Polyadenylated RNA population present in dormant spores of Dictyostelium discoideum

Abstract Total RNA has been isolated from dormant spores of Dictyostelium discoideum . Although the amount of RNA per cell is smaller in spores than in growing amoebae, the ratio of poly(A) sequences to total RNA remains similar. Diversity and base sequence complexity of the polyadenylated RNA population have been examined by molecular hybridization with complementary DNA primed with oligo(dT). By this technique, the number of RNA species detected at more than one copy per cell is approximately 3000. RNA species can be classified in three sets of relative abundance, corresponding respectively to species present on the average at 1000 copies, 50 and four copies per cell. By heterologous hybridization it is shown that a large number of RNA species in spores are the same as those found at other stages of the cell cycle, while 20–30% of the RNA by mass appears specific to the spore cell. The specificity of the spore RNA population resides in the specific accumulation of a small number of RNA species.