Molecular cloning, expression of alpha-amylase gene of Haliotis diversicolor supertexta and correlation with growth traits

We cloned the alpha-amylase gene cDNA of Haliotis diversicolor supertexta by rapid amplification of cDNA ends method (RACE) and reverse transcription polymerase chain reaction (RT-PCR) to analyze its tissue expression and correlation with growth traits. The results show that the full length of alpha-amylase gene cDNA was 2 260 bp with an open reading frame (ORF) of 2 088 bp encoding 695 amino acids. The alpha-amylase contained a signal peptide with 18 amino acid residues (MWAQYGIVSALLVLSASA). Two functional structure domains (domain A, domain C) were found in the protein of alpha-amylase. Domain A contained one catalytic center between 28^th and 396^th amino acids. The alpha-amylase mRNA expression in seven tissues (adductor muscle, intestine, digestive gland, stomach, mantle, rostral, foot) was observed, highest in stomach (326.803) and lowest in mantle (0.35). Significant difference was found in the expression of alpha-amylase between digestive and non-digestible tissues (P < 0.05). Significant positive correlation existed between alpha-amylase gene expression and growth traits (P < 0.05).