scholarly journals A simple, selective method for freeze-fracturing spherical cells.

1976 ◽  
Vol 71 (2) ◽  
pp. 674-680 ◽  
Author(s):  
H B Peng ◽  
L F Jaffe
Keyword(s):  
Plasma Membrane ◽  
Cell Monolayer ◽  
Selective Method ◽  
Freeze Fracturing ◽  
Thin Nickel ◽  
Nickel Screen ◽  
Spherical Cells ◽  
Outer Half

A simple and selective method for freeze-fracturing spherical cells is described. The cells are loaded into the holes of a thin nickel screen. A metal hat is applied to the cell monolayer and the whole assembly, hat-cells-screen, is frozen and then fractured by ripping the hat off. The fractured face on the screen is replicated. By varying the size of the screen holes and by applying the hat to either side of the screen, this method can selectively expose the E face (or the outer half of plasma membrane), the P face (or the inner half of the plasma membrane), or the cytoplasm of the cells. It also provides a means to produce fractures at a preselected area on the cell, if the cells can be loaded onto the screen in an oriented fashion.

Freeze-fracture observations on changes in the distribution of Filipin-sterol complexes during epididymal maturation and capacitation of boar spermatozoa

1990 ◽  
Vol 48 (3) ◽  
pp. 90-91
Author(s):  
N. Seki ◽  
Y. Toyama ◽  
T. Nagano
Keyword(s):  
Plasma Membrane ◽  
Essential Role ◽  
Freeze Fracture ◽  
Final Concentration ◽  
Freeze Fracturing ◽  
Physiological Conditions ◽  
Epididymal Maturation ◽  
Cacodylate Buffer ◽  
Sperm Membrane ◽  
Boar Spermatozoa

It is believed that i ntramembra.nous sterols play an essential role in membrane stability and permeability. To investigate the distribution changes of sterols in sperm membrane during epididymal maturation and capacitation, filipin has been used as a cytochemical probe for the detection for membrane sterols. Using this technique in combination with freeze fracturing, we examined the boar spermatozoa under various physiological conditions.The spermatozoa were collected from: 1) caput, corpus and cauda epididymides, 2) sperm rich fraction of ejaculates, and 3)the uterus 2hr after natural coition. They were fixed with 2.5% glutaraldehyde in 0.05M cacodylate buffer (pH 7.4), and treated with the filipin solution (final concentration : 0.02.0.05%) for 24hr at 4°C with constant agitation. After the filipin treatment, replicas were made by conventional freeze-fracture technique. The density of filipin-sterol complexes (FSCs) was determined in the E face of the plasma membrane of head regions.

An unusual cell surface modification: a double plasma membrane

1979 ◽  
Vol 39 (1) ◽  
pp. 355-372
Author(s):  
N.J. Lane ◽  
J.B. Harrison
Keyword(s):  
Plasma Membrane ◽  
Membrane Structure ◽  
Cell Layer ◽  
Peritrophic Membrane ◽  
Thin Sections ◽  
Double Membrane ◽  
Freeze Fracturing ◽  
Blood Sucking ◽  
Great Pressure ◽  
Insertion Sites

The occurrence of an unusual double plasma membrane structure is reported; it has been studied in conventional thin sections, after lanthanum-impregnation and with freeze-fracturing. This modification of the plasmalemma is found where the luminal cell membrane (I membrane) of gut microvilli in the haematophagous insect, Rhodnius prolixus, is surrounded by a second, outer membrane (O membrane), the 2 separated from one another by a highly regular I-O space of about 10 nm. Lanthanum impregnation reveals the presence of columns inclined at an angle, within this I-O space; as in the continuous junctions which link the lateral borders of these cells, these columns may maintain the very precise I-O distance. From the outer microvillar membranes radiate short spoke-like fibrils or sheets which encounter another more extensive system of myelin-like sheets. Freeze-fracturing reveals that the spoke-like sheets and the other ones which lie like a tube, around and parallel to the microvilli, contain linear ridges composed of particles, lying at random within layers of the myelin-like material which also extends into the lumen of the gut. The microvillar membanes, both O and I, fracture into faces containing rows of either PF particles or EF pits arranged as spiral ridges or grooves around the sides and across the tip of each microbillus. These could be the insertion sites of one or both of the I-O columns and spoke-like sheets while the sheets could represent a variant of peritrophic membrane. The double membrane may be a cellular device to increase the strength of the microvillar layer in these blood-sucking animals, since the cell layer must withstand great pressure owing to a sudden massive extension of the gut during a blood meal.

