mRNA expression levels of genes encoding BMP/Smad pathway molecules in pituiaries of Hu sheep with different fecundity.

Hu sheep is famous for its hyper-prolificacy in the world,and the BMP/Smad pathway is shown to have close relationships with reproduction in sheep.The present study was performed to determine the expressional differences of mRNAs encoding BMP/Smad pathway molecules in pituitaries of Hu sheep between high-fecundity and low-fecundity and to further investigate the relationships between their expressions and ovulation number.Sixteen adult Hu ewes,grouped as high-fecundity (HF) and low-fecundity (LF),were treated for synchronized estrous and sacrificed for tissue sampling and recording ovulation number.Expression levels in the pituitary of Hu sheep for BMP/Smad pathway molecule genes,including BMP2,BMP4,BMP7,BMPRⅠA,BMPRⅠB,BMPRⅡ,Smad1,Smad5 and Smad4 were investigated by real-time PCR.The results showed that there were no significant differences in BMP2,BMP7,BMPRⅠA,BMPRⅡ,Smad1 and Smad4 mRNA abundance in the pituitary between HF and LF group (P0.05),respectively.But BMP4,BMPRⅠB and Smad5 mRNA abundances in the pituitary were respectively higher in HF group than those in LF group (P0.01) and negatively correlated with ovulation number.It is suggested that the expressional differences of BMP4,BMPRⅠB and Smad5 in the pituitary between high-fecundity and low-fecundity group might be one of factors for high fecundity in Hu sheep.