Cadmium Accumulation and Metallothionein Biosynthesis in Cadmium-Treated Freshwater Mussel Anodonta woodiana

This study investigated the distribution of cadmium (Cd) and the protein level of metallothionein (MT) and examined the relationship of Cd accumulation and the MT concentration in different tissues of freshwater mussel Anodonta woodiana following Cd treatment. The mussels were exposed to Cd (4.21, 8.43, 16.86, 33.72 and 67.45 mg L^-1) for 24, 48, 72 and 96 h, respectively. After Cd treatment, the gills, mantle, foot, visceral mass and digestive gland tissues were collected for analysis. We found that, in the controls, Cd distributed in all tissues in the concentration order of gills>mantle>foot>visceral mass>digestive gland. Upon Cd treatment, Cd concentration significantly increased in all tissues. The highest Cd accumulation was found in the digestive gland, which was 0.142 mg g^-1 (P<0.05). MT levels in the gills and mantle of the mussels increased significantly (P<0.05), which were in positive correlation with Cd accumulation in the tissues (P<0.05). In conclusion, our results demonstrated a correlation between Cd accumulation and MT up-regulation in gills and mantle of the mussels after Cd treatment. It is suggested that the protein level of MT in gills and mantle of Anodonta woodiana is a good biomarker for Cd contamination.