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Ovulation rate and litter size are traits of fecundity and have a very remarkable economic value that leads to an increase in the production of meat, wool and milk. Therefore, exploring on the candidate and functional genes for these traits is very important. Growth differentiation factor 9 (GDF9), bone morphogenetic protein 15 (BMP15) and bone morphogenetic protein receptor-1B (BMPR1B) are the most important of these genes containing single nucleotide polymorphisms (SNPs) markers that are associated with high fertility in sheeps. The aim of this study was to determine the allelic and genotypic frequencies of seven of these SNPs including; G1, G4, G7 and G8 in GDF9 gene, B2 and B4 in BMP15 gene and FecB in BMPR1B gene among 532 sheeps from eleven of Iranian native breeds using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. For each mutation region, polymerase chain reactions and digestion reactions with specific endonuclease enzymes, were performed. The results showed that G1 mutation presents among ten breeds except Zandi, G4 mutation in all breeds, and the FecB mutation in two breeds; Kalakuei and Zandi. The G7, G8, B2 and B4 mutations were not observed in any of breeds, and all sheeps were homozygote wild type for these four positions. [ABSTRACT FROM AUTHOR]

Utilization of fecundity genes such as GDF9 and BMP15 can help improve reproductive traits in sheep breeding programme. To evaluate effects of missense mutations on protein function, the polymorphisms of GDF9 and BMP15 genes were screened in twelve mehraban sheep using DNA sequencing, followed by protein structure modeling. Six single nucleotide polymorphism (SNPs) known as FecG mutations (G1-G6), were detected in exons 1 and 2 of GDF9 gene. Mutations of G1 (GDF9 exon 1 g.2118 G>A), G4 (GDF9 exon 2 g.3451 T>C) and G6 (GDF9 exon 2 g.3974 G>A) have shown amino acid substitution. None polymorphism was detected in exon 1 and exon 2 of BMP15 gene. Based on identified polymorphisms, individuals were classified into three haplotypes of wild haplotype (without mutation), haplotype A (simultaneous mutations of G1, G2, G3 and G4) and haplotype B (simultaneous mutations of G5 and G6). The 3D-structure of GDF9 protein in A and B haplotypes was rotated 90° and 45° than wild haplotype, respectively. The missenses G1/p.Arg87His, G4/p.Glu241Lys and G6/p.Val332Ile variants were benign. However both the missenses of G7/p.Val371Met and G8/p.Ser315Phe were probably damaging. Phylogenetic tree of GDF9 gene revealed that individuals with A and B haplotypes were distinct from wild haplotypes with bootstrapping values of 63 and 76, respectively. In conclusion, GDF9 protein in A and B haplotypes showed a higher performance than wild haplotype due to synergism effects of simultaneous mutations. These types of mutations with effect on turn and helix of GDF9 conservative regions showed physical and functional interaction with TGFβ proteins. [ABSTRACT FROM AUTHOR]