Forcella Matilde, Berra Elisa, Giacchini Roberto, Parenti Paolo
Department of Environmental Sciences, University of Milano-Bicocca, Milan, Italy.
Arch Insect Biochem Physiol. 2007 Aug;65(4):181-94. doi: 10.1002/arch.20197.
Changes in enzyme activities, metabolite concentrations, and membrane transport activity underlying the Chironomus riparius larvae adaptive response to anoxia were investigated. Trehalose, malate, and aspartate degradation and alanine accumulation were recorded. During anoxia exposure, there was a boost of antioxidant defenses as shown by an increase of the specific activity of the enzymes catalase, glutathione-S-transferase, glutathione peroxidase, glutathione-synthase, malic enzyme, and NADP-dependent isocitrate dehydrogenase. The ratio, glutathione reduced over glutathione oxidized, decreased. Except for alanine and catalase, the parameters return to their basal value when larvae are transferred to normoxic conditions. To test whether antioxidant defenses had protective effects on membrane functionality, L-leucine uptake into brush border membrane vesicles and membrane lipid peroxidation was measured. No difference between membranes prepared from larvae exposed to anoxia and control larvae was found. The amino acid alanine, when present inside the vesicles, trans-stimulated leucine uptake. This effect could represent a mechanism to stimulate amino acid uptake and catabolism in vivo when free alanine concentration increases during hypoxic periods.
研究了摇蚊幼虫对缺氧适应性反应背后的酶活性、代谢物浓度和膜转运活性的变化。记录了海藻糖、苹果酸和天冬氨酸的降解以及丙氨酸的积累。在缺氧暴露期间，抗氧化防御增强，表现为过氧化氢酶、谷胱甘肽 - S - 转移酶、谷胱甘肽过氧化物酶、谷胱甘肽合成酶、苹果酸酶和NADP依赖性异柠檬酸脱氢酶的比活性增加。还原型谷胱甘肽与氧化型谷胱甘肽的比率降低。除丙氨酸和过氧化氢酶外，当幼虫转移到常氧条件下时，这些参数恢复到其基础值。为了测试抗氧化防御是否对膜功能有保护作用，测量了L - 亮氨酸进入刷状缘膜囊泡的摄取和膜脂质过氧化。未发现缺氧暴露幼虫制备的膜与对照幼虫制备的膜之间存在差异。当囊泡内存在氨基酸丙氨酸时，它会反刺激亮氨酸的摄取。这种效应可能代表一种机制，当缺氧期间游离丙氨酸浓度增加时，在体内刺激氨基酸摄取和分解代谢。
