Cloning and Expression Levels of Genes Relating to the Ovulation Rate of the Yunling Black Goat

This study investigated the nucleotide sequences and tissue expression levels of genes relating to the ovulation rate in Yunling black goats, a famous Yunnan province, China, local breed with low fecundity. Five genes, FSHB, FSHR, BMP15, BMPR1B, and ESR2, were investigated; the complete cDNA sequences of these genes were 390, 2088, 1185, 1509, and 1585 bp, respectively, and compared with Boer goats (a more fecund breed), the sequence identities were 99%, 99%, 99%, 100%, and 99%, respectively. There were two base differences in FSHB and BMP15, four in FSHR, and three in ESR2. There were fewer follicles and oocytes in Yunling black goats than in Boer goats. Expression levels of FSHB, FSHR, and BMP15 genes in Yunling black goats were lower, and expression levels of BMPR1B and ESR2 genes were higher. Serum FSH content was lower in Yunling black goats, but serum estrogen content was higher. Protein expression levels of FSHR, BMP15, BMPR1B, and ESR2 in ovary and pituitary correlated positively with gene mRNA expression levels. In Yunling black goats, the mRNA expression levels of FSHB, FSHR, and BMP15 positively correlated with litter size, but those of BMPR1B and ESR2 correlated negatively. Together, base changes and variations in mRNA and protein expression levels of genes relating to the ovulation rate result in low fecundity in the Yunling black goat. Reduced BMP15 and FSHR levels may be related to the observed fewer oocytes and, consequently, fewer follicles.