scholarly journals Dynamic changes of the luminal plasmalemma in stimulated parotid acinar cells. A freeze-fracture study.

1976 ◽  
Vol 70 (1) ◽  
pp. 59-74 ◽  
Author(s):  
P De Camilli ◽  
D Peluchetti ◽  
J Meldolesi
Keyword(s):  
Cell Surface ◽  
Particle Density ◽  
Freeze Fracture ◽  
Acinar Cells ◽  
Specific Information ◽  
Secretory Cycle ◽  
Granule Membrane ◽  
Fracture Study ◽  
Original Size ◽  
Rat Parotid

In the acinar cells of the rat parotid gland the two membranes participating in exocytosis, i.e., the luminal plasmalemma and the secretory granule membrane, are clearly distinguishable in freeze-fracture because of their different densities in particles. In order to obtain point-specific information about the fusion-fission of these two membranes that occurs during the secretory cycle, glands were studied at various times (5 min to 6 h) after stimulation with isoproterenol. We observed that, in the course of the release of secretion products and shortly afterwards, the enlarged luminal plasmalemma exhibits a mosaic organization consisting of an alternation of membrane patches of high (original plasmalemma) and low (fused granule membrane) particle density. The transition between these two patterns is usually sharp. Later, concomitant with the reformation of acinar canaliculi, the low particle density membrane is found at the cell surface but only bounding vacuolar infoldings, and then it finally disappears. These results suggest that (a) fusion of these membranes does not result in a random intermixing of the molecular components of the participating membranes, which retain their structural identity; and (b) the enlarged luminal plasmalemma reverts to its original size by a progressive, specific removal of the regions of low particle density from the cell surface.

Freeze-fracture study of the vestibular hair cell surface during development

1986 ◽  
Vol 175 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Daniel Favre ◽  
Dan Bagger-Sj�b�ck ◽  
Joseph-Pascal Mbiene ◽  
Alain Sans
Keyword(s):  
Cell Surface ◽  
Hair Cell ◽  
Freeze Fracture ◽  
Fracture Study

scholarly journals Freeze-fracture study of the Drosophila photoreceptor membrane: mutations affecting membrane particle density.

1982 ◽  
Vol 93 (3) ◽  
pp. 961-967 ◽  
Author(s):  
R H Schinz ◽  
M V Lo ◽  
D C Larrivee ◽  
W L Pak
Keyword(s):  
Vitamin A ◽  
Particle Density ◽  
Freeze Fracture ◽  
Specific Protein ◽  
Wild Type ◽  
Photoreceptor Membrane ◽  
Membrane Particles ◽  
Fracture Study ◽  
Freeze Fracture Electron Microscopy ◽  
Number Of Particles

The photoreceptor membrane of Drosophila melanogaster (wild type, vitamin A-deprived wild type, and the mutants ninaAP228, ninaBP315, and oraJK84) was studied by freeze-fracture electron microscopy. The three mutations caused a decrease in the number of particles on the protoplasmic face of the rhabdomeric membrane. The ninaAP228 mutation affected only the peripheral photoreceptors (R1-6), while the ninaBP315 mutation affected both the peripheral (R1-6) and the central photoreceptors (R7). The oraJK84 mutation, which essentially eliminates R1-6 rhabdomeres, was found to drastically deplete the membrane particles in the vestigial R1-6 rhabdomeres but not in the normal rhabdomeres of R7 photoreceptors, suggesting that the failure of the oraJK84 mutant to form normal R1-6 rhabdomeres may be due to a defect in a major R1-6 photoreceptor-specific protein in the mutant. In all cases in which both the rhabdomeric particle density and rhodopsin content were studied, the mutations or vitamin A deprivation was found to reduce both these quantities, supporting the idea that at least the majority of the rhabdomeric membrane particles are closely associated with rhodopsin. Vitamin A deprivation and the mutations also reduced the number of particles in the plasma membrane as in the rhabdomeric membrane, suggesting that both classes of membrane contain rhodopsin.

