Toxoplasma gondii: Membrane structure differences between zoites demonstrated by freeze fracture analysis

1991 ◽  
Vol 72 (1) ◽  
pp. 99-102 ◽  
Author(s):  
Gérard Torpier ◽  
Marie-Laure Dardé ◽  
Hubert Caron ◽  
Françoise Darcy ◽  
André Capron
Keyword(s):  
Toxoplasma Gondii ◽  
Membrane Structure ◽  
Freeze Fracture ◽  
Fracture Analysis

Freeze-fracture analysis of membrane events during early neogenesis of cilia in Tetrahymena: changes in fairy-ring morphology and membrane topography

1983 ◽  
Vol 60 (1) ◽  
pp. 137-156
Author(s):  
L.A. Hufnagel
Keyword(s):  
Cell Division ◽  
Membrane Structure ◽  
Freeze Fracture ◽  
Fracture Analysis ◽  
Basal Bodies ◽  
Membrane Topography ◽  
Fairy Rings ◽  
Dividing Cells ◽  
Cortical System ◽  
Membrane Particle

A freeze-fracture analysis of early neogenesis of somatic and oral cilia of Tetrahymena was conducted using exponentially grown cultures and also cells induced to undergo oral reorganization. In this report, presumptive ciliary domains (PCDs), sites of future outgrowth of somatic cilia, are identified and their membrane structure is described in detail. The fairy ring, an array of membrane particles that occurs within the PCD and appears to be a precursor of the ciliary necklace, is described. A sequence of early stages in the formation of the ciliary necklace of somatic cilia is deduced from topographical information and membrane particle arrangements and numbers. Evidence is presented that basal bodies are seated at the cell surface prior to initiation of necklace assembly and a possible role for the basal body in necklace assembly is suggested. In dividing cells, new oral cilia grow out prior to orientation of cilia-parasomal sac complexes relative to cell axes. In dividing cells and during oral reorganization, new cilia also develop prior to their alignment into membranelles. Thus, growth of cilia is independent of their spatial orientation. Fairy rings were not observed during oral reorganization. During cell division, proliferation of new cilia is accompanied by the formation of a network of junctions between a cortical system of membranous cisternae, the cortical ‘alveoli’. These interalveolar junctions may serve as tracks for early positioning and orientation of new oral basal bodies.

Warm and freeze-fracture of cotton seed radicles

1987 ◽  
Vol 45 ◽  
pp. 984-985
Author(s):  
E. L. Vigil ◽  
E. F. Erbe
Keyword(s):  
Thin Film ◽  
Water Vapor ◽  
Fracture Surface ◽  
Membrane Structure ◽  
Room Temperature ◽  
Freeze Fracture ◽  
Longitudinal Axis ◽  
Fracture Plane ◽  
Cotton Seeds ◽  
Condensed Water

In cotton seeds the radicle has 12% moisture content which makes it possible to prepare freeze-fracture replicas without fixation or cryoprotection. For this study we have examined replicas of unfixed radicle tissue fractured at room temperature to obtain data on organelle and membrane structure.Excised radicles from seeds of cotton (Gossyplum hirsutum L. M-8) were fractured at room temperature along the longitudinal axis. The fracture was initiated by spliting the basal end of the excised radicle with a razor. This procedure produced a fracture through the tissue along an unknown fracture plane. The warm fractured radicle halves were placed on a thin film of 100% glycerol on a flat brass cap with fracture surface up. The cap was rapidly plunged into liquid nitrogen and transferred to a freeze- etch unit. The sample was etched for 3 min at -95°C to remove any condensed water vapor and then cooled to -150°C for platinum/carbon evaporation.

Freeze–fracture analysis of muscle plasma membrane in Becker's muscular dystrophy

1994 ◽  
Vol 20 (5) ◽  
pp. 487-494 ◽  
Author(s):  
S. Shibuya ◽  
Y. Wakayama ◽  
T. Jimi ◽  
H. Oniki ◽  
T. Kobayashi ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Muscular Dystrophy ◽  
Freeze Fracture ◽  
Fracture Analysis ◽  
Muscle Plasma Membrane

Freeze-fracture study of the dynamics of Toxoplasma gondii parasitophorous vacuole development

Micron ◽  
2008 ◽  
Vol 39 (2) ◽  
pp. 177-183 ◽  
Author(s):  
Leandro Lemgruber ◽  
Wanderley De Souza ◽  
Rossiane Claudia Vommaro
Keyword(s):  
Toxoplasma Gondii ◽  
Parasitophorous Vacuole ◽  
Freeze Fracture ◽  
Fracture Study

scholarly journals Electrical and freeze-fracture analysis of the effects of ionic cadmium on cell membranes of human proximal tubule cells.

