摘要
为研究内分泌干扰物己烯雌酚(DES)对鱼类精巢发育和配子发生的影响,研究用DES(0.1、1和10μg/L,暴露20d)对内分泌干扰研究的经典模式动物——斑马鱼(Danio rerio)雄性成鱼进行了处理。组织学研究结果表明,DES严重影响斑马鱼精子发生。同时,研究克隆了斑马鱼与生殖细胞发育和减数分裂相关的vasa、dmc1的部分c DNA,对其组织和细胞表达模式进行了研究。结果表明,vasa仅表达于精巢的精原细胞、初级精母细胞和卵巢不同时期的生殖细胞;而dmc1则表达于精巢精母细胞和卵巢卵母细胞发育早期。半定量PCR结果表明,DES处理后vasa的表达没有明显变化;而dmc1的表达则被明显抑制,且呈时间依赖性和剂量依赖性效应;而转录因子dmrt1和雄激素合成关键酶基因P450 11β的表达也被显著抑制。因此本研究推测,DES可能通过抑制dmrt1和P450 11β的表达诱导了斑马鱼生殖细胞凋亡;并通过抑制dmc1的表达阻碍了减数分裂。
Diethylstilbestrol(DES) is a typical endocrine disruptor for aquatic animals in the Yangtze River of China. Here we investigated the effects of DES on testicular development and spermatogenesis of fish. Adult male zebrafish(Danio rerio) were used as experimental subjects and were exposed to DES(0.1, 1 and 10 μg/L) for 20 days. The histological results demonstrated that the DES exposure led to severe impacts on zebrafish spermatogenesis. To further elucidate mechanisms underlying this phenomenon, we cloned the c DNAs of vasa and dmc1 and analyzed their expression patterns at the tissue and cellular levels. Our results showed that vasa was exclusively expressed in spermatogonia and primary spermatocytes of testis, and that dmc1 was specifically expressed in spermatocytes of testis. Using semi-quantitative RT-PCR we found that DES dramatically suppressed the expressions of dmc1 in a dose- and time-dependent manner, but did not affect the expression of vasa. Moreover, the expression of dmrt1(the male sex determining gene) and P450 11β(the key enzyme responsible for 11-KT synthesis) were also suppressed by DES exposure. Given that these genes play a role in meiosis and spermatogenesis, we speculated that DES might induce the male germ cell apoptosis in zebrafish by suppressing the expression of dmrt1 and P450 11β, and might inhibit the expression of dmc1 which result in impeded meiosis.
引文
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