重金属Cd2+和Cu2+胁迫下泥蚶消化酶活性的变化

为了探讨重金属Cd²⁺和Cu²⁺胁迫对泥蚶消化酶活性的影响，运用酶学分析的方法，按《渔业水质标准》（GB 11607）规定的Cd²⁺、Cu²⁺最高限量值的1、2、5、10倍设置重金属离子Cd²⁺、Cu²⁺浓度及其组合，研究了在重金属Cd²⁺、Cu²⁺胁迫下，30d内泥蚶3种消化酶活性的变化规律。结果表明：与空白对照组相比，在重金属Cd²⁺、Cu²⁺或其组合的胁迫下，较低浓度组泥蚶的淀粉酶活性实验前期增强（即被诱导），实验后期减弱（即被抑制），较高浓度组泥蚶的淀粉酶活性从实验一开始就减弱，并保持在较低水平，毒性比较，同一重金属高浓度 > 低浓度，不同重金属及其组合Cu²⁺ > （Cd²⁺+Cu²⁺）组合 > Cd²⁺；泥蚶脂肪酶的活性实验前期增强，实验后期转为微减弱或减弱，毒性比较，同一重金属高浓度 > 低浓度，不同重金属及其组合（Cd²⁺+Cu²⁺）组合 > Cu²⁺ > Cd²⁺；泥蚶胃蛋白酶的活性实验前期增强，且活性呈现升高-降低-再升高-再降低的变化，实验后期分别表现微增强、微减弱和减弱，毒性比较，同一重金属高浓度 > 低浓度，不同重金属及其组合（Cd²⁺+Cu²⁺）组合 > Cu²⁺ > Cd²⁺。可见：环境中的Cd²⁺和Cu²⁺对泥蚶的消化酶活性起着明显的影响作用。

Changes of digestive enzyme activity of Tegillarca granosa exposed to cadmium and copper

In order to investigate the effect of Cd²⁺ and Cu²⁺ stress on digestive enzyme activity of Tegillarca granosa.enzyme analytical method was conducted to analyze the changes of the digestive enzyme activity of Tegillarca granosa exposed to different concentrations of Cd²⁺ or/and Cu²⁺ for 30 days. The concentrations of heavy metal ion Cd²⁺, Cu²⁺, and their combination (Cd²⁺+Cu²⁺) were set as one, two, five, and ten times of the corresponding maximum limit values according to the Water Quality Standard for Fisheries (GB 11607). The results showed that compared with the blank control groups, when Tegillarca granosa were exposed to low concentrations of Cd²⁺, Cu²⁺ and (Cd²⁺+Cu²⁺), their digestive enzyme activity increased at the early experimental period (or be induced), and then decreased at the later period (or be inhibited); when the Tegillarca granosa samples were exposed to high concentrations, the amylase activity decreased from the start and kept low level all along. For the same heavy metal ion, the toxicity of the high concentration groups was higher than that of the low concentration groups in the amylase activity analysis. In the comparison of the two heavy metal ions and their combination, the toxicity of the Cu²⁺ group was highest, followed by the (Cd²⁺+Cu²⁺) group, and the Cd²⁺ group was lowest. The lipase activity of Tegillarca granosa increased at the early experimental period, and then decreased moderately or weakly at the later period. For the same heavy metal ion, the toxicity of the high concentration groups was higher than that of the low concentration groups in the lipase activity analysis. In the comparison of the two heavy metal ions and their combination, the toxicity of the (Cd²⁺+Cu²⁺) group was highest, followed by the Cu²⁺ group, and the Cd²⁺ group was lowest. The pepsin activity of Tegillarca granosa increased at the early experimental period. In the middle period, the activity had the variance of being increased, decreased, increased again, and then decreased. At the later period, the activity increased weakly, decreased moderately, and decreased weakly for different ion groups. For the same heavy metal, the toxicity of the high concentration groups was higher than that of the low concentration groups in the pepsin activity analysis. In the comparison of the two heavy metals and their combination, the toxicity of the (Cd²⁺+Cu²⁺) group was highest, followed by the Cu²⁺ group, and the Cd²⁺ group was lowest. The results show that there were obvious stress of Cd²⁺ and Cu²⁺ in the environment for the digestive enzyme activity of Tegillarca granosa.