POLYPHOSPHATE IN LIFE CYCLE OF PHYSARUM-POLYCEPHALUM AND ITS RELATION TO RNA SYNTHESIS

1. The amount of polyphosphate and the rate of its synthesis varied throughout the synchronous mitotic cycle of the plasmodium of Physarum polycephalum. The highest content was observed shortly before mitosis. 2. Polyphosphate synthesis was higher in plasmodia grown in phosphate-rich medium than it was in those grown in phosphate-deficient medium. Increase in this substance also occurred under conditions of starvation. 3. Inhibition of RNA synthesis in the plasmodium by actinomycin D resulted in a marked stimulation of 32P incorporation into polyphosphate. No such correlation was found after inhibition of DNA synthesis by 5-fluorodeoxyuridine or of protein synthesis by cycloheximide. © 1969.