A freeze fracture study of the developing tegumental outer membrane of Schistosoma mansoni

Parasitology ◽  
1978 ◽  
Vol 76 (3) ◽  
pp. 327-348 ◽  
Author(s):  
Diane J. McLaren ◽  
D. J. Hockley ◽  
O. L. Goldring ◽  
B. J. Hammond
Keyword(s):  
Schistosoma Mansoni ◽  
Outer Membrane ◽  
Particle Density ◽  
Freeze Fracture ◽  
Low Level ◽  
Morphological Studies ◽  
Fracture Study ◽  
Immunocytochemical Techniques ◽  
Lung Worms

SummaryThe freeze fracture technique has been used to quantify changes in the integral components of the double outer membrane of Schistosoma mansoni during the 6-week period of development within the mouse. The intramembraneous particle (IMP) density on the P1 face begins to rise Within 6 h of host penetration, reaches a maximum at day 4 and then falls rapidly after day 9, so that it is at a low level between 3 and 6 weeks. The E1 face IMP density follows the same course as that of the P1 face except that maximum particle density is recorded on day 1 and the counts begin to fall on day 5. The IMP density on the P1 face remains at a consistently low level throughout development. The E2 face IMP density rises gradually to a peak at day 4, when the parasites have migrated to the lungs, and remains thereafter at a similar level, so that by 6 weeks the E2 face has a higher IMP density than the other three fracture faces. The E2 face IMP show a marked increase in size on day 4. Morphological studies indicate that a different type of inclusion body makes a transient appearance in the tegument of the lung worms, and immunocytochemical techniques show the lung worms to be nonimmunogenic. It is suggested, therefore, that the E2 face IMP may represent complexes of parasite antigens and acquired host antigens. The tegumental membranes of cultured specimens have also been examined by freeze fracturing and the IMP densities compared with those obtained from in vivo parasites; the cultured schistosomula have a lower E2 face particle density than the in vivo specimens.

Freeze-fracture study of adenovirus-induced KB cell surface alterations

1979 ◽  
Vol 124 (1) ◽  
pp. 139-150 ◽  
Author(s):  
Bernadette Hennache ◽  
Gérard Torpier ◽  
Pierre Boulanger
Keyword(s):  
Cell Surface ◽  
Freeze Fracture ◽  
Fracture Study

scholarly journals A freeze-fracture study of early membrane events during mast cell secretion.

1977 ◽  
Vol 73 (3) ◽  
pp. 660-671 ◽  
Author(s):  
S J Burwen ◽  
B H Satir
Keyword(s):  
Mast Cell ◽  
Plasma Membrane ◽  
Membrane Fusion ◽  
Ionic Composition ◽  
Freeze Fracture ◽  
Polymyxin B ◽  
Cell Secretion ◽  
Granule Membrane ◽  
Fracture Study ◽  
Freeze Fracture Electron Microscopy

The early membrane events taking place during mast cell secretion were followed in transmission and freeze-fracture electron microscopy. In order to slow down exocytosis and capture intermediate stages of membrane fusion, special conditions of incubation and stimulation were used. These were as follows: (a) the use of incubation media with altered ionic composition, and (b) stimulation with a low dosage of polymyxin B sulfate (4 microgram/ml) at low temperature (18 degrees C) for very short incubation times (30-60 s), with or without the presence of formaldehyde (0.8%). Under these conditions, unetchable circular impressions are found on the E face of the plasma membrane, 80-100 nm in diameter, with particles associated with their perimeters. In granule-to-granule fusion, the zone involved is demarcated by one or two rows of particles on the E face. In addition, raised circular areas of varying diameters (43-87 nm) surrounded by similar particles, also found on the E face, may represent potential sites before completion of fusion. Neither the circular impressions on the plasma membrane nor the sites on the granule membrane are permanent, but their appearance coincides with initiation of membrane fusion.

Freeze-Fracture Study of Microfilament Attachments to Membranes

1977 ◽  
Vol 35 ◽  
pp. 602-603
Author(s):  
N. Scott McNutt
Keyword(s):  
Cardiac Muscle ◽  
Thin Section ◽  
Actin Filaments ◽  
Particle Density ◽  
Freeze Fracture ◽  
Structural Type ◽  
Intercalated Disc ◽  
Fracture Study ◽  
Cross Bridges ◽  
Filamentous Material

Actin-containing microfilaments are part of contractile systems in many cells, and the functions of these systems require some type of attachment of microfilaments to membranes (1). This attachment is particularly necessary at the fascia adherens in the intercalated disc of cardiac muscle (2) and at the tips of intestinal microvilli (1). At these locations, the actin filaments are perpendicular to the membrane and a dense-filamentous material is present at the sites of attachment. Freeze-fracture studies of these membranes have revealed a decrease in P face particle density at the fascia adherens (2) and at the tips of intestinal microvilli (3). In contrast, when the microfilaments lie parallel to the plane of the membrane, another structural type of attachment is found which is mediated by fine cross-bridges instead of the dense filamentous material. These cross-bridges are visible in both thin-section and freeze-etch preparations (1,4). The freeze-fracture counterpart of this type of cross-bridge attachment has not been shown previously.

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