Submitted on September 10, 2009
Accepted on October 13, 2009
Altered Heterochromatin Binding by a Hybrid Sterility Protein in Drosophila Sibling Species
Joshua J. Bayes 1 and Harmit S. Malik 2*
1 Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98185, USA.; Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.; Present address: Dernburg Lab, MCB, University of California Berkeley, Berkeley, CA 94720, USA.
2 HHMI, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.; Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
* To whom correspondence should be addressed.
Harmit S. Malik , E-mail: hsmalik{at}fhcrc.org
Hybrid sterility of the heterogametic sex is one of the first postzygotic reproductive barriers to evolve during speciation, yet the molecular basis of hybrid sterility is poorly understood. We show that the hybrid male sterility gene Odysseus-site homeobox gene (OdsH) encodes a protein that localizes to evolutionarily dynamic loci within heterochromatin and leads to their decondensation. In D. mauritiana X D. simulans F1 male hybrids, OdsH from D. mauritiana (OdsHmau) acts as a sterilizing factor by associating with the heterochromatic Y chromosome of D. simulans, whereas D. simulans OdsH (OdsHsim) does not. Characterization of sterile hybrid testes revealed that OdsH expression and localization in the pre-meiotic phases of spermatogenesis differs between species. These results reveal that rapid heterochromatin evolution affects the onset of hybrid sterility.
