Changes in protein synthesis during alternate pathways of differentiation in the cellular slime mold Polysphondylium pallidum.

Acrylamide gel electrophoresis in the presence of sodium lauryl sulfate and autoradiography of dried gels were used to detect incorporation of [¹⁴C]acetate into specific polypeptides of developing cells. Twenty-four polypeptides showed changes in net rate of synthesis during light-induced aggregation and sorogenesis, and 15 bands changed during KCl-induced encystment. Most of the changes during aggregation were common to three strains of P. pallidum, but different from those exhibited by D. discoideum. They failed to occur if the cells were maintained in darkness, and the pattern of changes was altered by sublethal high temperature. A few changes were common to both aggregating and encysting cells, and to stalkforming cells induced by cyclic AMP. A pulse-chase experiment indicated that all detectable increases in net synthesis were caused by alterations in actual synthesis rather than in degradation. It is suggested that the observed changes in synthesis may be essential to the correlated pathways of cellular differentiation.