scholarly journals PHYSICOCHEMICAL DIFFERENCES BETWEEN FRAGMENTS OF PLASMA MEMBRANE AND ENDOPLASMIC RETICULUM

1966 ◽  
Vol 30 (3) ◽  
pp. 601-621 ◽  
Author(s):  
Donald F. Hoelzl Wallach ◽  
Virendra B. Kamat ◽  
Mitchell H. Gail
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Structural Changes ◽  
Ionic Composition ◽  
Ehrlich Ascites Carcinoma ◽  
Theoretical Background ◽  
Refractive Indices ◽  
Ehrlich Ascites ◽  
Isoelectric Ph ◽  
Turbidity Increase

Specific turbidities, densities, and refractive indices of fragments of plasma membrane (PM) and endoplasmic reticulum (ER) from Ehrlich ascites carcinoma have been measured. A spherical shell model of specified dimensions and refractive index was established for PM fragments. The ionic composition of the dispersion medium was varied systematically. Increases in Γ/2 caused increases in the turbidity of both PM and ER suspensions, the greatest effects being observed with Ca2+ and Mg2+. In the case of PM this effect is attributable mainly to aggregation, whereas "structural" changes account for most of the turbidity increase with ER. The pH was also varied systematically to obtain pH- density and turbidity profiles and to establish the isoelectric pH of the two membrane types (PM—3.6; ER—4.35). Turbidity was maximum at "isoelectric" pH, which corresponds in each case to the region of minimum charge on the particle surfaces. Both PM and ER show large increases of density at the "isoelectric" pH, but only ER shows substantial structurally based turbidity increase under these conditions. Both PM and ER show operation of electrostatic attractions near "isoelectric" pH. PM has been shown to have ionically distinctive inner and outer surfaces while ER shows no such dissymmetry. The necessary theoretical background for interpretation of turbidity and density measurements is included, as well as a discussion of the limitations of our conclusions and the biological importance of our results.

Restoration of adhesive potentials of Ehrlich ascites carcinoma cells by modification of plasma membrane

1991 ◽  
Vol 147 (1) ◽  
pp. 182-190 ◽  
Author(s):  
Alexei A. Bogdanov ◽  
Larisa V. Gordeeva ◽  
Boris A. Baibakov ◽  
Leonid B. Margolis ◽  
Vladimir P. Torchilin
Keyword(s):  
Plasma Membrane ◽  
Ehrlich Ascites Carcinoma ◽  
Carcinoma Cells ◽  
Ehrlich Ascites

scholarly journals A comparative study of the molecular structures of the plasma membranes and the smooth and the rough endoplasmic-reticulum membranes from rat liver

1972 ◽  
Vol 129 (3) ◽  
pp. 781-788 ◽  
Author(s):  
F. Morin ◽  
S. Tay ◽  
H. Simpkins
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Rat Liver ◽  
Rough Endoplasmic Reticulum ◽  
Plasma Membranes ◽  
Structural Changes ◽  
Molecular Structures ◽  
Endoplasmic Reticulum Membrane ◽  
Marker Enzyme ◽  
Membrane Phospholipids

Plasma-membrane as well as smooth-, rough- and degranulated-endoplasmic-reticulum-membrane fractions were isolated from the microsomal pellet of rat liver. The purity of these fractions, as determined by marker-enzyme activities, electron microscopy, cholesterol content and RNA content, was found to be adequate for a comparative structural study. Major differences in lipid and protein composition were found to exist between the plasma membrane and the endoplasmic reticulum, but not between the smooth and the rough fractions of the endoplasmic reticulum. Differences in the location of membrane protein thiol groups and the mobility of the membrane phospholipids were observed between the plasma membranes and the endoplasmic reticulum, and these could be explained by differences in protein and lipid composition. However, by employing fluorescence and spin-labelling techniques structural changes were also observed between the smooth and the rough endoplasmic-reticulum fractions. These results suggest that the structural heterogeneity existing between the two latter membrane fractions occurs near or on their membrane surfaces and is not due to the greater number of ribosomes bound to the rough endoplasmic-reticulum fraction.

Triple Fixation For Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 90-91 ◽  
Author(s):  
M. A. Hayat
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Beam ◽  
Plasma Membrane ◽  
Myelin Sheath ◽  
Good Deal ◽  
Granular Structure ◽  
Oxidizing Agent ◽  
Fixation Technique ◽  
Large Clusters

Potassium permanganate has been successfully employed to study membranous structures such as endoplasmic reticulum, Golgi, plastids, plasma membrane and myelin sheath. Since KMnO4 is a strong oxidizing agent, deposition of manganese or its oxides account for some of the observed contrast in the lipoprotein membranes, but a good deal of it is due to the removal of background proteins either by dehydration agents or by volatalization under the electron beam. Tissues fixed with KMnO4 exhibit somewhat granular structure because of the deposition of large clusters of stain molecules. The gross arrangement of membranes can also be modified. Since the aim of a good fixation technique is to preserve satisfactorily the cell as a whole and not the best preservation of only a small part of it, a combination of a mixture of glutaraldehyde and acrolein to obtain general preservation and KMnO4 to enhance contrast was employed to fix plant embryos, green algae and fungi.

scholarly journals Ion-Induced Volume Transition in Gels and Its Role in Biology

Gels ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 20
Author(s):  
Matan Mussel ◽  
Peter J. Basser ◽  
Ferenc Horkay
Keyword(s):  
Nonlinear Response ◽  
Structural Changes ◽  
Ionic Composition ◽  
Biological Systems ◽  
Experimental Results ◽  
Resting Potential ◽  
Cell Secretion ◽  
Solvent Quality ◽  
Volume Transition ◽  
Biological Milieu

Incremental changes in ionic composition, solvent quality, and temperature can lead to reversible and abrupt structural changes in many synthetic and biopolymer systems. In the biological milieu, this nonlinear response is believed to play an important functional role in various biological systems, including DNA condensation, cell secretion, water flow in xylem of plants, cell resting potential, and formation of membraneless organelles. While these systems are markedly different from one another, a physicochemical framework that treats them as polyelectrolytes, provides a means to interpret experimental results and make in silico predictions. This article summarizes experimental results made on ion-induced volume phase transition in a polyelectrolyte model gel (sodium polyacrylate) and observations on the above-mentioned biological systems indicating the existence of a steep response.

Trichosanthes dioica seed lectin inhibits Ehrlich ascites carcinoma cells growth in vivo in mice by inducing G 0 /G 1 cell cycle arrest

2021 ◽  
Author(s):  
Shaikh Shohidul Islam ◽  
Md. Rezaul Karim ◽  
A. K. M. Asaduzzaman ◽  
A. H. M. Khurshid Alam ◽  
Zahid Hayat Mahmud ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Ehrlich Ascites Carcinoma ◽  
Carcinoma Cells ◽  
Cycle Arrest ◽  
Ehrlich Ascites ◽  
Trichosanthes Dioica
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