镉和铅对菲律宾蛤仔脂质过氧化及抗氧化酶活性的影响

为了研究亚致死浓度的重金属对海洋贝类的毒性效应,探讨其可能的作用机理,在实验生态条件下以菲律宾蛤仔(Ru-ditapes philip pinarum)为目标生物,采用半静态毒性实验方法,研究了不同浓度Cd2+(0.0948、0.237和0.474mg·L-1)和Pb2+(0.276、0.690和1.380mg·L-1)对菲律宾蛤仔鳃和消化腺组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性以及丙二醛(MDA)含量的影响。结果显示:(1)鳃和消化腺中的抗氧化酶及MDA的变化呈现出类似的趋势,在胁迫初期,各浓度处理组菲律宾蛤仔鳃和消化腺组织SOD和CAT与对照组相比活性都显著升高(P<0.01),呈现出明显的诱导效应,而MDA含量与对照组相比差异不显著(P>0.05);随着胁迫时间的延长,高浓度Cd2+(0.474mg·L-1)和Pb2+(1.380mg·L-1)处理组中SOD、CAT活性快速下降,与对照组相比差异显著;低浓度处理组中的抗氧化活性虽然也较对照组有所下降,但总体下降幅度不如高浓度组明显,并且所历暴露时间较长。各浓度处理组中MDA含量变化一致,均呈现出先升高后降低的趋势,且含量均高于对照组。(2)通过相关性分析,菲律宾蛤仔消化腺组织中的SOD活性与Cd2+浓度的相关性大于鳃组织,与Pb2+浓度的相关性则小于鳃组织;消化腺组织中的CAT活性与Cd2+、Pb2+浓度呈抛物线型相关,与鳃组织CAT活性相关性不十分显著。这说明消化腺组织中SOD活性对Cd2+的敏感性大于鳃组织,消化腺组织中CAT活性对Cd2+、Pb2+的敏感性大于鳃组织。因此,菲律宾蛤仔消化腺中SOD、CAT对水环境中的重金属反应敏感,且存在一定的剂量-效应关系,消化腺组织中SOD和CAT活性与其他敏感性指标一起可以作为指示早期海洋重金属污染的生物标志物。

Effects of Cadmium and Lead on the Lipid Peroxidation and Levels of Antioxidant Enzymes in Ruditapes philippinarum

To investigate the toxic effects of heavy metal in sub-lethal concentration on marine shellfish, and discuss the possible mechanism, in the laboratory controlled conditions, the effect of different concentrations of heavy metal Cd²⁺ (0.0948, 0.237 and 0.474 mg·L^-1) and Pb²⁺ (0.276, 0.690 and 1.380 mg·L^-1) on superoxide dismutase (SOD), catalase (CAT) activities and malondialdehyde (MDA) in Ruditapes philippinarum were studied. The results showed that the variation of antioxidant enzymes in digestive gland and gills are almost the same. At the beginning of heavy mental stressed culture, SOD and CAT activity significantly increased both in clam gills and digestive gland in different treatments (P<0.01). MDA concentrations in treatment groups had no significant difference compared with control group (P>0.05). The activities of SOD and CAT in high Cd²⁺ (0.474 mg·L^-1) and Pb²⁺ (1.380 mg·L^-1) concentration treatment group decreased quickly, and had significant difference compared with control group. The decrease of SOD activity in low concentration treatment group were not as much as that in high concentration group. MDA concentration increased first then decreased, which was higher than that in controlgroup. The correlation between SOD activity in the digestive gland and the concentration of Cd²⁺ was higher than that in the gills organization. The correlation between SOD activity in the digestive gland and the concentration of Pb²⁺ was lower than that in the gills organization. The CAT activity in the digestive gland had obvious correlation with the concentration of Cd²⁺ and Pb²⁺. And there was no correlation between the CAT activity in the gills organization and the concentration of Cd²⁺ and Pb²⁺. The results showed that the SOD activity in the digestive gland had higher sensitivity to Cd²⁺ than that in the gills organization and the CAT activity in the digestive gland had higher sensitivity to Cd²⁺ and Pb²⁺ than that in the gills organization. Therefore, the SOD and CAT in the digestive gland is sensitive to heavy metal stress in the water environmental and has certain does-effect relationship. The SOD and CAT in the digestive grand of Ruditapes philippinarum could be considered as a potential biomarker to indicate the early-stage heavy mental pollution.