Detection of new mutations in exon 8 of BMPR1B gene in Iranian Lori-Bakhtyari, Shal, Ghezel and Afshari sheep breeds

Bone morphogenetic protein receptor-1B is one of the major genes significantly affect ewe ovulation rate. The aim of this study was to screen exon 8 of BMPR1B in single- and twin-birth ewes of Iranian Lori-Bakhtyari, Shal, Ghezel, and Afshari breeds. DNA was extracted from blood of ewes and rams from numerous sheep flocks and the genotype patterns were screened by PCR-SSCP approach. Results of SSCP analysis showed that there are three genotypic patterns in the four above-mentioned breeds. The highest abundant pattern and the lowest pattern were pattern 1 (73 %) and pattern 2 (8 %), respectively, in the whole flocks. There was a significant difference between these three genotypic patterns in terms of litter size attribute, so that ewes harboring Pattern 2 had the highest litter size average (1.7 lamb per parturition) while ewes carrying Pattern 3 had the lowest litter size average (1.4 lamb per parturition). Furthermore, the PCR amplicon from exon 8, containing these genotypic patterns, were sequenced. The sequencing results of candidate samples from different classes of SSCP showed that there were four new mutations in BMPR1B of Iranian sheep. Three of these mutations were nucleotide conversions, including G812T, T854A, and C855A mutations which caused to tryptophan to lysine (W219L), phenyl alanine to tyrosine (F233Y), and phenyl alanine to lysine (F233L) conversions, respectively. More importantly a C nucleotide insertion mutation corresponding to 855 nt of BMPR1B CDs was also observed which can cause to producing a stop codon at 266 amino acid position and consequently a dysfunctional polypeptide. In conclusion, these results clearly indicate the presence of important mutation in BMPR1B in Iranian sheep breeds which can significantly affect ewe fecundity attributes.