Cadmium accumulation and metallothionein biosynthesis in the fresh-water crab Sinopotamon henanense

To investigate metallothionein(MT)biosynthesis and cadmium accumulation in fresh-water crab Sinopotamon henanense,S.henanense were exposed to 0(control)、1 mg·L-1 and 5 mg·L-1 waterborne Cd(as CdCl2·2.5 H2O).Cd accumulation and MT levels in gills and hepatopancreas were examined with the Cd/Hemoglobin saturation method and flame atomic absorption spectrophotometry.Results showed that mortality in Cd-exposed crabs was minimal(-9.2%),and no growth effects occurred over the 22d exposure.Cadmium accumulation and MT levels were clearly tissue-specific after Cd exposure and revealed some time-dependence and dose-dependence.Cadmium levels rose remarkably during the exposure.The gill cadmium levels were much higher than those of the hepatopancreas and reached the highest level at 15.41±3.21μg·g-1.MT concentrations in the gills and hepatopancreas increased significantly after Cd exposure.The hepatopancreas MT levels were much greater than those of the gills and reached the highest level at 97.18±11.83μg·g-1.Calculation of the Cd-binding potential(CBP)for the gills and hepatopancreas revealed that in the hepatopancreas,MT was theoretically sufficient to bind all the Cd,but it was not sufficient to sequester all the Cd in the gills.