FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

High-efficiency promoters are necessary for the study of functions of foreign genes in vivo and in vitro. A sperm-mediated gene transfer technique was used to deliver a luciferase vector containing a cytomegalovirus (CMV), rous sarcoma virus (RSV), or simian virus 40 (SV40) promoters into oyster (Crassostrea gigas) eggs for comparison of promoter efficiency in larvae. We found that the RSV promoter began to function 16 h after fertilization, which was significantly earlier than the CMV and SV40 promoters. No significant difference in promoter efficiency was found between the RSV and CMV promoters, while the efficiency of the SV40 promoter was significantly lower than those of the RSV and CMV promoters at 24 and 32 h after fertilization. Based on the timing and strength of the promoters, the RSV promoter is better than the CMV promoter, and the CMV promoter is better than the SV40 promoter. This is the first report regarding comparisons of the efficiencies of the CMV, RSV, and SV40 promoters in oyster larvae. The results of this study may become important guidelines for the selection of a promoter for transgenic studies such as recombinant protein expression in the oyster. Further studies to obtain high-efficiency promoters for oyster larvae can use a synthesis of artificial promoters or cloning of homologous promoters. However, a comparison of the promoters’ efficiency must be conducted before transgenic studies are carried out.