Abstract: The full-length cDNA sequence of sarco/endoplasmic reticulum calcium ATPase isoform gene was isolated from the gill of Hyriopsis cumingii by using SMART RACE technique. The entire SERCA cDNA was 3 326 bp, including a 201-bp 5'-UTR, a 3 060-bp ORF and a 65-bp 3'-UTR, encoding a 1 019-amino acid protein, and no putative signal peptide was predicted. Four types of domains were found and the general structures of SERCA gene, containing phosphorylation region, fluorescein isothiocyanate site, 5'-(p-fluorosulfonyl) benzoyladenosinebinding site, phospholamban-binding motif and thapsigargin sites were also identified. Compared with SERCA homologs from seawater mollusks and other animals, the SERCA of H. cumingii had high similarity with them in both sequence and structure. Tissue-specific expression analysis revealed that SERCA mRNA was detected in all the sampled tissues, but was prominently expressed in the gill, mantle and hepatopancreas. When exposed to a series of increasing Ca²⁺ that lasted 7 days, the mRNA expression of SERCA gene in mantle was shown to be cove-shaped, ascending when Ca²⁺ concentration was more than 60 mg·L^-1 and peaking at 80 mg·L^-1. Moreover, the temporal expression of SERCA transcripts in mantle after 60 mg·L^-1 Ca²⁺ exposure was slightly down-regulated at 24 h, but up-regulated from 24 h to 48 h post-treatment, peaking at 48 h. The results of present study will provide useful information for further studies on function and regulation mechanism of SERCA gene.

Key words: Hyriopsis cumingii, SERCA, cloning, gene expression, calcium stimulation