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A Benenson

Publications and source records attributed to A Benenson.

7 recordsLinked to original sources
PubMed1983

Long-term effects of brain trypsinization before cell seeding on cell morphology and surface composition.

The relation between the pattern of proteins localized in the surface of astroglial cells and cell differentiation was investigated in primary cultures derived from neonatal rat brains, dissociated either mechanically (MDC) or by 3 (TDC3) and 30 minutes (TDC30) trypsinization. Morphological and ultrastructural studies revealed a bed layer composed of flat, polygonal young and differentiated astrocytes in all types of cultures and a surface layer composed of small, ovoide undifferentiated cells which were more numerous in TDC30 than in TDC3 and MDC. The enrichment in undifferentiated cells, induced by prolonged brain trypsinization prior cell seeding, was observed during two weeks in culture; latter, by day 20, the cell population in all cultures was that of differentiated astrocytes. The presence of structural and enzymatic cell markers indicated that the cell population in MDC and TDC3 as well as in TDC3, including the small cells, was of astroglial origin. Concomitant with the morphological changes, cells in TDC30 were less accessible to surface labeling than those composing MDC. Subsequent electrophoresis of the labeled surface proteins demonstrated that a 140-130 K complex was the most "sensible" to brain trypsinization and that their accessibility to the surface probing was maximal during the differentiation of astrocytes in MDC or of small cells in TDC30. By day 20, these components were not significantly labeled in both, MDC, and TDC30, cultures. The use of two types of astrocytes primary culture which were different in the ratio of differentiated to undifferentiated cells and their surface labeling at different growth stages showed a variation in the composition of surface proteins during the cell maturation. The increased accessibility of some surface proteins to external probing when the cells developed to differentiated astrocytes might suggest their involvement in cell differentiation.

Animals↗
PubMed1982

Isolation of cell surface membranes from cultured C6 glioblastoma cells.

Plasma membranes were isolated from C6 glioblastoma cells by two methods. In the first method cells were treated with concanavalin A and lysed in hypotonic medium. After partial separation of plasma membranes from other cell material, the lectin was displaced with alpha-methyl-D-mannoside. In the second method untreated cells or cells iodinated in a lactoperoxidase-catalyzed reaction were homogenized in isotonic medium. Membrane fractions obtained by either homogenization procedure were further purified by rate zonal and equilibrium centrifugations into linear density gradients. Disruption of the glioblastoma cell membrane gives rise to heterogeneous assemblies of membrane fragments. Two populations of plasma membranes were isolated from untreated and from iodinated cells: a "lighter" membrane fraction characterized by relatively lower sedimentation velocity and buoyant density, and a "heavier" membrane fraction of relatively faster sedimentation velocity and higher buoyant density. Both fractions showed electrophoretic patterns similar to those of 125I-labeled cell surface proteins. Their specific (Na+ + K+)-ATPase activity was seven- to eightfold the homogenate activity (recovery, 13.1%). Both fractions were, however, still contaminated by smooth endoplasmic reticulum, as judged from the activity of NADPH-dependent cytochrome c reductase (recovery, 2.4%). It is suggested that plasma membrane fragments present in the two fractions might differ in the organization of their structures, e.g., membrane vesicle intactness and membrane orientation.

Animals↗