title: Analysis of a novel gene, Sdgc, reveals sex chromosome-dependent differences of medaka germ cells prior to gonad formation.
abstract: In vertebrates that have been examined to date, the sexual identity of germ cells is determined by the sex of gonadal somatic cells. In the teleost fish medaka, a sex-determination gene on the Y chromosome, DMY/dmrt1bY, is expressed in gonadal somatic cells and regulates the sexual identity of germ cells. Here, we report a novel mechanism by which sex chromosomes cell-autonomously confer sexually different characters upon germ cells prior to gonad formation in a genetically sex-determined species. We have identified a novel gene, Sdgc (sex chromosome-dependent differential expression in germ cells), whose transcripts are highly enriched in early XY germ cells. Chimeric analysis revealed that sexually different expression of Sdgc is controlled in a germ cell-autonomous manner by the number of Y chromosomes. Unexpectedly, DMY/dmrt1bY was expressed in germ cells prior to gonad formation, but knockdown and overexpression of DMY/dmrt1bY did not affect Sdgc expression. We also found that XX and XY germ cells isolated before the onset of DMY/dmrt1bY expression in gonadal somatic cells behaved differently in vitro and were affected by Sdgc. Sdgc maps close to the sex-determination locus, and recombination around the two loci appears to be repressed. Our results provide important insights into the acquisition and plasticity of sexual differences at the cellular level even prior to the developmental stage of sex determination.
authors: Laboratory of Molecular Genetics for Reproduction, National Institute for Basic Biology, Okazaki 444-8787, Japan The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan.
authors: Toshiya
authors: T
authors: Nishimura
authors: Department of Physiological Chemistry, University of Würzburg, D-97074 Würzburg, Germany INRA, UR1037 Fish Physiology and Genomics, Rennes F-35000, France.
authors: Amaury
authors: A
authors: Herpin
authors: Interuniversity Bio-Backup Project Center, National Institute for Basic Biology, Okazaki 444-8585, Japan.
authors: Tetsuaki
authors: T
authors: Kimura
authors: Laboratory of Bioresources, National Institute for Basic Biology, Okazaki 444-8585, Japan.
authors: Ikuyo
authors: I
authors: Hara
authors: Genetic Strains Research Center, National institute of Genetics, Mishima 411-8540, Japan.
authors: Toshihiro
authors: T
authors: Kawasaki
authors: Laboratory of Molecular Genetics for Reproduction, National Institute for Basic Biology, Okazaki 444-8787, Japan.
authors: Shuhei
authors: S
authors: Nakamura
authors: Laboratory of Molecular Genetics for Reproduction, National Institute for Basic Biology, Okazaki 444-8787, Japan.
authors: Yasuhiro
authors: Y
authors: Yamamoto
authors: Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-0882, Japan.
authors: Taro L
authors: TL
authors: Saito
authors: Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-0882, Japan.
authors: Jun
authors: J
authors: Yoshimura
authors: Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-0882, Japan.
authors: Shinichi
authors: S
authors: Morishita
authors: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku 113-0033, Japan.
authors: Tatsuya
authors: T
authors: Tsukahara
authors: The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, Okazaki 444-8787, Japan.
authors: Satoru
authors: S
authors: Kobayashi
authors: The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan Interuniversity Bio-Backup Project Center, National Institute for Basic Biology, Okazaki 444-8585, Japan Laboratory of Bioresources, National Institute for Basic Biology, Okazaki 444-8585, Japan.
authors: Kiyoshi
authors: K
authors: Naruse
authors: The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan Functional Genomics Facility, National Institute for Basic Biology, Okazaki 444-8585, Japan.
authors: Shuji
authors: S
authors: Shigenobu
authors: Genetic Strains Research Center, National institute of Genetics, Mishima 411-8540, Japan The Graduate University for Advanced Studies (SOKENDAI), Mishima 411-8540, Japan.
authors: Noriyoshi
authors: N
authors: Sakai
authors: Department of Physiological Chemistry, University of Würzburg, D-97074 Würzburg, Germany Comprehensive Cancer Center Mainfranken, University Clinic Würzburg, D-97074 Würzburg, Germany.
authors: Manfred
authors: M
authors: Schartl
authors: Laboratory of Molecular Genetics for Reproduction, National Institute for Basic Biology, Okazaki 444-8787, Japan The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan mtanaka@nibb.ac.jp.
authors: Minoru
authors: M
authors: Tanaka
mesh_terms: D000818:Animals; D002452:Cell Count; D002469:Cell Separation; D002478:Cells, Cultured; D002874:Chromosome Mapping; D005260:Female; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D008040:Genetic Linkage; D056426:Genetic Loci / Q000235:genetics; D005854:Germ Cells / Q000166:cytology / Q000378:metabolism*; D006066:Gonads / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D008297:Male; D008938:Mitosis / Q000235:genetics; D009928:Organ Specificity / Q000235:genetics; D038081:Organogenesis / Q000235:genetics; D009990:Oryzias / Q000235:genetics* / Q000254:growth & development*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012730:Sex Chromosomes / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation / Q000235:genetics; D014998:Y Chromosome / Q000235:genetics
chemical_list: C110547:DMRT1 protein; D029941:Fish Proteins; D012333:RNA, Messenger; D014157:Transcription Factors
keywords: Germ cell; Medaka; Sex chromosome; Sexual identity