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Biomedical subjects

M Edidin

Publications and source records attributed to M Edidin.

123 records · Page 7Linked to original sources
PubMed1973

Fluidity of the surface of cultured muscle fibers. Rapid lateral diffusion of marked surface antigens.

Fluorescent antibody fragments of anti-muscle plasma membrane antibody bound as small fluorescent spots when applied by micropipetting to cultured myotubes. The spots were observed to enlarge with time. The rate of enlargement of fluorescent spots was greater when fragments were applied than when divalent antibody was used. It was also greater at 23 degrees -25 degrees C than at 0 degrees -4 degrees C. With glutaraldehyde-fixed cells no increase in the size of the spots was seen. The observations are consistent with the spread of fluorescent spots due to diffusion of surface protein antigens within the plane of a fluid membrane. From measurements of spot size against time, a diffusion constant of 1-3 x 10(-9) cm(2) s(-1) can be calculated for muscle plasma membrane proteins of mol wt approximately 200,000. This value is consistent with other observations on the diffusion of surface antigens and of labeled lipid molecules in synthetic and natural membranes.

Aldehydes↗
PubMed1972

Antigen cap formation in cultured fibroblasts: a reflection of membrane fluidity and of cell motility.

Reaction of antibody to surface Histocompatibility-2 antigens of cultured mouse fibroblasts causes aggregation of the cellular antigens into caps; these appear as areas of high antigen concentration localized away from the cell processes. Cap formation is inhibited when ATP generation by cells is interrupted, when the temperature is lowered, by addition of cycloheximide-especially over long time periods-and by colcemid. The observations are consistent with a role of the locomotor system of cells in the collection of small antigen-antibody aggregates into a large localized cap. Together with observations on the absence of caps in epithelial cells, these findings suggest that only cells, such as fibroblasts and lymphocytes, that bear leading ruffled membranes are capable of driving antigenantibody aggregates to form caps.

Animals↗
PubMed1969

An L-glutamine requirement for intercellular adhesion.

Intercellular adhesion presumably involves components of the cell surface, but the chemical nature of these substances is not known. The present studies suggest that complex carbohydrates are required for the adhesion of at least one type of animal cell. Single cells obtained from "embryoid bodies," the ascites-grown form of a mouse teratoma, aggregated in a complex tissue culture medium, but not in a glucose balanced salts solution. The active component of the tissue culture medium was identified as L-glutamine, and the only compounds found to replace it were the hexosamines D-glucosamine and D-mannosamine. A variety of studies indicated that the three compounds were active as a consequence of metabolic reactions. These results are consistent with known metabolic pathways and indicate that the conversion of nonadhesive to adhesive teratoma cells requires the synthesis of glycoproteins, glycolipids, and/or polysaccharides.

Adhesiveness↗
PubMedDate not supplied

The effect of temperature on the lateral diffusion of plasma membrane proteins.

Cooling is expected to gradually reduce the lateral diffusion of membrane proteins, at a rate predicted from the changes in viscosity and order observed on cooling defined lipids and lipid mixtures. However, a continuous change in diffusion rate with falling temperature is not observed in mammalian cells. Rather, on cooling below around 20 degrees C, protein diffusion rates are found to increase, reaching a new maximum at 15 degrees C. This anomaly in diffusion rate could result in irreversible changes in membrane structure when mammalian cells are cooled to temperatures below 20 degrees C.

Animals↗