Supplementary Material for: <i>Sox100B</i>, a <i>Drosophila</i> Group E Sox-domain Gene, Is Required for Somatic Testis Differentiation
2009-04-01T00:00:00Z (GMT) by
Sex determination mechanisms are thought to evolve rapidly and show little conservation among different animal species. For example, the critical gene on the Y chromosome, <i>SRY</i>, that determines sex in most mammals, is not found in other animals. However, a related Sox domain transcription factor, <i>SOX9</i>, is also required for testis development in mammals and exhibits male-specific gonad expression in other vertebrate species. Previously, we found that the <i>Drosophila</i> orthologue of <i>SOX9</i>, <i>Sox100B</i>, is expressed male-specifically during gonad development. We now investigate the function of <i>Sox100B</i> and find, strikingly, that <i>Sox100B</i> is essential for testis development in <i>Drosophila</i>. In <i>Sox100B</i> mutants, the adult testis is severely reduced and fails to interact with other parts of the reproductive tract, which are themselves unaffected. While a testis initially forms in <i>Sox100B</i> mutants, it fails to undergo proper morphogenesis during pupal stages, likely due to defects in the pigment cells. In contrast, no substantive defects are observed in ovary development in <i>Sox100B</i> mutant females. Thus, as is observed in mammals, a <i>Sox9</i> homolog is essential for sex-specific gonad development in <i>Drosophila</i>, suggesting that the molecular mechanisms regulating sexually dimorphic gonad development may be more conserved than previously suspected.