Lomasomes and vesicles in Poria monticola

1971 ◽  
Vol 49 (12) ◽  
pp. 2075-2079 ◽  
Author(s):  
J. A. Brushaber ◽  
S. F. Jenkins Jr.
Keyword(s):  
Plasma Membrane ◽  
Membrane Structure ◽  
Structure Characteristic ◽  
Wall Formation ◽  
Pinocytotic Vesicles ◽  
True Structure ◽  
Tubular Bodies ◽  
In Cells

A study of the vesicular and tubular bodies observed in cells of Poria monticola was done with particular regard to their form, origin, and membrane structure. The membranes of lomasomes and pinocytotic vesicles display the sometimes asymmetric, distinctly trilaminar structure characteristic of the plasma membrane. Lomasomes are abundant and vary in appearance depending upon the method of fixation used. Nonlamellar associations of vesicles and short tubules probably represent the true structure of lomasomes in this organism. These lomasomes originate from the plasma membrane and do not appear to be associated exclusively with wall formation.

Ultracryotomy of biological tissues to preserve membrane structure

1976 ◽  
Vol 20 (3) ◽  
pp. 687-698
Author(s):  
S. Hodson ◽  
L. Williams
Keyword(s):  
Plasma Membrane ◽  
Biological Tissue ◽  
Membrane Structure ◽  
Freeze Drying ◽  
Biological Tissues ◽  
Ice Crystal ◽  
Transfer Stage ◽  
In Cells

A vacuum transfer stage is described which permits visualization of ultracryotome sections without the considerable distortions found in sections which have either thawed or rehydrated after freeze drying. Membrane structure-nucleus, nucleolus, mitochondria with their cristae and plasma membrane-was observed only in cells at the surface of the tissue which had undergone the fastest freezing rates. Inspection of knife damage in sections through these superficial cells showed that glass or diamond knives which are perfectly adequate for sectioning resin-embedded tissues are less suited to sectioning frozen biological tissue. Deeper in the tissue, where the freezing rates were slower, ice crystal cavities destroyed all membranous structures.

scholarly journals EXOCYTOSIS OF LATEX BEADS DURING THE ENCYSTMENT OF ACANTHAMOEBA

1972 ◽  
Vol 52 (1) ◽  
pp. 117-130 ◽  
Author(s):  
James R. Stewart ◽  
Robert A. Weisman
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Cyst Wall ◽  
Actinomycin D ◽  
Acanthamoeba Castellanii ◽  
Ultrastructural Analysis ◽  
Synthetase Activity ◽  
Wall Formation ◽  
Latex Beads ◽  
In Cells

Cells of Acanthamoeba castellanii (Neff) are known to form mature cysts characterized by a cellulose-containing cell wall when transferred to a nonnutrient medium. Amebas which engulfed latex beads before encystment formed mature cysts essentially devoid of bead material. The encystment of bead-containing cells appeared to be similar to that of control cells since no important differences between the two were observed with respect to cellular levels of glycogen or protein, cellulose synthetase activity, the amount of cyst wall polysaccharide formed, or the percentage of cysts formed. Actinomycin D and cycloheximide inhibited encystment as well as bead expulsion. Ultrastructural analysis revealed that the beads, which initially were contained in phagocytic vesicles, were released from the cell by fusion of vesicular membranes with the plasma membrane. Exocytosis was observed in cells after 3 hr of encystment, with most of the beads being lost before cyst wall formation. Each bead-containing vesicle involved in expulsion was conspicuously demarcated by an area of concentrated cytoplasm, which was more homogeneously granular than the surrounding cytoplasm. Beads were not observed in the cytoplasm of mature cysts but were occasionally found in the cyst wall.

A modified liquid-mosaic model of plasma membrane structure

1998 ◽  
Vol 30 (4-5) ◽  
pp. 328-329 ◽  
Author(s):  
V. K. Rybal'chenko
Keyword(s):  
Plasma Membrane ◽  
Membrane Structure ◽  
Mosaic Model

Duchenne dystrophy: alteration in muscle plasma membrane structure

Science ◽  
1977 ◽  
Vol 196 (4293) ◽  
pp. 1005-1007 ◽  
Author(s):  
D. Schotland ◽  
E Bonilla ◽  
M Van Meter
Keyword(s):  
Plasma Membrane ◽  
Membrane Structure ◽  
Duchenne Dystrophy ◽  
Muscle Plasma Membrane

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.

Synaptic Plasma Membrane Structure and Polarity of Long-Sleep and Short-Sleep Mice

1994 ◽  
Vol 309 (2) ◽  
pp. 369-376 ◽  
Author(s):  
F. Schroeder ◽  
S.M. Colles ◽  
G.P. Kreishman ◽  
C.E. Heyliger ◽  
W.G. Wood
Keyword(s):  
Plasma Membrane ◽  
Membrane Structure ◽  
Synaptic Plasma Membrane ◽  
Short Sleep ◽  
Long Sleep

Optimization and Application of a Biotinylation Method for Quantification of Plasma Membrane Expression of Transporters in Cells

2017 ◽  
Vol 19 (5) ◽  
pp. 1377-1386 ◽  
Author(s):  
Vineet Kumar ◽  
Tot Bui Nguyen ◽  
Beáta Tóth ◽  
Viktoria Juhasz ◽  
Jashvant D. Unadkat
Keyword(s):  
Plasma Membrane ◽  
Membrane Expression ◽  
Plasma Membrane Expression ◽  
In Cells

scholarly journals Agonist-induced Ca2+ influx in human neutrophils is secondary to the emptying of intracellular calcium stores

1991 ◽  
Vol 277 (1) ◽  
pp. 73-79 ◽  
Author(s):  
M Montero ◽  
J Alvarez ◽  
J Garcia-Sancho
Keyword(s):  
Plasma Membrane ◽  
Intracellular Calcium ◽  
Time Course ◽  
Human Neutrophils ◽  
Calcium Stores ◽  
Free Medium ◽  
Prolonged Incubation ◽  
Intracellular Calcium Stores ◽  
Cytochrome P 450 ◽  
In Cells

Emptying of the intracellular calcium stores of human neutrophils, by prolonged incubation in Ca(2+)-free medium, by treatment with low concentrations of the Ca2+ inophore ionomycin, or by activation with cell agonists, increased the plasma-membrane permeability to Ca2+ and Mn2+. The chemotactic peptide formylmethionyl-leucyl-phenylalanine and the natural agonists platelet-activating factor and leukotriene B4 released different amounts of calcium from the stores and induced Ca2+ (Mn2+) uptake, the rate of which correlated inversely with the amount of calcium left in the stores. The increased Mn2+ uptake induced by these agonists was persistent in cells incubated in Ca(2+)-free medium, but returned to basal levels in cells incubated in Ca(2+)-containing medium, with the same time course as the refilling of the calcium stores. The calcium-stores-regulated Mn2+ influx, including that induced by agonists, was prevented by cytochrome P-450 inhibitors. We propose that agonist-induced Ca2+ (Mn2+) influx in human neutrophils is secondary to the emptying of the intracellular stores which, in turn, activates plasma-membrane Ca2+ channels by a mechanism involving microsomal cytochrome P-450, similar to that described previously in thymocytes [Alvarez, Montero & Garcia-Sancho (1991) Biochem. J. 274, 193-197].

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