Evidence for the presence of messenger ribonucleic acid in Allomyces macrogynus mitospores.

Sucrose density gradient analysis was used to show that polysomes were present in the mitospores of Allomyces macrogynus. Fifty percent of the spore monosomes were shown to be resistant to dissociation by 0.8 M KCl, indicating that messenger ribonucleic acid (mRNA) was bound to them. These polysomes and all the spore ribosomes were contained in the nuclear cap. Only 4S RNA could be demonstrated in the extra-cap fraction. Hybridization studies using 3H-labeled polydeoxythymidylic acid indicated that polyadenylate was present to the extent of 0.08% of the total spore RNA. Sixty-eight percent of the polyadenylic acid is found in the nuclear cap, and 32% is found in the extra-cap fraction. It was demonstrated that [3H]uridine was taken up by the spores and converted to uridine triphosphate. Lack of incorporation of 3H into RNA indicated that the spores do not synthesize RNA. Thus, the mRNA found in spores is synthesized prior to spore formation.