title: Neighboring genes for DNA-binding proteins rescue male sterility in Drosophila hybrids.
abstract: Crosses between closely related animal species often result in male hybrids that are sterile, and the molecular and functional basis of genetic factors for hybrid male sterility is of great interest. Here, we report a molecular and functional analysis of HMS1, a region of 9.2 kb in chromosome 3 of Drosophila mauritiana, which results in virtually complete hybrid male sterility when homozygous in the genetic background of sibling species Drosophila simulans. The HMS1 region contains two strong candidate genes for the genetic incompatibility, agt and Taf1 Both encode unrelated DNA-binding proteins, agt for an alkyl-cysteine-S-alkyltransferase and Taf1 for a subunit of transcription factor TFIID that serves as a multifunctional transcriptional regulator. The contribution of each gene to hybrid male sterility was assessed by means of germ-line transformation, with constructs containing complete agt and Taf1 genomic sequences as well as various chimeric constructs. Both agt and Taf1 contribute about equally to HMS1 hybrid male sterility. Transgenes containing either locus rescue sterility in about one-half of the males, and among fertile males the number of offspring is in the normal range. This finding suggests compensatory proliferation of the rescued, nondysfunctional germ cells. Results with chimeric transgenes imply that the hybrid incompatibilities result from interactions among nucleotide differences residing along both agt and Taf1 Our results challenge a number of preliminary generalizations about the molecular and functional basis of hybrid male sterility, and strongly reinforce the role of DNA-binding proteins as a class of genes contributing to the maintenance of postzygotic reproductive isolation.
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138; Department of Biology, Lund University, 22362 Lund, Sweden mlienard@fas.harvard.edu dhartl@oeb.harvard.edu.
authors.forename: Marjorie A
authors.initials: MA
authors.lastname: Liénard
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138;
authors.forename: Luciana O
authors.initials: LO
authors.lastname: Araripe
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138; mlienard@fas.harvard.edu dhartl@oeb.harvard.edu.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Hartl
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila / Q000235:genetics* / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics*; D005260:Female; D007248:Infertility, Male / Q000235:genetics*; D008297:Male; D013081:Sperm Motility; D019076:Transgenes
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins
keywords: gene conflict; hybrid male sterility; postzygotic reproductive isolation; transcription factor