ENU mutagenesis and a trial to isolate mutant alleles for specific genes located in the sex-determining region of the Japanese medaka.

用乙基亚硝基脲诱变青鳉雄性精原细胞，分离性别决定区的突变等位基因。我们使用同源株Hd-rR.Y^<HNI>，其雄性具有来自Hd-rR株的遗传背景，并且在其Y染色体中仅具有包括来自HNI株的性别决定因子（和r基因座）的染色体区域。将性别反转的XY雌性与XY雄性交配，获得YY雄性。利用性连锁DNA标记SL 1检测YY男性. YY（RR ; red）和XY（Rr ; red）雄性用1 mM ENU诱变，并与未处理的XX（rr ;白色）雌性交配。共746个后代（402个男性和344个女性）产生的XY男性。所有雌性均为白色，391只雄性为红色。通过交配实验，证实11只白色雄性为性反转XX个体。269只雄性后代均为红色.因此，本研究未获得突变体。为了获得性别决定区的突变等位基因，需要继续进行诱变实验。

Ethylnitrosourea mutagenesis of spermatogonia in male medaka was performed to isolate mutant alleles in the sex-determining region. We used a congenic strain, Hd-rR.Y^<HNI>, the male of which has a genetic background derived from the Hd-rR strain, and has only the chromosomal region including the sex-determining factor (and r locus) from the HNI strain in its Y chromosome.1. Sex-reversed XY females were mated with XY males, and YY males were obtained. A sex-linked DNA marker SL1 was used for detection of YY males.2. YY (RR ; red) and XY (Rr ; red) males were mutagenized with 1mM ENU and mated with non-treated XX (rr ; white) females.3. A total of 746 offspring (402 males and 344 females) were produced from XY males. All females were white and 391 males red. Eleven white males were demonstrated to be sex-reversed XX individuals by mating expriment. All 269 male off spring from the YY males were red.4. Thus no mutants were obtained in the presentstudy. In order to get mutant alleles in the sex-determining region, it is necessary to continue mutagenesis experiment.