Complex microsatellite dynamics in the myostatin gene within ruminants

Molecular characterization of Myostatin gene from Zhikong scallop Chlamys farreri (Jones et Preston 1904)

The scallop is an economically important sea food prized for its large and delicious adductor muscle. Studying the molecular basis of scallop muscle growth is important for both scallop breeding and our understanding of muscle mass regulation in bivalve. Myostatin (MSTN) is a conserved negative regulator of muscle growth and development. Here we report the MSTN gene from Zhikong scallop (Chlamys farreri Jones et Preston 1904). The C. farreri MSTN consists of 11651 nucleotides encoding 457 amino acids. The gene has a 3-exon/2-intron structure that is conserved with vertebrate homologs. The exons are 586, 380 and 408 bp in length, respectively, and separated by introns of 5086 and 1518 bp. The protein sequence contains characteristic conserved residues including a cleavage motif of proteolysis (RXXR) and nine cysteines. Three transcription initiation sites were found at 62, 146, and 296 bp upstream of the translation start codon ATG. In silico analysis of the promoter region identified a TATA-box and several muscle-specific regulatory elements including COMP, MEF2s, MTBFs and E-boxes. Minisatellite DNA was found in intron 1. By fluorescence in situ hybridization (FISH), the gene was mapped to the long arm of a pair of middle subtelocentric chromosome. Quantitative analysis of MSTN transcripts in embryos/larvae indicated high expression level in gastrulae and limited expression at other stages. In adult scallops, MSTN is predominantly expressed in striated muscle, with different expression levels in other tissues. Our data provide valuable genomic and expression information which will aid the further study on scallop MSTN function and MSTN evolution.