Cadmium Uptake and Bioaccumulation inXenopus laevisEmbryos at Different Developmental Stages

The uptake of cadmium inXenopus laevisembryos was studied by exposing them to solutions containing cadmium concentrations ranging from 0.1 to 2 mg Cd2+/L at seven developmental stages for 72 h. The uptake values were from 0.0027 μg Cd2+/embryo (two blastomeres stage) to 0.081 μg Cd2+/embryo (hindlimb bud distinct stage). During early developmental stages, a limited permeability to cadium could play a significant role for the survival of embryos. At the last developmental stage evaluated there was a significantly higher uptake of cadmium simultaneously with a very significant increase in the resistance against cadmium toxicity. The cadmium bioaccumulation factor (BF) ranged from 5 to 460. As a general pattern at all developmental stages the BF was higher in embryos exposed to the lower cadmium concentration, and as development advanced the BF increased.