Cerenkov light and the production of photoreactivatable damage in X-irradiated E. coli.
Cerenkov light and the production of photoreactivatable damage in X-irradiated E. coli.
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切伦科夫光和 X 辐照大肠杆菌中光再激活损伤的产生。
DOI：
10.1080/09553008114550681
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
Ward,JF
中科院分区：
文献类型：
--
作者：
Redpath,JL;Zabilansky,E;Morgan,T;Ward,JF
1.介绍几个研究人员最近报道了光复活的损伤诱导的E。（Myasnik和Morozov 1977，Redpath和Tortorello 1977，Wang和Smith 1978，Vinicombe，Moss和Davies 1978，Redpath和Zabilansky 1979，Morozov和Myasnik 1980）。Myasnik和Morozov（1977）表明，光复活只能在同时携带两个基因（uvr、rec或uvr、exr）突变的菌株中观察到。Redpath和Tortorello（1977年）和Vinicombe et al.（1978）表明，在X射线或Y射线照射期间，光复活的程度与氧的存在无关。Wang和Smith（1978）观察到在大肠杆菌中产生含胸腺嘧啶的环丁二嘧啶。大肠杆菌DNA的400 krad的γ射线，并得出结论，光复活观察到电离辐射后的菌株，被阻断在切除修复和至少部分阻断在复制后修复是由于生产的痕量的胸腺嘧啶二聚体。此外，Wang和Smith还表明，相同的光复活酶参与UV和γ射线诱导的损伤的光复活。Redpath和Zabilansky（1979年）证明了咖啡因对光复活的抑制作用;自由基清除剂和自由基修复剂二硫苏糖醇对光复活损伤的产生缺乏抑制作用;光复活损伤的产生依赖于损伤诱导X射线的能量。后一种观察最近得到了Myasnik、Morozov和Petin（1980）的证实。由于光复活通常被认为是一种与修复紫外线损伤有关的现象，因此必须考虑与电离辐射有关的紫外线辐射源。一个明显的来源是切伦科夫辐射。切伦科夫辐射是当带电粒子在其穿过的介质中超过光速时发出的。在真空中，光速不会被超过，但在介质中，如水，光速是c/n（其中c是真空中的光速，n是水相对于空气的折射率），因此可以被相对低能量的电子超过。切伦科夫辐射现象的综述可以在杰利（1958）中找到。
1. Introduction Several investigators have recently reported on the photoreactivation of damage induced in E. coli by ionizing radiation (Myasnik and Morozov 1977, Redpath and Tortorello 1977, Wang and Smith 1978, Vinicombe, Moss and Davies 1978, Redpath and Zabilansky 1979, Morozov and Myasnik 1980). Myasnik and Morozov (1977) showed that photoreactivation could only be observed in strains carrying mutations simultaneously in two genes, uvr, rec, or uvr, exr. Redpath and Tortorello (1977) and Vinicombe et al.(1978) showed that the extent of photoreactivation was independent of the presence of oxygen during X-or y-irradiation. Wang and Smith (1978) observed the production of thymine-containing cyclobutadipyrimidines in E. coli DNA by 400 krad of y-rays and concluded that photoreactivation observed after ionizing radiation in strains that are blocked in excision repair and at least partially blocked in post-replication repair is due to production of trace amounts of thymine dimers. Furthermore, Wang and Smith have also shown that the same photoreactivation enzyme is involved in the photoreactivation of UV and y-ray induced damage. Redpath and Zabilansky (1979) demonstrated an inhibition of photoreactivation by caffeine; a lack of suppression of the production of photoreactivatable damage by the free radical scavenger and radical repair agent, dithiothreitol; and a dependence of the yield of photoreactivatable damage on the energy of the damage-inducing X-rays. This latter observation has recently been confirmed by Myasnik, Morozov and Petin (1980). Since photoreactivation is generally considered to be a phenomenon associated with repair of UV damage it is important that sources of UV radiation related to ionizing radiation be considered. One obvious source is Cerenkov radiation. Cerenkov radiation is emitted when a charged particle exceeds the speed of light in the medium through which it passes. In vacuo the speed of light is not exceeded but in a medium such as water the speed of light is c/n (where c is the speed of light in vacuo and n is the refractive index of water relative to air) and consequently can be exceeded by relatively low energy electrons. A review of the phenomenon of Cerenkov radiation may be found in Jelley (1958).