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Switching mechanism of the master sex-determining gene in medaka fishes
http://hdl.handle.net/10191/20782
http://hdl.handle.net/10191/20782905f5ba0-ebb4-4f23-a642-1d6ff16c941c
| 名前 / ファイル | ライセンス | アクション |
|---|---|---|
本文 (5.4 MB)
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| Item type | 学位論文 / Thesis or Dissertation(1) | |||||
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| 公開日 | 2013-01-22 | |||||
| タイトル | ||||||
| タイトル | Switching mechanism of the master sex-determining gene in medaka fishes | |||||
| タイトル | ||||||
| タイトル | Switching mechanism of the master sex-determining gene in medaka fishes | |||||
| 言語 | en | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源 | http://purl.org/coar/resource_type/c_46ec | |||||
| タイプ | thesis | |||||
| その他のタイトル | ||||||
| その他のタイトル | メダカ属魚類における性決定遺伝子の転換機構 | |||||
| 著者 |
Myosho, Taijun
× Myosho, Taijun |
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| 著者別名 | ||||||
| 識別子Scheme | WEKO | |||||
| 識別子 | 50072 | |||||
| 姓名 | 明正, 大純 | |||||
| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Three sex-determining genes, SRY (mammals), Dmy (medaka, Oryzias latipes) and DM-W (Xenopus laevis), have been identified to date in vertebrates. However, how and why a new sex-determining gene appears remains unknown, as do the switching mechanisms of the master sex-determining gene. In this study, I identified two novel sex determining gene, GsdfY in O. luzonensis and GsdfbY in O. pectoralis, from which the appearance process differs although it evolved from same ancestral gene. First, I used positional cloning to search for the sex-determining gene in O. luzonensis and found that Gsdf^Y (gonadal soma derived growth factor on the Y chromosome) has replaced Dmy as the master sex-determining gene in this species. I found that Gsdf^Y showed high expression specifically in males during sex differentiation. Furthermore, the presence of a genomic fragment that included Gsdf^Y converts XX individual into fertile XX males. Luciferase assays demonstrated that the upstream sequence of Gsdf^Y contributes to the male-specific high expression. Gsdf is downstream of Dmy in the sex-determining cascade of O. latipes, suggesting that emergence of the Dmy-independent Gsdf allele led to the appearance of this novel sex-determining gene in O. luzonensis. Next, by identifying the sex determination system and the sex chromosomes in seven Oryzias species, I examined a possibility whether Gsdf is the SD gene in these species. Linkage analysis demonstrated that sex determination system of six species were XX-XY and that the sex chromosomes of these species as follows; LG 4 in O.sp (Laos), LG 24 in O. celebensis, LG 24 in O. woworae, LG 24 in O. matanenssis, LG 10 in O. profundicola and LG 10 in O. marumoratus. Since sex chromosomes homologous to LG 12 have not been found, Gsdf homologue cannot be the SD gene in these species. Finally, in O. pectoralis, I found two copies of Gsdf, one was located on LG 12 (Gsdf orthologue), another on LG 1. Gsdf on LG 1 showed male-specific inheritance. Since Gsdf is mapped on LG 12 in O. latipes and its close relatives, I regarded Gsdf on LG 1 was a duplicated copy of Gsdf (GsdfbY). The Sex-determining region including GsdfbY was mappped on the long arm near the telomere of LG 1. This region is equivalent to about 500 kbp in the O. latipes genome. I examined the expression profiles of Gsdf and GsdfbY during the sex differentiation stages. RT-PCR revealed that in XY embryo, GsdfbY showed high expression from 2 days before hatching (dbh) to the hatching day just before the period when the sex difference in the gonad became manifest. Expression of Gsdf was detected at very low levels at 2 dbh and became a similar high level to GsdfbY at the hatching day. In XX embryo, expression of Gsdf was low from 2 dbh to the hatching day. These results suggest that GsdfbY has acquired a novel earlier expression pattern during sex-determining period. Finally, I performed gain-of-function experiment. Sex-reversed XX males were obtained by microinjection of a genomic fragment that included GsdfbY. These results demonstrated that GsdfbY is the prime candidate for the sex-determining gene of O. pectoralis. | |||||
| 内容記述 | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | 新潟大学大学院自然科学研究科 | |||||
| 内容記述 | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | 平成24年3月23日 | |||||
| 内容記述 | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | 新大院博（理）甲第351号 | |||||
| 書誌情報 | p. 1-61, 発行日 2012-03-23 | |||||
| 出版者 | ||||||
| 出版者 | 新潟大学 | |||||
| 著者版フラグ | ||||||
| 値 | author | |||||
| 学位名 | ||||||
| 学位名 | 博士（理学） | |||||
| 学位授与機関 | ||||||
| 学位授与機関名 | 新潟大学 | |||||
| 学位授与年月日 | ||||||
| 学位授与年月日 | 2012-03-23 | |||||
| 学位授与番号 | ||||||
| 学位授与番号 | 13101甲第3650号 | |||||
| 学位記番号 | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | 新大院博（理）甲第351号 | |||||
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Cite as
Myosho, Taijun, 2012, Switching mechanism of the master sex-determining gene in medaka fishes: 新潟大学, p. 1–61.
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