Kysela B P, Arrand J E, Michael B D
Cancer Research Campaign Gray Laboratory, Mount Vernon Hospital, Northwood, Middlesex, UK.
Int J Radiat Biol. 1993 Nov;64(5):531-8. doi: 10.1080/09553009314551741.
We have compared DNA double-strand break (dsb) induction and rejoining, using field-inversion gel electrophoresis, with survival in mutant (XR-V15B) and in wild-type parental (V79B) hamster cell lines after low dose neutron and X-irradiation. We found that neutrons do not appear to induce more dsbs than X-rays and deduce that increased sensitivity to neutrons is therefore not due to a higher initial yield of dsbs. Even with low doses of neutrons, there is a visible increase in the production of a smaller subset of DNA fragments which arise only after very high dose X-irradiation. In both cell lines, dsbs induced by neutrons are rejoined more slowly than those induced by X-rays. At long repair times (4 and 17 h) there are no significant differences in the fractions of unrejoined dsbs between neutrons and X-rays. We propose that neutron-induced dsbs have a higher probability of becoming lethal because they are more likely to be misrepaired during the slow stage of rejoining.
我们使用脉冲场凝胶电泳比较了低剂量中子和X射线照射后，突变型（XR-V15B）和野生型亲本（V79B）仓鼠细胞系中DNA双链断裂（dsb）的诱导和重新连接情况，并与细胞存活情况进行了对比。我们发现，中子诱导产生的dsb似乎并不比X射线更多，由此推断，对中子的敏感性增加并非由于dsb的初始产量更高。即使是低剂量的中子照射，也会出现一种仅在非常高剂量X射线照射后才会产生的较小DNA片段子集的产量明显增加的情况。在这两种细胞系中，中子诱导产生的dsb重新连接的速度比X射线诱导产生的dsb更慢。在较长的修复时间（4小时和17小时），中子和X射线诱导产生的未重新连接的dsb比例没有显著差异。我们认为，中子诱导产生的dsb更有可能变得具有致死性，因为它们在重新连接的缓慢阶段更有可能被错误修复。