Structural organization of the rhizobial root nodule of alfalfa

1977 ◽  
Vol 55 (1) ◽  
pp. 35-43 ◽  
Author(s):  
J.C. Tu
Keyword(s):  
Plasma Membrane ◽  
Structural Organization ◽  
Plasma Membranes ◽  
Root Nodule ◽  
Root Nodules ◽  
Meristematic Tissue ◽  
Freeze Fracturing ◽  
Infected Root ◽  
Thin Sectioning ◽  
Membrane Envelope

The structural organization of mature root nodules of Medicago saliva L. is studied by thin-sectioning, scanning, and freeze-fracturing techniques. The nodules are club-shaped, with their meristematic tissue near the tip of each nodule. The bacteroidal cells situated closer to the tip area are young, whereas those located closer to the neck where the nodule and root join are older. The shape of the bacteroids changes as they grow older. The bacteroids evolve gradually from uniform long-rod or long-club shapes into short-club, short-rod. pear-shaped, ellipsoid, spherical, and Y-shapes, which in turn evolve into pear and spherical shapes. During the early part of the bacteroid's life, the bacteroid is enclosed in a membrane envelope. In older bacteroidal cells, it was observed that a few membrane envelopes contained more than one bacteroid. In senescent bacteroidal cells, the membrane envelopes have disintegrated and dissolved. The plasma membranes of mature bacteroidal cells have high endo- and exo-cytotic activities relative to nonrhizobial-infected root nodule cells or newly infected bacteroidal cells. Endo- and exo-cytotic activities are also evident on the membrane envelopes of bacteroids. The plasma membrane of the bacteroids appears to have no endo- and exo-cytotic activity, for the vesicle-like structures observed on the plasma membrane in thin-sectioning and freeze-fracturing preparations are in fact constricted invaginations of the plasma membrane of the bacteroids, somewhat resembling the cristae of mitochondria.

alpha-Spectrin is required for ovarian follicle monolayer integrity in Drosophila melanogaster

Development ◽  
1997 ◽  
Vol 124 (2) ◽  
pp. 353-362 ◽  
Author(s):  
J.K. Lee ◽  
E. Brandin ◽  
D. Branton ◽  
L.S. Goldstein
Keyword(s):  
Plasma Membrane ◽  
Ovarian Follicle ◽  
Cell Monolayer ◽  
Follicle Cell ◽  
Membrane Skeleton ◽  
Follicle Cells ◽  
Apical Surface ◽  
Cell Hyperplasia ◽  
Cell Plasma ◽  
Alpha Spectrin

To understand the role of the spectrin-based membrane skeleton in generating epithelial polarity, we characterized the distribution of membrane skeletal components in Drosophila ovarian follicle cells and in somatic clones of mutant cells that lack alpha-spectrin. Immunolocalization data reveal that wild-type follicle cells contain two populations of spectrin heterodimers: a network of alphabeta heterodimers concentrated on the lateral plasma membrane and an alphabetaH population targeted to the apical surface. Induction of somatic clones lacking alpha-spectrin leads to follicle cell hyperplasia. Surprisingly, elimination of alpha-spectrin from follicle cells does not appear to prevent the assembly of conventional beta-spectrin and ankyrin at the lateral domain of the follicle cell plasma membrane. However, the alpha-subunit is essential for the correct localization of betaH-spectrin to the apical surface. As a consequence of disrupting the apical membrane skeleton a distinct sub population of follicle cells undergoes unregulated proliferation which leads to the loss of monolayer organization and disruption of the anterior-posterior axis of the oocyte. These results suggest that the spectrin-based membrane skeleton is required in a developmental pathway that controls follicle cell monolayer integrity and proliferation.

Sign in / Sign up

Export Citation Format

Share Document