scholarly journals Cytoskeletal network underlying the human erythrocyte membrane. Thin-section electron microscopy.

1980 ◽  
Vol 85 (3) ◽  
pp. 567-576 ◽  
Author(s):  
S Tsukita ◽  
S Tsukita ◽  
H Ishikawa
Keyword(s):  
Electron Microscopy ◽  
Human Erythrocyte ◽  
Erythrocyte Membranes ◽  
Human Erythrocyte Membrane ◽  
Thin Sections ◽  
Cytoskeletal Network ◽  
Thin Section Electron Microscopy ◽  
Human Erythrocyte Membranes ◽  
Section Electron

A filamentous network underlying the human erythrocyte membranes can be clearly visualized in situ by electron microscopy of thin sections of specimens fixed with tannic acid-glutaraldehyde. The network is composed of two layers: the first, a layer of vertical components with granular appearance, which are seen to be directly associated with the membrane proper, and the second, a horizontally disposed, anastomosing meshwork of filamentous components, approximately 9 nm in thickness, which are attached to the vertical components. The diameter and appearance of the filamentous components are similar to those of purified spectrin. EDTA treatment (0.1 mM, pH 8.0), which was used to extract spectrin and actin, resulted in the disappearance of the filamentous meshwork, leaving only the granular components.

scholarly journals Electron microscope study of reassociation of spectrin and actin with the human erythrocyte membrane

1981 ◽  
Vol 90 (1) ◽  
pp. 70-77 ◽  
Author(s):  
S Tsukita ◽  
S Tsukita ◽  
H Ishikawa ◽  
S Sato ◽  
M Nakao
Keyword(s):  
Erythrocyte Membrane ◽  
Human Erythrocyte ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Erythrocyte Membranes ◽  
Human Erythrocyte Membrane ◽  
Thin Sections ◽  
Fixation Treatment ◽  
Human Erythrocyte Membranes ◽  
Inside Out

Reassociation of spectrin and actin with human erythrocyte membranes was studied by stereoscopic electron microscopy of thin sections combined with tannic acid- glutaraldehyde fixation. Treatment of the erythrocyte membrane with 0.1 mM EDTA (pH 8.0) extracted more than 90 percent of the spectrin and actin and concomitantly removed filamentous meshworks underlying the membranes, followed by fragmentation into small inside-out vesicles. When such spectrin-depleted vesicles were incubated with the EDTA extract (crude spectrin), a filamentous meshwork, similar to those of the original membranes, was reformed on the cytoplasmic surface of the vesicles. The filamentous components, with a uniform thickness of 9 nm, took a tortuous course and joined one another often in an end-to-end fashion to form a irregular but continuous meshwork parallel to the membrane. Purified spectrin was also reassociated with the vesicles in a population density of filamentous components almost comparable to that of the crude spectrin-reassociated vesicles. However, the meshwork formation was much smaller in extent, showing many independent filamentous components closely applied to the vesicle surface. When muscle G-actin was added to the crude spectrin- or purified spectrin- reassociated vesicles under conditions which favor actin polymerization, actin filaments were seen to attach to the vesicles through the filamentous components. Two modes of association of actin filaments with the membrane were seen: end-to-membrane and side-to- membrane associations. In the end-to-membrane association, each actin filament was bound with several filamentous components exhibiting a spiderlike configuration, which was considered to be the unit of the filamentous meshwork of the original erythrocyte membrane.

scholarly journals Toroidal bands in polytene chromosomes of Drosophila

1983 ◽  
Vol 64 (1) ◽  
pp. 255-264
Author(s):  
V. Sorsa
Keyword(s):  
Electron Microscopy ◽  
Drosophila Melanogaster ◽  
Salivary Gland ◽  
Thin Section ◽  
Polytene Chromosomes ◽  
Thin Sections ◽  
Sister Chromatids ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

Results obtained from the thin-section electron microscopy of salivary gland chromosomes of Drosophila melanogaster mainly support the concept of cable-like organization of polytene chromosomes, with disk-like bands composed of parallel bundles of homologous chromomeres. Outward orientation of loop fibres may generally cause a toroidal bending in the chromomere bundles. Both longitudinal and transverse sections of polytene chromosomes indicate that the bands may contain toroidal subunits. Torus-shaped bands were only found in thin sections of the most distal and most proximal regions, as well as in certain heavy bands at the late-replicating regions of polytenized interphase chromosomes. This suggests that an incomplete duplication of chromomeres may be a reason for torus formation, by preventing the separation of sister chromatids at the earliest phases of the polytenization process. The appearance of more numerous, but smaller, subunits in thin-sectioned faint bands is interpreted as a consequence of more complete segregation of sister chromatids in those bands during polytenization.

