RESUMO
Myostatin, a transforming growth factor-beta superfamily member, has been well documented as a negative regulator of muscle growth and development. Myostatin, which has 376 amino acids, is synthesized as a precursor protein. Polymorphism of the myostatin gene in Makoei sheep was investigated by PCR and single-strand conformation polymorphism technique (SSCP). Genomic DNA of 92 sheep was isolated from whole blood. A 417-bp myostatin intron I segment was amplified by standard PCR, using locus-specific primers. Four SSCP patterns, representing four different genotypes, were identified. The frequencies of the genotypes were 0.413, 0.293, 0.130, and 0.163 for AD, AC, AE, and BC, respectively. Allele frequencies were 0.4185, 0.0815, 0.2283, 0.2065, and 0.0652 for A, B, C, D, and E, respectively. Observed heterozygosity was 0.7192. There was significant deviation from Hardy-Weinberg equilibrium for this locus. Analysis of myostatin gene sequences revealed heterozygous SNPs, which were in agreement with results obtained in the SSCP analysis. We concluded that SSCP analysis is a quick, sensitive and reliable technique for determination of DNA polymorphisms. The effect of these genotypes on some traits was investigated, and the AD genotype was found to be associated with birth weight. No phenotypic associations were detected with the other genotypes. No associations of myostatin variants with weight gain were detected. We conclude that polymorphism in the ovine myostatin gene is associated with birth weight, but not with weight gain in Iranian Makoei sheep.