重金属镉胁迫对白纹伊蚊幼虫海藻糖代谢的影响

【目的】深入了解镉对白纹伊蚊Aedes albopictus的毒害作用机理和白纹伊蚊对极端环境的适应机制，揭示重金属胁迫对白纹伊蚊种群发生、疾病传播等可能存在的影响，为卫生害虫防控等提供参考依据。【方法】分别用200 mL配制好的50, 100, 200, 300和400 mg/L镉溶液对放置于320 mL一次性杯中长势一致的白纹伊蚊3龄末至4龄初幼虫急性染毒12 h，以双蒸水养殖幼虫作为对照。通过生化方法测定处理后12 h白纹伊蚊幼虫体内海藻糖、葡萄糖和总糖原含量以及可溶性海藻糖酶(TRE1)和膜结合型海藻糖酶(TRE2)活力，并采用qRT PCR测定这些幼虫体内海藻糖合成酶基因(TPS), TRE1和TRE2表达量。【结果】在200和300 mg/L重金属镉处理12 h时白纹伊蚊幼虫海藻糖含量显著增加，在高镉浓度(300和400mg/L)处理时葡萄糖含量显著下降，而不同镉浓度急性处理对总糖原含量没有影响。TRE1和TRE2活力在高镉浓度(300和400 mg/L)处理时显著下降。300 mg/L镉处理组TPS相对表达量达到最高值，TRE1和TRE2相对表达量在高镉浓度(300和400 mg/L)处理时显著下降，与酶活力变化趋势表现一致。【结论】当镉浓度低于半致死浓度(217 mg/L)时，镉急性胁迫使白纹伊蚊幼虫TPS基因表达上调，而TRE基因则表达量下降，TRE活力降低，从而促使葡萄糖转化为海藻糖，通过海藻糖的积累来应对镉胁迫压力。这些结果说明海藻糖在白纹伊蚊在重金属应激中起一定作用，白纹伊蚊幼虫可以通过合成海藻糖从而提高应对镉胁迫的抗逆能力。

Effects of heavy metal cadmium on the trehalose metabolism in Aedes albopictus (Diptera:Culicidae) larvae

【Aim】 This study aims to understand the toxic effects of cadmium on Aedesalbopictus and its adaptation to the extreme environment, and to reveal the possibleeffects of heavy metal stress on the occurrence of mosquitoes and disease transmission, soas to provide reference for the control of hygienic pests. 【Methods】 The late 3rd instarto early 4th instar larvae of A. albopictus with the same growth status in 320 mLdisposable cups were acutely exposed to 200 mL prepared 50, 100, 200, 300, and 400 mg/LCd²⁺ solution, respectively, for 12 h, and the larvae cultured in double distilled waterwere used as the control. The contents of trehalose, sucrose and total glycogen, and theactivities of soluble trehalase (TRE1) and membrane-bound trehalase (TRE2) in the larvaeat 12 h post treatment were determined by biochemical methods, and the relative expressionlevels of trehalose-6-phosphate synthase gene (TPS), TRE1 and TRE2 in these larvae weredetected by qRT-PCR. 【Results】 The results showed that the trehalose content in A.albopictus larvae exposed to 200 and 300 mg/L Cd²⁺ solution for 12 h increasedsignificantly, while the glucose content in larvae exposed to high concentrations of Cd²⁺solution (300 and 400 mg/L) decreased significantly, as compared with the control. Theacute treatment of different Cd²⁺ concentrations had no effect on the total glycogencontent. The activities of TRE1 and TRE2 in larvae exposed to high concentrations of Cd²⁺(300 and 400 mg/L) decreased significantly as compared with those in the control group. Therelative expression level of TPS was the highest in the 300 mg/L Cd²⁺ treated group. Therelative expression levels of TRE1 and TRE2 in larvae exposed to high concentrations ofCd²⁺ solution (300 and 400 mg/L) decreased significantly as compared with those in thecontrol group. 【Conclusion】 The acute stress of Cd²⁺ up-regulates the expression of TPSgene in A. albopictus larvae when the Cd²⁺ concentration is lower than the LC₅₀ value (217mg/L), while the relative expression level of TRE gene and the TRE activity decrease, thereby promoting the conversion of glucose to trehalose and resisting the Cd²⁺ stress bythe production of trehalose. These results indicate that trehalose may play a role in heavymetal stress in A. albopictus larvae, which can improve the resistance to Cd²⁺ stress bytrehalose synthesis.