title: An autosomal locus controls sex reversal in interspecific XY hybrids of the medaka fishes.
abstract: Although the two medaka species Oryzias latipes and O. curvinotus share the sex-determining gene Dmy, XY sex reversal occurs in interspecific hybridization between O. latipes females of the Hd-rR inbred strain and O. curvinotus males. In this Hd-rR-curvinotus mating, all XX and XY hybrids developed as females. In this study, we used another O. latipes inbred strain (HNI) for the mating, and found that 23% of XY hybrids developed as males, although all XX and the remaining XY hybrids developed as females. Linkage analysis using 236 XY hybrid males obtained from (Hd-rR × HNI) F(1) females showed that a single major locus, Hybrid maleless (Hml), on autosomal linkage group 17, contributed to the strain difference in the XY sex reversal. Furthermore, we found that crossing females of a different O. latipes inbred strain, HO4C, did not cause XY sex reversal in the interspecific hybrids, and that the XY hybrids from (Hd-rR × HO4C) F(1) females showed a 1:1 sex ratio. XY hybrid males had the HO4C allele at sequence-tagged site loci around the Hml locus whereas XY females had the Hd-rR allele, confirming the strong contribution of this locus to XY sex reversal. Reverse transcriptase PCR analysis showed a reduced expression of Dmy(curvinotus) in XY fry of the Hd-rR-curvinotus hybrids at hatching. These results suggest that the Hd-rR allele at the Hml locus interfere with the function of Dmy(curvinotus) on a hybrid background, thus resulting in XY sex reversal.
authors.affiliation: Graduate School of Science and Technology, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kato
authors.forename: Y
authors.initials: Y
authors.lastname: Takehana
authors.forename: Y
authors.initials: Y
authors.lastname: Fukuda
authors.forename: K
authors.initials: K
authors.lastname: Naruse
authors.forename: M
authors.initials: M
authors.lastname: Sakaizumi
authors.forename: S
authors.initials: S
authors.lastname: Hamaguchi
mesh_terms: D000818:Animals; D002678:Chimera / Q000235:genetics*; D002874:Chromosome Mapping; D005260:Female; D008040:Genetic Linkage; D006824:Hybridization, Genetic; D008297:Male; D009990:Oryzias / Q000235:genetics*; D012730:Sex Chromosomes / Q000235:genetics*; D019849:Sex Determination Processes