RESUMEN
Background: Multiple births occur frequently in some Iranian sheep breeds, while infertility scarcely occurs. Mutation detection in major fecundity genes has been explored in most of Iranian sheep flocks over the last decade. However, previously reported single nucleotide polymorphisms [SNPs] for bone morphogenetic protein receptor-[BMPR]-1B and growth differentiation factor] GDF9[known to affect fertility have not been detected. This study was conducted to assess whether any significant mutations in GDF9 were extracted from slaughtered ewe ovaries of Iranian Afshari sheep breed
Materials and Methods: Ovaries defined as poor, fair, and excellent quality based on external visual appearance of follicles were used for histology and RNA extraction processes. High quality RNAs underwent reverse transcriptase-polymerase chain reaction [RT-PCR] from GDF9 mRNA, and the products sequenced
Results: No streak ovaries, which are considered indicators of infertility due to homozygocity for some mutations in GDF9 and BMP15, were found. Sequencing results from GDF9 cDNA showed that G2 [C471T], G3 [G477A], and G4 [G721A] mutations were observed from 1, 4, and 1 out of 12 ewes, respectively. Though all 3 mutations were previously reported, this is the first report on their presence in Iranian breeds. The first and second mutations do not alter the amino acids, while G4 is a non-conservative mutation leading to E241K in the prohormone
Conclusion: As the G4 mutation was observed only in ovaries defined superficially as top quality, it could be considered as one of reasons for higher ovulation rate in some sheep. Furthermore since multiple mutations were observed in some cases, it might be possible that combinations of minor mutations in GDF9 and BMP15 interact to affect fecundity in some Iranian sheep breeds