Our objective is to describe in detail the way in which the patterns of protein synthesis are modified by the action of specific control genes during development of the simple eukaryote Volvox carteri. The control gene mutations to be analyzed include those at the regA locus (which cause somatic cells to dedifferentiate and redifferentiate as reproductive cells), the lag locus (which cause delayed development of reproductive cells) and the sex c locus (which cause the development of sexual individuals in the absence of the sexual inducer normally required). Cell type- and stage-specific patterns of polypeptide labelling have been characterized using 1-D SDS-PAGE of cell extracts following a series of one hour exposures of synchronous asexual cultures to 35 50 4 equals in vivo. These studies will be extended (a) by utilization of 2-D SDS-PAGE, (b) by analysis of sexually-induced wild type cultures and (c) by analysis of the mutant strains described above. Because substantial translational control of protein synthesis appears to exist in this species detailed comparisons will be made between in vivo labelling patterns and those obtained by translation of isolated RNAs in cell-free protein synthetic systems. It is hoped that these studies will lay the ground work for subsequent analysis of transcriptional regulation and elucidation of the molecular mechanisms by which these control genes function to regulate expression of large batteries of control genes during cytodifferentiation.