Interaction of Penicillin G with the Human Erythrocyte Membrane and Models

1996 ◽  
Vol 51 (3-4) ◽  
pp. 243-248
Author(s):  
M. Suwalsky ◽  
F. Villena ◽  
F. Aguilar ◽  
C. P. Sotomayor
Keyword(s):  
Human Erythrocyte ◽  
Penicillin G ◽  
Erythrocyte Membranes ◽  
Molecular Models ◽  
X Ray Diffraction ◽  
Human Erythrocyte Membrane ◽  
Red Cell Membrane ◽  
Large Unilamellar Vesicles ◽  
Major Toxicity ◽  
Human Erythrocyte Membranes

Abstract Penicillin G (PEN) is a widely used antibiotic whose mechanism of action is related to the interference with the synthesis of bacteria cell wall. In order to evaluate its perturbing effect upon human cell membranes PEN was made to interact with human erythrocytes, isolated resealed human erythrocyte membranes and molecular models. The latter were multibilayers of the phospholipids dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidyl-ethanolamine (DMPE) as well as DMPC large unilamellar vesicles. These studies were per­ formed by scanning electron microscopy, fluorescence spectroscopy and X-ray diffraction methods. The observed results coincide in that PEN did not exert any significant effect upon the structures of the red cell membrane neither on its molecular models. This is in agreement with its reported lack of major toxicity and hem atological reactions.

Kinetic Attributes of Na+, K+ ATPase and Lipid / Phospholipid Profiles of Rat and Human Erythrocyte Membrane

2000 ◽  
Vol 55 (9-10) ◽  
pp. 770-777 ◽  
Author(s):  
Hetal G. Patel ◽  
Radha V. Aras ◽  
Surendra S. Katyare
Keyword(s):  
Phase Transition ◽  
Human Erythrocyte ◽  
Enzyme Stability ◽  
Total Phospholipid ◽  
Erythrocyte Membranes ◽  
Kinetic Properties ◽  
Human Erythrocyte Membrane ◽  
Human Enzyme ◽  
Human Erythrocyte Membranes ◽  
Acidic Phospholipids

Abstract Kinetic properties of Na+, K+ ATPase of membranes from rat and human erythrocytes were examined. The enzyme stability decreased with incubation time. The Vmax of the human enzyme was about 4 times lower than the values of the rat enzyme. However the energies of activation were higher. Phase transition temperature for the rat and the human enzyme was 24 °C and 17 °C, respectively. The human erythrocyte membranes were characterized by lower total phospholipid and cholesterol contents and were relatively more fluid. The human membranes contained lower proportions of acidic phospholipids which correlated well with the lower Vmax of the enzyme; the proportion of lysophosphoglyceride and sphingomyelin was higher in the human membrane.

Spin Label Studies of Erythrocytes during Storage of Blood

1989 ◽  
Vol 44 (9-10) ◽  
pp. 824-828 ◽  
Author(s):  
G. P. Pessina ◽  
L. Ciccoli ◽  
M. P. Picchi ◽  
G. Fanetti
Keyword(s):  
Human Erythrocyte ◽  
Spin Label ◽  
Room Temperature ◽  
Esr Spectra ◽  
Erythrocyte Membranes ◽  
Artificial Ageing ◽  
Human Erythrocyte Membrane ◽  
Signal Decay ◽  
Human Erythrocyte Membranes ◽  
Protein Free Medium

The kinetic behavior of the spin label MAL-6 in the interaction with differently aged human erythrocyte membranes was evaluated by monitoring the rate of disappearance of the room temperature ESR signal due to the MAL-6 spin label added to blood after storage at 4 °C or after incubation of red cells at 37 °C in a protein-free medium. After 35 days of blood storage or 60 h of erythrocytes incubation at 37 °C the decrease of the intensity of the MAL-6 ESR spectra in respect to control samples is markedly enhanced and the correspondent kinetic constants significantly increase. Signal decay of MAL-6 is a further proof that during storage of blood under blood bank conditions or during an artificial ageing of erythrocytes at 37 °C, profound modifications occur in the human erythrocyte membrane.

