镉脉冲暴露中金属硫蛋白的诱导-恢复和代际效应

摘要

Since constant concentration exposure of toxicants to aquatic organism is unusual in the environment, pulsed exposures may represent true risk to aquatic biota more accurately. The model organism Daphnia magna was exposed by 4 concentrations,6 h pulses of cadmium and the change of metallothioneins( MT) and tolerance and offspring were observed after exposure. The pulsed exposure of cadmium was able to significantly induce the synthesis of MT in Daphnia magna. The increase of MT caused by delayed effect was observed after exposure and this may be process by which the organism increases detoxification threshold. The induction of MT in offspring was more sensitive to cadmium exposure. Based on these results,risk assessment for pulsed exposure of cadmium should take the effect of recovery and the influence on offspring in to account.%生物暴露于浓度稳定的污染水环境的现象是少见的,脉冲暴露更符合水生生物生存环境的实际威胁.以4个浓度的镉对模式生物大型溞( Daphnia magna)进行6 h的脉冲暴露,观察暴露后母代F0 和子代F1 的金属硫蛋白( MT)和耐性的变化,比较代际间的差别.结果表明:镉脉冲暴露可显著诱导大型溞体内MT的合成.在暴露完成后的恢复期,观察到由延迟效应引起的MT含量的增加,并认为这可能是生物提高其解毒阈值的过程;母代经过脉冲后,其子代MT的合成能力明显高于未受脉冲暴露的母代F0 ,子代的MT诱导对镉的刺激更加敏感.依此提出了对于镉等重金属脉冲暴露的生态风险性评价应该注意恢复作用和代际效应的建议.