Abstract：Bone morphogenetic protein 15 (BMP15) is an important regulation factor of reproductive traits in sheep (Ovis aries), however, the specific mechanism now is not certain. This study aimed to investigate the relationships between the expression levels of BMP15 mRNA and the mutations of BMP15 gene and fecundity in different sheep breeds. The expression profilings in tissues and the expression levels in ovary were determined between high fecundity breed (Small Tail Han sheep) and low fecundity breeds (Tan sheep and Sunite sheep) by using RT-PCR and qRT-PCR methods, respectively. The 3 new mutations in ovine BMP15 gene were detected in 16 sheep populations of different fecundity by using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and sequencing methods, individually. The results showed that BMP15 mRNA was detected in sheep ovary, oviduct, uterus, spleen, duodenum, skeletal muscle and subcutaneous fat, and the BMP15 mRNA of ovary was higher than that of other tissues; The BMP15 expression levels were different in ovary of 3 breeds, and Small Tail Han sheep (high fecundity breed) was significant lower than that of Tan sheep and Sunite sheep (low fecundity breeds) (P＜0.05), Tan sheep and Sunite sheep had no significant difference in ovary (P＞0.05); The new mutations of FecXGr, FecXO and G971A were not detected in all of the 16 sheep populations. The results implied that the BMP15 mRNA expression level was high in ovary and the ovulation performance and the litter size of sheep were negative correlation with the expression level of BMP15 in ovary. This study will provide a reference for revealing the functional mechanism of the regulatory factors of fecundity in sheep.
