Copy number variation of ZNF280BY across eight sheep breeds and its association with testicular size of Hu sheep.

ZNF280BY, a bovid-specific Y chromosome gene, was firstly found to be highly expressed in bovine testis, indicating that it may play important roles in testicular development and male fertility. In this study, we firstly cloned the full-length cDNA of ovine ZNF280BY containing 1,993 bp, and with a 1,632 bp open reading frame. ZNF280BY was predominantly expressed in the testis, and its expression level was significantly higher in large testis than in small testis in Hu sheep at 6 months of age. In addition, the expression level of ZNF280BY significantly increased during testicular development, showing the highest expression level at 12 mo of age. ZNF280BY showed copy number variation (CNV) in 723 rams from eight sheep breeds, ranging from 17 to 514 copies, with a median copy number of 188. Pearson correlation analysis showed that the CNV of ZNF280BY was negatively correlated with testis size in Hu sheep. Furthermore, its mRNA expression level in testis had no significant correlation with the CNV but was significantly correlated with testis size. This study concluded that the expression of ZNF280BY was closely related to testicular development, and the CNV of ZNF280BY could be used as an important genetic marker to evaluate the ram reproductive capacity at an early stage in Hu sheep.