Rickettsia-like and mycoplasma-like organisms associated with two yellows-type diseases of strawberries in Queensland

1979 ◽  
Vol 30 (6) ◽  
pp. 1101 ◽  
Author(s):  
RS Greber ◽  
DH Gowanlock
Keyword(s):  
Electron Microscopy ◽  
The Other ◽  
Thin Sections ◽  
Flower Production ◽  
Flower Abortion ◽  
Leaf Chlorosis ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Sieve Tubes ◽  
Section Electron Microscopy

Two yellows-type diseases occur in Queensland strawberries. Affected plants show purple or bronze pigmentation of older leaves, followed by the production of small chlorotic leaves. Flower production is inhibited, and some affected plants die. Thin-section electron microscopy showed that there were two diseases, one associated with rickettsia-like organisms (RLO) and the other with mycoplasma-like organisms (MLO), both of which were found only in sieve tubes. The MLO disease caused flower abortion but not green petals, and was not transmitted by Orosius argentatus (Evans), the tomato big bud vector. The RLO disease produced more bronze pigmentation and the young leaf chlorosis was interveinal rather than marginal. This organism was sensitive to penicillin, and soil drenches of 1 mg/ml every 5 days for 7 weeks caused complete remission of symptoms. No organisms were seen in thin sections of leaves after treatment. Although these RLO morphologically resembled those associated with rugose leaf curl (RLC) disease of legumes, experiments with the RLC vector Austroagallia torrida Evans indicated that they were probably distinct.

scholarly journals Are polyphosphoinositides associated with glycophorin in human erythrocyte membranes?

1979 ◽  
Vol 179 (2) ◽  
pp. 441-444 ◽  
Author(s):  
S D Shukla ◽  
R Coleman ◽  
J B Finean ◽  
R H Michell
Keyword(s):  
Erythrocyte Membrane ◽  
Human Erythrocyte ◽  
Erythrocyte Membranes ◽  
Human Erythrocyte Membrane ◽  
Human Erythrocyte Membranes ◽  
Partition Method ◽  
Triton X

Glycophorin prepared by a lithium di-iodosalicylate-extraction/phenol-partition method was rich in polyphosphoinositides (phosphatidyl-myo-inositol 4-phosphate and phosphatidyl-myo-inositol 4,5-bisphosphate), but glycophorin extracted by Triton X-100 showed no such enrichment. The enrichment observed in the former preparations appeared not to be caused by pre-existing association between glycophorin and polyphosphoinositides in the human erythrocyte membrane, but to be largely a consequence of the preparative procedures.

The Infection of Cells by Bullet-Shaped Viruses

1969 ◽  
Vol 27 ◽  
pp. 372-373
Author(s):  
Frederick A. Murphy ◽  
Alyne K. Harrison ◽  
Sylvia G. Whitfield
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Host Cell ◽  
Thin Section ◽  
Cultured Cells ◽  
Cell Infection ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

scholarly journals Interaction of platelet plasma membranes with thrombin-activated platelets

Blood ◽  
1981 ◽  
Vol 57 (2) ◽  
pp. 305-312 ◽  
Author(s):  
HR Prasanna ◽  
HH Edwards ◽  
DR Phillips
Keyword(s):  
Human Erythrocyte ◽  
Plasma Membranes ◽  
Membrane Binding ◽  
Human Platelets ◽  
Platelet Membrane ◽  
Erythrocyte Membranes ◽  
Functional Sites ◽  
Activated Platelets ◽  
Platelet Membranes ◽  
Human Erythrocyte Membranes

Abstract This study described the binding of platelet plasma membranes to either control or thrombin-activated platelets. Glycoproteins in plasma membranes isolated from human platelets were labeled by oxidation with periodate followed by reduction with [3H]NaBH4. Labeled membranes were incubated with either control or thrombin-activated platelets. The amount of membranes bound was measured by separating platelets with bound membranes from solution by rapid centrifugation through 27% sucrose and determining the amount of radioactivity associated with platelets. Five- to sevenfold more membranes bound to thrombin- activated platelets than to control platelets. This enhanced binding of labeled membranes was completely inhibited by an excess of unlabeled platelet membranes. Human erythrocyte membranes had little affinity for either washed or thrombin-activated platelets and therefore did not compete for platelet-membrane binding. Binding of platelet membranes to thrombin-treated platelets was inhibited by prior incubation of the platelets with PGI2 suggesting that the enhanced binding of membranes was to activated platelets. This study demonstrates that the purified platelet membranes have functional sites that can mediate membrane binding to platelets and that quantitation of membrane binding appears to reflect the increased aggregation capability of activated platelets.

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