Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Japan.
Sex Dev. 2011;5(5):250-8. doi: 10.1159/000330365. Epub 2011 Aug 11.
We identified a sex-linked, recessive body color gene, presently designated w (whitish-yellow), in the frog Rana rugosa from the Iwakuni population in Western Japan. This is the first time a sex-linked body color gene was found in amphibians so far. In this population of R. rugosa, males are the heterogametic sex, but the sex chromosomes are still homomorphic. When heterozygous males (Ww), which were produced by crossing a whitish-yellow female (ww) found in the field and a wild-type male (WW) of the same population, were backcrossed to the homozygous whitish-yellow female (ww), the resultant male offspring were all wild-type, whereas the females were all whitish-yellow. This result definitely indicates that w is recessive and X-linked, and its wild-type allele W is located on the Y chromosome. Using this strain (X(w)X(w) female and X(w)Y(W) male), we found that expression of Dmrt1 and Rspo1, which are involved in testicular and ovarian differentiation in vertebrates, was higher in males and females, respectively, prior to the onset of the sexually dimorphic expression of Cyp17 and Cyp19, which are involved in biosynthesis of sex steroids and are critical markers of gonadal sex differentiation.
我们在来自日本西部岩国市的青蛙 Rana rugosa 中发现了一个与性别相关的隐性体色基因，目前命名为 w（黄白色）。这是迄今为止在两栖动物中首次发现与性别相关的体色基因。在这个 R. rugosa 种群中，雄性是异型性别的，但性染色体仍然是同形的。当通过将在野外发现的黄白色雌性（ww）与同一种群的野生型雄性（WW）杂交产生的杂合雄性（Ww）回交至纯合黄白色雌性（ww）时，雄性后代均为野生型，而雌性均为黄白色。这一结果明确表明 w 是隐性且与 X 染色体连锁的，其野生型等位基因 W 位于 Y 染色体上。利用这个品系（X(w)X(w) 雌性和 X(w)Y(W) 雄性），我们发现，参与脊椎动物睾丸和卵巢分化的 Dmrt1 和 Rspo1 的表达在雄性和雌性中分别升高，然后才出现 Cyp17 和 Cyp19 的性别二态性表达，后者参与性激素的生物合成，是性腺性别分化的关键标记物。
