STUDIES ON CONIDIA OF ASPERGILLUS ORYZAE .9. PROTEIN SYNTHESIZING ACTIVITY OF DORMANT CONIDIA

Kinetic studies of phenylalanine incorporation show that lower incorporation with the conidia system of Aspergillus oryzae is not due to a leveling off of the incorporation but due to ribosomes which are very unstable. Conidia ribosomes melt at lower temperature and are more rapidly autolyzed than vegetative cell ribosomes, possibly due to the presence of a nuclease. Incubation of conidia ribosomes with S-100 at 6° for 2 h causes a loss of 60-70% of protein synthesizing activity. Inactivation curves suggest that about 70% of the protein synthesizing activity in vegetative cells would be expected in dormant conidia before disruption. It may be concluded that poly U-directed protein synthesizing machineries in conidia and vegetative cells are essentially identical. © 1969.