Comparative analysis on mRNA expression level and methylation status of DAZL gene between cattle-yaks and their parents.

The autosomal gene Deleted in Azoospermia Like (DAZL) is essential for spermatogenesis. The absence of DAZL gene will lead to meiotic arrest, spermatogenetic failure and male infertility, and so it was usually considered as a candidate gene for male infertility in cattle-yaks. To study the regulatory mechanism of DAZL expression in cattle-yaks, DAZL mRNA expression and DAZL gene methylation patterns in testes of cattle, yaks and cattle-yaks were examined using real-time PCR and bisulfite sequencing. The results showed that DAZL mRNA expression in testes of cattle-yaks was lower than that in cattle and yak (about 1/2-1/3 of cattle and yak). The methylation level of DAZL in cattle-yaks (85.6%) was significantly higher than that in cattle (69.8%) and yaks (71.4%) (P<0.01). The methylation and mRNA expression level of DAZL was significantly negatively correlated in the testes of cattle-yaks and their parents (P<0.01). We propose that the methylation of DAZL gene plays an important role in DAZL transcriptional regulation and maybe have a severe effect on spermatogenesis and male sterility in cattle-yaks.