Genetic analysis of an intersex allele (ix5) that regulates sexual phenotype of both female and male Drosophila melanogaster

An allele of intersex (ix(5)) of Drosophila melanogaster has been characterized. The genetic analysis of the allele demonstrated that like other point mutations of ix, the ix(5) allele also transformed diplo-X individuals into intersexes. The ix(5) mutation also affects the arrangement of sex comb bristles on the forelegs of males, although they had morphologically nearly normal male genitalia. They often fail to display a sustained pattern of courtship activity when tested. Orcein-stained squash preparations of testes from ix(5) males revealed a defect in spermatogenesis. Our results, taken together with those of McRobert & Tompkins (1985), indicate that the ix(+) gene also functions in male sex determination.