中文摘要：

【目的】了解牦牛和犏牛睾丸组织中DDX4基因mRNA表达水平和启动子区甲基化状态。【方法】采用real-time PCR技术检测牦牛和犏牛睾丸组织DDX4基因mRNA表达水平,采用克隆测序技术获得牦牛和犏牛DDX4基因启动子区序列,采用亚硫酸氢钠测序法检测牦牛和犏牛睾丸组织中DDX4基因启动子区甲基化状态。【结果】牦牛睾丸组织中DDX4基因mRNA表达水平极显著高于犏牛（P〈0.01）;牦牛和犏牛DDX4基因启动子区1 370 bp,含有核心启动子区（251 bp）和CpG岛（918 bp）。犏牛睾丸组织中DDX4基因启动子区甲基化水平（86.5%）极显著高于牦牛（67.0%）（P〈0.01）。【结论】牦牛睾丸组织DDX4基因表达水平极显著高于犏牛,获得了牦牛和犏牛DDX4基因启动子区序列,且犏牛睾丸组织中DDX4基因启动子区甲基化水平极显著高于牦牛（P〈0.01）。

英文摘要：

[Objective] The study was aimed to investigate the expression levels and promoter methylation status of DDX4 gene in the testes of yak and cattle-yak. [ Method ] Real-time PCR was employed to examine the expression levels in the testes of yak and cattle-yak. Clone sequencing was applied to acquire the promoter sequences of DDX4 gene of yak. The promoter methylation status of DDX4 gene in the testes of yak and cattle-yak was analyzed by using sodium bisulfite sequencing. [Result] The mRNA expression level of DDX4 gene in the testis of yak was significantly higher than that of cattle-yak （P~0.01）. The length of the promoter sequences of the DDX4 gene was 1 370 bp, which included a core promoter （251 bp） and a CpG island （918 bp）. The promoter methylation level of DDX4 gene in the testes of cattle-yaks （86.5%） was significantly higher than that in yak （67.0%） （P〈0.01）. [Conclusion] Results of the study showed that the testicular expression level of DDX4 might be involved in cattle-yak male sterility, and the promoter hypermethylation was correlated to the lower expression of DDX4 in the testes of cattle-yak.