镉胁迫对不同镉富集能力海水养殖贝类抗氧化能力的影响——以扇贝和菲律宾蛤仔为例

为研究具有不同镉(Cd)富集能力的扇贝和菲律宾蛤仔在相同镉胁迫环境下的抗氧化能力反应的差异,将2种贝类于0.05mg·L-1Cd环境中暴露10 d,分别于第0天、2天、4天、6天、8天、10天分别取样检测内脏团中SOD、CAT、GPx、GST酶活性和GSH含量,同时分析内脏团中Cd的含量。结果表明,对于Cd胁迫组,扇贝和菲律宾蛤仔内脏团中SOD和CAT酶活反应相似,均呈先被诱导后被抑制的规律,且2种贝类的SOD和CAT活性差异较小。2种贝类内脏团中GSH含量、GST和GPx活性变化差异较大:扇贝内脏团中GSH含量显著降低(p0.05),GST和GPx活性均在第2天和第4天时处于显著诱导状态(p0.05),从第6天时处于抑制状态,而菲律宾蛤仔内脏团中GSH含量、GST和GPx活性在Cd暴露期间无显著变化,且2种贝类间比较,扇贝内脏团中GSH含量和GST活性在整个实验期间始终显著高于菲律宾蛤仔(p0.05),GPx活性从第4天开始高于菲律宾蛤仔;对于无镉污染的对照组,扇贝和菲律宾蛤仔内脏团中SOD、CAT和GPx活性无显著差异,但扇贝内脏团中GSH含量和GST活性显著高于菲律宾蛤仔,其中前者GSH含量约为后者的22倍。研究同时表明在相同镉环境下扇贝内脏团对Cd的富集浓度和富集速率均远高于菲律宾蛤仔。本研究明确了2种贝类在相同镉环境下的抗氧化反应的差异,推断出扇贝内脏团中高含量的GSH以及较高的GST和GPx活性可能在扇贝高富集、高耐受Cd方面起重要作用。

Effects of Cadmium Stress on the Antioxidant Responses in Two Biovalves with Different Accumulation Abilities for Cadmium: A Case Study on the Scallop Chlamys farreri and the Clam Ruditapes philippinarum

In order to find out the difference in the antioxidant responses in two bivalves (the scallop Chlamys farreri and the clam Ruditapes philippinarum) which have different abilities for accumulating cadmium (Cd), two bivalves were exposed to 0.05 mg L^-1 Cd for 2, 4, 6, 8 and 10 days. The activities of SOD, CAT, GPx and GST, the content of GSH and the concentration of cadmium in the visceral mass of two bivalves were analyzed. Results showed that for the treated groups, the activities of SOD and CAT in the two bivalves displayed similar response variability, which were induced firstly and then were inhibited during the period of 10 days. In addition, the activities of SOD and CAT were similar in two bivalves. However, GSH content, GST and GPx activities had great differences in two bivalves. The GSH content in C. farreri significantly decreased (p <0.05), while the GST and GPx activities were significantly induced on the second and fourth day (p <0.05), and were inhibited from the sixth day. In contrast, the GST and GPx activities, and GSH content in R. philippinarum had no significant changes. In addition, GSH content and GST activity in C. farreri were significantly higher than those of R. philippinarum during the 10-day exposure. The GPx activity in C. farreri was also higher (p <0.05) than that of R. philippinarum from the fourth day. For the control groups, the activities of SOD, CAT and GPx had no significant differences between C. farreri and R. philippinarum, while the GSH content and GST activity in C. farreri were much higher than that of R. philippinarum. Specifically, the GSH content in C. farreri was almost 22 times of that of R. philippinarum in the control groups. Moreover, C. farreri had higher Cd accumulation rate and concentration than those of R. philippinarum. It is found that the two bivalves with different abilities for accumulating Cd did show different responses in antioxidant systems under the same Cd-stress conditions. High content of GSH, and higher GST and GPx activities may help to explain the scallop C. farreri have higher ability to defense and detoxify the Cd than the clam R. philippinarum.