Relationships between Metallothionein and Metals in Oysters and Rock-shells of Taiwan

Heavy metals are often bound up in the liver and kidney by a low molecular weight protein, metallothionein. Few studies have investigated metallothionein levels in shellfish of Taiwan. The purpose of this study is to investigate metal and metallothionein concentrations, and inter-and intra-tissue relationships between metallothionein, the essential metals Zn and Cu, and the nonessential metals Pb, Hg. The results show that Cu and Zn concentrations in oysters and rock-shells varied, depending on the species and sampling location. However, higher Pb and Cd concentrations (Pb: 1.42μg/g and Cd: 5.77μg/g wet weight) were obsersed in oysters from the Lukang coastal area. In the Lukang area, the concentrations of Zn (1437μg/g) and Cu (922 μg/g) in rock-shells are higher than those concentrations (721 μg/g and 320 μg/g, respectively) in oysters. In addition, the metallothioneins were isolated All MT-containing fractions were measured at 250 and 280 nm using a spectrophotometer of oysters and rock-shells collected from the Hsiangshan, Lukang, and Putai coastal areas. The high absorbance values are 1.50 and 2.00 at 280 nm for oysters and rock-shells. In general, the higher metallothionein concentration was found in rock-shells. The list of metals in order of increasing binding affinity for metallothioein is Pb