Characterization And Single Nucleotide Polymorphisms Analysis Of The Myostatin Gene In Bay Scallop, Argopecten Irradians

Myostatin (MSTN) is a member of the transforming growth factor-βsuperfamily that negatively regulates growth of skeletal muscle tissue in avariety of species. Since it is involved in the differentiation and proliferationof muscle fibers, MSTN is considered a candidate gene for aquacultureimprovement.In this study, we cloned and characterized the MSTN gene from the bayscallop, Argopecten irradians, and named it as Ai-MSTN gene. Ai-MSTNcontains three exons with1380bp in the open reading frame encoding459amino acids and is77amino acids longer than previously reported. Its5'-UTRupstream region contains cis-regulatory elements of E-boxes, and its3'-UTRregion contains one putative polyadenylation signal ATTAAA found at18ntupstream of the poly (A) site.Phylogenetic analysis of the Ai-MSTN polypeptide confirmed itsevolutionary relationship and species separation with other known MSTNs.The3D structure of Ai-MSTN was similar to that of the known mouse MSTN.Expression analysis revealed that Ai-MSTN was expressed not only in thehepatopancreas, heart, gill, adductor muscle, gonad and mantle of the bayscallop, but also in its haemolymphe, which was first reported in mollusks.Moreover, Ai-MSTN mRNA was detected in different embryonic developmentstages and even in unfertilized eggs.Single nucleotide polymorphisms (SNPs) Ai-MSTN were discovered andscreened in a selected variety of bay scallop,"Zhongkehong". Two novelSNPs were identified by re-sequencing all3exons and300bp of the5'upstream region of Ai-MSTN. One SNP was located in5'-flanking region andanother was located in coding regions in exon2. Association analysis revealedthat the SNP in exon2was associated with increased growth in body mass, adductor muscle mass, shell length and shell height (P<0.05) in the selectedvariety.These findings provide genomic and protein information and expressionprofiles of the Ai-MSTN gene and lay the groundwork for further investigationof the functional significance of this gene.