Research on the anti-oxidative stress system in insects

研究了葱蛆迪利亚（Delia antiqua）体内超氧化物歧化酶（SOD）活性的变化及其与幼虫生长和对氧化胁迫反应的关系。特定的SOD活性是非常高的，在新孵化的幼虫，但它迅速下降时，他们开始喂养的合成饲料，这是免费的植物次生化合物。相反，在饲喂洋葱片或其匀浆后的几个小时内，SOD活性增加。洋葱乙醇提取物对SOD活性无明显影响，推测洋葱中SOD诱导物是由组织损伤（包括昆虫取食）产生的。天然分子量估计为32，000。SDS-PAGE显示16，000个亚基中只有一个亚基，表明SOD是同源二聚体。等电聚焦显示pI为5.3、5.5和5.7的3种电荷异构体。纯化的SOD比活力为4250单位/mg蛋白。抗迪利亚SOD的单克隆抗体（aSOD 2B 7）只识别果蝇属的SOD，而抗果蝇SOD的单克隆抗体（aSOD 1H 11）也识别果蝇属的SOD。

The changes of superoxide dismutase (SOD) activity in the onion maggot, Delia antiqua, were investigated in relation to the growth of larvae and its responsiveness to oxidative stress. Specific SOD activity was very high in the newly hatched larvae, but it decreased rapidly when they started feeding a synthetic diet, which is free from plant secondary compounds. By contrast, SOD activity was increased in a few hours after feeding onion pieces or its homogenate. As ethanol extract of onion had no apparent effect on SOD activity, SOD-inducing compound (s) in onion was considered to be produced by tissue injuries, including those caused by insect feeding.SOD of D.antiqua was purified to apparent homogeneity by ammonium sulfate fractionation, followed by anion exchange, hydrophobic interaction and gel filtration chromatographies. Native molecular weight was estimated as 32,000. SDS-PAGE revealed only one subunit of 16,000, indicating SOD is a homodimer. Isoelectric focusing revealed 3 charge isomers of pIs 5.3,5.5 and 5.7. Specific activity of purified SOD was 4250 units/mg protein. A monoclonal antibody (MAb, aSOD2B7) raised against Delia SOD recognized only SOD of the same genus, but another MAb (aSOD1H11) recognized SOD of Drosophila melanogaster as well.