytoplasmic enzymes. To correlate the changes in cell membrane permeability with the enzyme release, we used colloidal lanthanum (La+++) as a histological permeability marker in the isolated perfused hearts. The hearts removed from sprague-Dawley rats were perfused with standard Krebs-Henseleit medium gassed with 95% O2 + 5% CO2. The hypoxic medium contained mannitol instead of dextrose and was bubbled with 95% N2 + 5% CO2. The final osmolarity of the medium was 295 M osmol, pH 7. 4.

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Flagellar Attachment in Selected Trypanosomes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072927 ◽

1973 ◽

Vol 31 ◽

pp. 496-497

Author(s):

J. J. Paulin

Keyword(s):

Cell Membrane ◽

Lateral Surface ◽

The Body ◽

Flagellar Pocket ◽

Integral Component ◽

Free Flagellum ◽

Flagellar Axoneme

Movement in epimastigote and trypomastigote stages of trypanosomes is accomplished by planar sinusoidal beating of the anteriorly directed flagellum and associated undulating membrane. The flagellum emerges from a bottle-shaped depression, the flagellar pocket, opening on the lateral surface of the cell. The limiting cell membrane envelopes not only the body of the trypanosome but is continuous with and insheathes the flagellar axoneme forming the undulating membrane. In some species a paraxial rod parallels the axoneme from its point of emergence at the flagellar pocket and is an integral component of the undulating membrane. A portion of the flagellum may extend beyond the anterior apex of the cell as a free flagellum; the length is variable in different species of trypanosomes.

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Trophoblast Cell Membrane Interactions at Implantation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068540 ◽

1970 ◽

Vol 28 ◽

pp. 310-311

Author(s):

A. C. Enders

Keyword(s):

Epithelial Cells ◽

Cell Membrane ◽

Membrane Fusion ◽

Trophoblast Cell ◽

Membrane Interactions ◽

Uterine Epithelial Cells ◽

Functional Complex ◽

Cytotrophoblast Cells ◽

Complex Relationships ◽

Syncytial Trophoblast

The alteration in membrane relationships seen at implantation include 1) interaction between cytotrophoblast cells to form syncytial trophoblast and addition to the syncytium by subsequent fusion of cytotrophoblast cells, 2) formation of a wide variety of functional complex relationships by trophoblast with uterine epithelial cells in the process of invasion of the endometrium, and 3) in the case of the rabbit, fusion of some uterine epithelial cells with the trophoblast.Formation of syncytium is apparently a membrane fusion phenomenon in which rapid confluence of cytoplasm often results in isolation of residual membrane within masses of syncytial trophoblast. Often the last areas of membrane to disappear are those including a desmosome where the cell membranes are apparently held apart from fusion.

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