Polymorphism of GDF9, BMP15, BMP1B, KISS-1 and GPR54 genes and their relationship with litter size in two Egyptian sheep breeds with expression analysis of KISS-1 and GPR54 genes

Reproductive performance is an important economic trait in sheep. This study was carried out to investigate the effect of some polymorphic sites, that assumed to be linked to fertility and reproduction process, on Egyptian sheep prolificacy. In the first part, 12 SNPs that locate in 5 different genes (GDF9, BMP15, BMPR-1B, KISS-1 and GPR54) were genotyped using the iPLEX Gold technology (SEQUENOM) in both Rahmani and Ossimi ewes. Only one mutation showed polymorphism that is a 5 bp insertion / deletion (TTCTT) in 5' regulatory region of the GPR54 gene. However, no significant association was observed between this polymorphism and litter size. In the second part, two genes (KISS-1 and GPR54) were subjected for gene expression analysis using real time PCR technique in different ovarian cell compartments. The results showed that both KISS-1 and GPR54 genes were expressed in both mature and immature oocytes. However, the two genes were strongly expressed in bad quality oocytes compared to good quality oocytes. GPR54 gene was expressed in granulosa cells and corpus leuteum tissue while KISS-1 gene was neither detected in granulosa cells nor corpus leuteum tissue. The results of gene expression could be used for better understanding of ovulation process in sheep.