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Biomedical subjects

M M Burger

Publications and source records attributed to M M Burger.

At least 163 records · Page 9Linked to original sources
PubMed1974

Membrane fatty acid replacements and their effect on growth and lectin-induced agglutinability.

The growth of 3T3 and SV101 3T3 cells in a lipid-depleted medium is enhanced by the addition of biotin or some fatty acids. The extent of enhancement depends on the fatty acid(s) supplied. The presence of linoleate is unique, since it induces a morphological alteration in 3T3 cells resulting in a cell similar to an SV101-transformed 3T3 cell. Analyses of the fatty acids from the membrane phosphatides show that the exogenously supplied fatty acids are incorporated and alter the fatty acid composition. This is most clearly evident with heptadecanoate-grown cells, in which this fatty acid and its derivatives comprise over 45% of the fatty acids in the phospholipids. The fatty acid replacements have a striking effect on the temperature dependence of agglutination by wheat germ agglutinin and concanavalin A, implying that fluidity is involved in agglutination. These temperature dependencies and the effect of fatty acid replacements on them were different for the two lectins, but similar for both transformed and untransformed cells. These observations are interpreted as suggesting that the lipid phase is heterogeneous, and that transformed and untransformed cell membranes have regions of similar fluidity.

Agglutination↗
PubMed1973

Surface changes in temperature-sensitive Simian virus 40-transformed cells.

A binding assay that shows consistent differences in the amounts of tritium-labeled concanavalin A that bind to normal and virally transformed cells was used to study the kinetic changes of cell surface in SV40-transformed 3T3 cells that express the transformed phenotype in a temperature-sensitive manner (tsSV3T3 cells). The increase in concanavalin A binding, which paralleled the appearance of the characteristics of transformed cells, was dependent on the synthesis of cellular DNA. In agreement with the results of binding studies, exponentially growing tsSV3T3 cells agglutinated at much lower lectin titers (concanavalin A as well as wheat-germ agglutinin) at 32 degrees than at 39 degrees .

Agglutination↗
PubMed1973

The relationship of concanavalin A binding to lectin-initiated cell agglutination.

We have investigated the relationship of concanavalin. A binding to the cell surface of normal and transformed cells and the subsequent agglutination of the transformed cells. At room temperature almost no differences could be detected in agglutinin binding between transformed and untransformed cells. At 0 degrees C, however, where endocytosis was negligible, the transformed cells bound three times more agglutinin. However, transformed cells and trypsin-treated normal cells do not agglutinate at 0 degrees C although the amounts of agglutinin bound at 0 degrees C are sufficient to permit agglutination when such cells are shifted up to room temperature. Both transformed and trypsin-treated normal cells show a marked increase in agglutination at 15 degrees C as compared to agglutination at 0 degrees C. From this, as well as the observation that mild glutaraldehyde fixation of the cell surface inhibited agglutination but not agglutinin binding, it was concluded that concanavalin A-mediated cell agglutination requires free movement of the agglutinin receptor sites within the plane of the cell surface.

Animals↗