Identification and expression characterization of the myostatin (MSTN) gene and association analysis with growth traits in the razor clam Sinonovacula constricta.

Myostatin (MSTN) is a member of the transforming growth factor-β superfamily (TGF-β) and is an important negative regulator of muscle growth in vertebrates. In this study, we cloned and analyzed the MSTN gene (Sc-MSTN) from razor clam (Sinonovacula constricta). The full length of Sc-MSTN cDNA sequence consists of 4226 base pairs (bp), comprising a 522-bp 5' untranslated region (UTR), a 2342-bp 3'UTR, and an open reading frame (ORF) that is 1362 in length. The ORF encodes 453 amino acids with a RXXR proteolytic site and nine conserved cysteines. Quantitative real-time PCR analysis revealed that the Sc-MSTN transcript was expressed in a wide range of tissues but appeared to exhibit the greatest level of expression in the foot. The transcript was widely detected in early developmental stages, showing the highest expression in the trochophore stage. Furthermore, six SNPs were identified in the coding region of the Sc-MSTN gene using direct sequencing. SNP-1 is non-synonymous and involves an amino acid change from Leu to Ser. Association analysis showed that SNP-1 and SNP-6 had significant influences on shell length (SL). The results suggested that MSTN could be selected as a candidate gene for the future molecular breeding of razor clam strains.