title: The process of a Y-loss event in an XO/XO mammal, the Ryukyu spiny rat.
abstract: The Ryukyu spiny rat, Tokudaia osimensis, has an XO/XO sex chromosome constitution, lacking a Y chromosome and the mammalian sex-determining gene SRY. To investigate the Y-loss event, we traced three proto-Y-linked genes, RBMY1A1, EIF2S3Y, and KDM5D, in the genome. The original Y-linked RBMY1A1 was lost as well as SRY, and the remaining RBMY1A1 was a processed pseudogene on autosome. In contrast, EIF2S3Y and KDM5D were conserved in genomes of both sexes as a result of their translocation from the Y chromosome to the X chromosome and/or autosomes. Furthermore, these genes were expressed in gonads and brains of both sexes. Our study indicated a loss of Y-linked genes with important male functions to be necessary for the Y chromosome to disappear. These functions might have been retained through the acquisition of new genes, and therefore, the Y-loss has had no harmful effect on the maintenance of this species.
authors.affiliation: Laboratory of Animal Cytogenetics, Graduate School of Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo, Japan. asatok@cris.hokudai.ac.jp
authors.forename: Asato
authors.initials: A
authors.lastname: Kuroiwa
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Ishiguchi
authors.forename: Fumio
authors.initials: F
authors.lastname: Yamada
authors.forename: Abe
authors.initials: A
authors.lastname: Shintaro
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Matsuda
mesh_terms: D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D020732:Cytogenetic Analysis; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D015870:Gene Expression; D050172:Genes, X-Linked; D050173:Genes, Y-Linked; D024282:Genes, sry; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008540:Meiosis; D051379:Mice; D051189:Murinae / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D011544:Pseudogenes; D012729:Sex Chromosome Aberrations; D051876:Sex-Determining Region Y Protein / Q000235:genetics; D013091:Spermatogenesis; D014178:Translocation, Genetic; D014960:X Chromosome / Q000235:genetics; D014998:Y Chromosome / Q000235:genetics* / Q000648:ultrastructure
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D051876:Sex-Determining Region Y Protein; C497746:Sry protein, mouse