P450 aromatase expression in the temperature-sensitive sexual differentiation of salamander (Hynobius retardatus) gonads.
P450 aromatase expression in the temperature-sensitive sexual differentiation of salamander (Hynobius retardatus) gonads.
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DOI：
10.1387/ijdb.041916ns
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
Natsuko Sakata;Y. Tamori;M. Wakahara
中科院分区：
文献类型：
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作者：
Natsuko Sakata;Y. Tamori;M. Wakahara
两栖动物性腺的性别分化被认为是由基因控制的，但在表观遗传或环境方面发生了变化。从孵化到变态阶段，在一定的温度下饲养延迟小蜥蜴幼虫时，高温(28℃)只诱导雌性性腺(卵巢)，而中等温度(20℃和23℃)或较低温度(16℃)则产生1：1的性腺形态比例。温度敏感期被限制在孵化后15-30天，恰好在性别分化之前或发生时。从成体性腺中分离得到小海豚P450芳香酶(P450 aromatase，P450arom)基因，并测定其部分核苷酸或氨基酸序列，结果表明该基因与多种脊椎动物的同源性较高。P450arom基因主要在成体卵巢和脑中表达，在睾丸中表达较弱，在其他躯体器官中不表达。用定量竞争RT-PCR方法检测到正常发育幼虫P450arom的表达具有典型的性别二型性，在雌性性腺中表达较强，而在雄性性腺中表达很弱。这种二型性比性腺的形态分化早得多。当幼虫在雌性产生温度(28℃)下饲养时，所有温度处理的幼虫都检测到强表达，表明P450arom上调，即使在遗传雄性中也是如此。我们的结果证实了P450arom调节在性腺分化中的重要性，并表明P450arom的上调参与了该物种对温度敏感的性逆转过程。
Sex differentiation of gonads in amphibians is believed to be controlled genetically, but altered epigenetically or environmentally. When larvae of the salamander Hynobius retardatus were reared at defined temperatures from hatching to metamorphic stages, a high temperature (28 degrees C) induced exclusively female gonads (ovaries), whereas intermediate (20 and 23 degrees C) or lower (16 degrees C) temperatures produced a 1:1 sex ratio of the morphological gonads. The thermosensitive period was determined to be restricted from 15 to 30 days after hatching, just before or when sexual differentiation occurred. Hynobius P450 aromatase (P450arom) cDNA was isolated from adult gonads and the partial nucleotide or deduced amino acid sequences were determined, showing a high level of identity with various vertebrate species. The P450arom gene was expressed predominantly in the adult ovary and brain, weakly in testis, but not in other somatic organs. A typical sexual dimorphism in P450arom expression was detected in normally developing larvae by a quantitative competitive RT-PCR; strong expression in the female gonads but very weak in male gonads. The dimorphism was detected much earlier than the morphological sexual differentiation of the gonads. When larvae were reared at the female-producing temperature (28 degrees C), strong expression was detected in all the temperature-treated larvae, suggesting that P450arom was up-regulated, even in genetic males. Our results confirm the importance of the P450arom regulation in the sexual differentiation of gonads and demonstrate that an up-regulation of P450arom is involved in the process of temperature-sensitive sex reversal in this species.