DNA, RNA AND PROTEIN-SYNTHESIS DURING GERMINATION OF SPORES IN CELLULAR SLIME-MOLD DICTYOSTELIUM-DISCOIDEUM

During synchronized germination of spores of D. discoideum, protein synthesis begins almost concomitantly with syntheses of messenger-like RNA (mlRNA) and 4-5S RNA (presumably tRNA) in the swollen spore stage and the initiation of ribosomal RNA (rRNA) synthesis is somewhat delayed. DNA synthesis occurs in the early stages of the amoeba emergence phase. Cycloheximide (200 .mu.g/ml) blocked spore germination as well as total protein synthesis, whereas actinomycin D (60 .mu.g/ml) did not affect either. This concentration of actinomycin D selectively inhibited formation of rRNA but did not influence the synthesis of mlRNA. Examinations of RNA labeled with [14C]uracil during germination indicated that polysomes initially detectable in the course of the germination process contain 14C-labeled mlRNA. It was concluded that at least some of mRNA synthesized during germination of D. discoideum spores is involved in protein synthesis required for the germination.