镉暴露对文蛤和四角蛤蜊行为和生物转化功能的影响

Effects of cadmium exposure on behavior and biotransformation functions of clams Meretrix meretrix and Mactra veneriformis

为探讨镉暴露对文蛤和四角蛤蜊行为和生物转化功能的影响,将两种蛤分别暴露于含Cd浓度为0.05 mg·L、0.10 mg·L和0.25 mg·L的海水中,取样测定其滤食率(FR)、耗氧率(RR)以及组织的谷胱甘肽硫转移酶(GST)的活性。结果显示,除0.05 mg·L暴露组文蛤的耗氧率并未出现明显变化外,其它暴露组的滤食率和耗氧率均随时间明显下降,滤食率下降幅度较耗氧率明显;两种蛤的消化盲囊和鳃丝GST酶活性在各浓度组的开始阶段均呈现上升趋势(除0.05 mg·L暴露组文蛤消化盲囊的GST活性无变化外),而GST活性在高浓度组后期明显下降,均明显低于或接近对照组水平。结果表明,0.10 mg·L和0.25 mg·L暴露组Cd对两种蛤均造成了明显的毒性效应,两种蛤的滤食行为比耗氧行为敏感,文蛤行为指标和GST酶活性被抑制时间点明显晚于四角蛤蜊,四角蛤蜊受到的威胁更明显,鳃丝各指标被抑制的时间点都早于消化盲囊,鳃丝体现的毒性效应更明显,行为指标和GST酶相结合能较为恰当评价Cd对文蛤和四角蛤蜊机体影响的程度。

The effects of cadmium exposure on the behavior and biotransformation function of Meretrix meretrix and Mactra veneriformis were studied. The clams were exposed to seawater with Cdconcentrations of 0.05 mg·L, 0.10 mg·Land 0.25 mg·L, respectively. The filtration rate(FR), respiration rate(RR) and the activity of glutathione S-transferase(GST) in tissues were measured. The results showed that the respiration rate of Meretrix meretrix in 0.05 mg·Lexposure group did not change significantly, the filtration rate and respiration rate of other exposure groups decreased significantly with time, and the filtration rate decreased significantly compared with the respiration rate. The activity of GST in the digestive gland and gill filament of two clams showed an increasing trend at the beginning except that the digestive gland GST activity of Meretrix meretrix exposed to 0.05 mg·Lhad no change. However, GST activity of high concentration group decreased significantly and were close to or lower than the control group in the later stage. The results indicated that Cdof 0.10 mg·Land 0.25 mg·Lexposed groups had significant toxic effects on two species, and the filtration behaviors of the two species were significantly more sensitive than respiration behaviors. The inhibition time points of the behavior index and GST enzyme activity of the Meretrix meretrix were significantly later than that of Mactra veneriformis. The threat of Cdto the Mactra veneriformis was more obvious than that to Meretrix meretrix. The inhibition time point of gills was earlier than that of digestive gland, so the gills appeared more toxic effects. Effects of Cdon the Meretrix meretrix and Mactra veneriformis can be better evaluated by combining the behavior index and GST enzyme.