中文摘要：

为了探索胚胎移植过程中妊娠率的根本原因。本研究以高繁殖力小尾寒羊为试验对象,采用公认的CIDR结合外源激素处理使其同期发情,与自然发情及乏情的小尾寒羊作对比,分析了转化生长因子TGF-β3基因在卵巢细胞中的表达差异,同时对其启动子区的甲基化岛进行了分析。结果发现,自然发情绵羊和外源激素处理发情的羊在发情表现和时间上无明显差别,但是TGF-β3基因在转录水平和蛋白水平上自然发情绵羊显著高于外源激素处理发情的羊,而同期处理发情的羊显著高于乏情期绵羊卵巢细胞内的表达。自然发情和激素处理的绵羊TGF-β3基因启动子甲基化水平分别为25.8%和53.3%,而乏情期绵羊TGF-β3基因启动子处于超甲基化水平达到70.0%。以上结果说明外源激素处理的同期发情小尾寒羊尽管在发情表现、时间等与自然发情的绵羊类似,但是胚胎发育和着床重要调控基因TGF-β3的表达和甲基化模式存在显著性差异这也许是目前胚胎移植后着床率低下的原因之一。

英文摘要：

In order to explore the underlying reason of pregnancy rate after embryo transplantation, Small--tail han sheep with high fertility were used as experimental animals in this study, and exogenous hormones and CIDR were used to make syn- chronize estrus. Compared with natural oestrous and anestrous Small-- tail han sheep, the expression difference of transforming growth factor--beta 3 （TGF--β3） gene in ovarian cells and the methylation levels of TGF--β3 promoter was analyzed. The re suits showed that there was no significantly difference in estrus performance and time between natural oestrous sheep and treated oestrous sheep by exogenous hormones,but in the transcription level and protein level of TGF--β3 gene, natural oestrous sheep was significantly higher than treated oestrous sheep by exogenous hormones, and treated oestrous sheep by exogenous hormones were significantly higher than that of anestrous sheep. The methylation levels of TGF-β3 gene promoter were 25. 8% and 53.3% in natural oestrous sheep and treated oestrous sheep by exogenous hormones, respectively. While in anestrous sheep the supermethylation level was 70.0%. These results suggested that treated oestrous sheep by exogenous hormones in estrus performance and time were similar to natural oestrous sheep, but it was important to regulate embryo development and implantation in the expression and methylation pattern of TGF--β3 gene. And there were significantly different between them, which may be one reason resulting in the low implantation rate after embryo transplantation.