Mutation in a structural gene for a beta-tubulin specific to testis in Drosophila melanogaster

By two-dimensional gel electrophoresis of tubulins prepared from tissues of Drosophila melanogaster we have identified a beta-tubulin subunit that is present only in the testis. Furthermore, we have isolated, as a male sterile, a third chromosome dominant mutation [ms(3)KKD] in the structural gene for this beta-tubulin. Males heterozygous for this mutation produce no motile spermatozoa. Beginning with meiosis, all processes in spermatogenesis are abnormal to some extent. Many microtubules (including both cytoplasmic microtubules and doublet tubules of the axoneme) show aberrant structure in cross section, and the overall morphology of the developing spermatids is disorganized. Testes from these males were shown, by two-dimensional gel electrophoresis, to contain both the normal testis-specific beta-tubulin and an electrophoretic variant of this tubulin in equal amounts. Both wild-type and mutant testis-specific beta-tubulins were characterized by vinblastine sulfate precipitation, coassembly with purified Drosophila embryo tubulin, and peptide mapping.