CO_2浓度升高对粘虫幼虫体内酶活性的影响

Effects of elevated CO_2 concentration on enzyme activity of oriental armyworm, Mythimna separata(Walker)(Lepidoptera: Noctuidae) larvae

【目的】阐明大气CO_2浓度升高对粘虫Mythimna separata(Walker)幼虫不同龄期体内酶活性的影响机制。【方法】测定分析了人工气候箱内不同CO_2浓度(800mL/L和400mL/L)条件下,粘虫幼虫体内4种解毒酶[羧酸酯酶(Car E)、乙酰胆碱酯酶(Ach E)、微粒体多功能氧化酶(MFO)和谷胱甘肽-S-转移酶(GST)]、3种保护酶[超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)]和4种蛋白酶(总蛋白酶、强碱性类胰蛋白酶、弱碱性类胰蛋白酶和类胰凝乳蛋白酶)活性的变化。【结果】(1)粘虫不同龄期幼虫体内4种解毒酶的活力均随着CO_2浓度升高而显著上升(P<0.05);(2)粘虫幼虫体内的保护酶中SOD酶活性在CO_2浓度为800mL/L条件下低于对照(CO_2浓度为400mL/L)条件下的酶活性,其中4至6龄幼虫的下降趋势较为显著(P<0.05),而POD、CAT酶活性均呈上升趋势,800mL/L浓度下的CAT活力均显著高于对照(P<0.05);(3)高CO_2浓度条件下粘虫总蛋白酶的酶活性随着龄期的增加呈现先上升后下降的趋势,强碱/弱碱性类胰蛋白和类胰凝乳蛋白3种酶的比活力均低于400mL/L CO_2浓度下的比活力,其中类胰凝乳蛋白酶比活力显著低于对照条件下的比活力(P<0.05)。【结论】在高CO_2浓度条件下,粘虫幼虫体内的大多数酶系活力呈现下降趋势,大部分解毒酶和蛋白酶活性受到抑制,SOD、CAT和POD 3种保护酶的动态平衡受到干扰而影响其正常的生理代谢,机体受损伤并随龄期的增加而加重。

[Objectives] To determine the enzymatic response of different larval instars of the armyworm（Mythimna separata（Walker）） to elevated atmospheric CO_2 concentration. [Methods] The activity of detoxifying, protective, and protease, enzymes in different larval instars were measured under different atmospheric CO_2 concentrations（800 μL/L and 400 μL/L） in an artificial climate chamber. [Results]（1） The activity of four detoxifying enzymes increased significantly in different instars at higher CO_2 concentrations（P0.05）.（2） Superoxide dismutase（SOD） activity tended to decline at a CO_2 concentration of 800 μL/L, especially in fourth to sixth instar larvae（P0.05）. Peroxidase（POD） and catalase（CAT） activity tended to increase at 800 μL/L CO_2 concentration, and CAT activity was significantly higher than that in the control at 400 μL/L CO_2 concentration（P0.05）.（3） At 800 μL/L CO_2 concentration, total protease activity increased with instar number and showed a rising, then falling, trend. Activity of the other three protease enzymes was lower than that at 400 μL/L concentration, and the activity of the chymotrypsin-like enzyme was significantly lower than in the control for all instars（P0.05）. [Conclusion] Most enzyme activity tended to decline at higher CO_2 concentrations; detoxifying and protease enzymes were suppressed, and the balance between SOD, CAT and POD was disrupted, disturbing the normal physiological metabolism. The resultant damage increased in successive instars.