Molecular cloning and expression analysis of tyrosinases () in four shell-color strains of Manila clam .

The Manila clam () is an economically important molluscan bivalve with variation in pigmentation frequently observed in the shell. In nature, tyrosinase is widely distributed in invertebrates and vertebrates, and plays a crucial role in a variety of physiological activities. In this study, a tyrosinase gene ( 9) was cloned and the expression level of genes ( 6, 9, 10, and 11) were investigated in different shell colors. Quantitative real-time PCR showed that genes were significantly expressed in the mantle, a shell formation and pigmentation-related tissue. Moreover, the expression pattern of the genes in the mantle of different shell-color strains was different, suggesting that tyrosinases might be involved in different shell-color formation. In addition, the expression profile of 6, 9, 10, and 11 genes were detected at different early developmental stages and the expression level varied with embryonic and larval growth. RNA interference (RNAi) results showed that the expression level of 9 in the RNAi group was significantly down-regulated compared to control and negative control groups, indicating that 9 might participate in shell-color formation. Our results indicated that genes were likely to play vital roles in the formation of shell and shell-color in .