A Transformation-induced Alteration of Cellular Membranes in Crown Gall Tumor Cells.
Phospholipids were utilized as a membrane marker to test for transformation-induced alteration of cellular membranes of cultured crown gall cells of Vinca rosea L. Fully transformed cells contained less than half the amount of phospholipids (7.8 micrograms lipid P per gram fresh weight) of normal V. rosea cells (21.4 micrograms lipid P per gram fresh weight). The normal V. rosea callus cells were not significantly different (P > 0.05) in phospholipid content from partially transformed crown gall cells (20.7 micrograms lipid P per gram fresh weight). Stimulation to rapid growth of the partially transformed cells by adding higher concentrations of inorganic salts and auxin did not significantly alter their phospholipid content (23.1 micrograms lipid P per gram fresh weight). These findings suggest that the transformation process is directly responsible for an alteration of the cellular membranes and that the membrane alteration cannot be attributed to secondary effects associated with the rapid growth of these neoplastic cells.Five classes of phospholipids were identified and quantified. Average percentage of total phospholipids contained in each class were as follows: phosphatidylcholine, 38.5 +/- 4.3; phosphatidylethanolamine, 22.2 +/- 0.8; phosphatidylinositol, 12.3 +/- 2.9; phosphatidylserine, 0.8 +/- 0.4; phosphatidic acid, 4.7 +/- 1.3. Several unidentified phospholipids were also quantified. The relative amounts of the various classes of phospholipid compounds in normal and crown gall cells of V. rosea were not significantly different.
Cockerham
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Department of Biology, University of North Carolina, Charlotte, North Carolina 28223.