Genetic and molecular features of Su(P), a gene that interacts with ref(2)P in male fertility of Drosophila melanogaster

The ref(2)P gene is involved in the control of sigma rhabdovirus multiplica tion in Drosophila melanogaster. ref(2)P activity is also necessary for mal e fertility. However, in one-third of laboratory strains tested, males that lacked ref(2)P activity were fertile. In all such strains studied, the mal e sterility phenotype was abolished due to the presence of a particular all ele at the Src(PI locus, at 73B1-2. These spontaneous suppressor alleles we re dominant. We were able to induce dominant suppressor alleles at the Su(P ) locus by X-ray mutagenesis and hybrid dysgenesis, suggesting that null al leles of Su(P) confer the dominant suppressor phenotype. The Su(P) gene was cloned by P element tagging. The P element-tagged alleles identified a Su( P) transcript as a 1.4-kb mRNA produced in the soma of both males and femal es, which is also abundant in ovaries.