Department of Animal Sciences, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad, 500 046, India.
Fish Physiol Biochem. 2005 Apr;31(2-3):143-7. doi: 10.1007/s10695-006-0016-3.
The objective of the present study is to observe the effect of exogenous steroids, methyl testosterone (MT) and ethynyl estradiol (EEL) on gonadal differentiation and analyze its effect on the expression of several genes during testicular and ovarian differentiation in juvenile catfish. Exogenous hormone treatments (MT and EEL) were given by immersion at different days of hatching. The histological analysis revealed that the EEL- and MT-treatments resulted in the initiation of ovarian and testicular differentiation, respectively. This is further supported by specific expression of two forms of DMRT1 in the MT-treated group but not in the EEL-treated group at 47 days after hatching (dah). The reverse is true for the expression of ovarian aromatase. Results of the semi-quantitative RT-PCR show that brain aromatase transcript levels are high in 47 dah control (histologically female) and 47 dah EEL-treated fish, as compared to 47 dah MT-treated fish. At 60 dah, brain aromatase showed elevation in its expression. Interestingly, the expression pattern of 3 beta-HSD did not show any change in EEL- and MT-treated fish. The present study also provides a strategy to study sex differentiation, for those species where genetic sex population is unavailable.
本研究旨在观察外源性类固醇甲基睾酮（MT）和乙炔雌二醇（EEL）对性腺分化的影响，并分析其在幼鲶鱼睾丸和卵巢分化过程中对几种基因表达的影响。通过孵化后不同天数的浸泡给予外源性激素处理（MT 和 EEL）。组织学分析表明，EEL 和 MT 处理分别导致卵巢和睾丸分化的启动。这进一步得到了在孵化后 47 天（dah）时，MT 处理组中两种形式的 DMRT1 的特异性表达而 EEL 处理组中没有表达的支持。卵巢芳香酶的表达则相反。半定量 RT-PCR 结果表明，与 47 dah MT 处理鱼相比，47 dah 对照组（组织学上为雌性）和 47 dah EEL 处理鱼的脑中芳香酶转录本水平较高。有趣的是，EEL 和 MT 处理鱼中 3β-HSD 的表达模式没有任何变化。本研究还为那些无法获得遗传性别群体的物种提供了一种研究性别分化的策略。