1993 ◽  
Vol 101 (6) ◽  
pp. 510-516 ◽  
Author(s):  
D J Hazen-Martin ◽  
J H Todd ◽  
M A Sens ◽  
W Khan ◽  
J E Bylander ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Cell Membranes ◽  
Freeze Fracture ◽  
Fracture Analysis ◽  
Proximal Tubule Cells ◽  
Tubule Cells ◽  
Human Proximal Tubule

A technique for freeze fracturing minute amounts of isolated cardiac membrane

1981 ◽  
Vol 241 (6) ◽  
pp. H891-H893
Author(s):  
Y. Shibata ◽  
C. K. Manjunath
Keyword(s):  
Membrane Structure ◽  
Freeze Fracture ◽  
Multiple Fractures ◽  
Freeze Fracturing ◽  
Internal Membrane ◽  
Unequivocal Identification ◽  
Biochemical Studies ◽  
Membrane Type ◽  
Dialysis Bag ◽  
Internal Membrane Structure

Electron microscopy (EM) of freeze-fractured membranes provides more information about internal membrane structure than EM of thin-sectioned or negatively stained material. However, it has heretofore been impractical to use freeze fracture routinely for analysis of highly purified membrane fractions obtainable in small (micrograms) amounts, because the technique, when conventionally applied to minute pellets, yields only one fracture of unpredictable quality; it also precludes in parallel biochemical studies by using up the entire preparation. To solve this problem, we have developed a method for freeze fracturing tiny droplets of suspended membranes containing 1-10 micrograms membrane protein, thereby allowing both multiple fractures and biochemical studies. Before fracture, the final membrane fractions can be concentrated, subjected to experimental manipulations, cross-linked, and glycerinated in a dialysis bag. The technique is illustrated on isolated gap junctions from rabbit hearts, which were chosen because their unique internal membrane structure allows unequivocal identification of membrane type based on structural criteria.

scholarly journals Freeze-fracture analysis of the membrane lesion of human complement.

1983 ◽  
Vol 97 (3) ◽  
pp. 618-626 ◽  
Author(s):  
J Tranum-Jensen ◽  
S Bhakdi
Keyword(s):  
Transmembrane Protein ◽  
Freeze Fracture ◽  
Fracture Analysis ◽  
Membrane Insertion ◽  
Membrane Bilayer ◽  
Face Ring ◽  
Circular Structure ◽  
Protein Channel ◽  
Classical Ring ◽  
Membrane Lesion

The structure and membrane insertion of the human C5b-9(m) complex, generated by lysis of antibody-coated sheep erythrocytes with whole human serum under conditions where high numbers of classical ring-shaped lesions form, were studied in single and complementary freeze-fracture replicas prepared by unidirectional and rotary shadowing. The intramembrane portion of the C5b-9(m) cylinder was seen on EF-faces as an elevated, circular structure. In nonetched fractures it appeared as a solid stub; in etched fractures a central pit confirmed the existence of a central, water-filled pore in the molecule. Complementary replicas showed that each EF-face ring corresponded to a hole in the lipid plateau of the PF-face. Etched fractures of proteolytically stripped membranes revealed the extramembrane annulus of the C5b-9(m) cylinder on ES-faces and putative internal openings on PS-faces. Allowing for the measured thickness of deposited Pt/C, the dimensions of EF-face rings and ES-face annuli conformed to anticipations derived from negatively stained preparations. Our results support the concept that the hollow cylindrical C5b-9(m) complex penetrates into the inner leaflet of the target erythrocyte membrane bilayer, forming a stable transmembrane protein channel.

scholarly journals Phagocytosis of bacteria by polymorphonuclear leukocytes: a freeze-fracture, scanning electron microscope, and thin-section investigation of membrane structure

1978 ◽  
Vol 76 (1) ◽  
pp. 158-174 ◽  
Author(s):  
PL Moore ◽  
HL Bank ◽  
NT Brissie ◽  
SS Spicer
Keyword(s):  
Plasma Membrane ◽  
Electron Microscope ◽  
Membrane Fusion ◽  
Thin Section ◽  
Membrane Structure ◽  
Freeze Fracture ◽  
Vacuole Membrane ◽  
Attachment Sites ◽  
Pmn Leukocytes ◽  
Scanning Electron

The changes in membrane structure of rabbit polymorphonuclear (PMN) leukocytes during bacterial phagocytosis was investigated with scanning electron microscope (SEM), thin-section, and freeze-fracture techniques. SEM observations of bacterial attachment sites showed the involvement of limited areas of PMN membrane surface (0.01-0.25μm(2)). Frequently, these areas of attachment were located on membrane extensions. The membrane extensions were present before, during, and after the engulfment of bacteria, but were diminished in size after bacterial engulfment. In general, the results obtained with SEM and thin-section techniques aided in the interpretation of the three-dimensional freeze-fracture replicas. Freeze-fracture results revealed the PMN leukocytes had two fracture faces as determined by the relative density of intramembranous particles (IMP). Membranous extensions of the plasma membrane, lysosomes, and phagocytic vacuoles contained IMP's with a distribution and density similar to those of the plasma membrane. During phagocytosis, IMPs within the plasma membrane did not undergo a massive aggregation. In fact, structural changes within the membranes were infrequent and localized to regions such as the attachment sites of bacteria, the fusion sites on the plasma membrane, and small scale changes in the phagocytic vacuole membrane during membrane fusion. During the formation of the phagocytic vacuole, the IMPs of the plasma membrane appeared to move in with the lipid bilayer while maintaining a distribution and density of IMPs similar to those of the plasma membranes. Occasionally, IMPs were aligned to linear arrays within phagocytic vacuole membranes. This alignment might be due to an interaction with linearly arranged motile structures on the side of the phagocytic vacuole membranes. IMP-free regions were observed after fusion of lysosomes with the phagocytic vacuoles or plasma membrane. These IMP-free areas probably represent sites where membrane fusion occurred between lysosomal membrane and phagocytic vacuole membrane or plasma membrane. Highly symmetrical patterns of IMPs were not observed during lysosomal membrane fusion.

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