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'Membrane Fusion' in keywords Facet   section ZfN Section C  [X]
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1985 (1)
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1Author    Natalia Stoicheva, Iana Tsoneva, DimiterS. Dimitrov, Ivan PanaiotovRequires cookie*
 Title    Kinetics of Calcium-Induced Fusion of Cell-Size Liposomes with Monolayers in Solutions of Different Osmolarity  
 Abstract    The effects o f osmolarity, calcium concentration and cell-size lip osom es in the subphase on the surface tension o f phospholipid monolayers were investigated. The m onolayers were spread from chloroform solutions o f phosphatidic acid at air/w ater solution interface. The liposom es (o f average diameter 3 |im) were formed from phosphatidic a cid /e g g lecithin (1 :2) m ixtures in water or 0.1 M water solutions o f sucrose. For this system there were critical concentrations o f calcium ions to produce a large reduction o f the monolayer surface tension. The threshold calcium concentrations depended upon the sucrose concentration in the subphase. W ithout sucrose the threshold calcium concentration was 8 mM, while for isoosm otic sucrose solutions (0.1/0.1 M in /o u t o f lip osom e) it was 14 mM. It sharply increased to 28 mM CaCl2 at sucrose concentration difference across the lip osom e m em ­ brane 0.02 M and decreased to 26 mM, 19 mM, and 18 m M w ith further increase o f that difference to 0.04 m, 0.06 M, and 0.08 M, respectively. The rate o f monolayer surface tension decrease was m easured as a function o f tim e at 30 mM CaCl2 and different sucrose concentrations in the subphase solution. The initial rates at first decreased with increasing the osmotic pressure and after that they increased. The m inim um occurred at sucrose concentration gradient across the lip osom e m em brane 0.02 M, i.e., at the point o f maximum threshold calcium concentration required for large decrease o f the m onolayer surface tension. These facts may be explained by recent theories o f dynam ics o f adhesion, instability and fusion o f membranes m odeled as thin films. 
  Reference    Z. Naturforsch. 40c, 92 (1985); received July 16 1984 
  Published    1985 
  Keywords    Membrane Fusion, Giant Liposomes, Phospholipid M onolayers 
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 TEI-XML for    default:Reihe_C/40/ZNC-1985-40c-0092.pdf 
 Identifier    ZNC-1985-40c-0092 
 Volume    40 
2Author    Flavia Pasquali, G. Ianfranco, M. Enestrina, R. Enzo, A. NtoliniRequires cookie*
 Title    Fusion of Large Unilamellar Liposomes Containing Hemocyanin with Planar Bilayer Membranes  
 Abstract    Large unilamellar vesicles were prepared by detergent rem oval from micelles containing phosphatidylcholine, phosphatidylethanolam ine and phosphatidylserine. Liposomes were then interacted with Megathura crenulata hemocyanin, a well studied channel former. Incubation o f the resulting proteoliposomes on one side of a phosphatidylserine-containing planar bilayer under fusion conditions yielded strong current increases. Such increase is due to insertion o f ionic channels from the liposomes into the planar bilayer. Studying the effects o f Ba2+ on the electrical properties of the channel we could show that the protein is always inserted into a bilayer during this process, i.e. fusion of proteoliposomes with the artificial m em brane occurs. The strong non linearity of the current-voltage curve of the hemocyanin pore could be used as a probe o f the extent to which fusion preserves the orientation of the channel through the bilayer. 
  Reference    Z. Naturforsch. 39c, 147—155 (1984); received September 22 1983 
  Published    1984 
  Keywords    Membrane Fusion, Large Liposomes, Planar Bilayer, Hemocyanin Channel, Asymmetrical Insertion 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0147.pdf 
 Identifier    ZNC-1984-39c-0147 
 Volume    39 
3Author    Marvin Stromer, Wilhelm HasselbadhRequires cookie*
 Title    Fusion of Isolated Sarcoplasmic Reticulum Membranes  
 Abstract    Fragmented sarcoplasmic reticulum (FSR) vesicles from rabbit muscle were suspended in 1.5 — 5% glycerol solutions and were pelleted onto aluminum foil disks in a modified centrifuge tube. Examination of these pellets in the electron microscope after drying for 2 — 2.5, 4 — 5.5, and 21 hours revealed a progression of changes. First, distances between individual, round vesicles decreases. Next, somewhat flattened vesicles establish limited areas of contact with adjacent vesicles. Finally, vesicle fusion occurs and extended areas of double bilayers are formed. A water loss-time interaction appears to be needed for the fusion process. A Hg-phenyl azoferritin com­ pound was used as a marker to identify intra-and extra-vesicular space in the fused samples. Quantitative measurements of birefringence during imbibition of pellet slices in a graded series of glycerol solutions indicates a steadily increasing amount of birefringence until 60 — 80% glycerol (»/ = 1.41 —1.43) is readied. The plateau seen in this part of the curve is again followed by steadily increasing birefringence at higher glycerol concentrations. This interruption in the birefringence curve is presumably due to a matching of the refractive indices of the glycerol solution and a lipid component in the membranes. 
  Reference    (Z. Naturforsch. 31c, 703 [1976]; received August 23 1976) 
  Published    1976 
  Keywords    Membrane Fusion, Sarcoplasmic Reticulum, Glycerol, Electron Microscopy, Polarizing Microscopy 
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 TEI-XML for    default:Reihe_C/31/ZNC-1976-31c-0703.pdf 
 Identifier    ZNC-1976-31c-0703 
 Volume    31 
4Author    B. Agostini, M. Stromer, W. HasselbadiRequires cookie*
 Title    Effect of Lipid Modification on Fusion of Sarcoplasmic Reticulum Vesicles  
 Abstract    Freeze fracture technique ascertains that sarcoplasmic reticulum vesicles fuse during aniso-diametric dehydration which leads to the formation of sheetlike structure o f a mean extension of 5000 A . M odification of the membrane lipids by phospholipase A 2 digestion or the incorporation of deoxycholate facilitates the coalescence of the vesicles, while it is com pletely prevented by lipid removal. Membrane fusion during anisodiametric dehydration is considered as resulting from the close contact of highly curved edges from which the 
  Reference    Z. Naturforsch. 33c, 428 (1978); received A p ril 11 1978 
  Published    1978 
  Keywords    Membrane Fusion, Sarcoplasmic Reticulum, Freeze Fracturing, Anisometric Dehydration, L ipid Modification 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-0428.pdf 
 Identifier    ZNC-1978-33c-0428 
 Volume    33