GENETIC INVESTIGATION OF CAMP-DEPENDENT PROTEIN-KINASE FUNCTION IN DROSOPHILA DEVELOPMENT

The cAMP-dependent protein kinase (PKA) has been shown to mediate the vast majority of cellular responses to the intracellular second messen ger, cAMP, in eukaryotes. To study the role of cAMP signal transductio n in Drosophila development, we have isolated and molecularly characte rized mutations of varying severity in the Drosophila PKA gene, DC0. B iochemical measurements indicate that DC0 is either the sole or the ma jor PKA catalytic subunit gene in Drosophila. Adult females heterozygo us for a strong and a weak DC0 allele fail to lay eggs and show a stri king and novel defect in oogenesis that includes the formation of egg chambers containing multinucleate nurse cells. Females heterozygous fo r two weak DC0 alleles are fertile but produce offspring showing a var iety of defects in embryogenesis, including preblastoderm arrest and a lterations in cuticular patterning. Animals zygotically null for DC0 d ie as morphologically normal first-instar larvae, implying that matern ally encoded protein, which perdures for at least 12 hr, suffices for embryogenesis. Animals hemizygous for weak DC0 alleles survive for sev eral days as larvae but grow slowly. Mitotic recombination experiments in the adult eye indicate that the DC0 gene is not required autonomou sly either for cell viability or normal growth rates. These results ar gue that cAMP-mediated signal transduction is essential at a variety o f stages during the development of a metazoan.