title: A novel sex determination system in a close relative of the house mouse.
abstract: Therian mammals have an extremely conserved XX/XY sex determination system. A limited number of mammal species have, however, evolved to escape convention and present aberrant sex chromosome complements. In this study, we identified a new case of atypical sex determination in the African pygmy mouse Mus minutoides, a close evolutionary relative of the house mouse. The pygmy mouse is characterized by a very high proportion of XY females (74%, n = 27) from geographically widespread Southern and Eastern African populations. Sequencing of the high mobility group domain of the mammalian sex determining gene Sry, and karyological analyses using fluorescence in situ hybridization and G-banding data, suggest that the sex reversal is most probably not owing to a mutation of Sry, but rather to a chromosomal rearrangement on the X chromosome. In effect, two morphologically different X chromosomes were identified, one of which, designated X*, is invariably associated with sex-reversed females. The asterisk designates the still unknown mutation converting X*Y individuals into females. Although relatively still unexplored, such an atypical sex chromosome system offers a unique opportunity to unravel new genetic interactions involved in the initiation of sex determination in mammals.
authors.affiliation: Institut des Sciences de l'Evolution (UMR CNRS/Université Montpellier II), Montpellier, France. frederic.veyrunes@univ-montp2.fr
authors.forename: Frederic
authors.initials: F
authors.lastname: Veyrunes
authors.forename: Pascale
authors.initials: P
authors.lastname: Chevret
authors.forename: Josette
authors.initials: J
authors.lastname: Catalan
authors.forename: Riccardo
authors.initials: R
authors.lastname: Castiglia
authors.forename: Johan
authors.initials: J
authors.lastname: Watson
authors.forename: Gauthier
authors.initials: G
authors.lastname: Dobigny
authors.forename: Terence J
authors.initials: TJ
authors.lastname: Robinson
authors.forename: Janice
authors.initials: J
authors.lastname: Britton-Davidian
mesh_terms: D000818:Animals; D033481:Chromosomes, Mammalian / Q000235:genetics; D005260:Female; D024282:Genes, sry; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D051379:Mice; D010641:Phenotype; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012729:Sex Chromosome Aberrations; D012730:Sex Chromosomes / Q000235:genetics; D019849:Sex Determination Processes; D014960:X Chromosome / Q000235:genetics*