Molecular characterization and expression pattern of an α-amylase gene (HcAmy) from the freshwater pearl mussel, Hyriopsis cumingii

The freshwater pearl mussel Hyriopsis cumingii is of commercial importance because it produces the freshwater pearl; however, knowledge about the molecular characterization and regulation mechanisms of alpha-amylase remains unknown for this species. In this study, the full-length cDNA of the a-amylase gene (HcAmy) was isolated from H. cumingii by the rapid amplification of cDNA ends. Tissue-specific expression analysis showed that HcAmy mRNA was mainly expressed in the hepatopancreas; although, the gene was also expressed in the adductor muscle, intestine, gill, and crystalline style. After 2 weeks starvation, the expression of HcAmy mRNA in the hepatopancreas was upregulated at 24 h after re-feeding or when exposed to algal concentration of 32 mu g/L chlorophyll-a, indicating that the HcAmy mRNA expression in H. cumingii is regulated by algal availability. The results of this study confirm that the HcAmy gene is an important component of the carbohydrate metabolism of H. cumingii fed phytoplankton. In addition, this study demonstrates that the modulation of this gene is dependent on environmental food availability, including starvation, re-feeding time following a period of starvation, and algal concentrations during re-feeding.