mRNA expression profiles of proteolytic genes during the process of ovulation in ovarian follicles of sturgeons

In sturgeon aquaculture, oocyte maturation and ovulation are induced by the administration of hormones such as luteinizing hormone–releasing hormone analog (LHRHa). However, ovulation often fails to occur, probably as a result of inappropriate hormone injection timing. It is thus necessary to understand the molecular mechanisms of sturgeon ovulation responsible for producing good-quality eggs. In this study, we investigated the proteolytic genes and their inhibitory genes in a de novo transcriptome constructed using RNA samples of ovarian follicles from Amur sturgeon ( Acipenser schrenckii ). We subsequently identified 14 mmp , nine adam , ten adamts , nine cathepsins , and three timp contigs by a homology search with BLASTx. We compared the messenger RNA (mRNA) levels of these genes in the ovarian follicles of anovulated and ovulated Amur sturgeons using RNA sequencing and quantitative PCR analysis. The results showed that the mRNA levels of mmp16 , adam23 , adamts9 , and timp2 were significantly increased by LHRHa injection only in ovulated sturgeons. We also examined the expression patterns in sterlet ( Acipenser ruthenus ) ovarian follicles in in vitro culture. adamts9 mRNA levels were drastically upregulated by the administration of 17α-hydroxyprogesterone, suggesting that Adamts9 is a key factor in successfully inducing ovulation in sturgeons. Clarifying the functions of these four genes during ovulation will lead to improved sturgeon seedling production technologies.