Effects of mutation in myostatin exon 3 on growth and carcass characteristics of Savak Akkaraman sheep

The myostatin gene (MSTN) is one of the main regulatory genes involved in muscle growth and development in many animals. This study aims to determine the variations in the exon 3 region associated with MSTN expression in Savak Akkaraman sheep and analyze their relationship with growth characteristics. Molecular analyses (RLFP, Real-Time PCR and DNA sequencing) were performed using DNA and RNA isolations from 70 different sheep blood and meat samples. As a result of the study, exon 3 region analysis was performed using NgomIV, AluI, DraI, HaeIII and MspI restriction endonucleases to determine the genetic diversity in Savak Akkaraman sheep breed. Two genotypes (MM and Mm) were detected for MSTN/MspI and a monomorphic mm genotype indicating the conserved exon 3 region for MSTN/HaeIII. Additionally, four new Single Nucleotide Polymorphisms (SNPs) were detected at different positions (164th, 204th, 347th, and 441th) in the working exon region. Two of these SNPs (204th T→G: isoleucine→ methionine and 347th C→A-G: proline→glutamine-arginine) caused amino acid changes. In expression studies, it was determined that MSTN gene expression was higher in female sheep than in male sheep (p<0.05). The MM genotype (MSTN/MspI) was significantly associated with increased weight gain and MSTN expression, while TT genotype at SNP 204 and GG genotype at SNP 347 was found to be associated with meat yield and growth traits (p<0.05). As a result, the genetic differences and functional effects of the new genotypes determined in this study may shed light on breeding strategies aiming to increase meat production.