Lethal and Mutagenic Lesions Produced in DNA by Exposure to X-Rays and Activi Oxygen Species

暴露于 X 射线和活性氧在 DNA 中产生致命和诱变损伤

基本信息

批准号：
02680168
负责人：
YONEI Shuji
金额：
$ 1.28万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02680168/
关键词：
Active oxygen spesies X-rays Oxidative DNA damage DNA repair Adaptive response Gene expression Mutagenesis DNA損傷 oxyR遺伝子遺伝子発現誘導 sodA遺伝子突然変異原性

项目摘要

1. Mud phage was used to isolate at least four gene fusions to the lacZ gene(soi : : lacZ, soi for superoxide inducible)that were induced by treatment with superoxide generators such as methyl viologen(paraquat)and menadione. The induction of -galactosidase in these fusion strains with the superoxide radical generating agents required aerobic metabolism. Hyperoxygenation(i. e., bubbling of cultures with oxygen gas)also induced the fusions. On the other hand, hydrogen peroxide did not induce the fusions at concentrations that are known to invoke an adaptive response. Introduction of oxyr, htpr or reca mutations did not affect the induction. Three of the fusion strains exhibited increased sensitivity to methyl viologen but not to hydrogen peroxide. All these fusions were located in the 6- to 36-min region of the Escherichia coli chromosome.2. It was also found that certain membrane-briding drugs(anesthetics)which disturb the membrane-bound respiratory activity induce Mn-superoxide dismutase only under aerobic conditions. The results suggested that such membrane-binding drugs generate superoxide as a result of disruption of the electron transport system of the membrane by the action of the drugs.3. The experiments revealed that nth and xthnfo mutants of E. coli showed increased sensitivity to mutagenic effect of X-rays and hydrogen peroxide, indicating that thymine glycols and AP sites produced in DNA were a main premutagenic lesion in bacterial cells. It was also found that 8-hydroxy-guanine was also premutagenic and a cause for GC-TA transversion.

1. 使用泥噬菌体分离出至少 4 个与 lacZ 基因融合的基因（soi : lacZ，soi 表示超氧化物诱导型），这些基因融合是通过超氧化物产生剂（如甲基紫精（百草枯）和甲萘醌）处理诱导的。在这些具有超氧自由基生成剂的融合菌株中诱导β-半乳糖苷酶需要有氧代谢。高氧合（即用氧气使培养物鼓泡）也诱导了融合。另一方面，过氧化氢在已知引起适应性反应的浓度下不会诱导融合。 oxyr、htpr 或 reca 突变的引入不影响诱导。三种融合菌株表现出对甲基紫精的敏感性增加，但对过氧化氢的敏感性不增加。所有这些融合体均位于大肠杆菌染色体的6至36分钟区域。2．还发现某些干扰膜结合呼吸活动的膜结合药物（麻醉剂）仅在有氧条件下诱导锰超氧化物歧化酶。结果表明，此类膜结合药物由于药物作用破坏膜的电子传递系统而产生超氧化物。3．实验表明，大肠杆菌的nth和xthnfo突变体对X射线和过氧化氢的诱变作用表现出更高的敏感性，表明DNA中产生的胸腺嘧啶二醇和AP位点是细菌细胞中主要的诱变前病变。还发现 8-羟基-鸟嘌呤也是诱变前的，并且是 GC-TA 颠换的原因。