镉污染对不同生境拟水狼蛛氧化酶和金属硫蛋白应激的影响

为探讨镉(Cd)对机体抗氧化功能及金属硫蛋白(MT)的影响，在室内分别用不添加Cd2 和添加浓度为20 mgkg-1 Cd2 培养基培养的黑腹果蝇来饲喂4种不同生境下(S1，S2，S3和S4)拟水狼蛛，于饲喂5d、10d和20d后，分别测定其体内MT和丙二醛 (MDA)的含量及超抗氧化酶(GST、SOD和CAT)活性。结果表明：1，不同生境拟水狼蛛用不添加Cd2 培养基培养的黑腹果蝇饲喂后，不添加Cd2 对照组拟水狼蛛镉的积累量和MT含量无显著变化，但均显著低于添加Cd2 污染组。添加Cd2 污染组拟水狼蛛镉的积累量和MT含量都显著高于对照组，且均随着饲喂时间的延长而显著升高，具有明显的时间–效应关系(p<0.05)。2，在饲喂5d和10d后，不添加Cd饲喂的拟水狼蛛MDA含量和抗氧化酶系差异都不显著。添加Cd2 污染组(S1，S2和S3)MDA含量显著高于对照组(S4)，MDA含量与饲喂时间呈显著正相关(p<0.05)；GST、SOD和CAT等抗氧化酶活性污染组显著低于对照组，与饲喂时间呈显著负相关(p<0.05)；饲喂20d后，污染组MDA含量和抗氧化酶（SOD和CAT）活性均与对照组无显著差异，但GST活性差异显著。

Effects of Cadmium pollution on oxidative stress and metallothionein content in Pirata subpiraticus (Araneae: Lycosidae) in different habitats

Heavy metals such as Cadmium (Cd) are one of the most fundamental causes of soil and water pollution in industrialized and developing countries. Cadmium (Cd) is a heavy metal that accumulates in the environment and causes pollution as well as intoxication of both vertebrates and invertebrates, although the mechanisms responsible for the toxicity of Cd are not well understood. Organisms inhabiting chronically polluted environments require additional expenditure of energy for supplementary detoxification. Superoxide dismutase, catalase and glutathione S-transferase (GST), play key roles in protecting organisms from endogenous reactive oxygen species, whose activities are enhanced by environmental contaminants. The wolf spider Pirata subpiraticus (Araneae,Lycosidae) is a common, surface-active wolf spider that inhabits very wet places and can be used as a very important bio-indicator for heavy metals pollution. Here, we used the wolf spider P. subpiraticus as an organism to evaluate the oxidative stress and metallothionein (MT) content. The wolf spider P. subpiraticus inhabiting at four meadow sites along a gradient of heavy metal pollution (the polluted sites: S1, S2 and S3; the control site: S4) were collected and fed with the fruit flies Drosophila melanogaster under free and 20 mg/kg Cd2 medium, respectively. The contents of MT and malondialdehyde (MDA), and the activities of antioxidases of P. subpiraticus were determined. There were no significant differences in Cd accumulation and MT content in P. subpiraticus fed with Cd-free fruit flies. In contrast, Cd accumulation and MT content were significantly less compared with that fed with 20 mg/kg Cd fruit flies. Feeding the fruit flies Drosophila melanogaster with 20 mg/kg Cd2 medium significantly increased Cd accumulation and MT contents of P. subpiraticus from polluted sites, which exhibited the typical time-dependent pattern compared with the control (p <0.05). There were no significant differences in MDA and antioxidant enzymes of P. subpiraticus fed with Cd-free. However, MDA of P. subpiraticus from the polluted sites successively increased and positively correlated with time compared with the control. On the contrary, the activities of GST, SOD, and CAT of P. subpiraticus from the polluted sites successively decreased and negatively correlated with time compared with the control. After 20 days, there were no significant differences in MDA, SOD, and CAT in P. subpiraticus from all sites, except GST. This research indicates that MT production may be an important mechanism enabling P. subpiraticus populations to persist in ecosystems polluted with heavy metals above a certain level and antioxidant enzymes play key roles in protecting organisms from heavy metals polluted.