典型重金属胁迫对日本沼虾的氧化损伤及交互作用

为深入探讨水体不同浓度重金属联合对水生生物的慢性毒性机制,本研究以日本沼虾(Macrobranchium nipponense)为受试生物,镉(Cd)和铅(Pb)为目标金属,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、金属硫蛋白(MT)和丙二醛(MDA)为测试终点,研究不同浓度的Cd和Pb单一及联合暴露对日本沼虾的氧化损伤及交互作用。实验结果表明:Cd对虾的致死浓度为1 mg·L-1,当其与同浓度Pb联合时,致死毒性增强;在0.01 mg·L-1和0.1 mg·L-1下联合时均表现为拮抗作用。不同处理组对标志物产生不同程度的诱导或抑制效应,其中,SOD活性均受到胁迫抑制,0.1 mg·L-1Cd暴露10 d后对肝胰腺SOD抑制率达53.38%,0.1 mg·L-1Pb暴露10 d后对肌肉SOD抑制率达70.02%;CAT活性整体受胁迫激活,肝胰腺与肌肉CAT活性在时间尺度上呈现相反的变化规律;肝胰腺中MT和MDA对重金属的敏感性要高于肌肉;综合生物标志物响应(IBR)评价表明,机体在时间尺度上可通过酶活性调节而具有一定的解毒功能,但并不能消除重金属引起的氧化损伤,且重金属单一毒性要高于联合毒性,其中Cd对肝胰腺毒性最大,Pb对肌肉毒性最大。研究结果能够为水体重金属生态风险预警、水质基准制定及流域水环境管理提供依据。

Oxidative Damage and Interaction Induced by Typical Heavy Metals in Waters on the Macrobranchium nipponense

In order to systematically explore the mechanism of chronic biotoxicity of heavy metals in waters on aquatic organisms,biological toxicity bioassay of Macrobranchium nipponense exposing under Cd and Pb were conducted in laboratory.Superoxide dismutase (SOD),catalase (CAT),metallothionein (MT) and malondialdehyde (MDA) were yet used as biomarkers to investigate the single and joint toxicity of Cd and Pb and their interaction on hepatopancreas and muscles of organisms.The results indicated that Cd with concentration of 1 mg· L-1 can produce lethal toxicity to shrimp.When associated with 1 mg· L-1 Pb,the lethal toxicity increased and synergy effect was observed.However,the antagonistic effects were observed under the co-exposure of Cd and Pb with concentrations of 0.01 mg·L-1 and 0.1 mg·L-1,respectively.And different treatments can also cause inducing or inhibiting effects with different degrees.Among them,SOD activity was inhibited by heavy metal stress in all parts of the organism,particularly in hepatopancreas where SOD activity was inhibited by 53.38％ after the shrimp being exposed to 0.1 mg·L-1 Cd for 10 d.The inhibition rate of SOD activity in muscle achieved the highest value with 70.02％ when exposed to 0.1 mg·L-1 Pb for 10 d.Most of the CAT activity in hepatopancreas can be activated by heavy metal stress.An opposite tendency of CAT activity change in hepatopancreas and muscle was observed after 10-day exposure.MT and MDA contents in hepatopancreas were more sensitive than those in muscle.Moreover,the integrated biomarker response (IBR) revealed that the river shrimp itself has a certain heavy metal detoxification function in the time scale through the regulation of enzyme activity,but the oxidative damage caused by heavy metals was not eliminated.The toxicity of single heavy metal was higher than the combined ones.The toxicity of Cd to hepatopancreas and Pb to muscle were the highest.The results obtained could provide the basis for the early warning of ecological risk induced by metals,developing water quality criteria and basin water environment management.