A copper-induced metallothionein gene from Exopalaemon carinicauda and its response to heavy metal ions

A full-length copper-induced metallothionein ( EcMT-Cu ) cDNA was obtained from Exopalaemon carinicauda (Holthuis) and it contained a 198bp open reading frame that encoded a peptide with 65 amino acid residues. Twenty-one cysteines were found in deduced amino acid sequence and the cysteine (Cys)-rich characteristic was also reported in different types of metallothioneins from other species. EcMT-Cu mRNA expression profile showed that it is the hepatopancreas specific gene. The expression of EcMT-Cu was extremely different when shrimp were exposed to seawater containing 50 μM CuSO 4 or 2.5 μM CdCl 2. The expression of EcMT-Cu in shrimp was significantly up-regulated at 12 and 24 h after exposure to CuSO 4, however, its expression was not induced compared to that of pretreatment ( p > 0.05) when shrimp were exposed to CdCl 2. The transcript of EcMT-Cu was found to be extremely low at gastrula and nauplius stage and expression of EcMT-Cu could be detected from egg protozoa stage.