The scallop IGF2 mRNA-binding protein gene PyIMP and association of a synonymous mutation with growth traits.

Insulin-like growth factor 2 mRNA-binding proteins (IMPs) function in localization, stability and translational control of their target RNAs. In this study, we identified an IMP gene (PyIMP) from Yesso scallop, Patinopecten yessoensis. The complete DNA sequence of PyIMP was 22,875 bp, consisting of seventeen exons and sixteen introns. The full-length cDNA sequence was 3,293 bp, with an open reading frame of 1,776 bp, encoding 592 amino acids. PyIMP exhibited characters typical of IMPs, namely two RNA recognition motifs and four hnRNP K homology domains. Real-time quantitative reverse transcription PCR analysis indicated that PyIMP was universally expressed, with higher expression levels in the gonad of adult scallops, and in gastrulae and trochophore larvae at developmental stages. A synonymous mutation SNP, c.852A>G, which showed significant associations with growth traits of Yesso scallop, was identified in this gene. Scallops with the AA genotype at this locus had significantly higher trait values than those with the GG genotype for shell length, shell height, body weight, soft tissue weight and striated muscle weight (P < 0.05). Meanwhile, the expression of PyIMP in AA type scallops was significantly higher than that in the GG type, implying a positive effect of PyIMP on scallop growth. PyIMP represents the first mRNA-binding protein gene characterized in mollusks, and SNP c.852A>G will be useful for a better understanding of the role of mRNA-binding proteins in bivalves and for scallop breeding.