Protein and Ribonucleic Acid Synthesis during Germination of Uredospores

Existing evidence suggests that there is no net synthesis of protein during germination of spores of some obligate parasites. The problem was reinvestigated with enzymatic hydrolysis, rather than acid hydrolysis or solubility properties, to estimate changes in protein and RNA. Procedures are detailed for the use of uniformly labeled (14)C-uredospores for the isolation and quantitative assay of amino acids and nucleosides resulting from hydrolysis.During early stages of germination in the absence of exogenous substrates, nucleosides derived enzymatically from RNA do not increase nor does the base composition vary. The bases of the free nucleotide pool, although varying in concentration from the RNA bases, also remain constant during this time. After 16 or 24 hours, bases from both sources decrease appreciably, and the decline is correlated with leakages to the external medium.In contrast to previous reports, amino acids released by proteases increased 20 to 25% during the first 3 to 5 hours of germination but decreased after 16 to 24 hours. The results suggest that spores of obligate parasites have a functional protein synthetic system which is involved in germination. Previous negative findings may have resulted from a lack of specificity in the analytic procedures employed, coupled with the possibility that protein or amino acid is associated with the walls of spores and the walls of germ tubes.