Changes in messenger RNAs and protein synthesis during germination of Rhizopus stolonifer sporangiospores

Sporangiospores of Rhizopus stolonifer were pulse-labeled with [³⁵S]methionine at various times during germination in order to identify germination-specific proteins. In addition, the in vivo synthesized proteins were compared with in vitro synthesized products encoded by either total messenger RNA or polysomal messenger RNA isolated at comparable time periods to determine if the majority of the proteins synthesized during spore germination were under transcriptional or translational control. We conclude that, with few exceptions, the majority of the proteins synthesized were under transcriptional control. A few proteins were synthesized only at discrete time periods during the germination process and, thus, may be germination-specific proteins. However, at no time during germination did we find a germination-specific protein synthesized which represented a major fraction of the total proteins synthesized.