Abstract
Genetic studies showed that the introgression of one small X chromosomal region, namely Odysseus, from Drosophila mauritiana into D. simulans causes the hybrid male sterility. One homeobox gene, OdsH, was identified as the major factor of this system, although it requires other nearby gene(s) to be co-introgressed to confer full sterility. In order to determine whether OdsH is indeed responsible for this hybrid sterility, genetic crossing experiments were performed to compare two alleles, OdsHmau and OdsHsim, in a specific genetic background. We generated the transgene flies that carried OdsHmau or OdsHsim by inducing OdsHmel-5’ genomic region or β2-tubulin promoter by P transformation. To unveil whether OdsH is related to hybrid sterility, we measured the relative sperm quantity of the offspring carrying an introgressed segment and OdsHmau or OdsHsim transgene. Based on the relative sperm quantity, we found that transgenic OdsHmau could decrease the D. simulans sperms quantity in the specific genetic background. These results indicate that OdsHmau plays an important role in hybrid sterility.