Frankenberg-Schwager M, Frankenberg D, Harbich R
Gesellschaft für Strahlen-und Umweltforschung mbH, Institut für Biophysikalische Strahlenforschung, Frankfurt, Federal Republic of Germany.
Radiat Res. 1991 Dec;128(3):243-50.
DNA double-strand breaks (DSBs) are 2.9 times more frequently induced in yeast cells exposed to sparsely ionizing 30-MeV electrons under oxic compared to anoxic conditions. The rejoining of DSBs induced under anoxic conditions was investigated under conditions allowing repair of potentially lethal damage and compared to the rejoining of DSBs induced in oxic cells. In contrast to the biphasic rejoining kinetics of DSBs induced in oxic cells, the rejoining kinetics of DSBs induced in anoxic cells is complicated by the formation of secondary DSBs. These arise during postirradiation incubation of cells, presumably as a consequence of repair processes acting on radiation-induced lesions other than DSBs. These secondary DSBs may at least partially explain the finding that a greater fraction of unrejoinable DSBs is present in cells irradiated under anoxic compared to oxic conditions. As a consequence, the oxygen enhancement ratio of the yield of the remaining DSBs is decreasing in the course of DSB rejoining.
与缺氧条件相比，在有氧条件下暴露于稀疏电离的30兆电子伏特电子的酵母细胞中，DNA双链断裂（DSB）的诱导频率高出2.9倍。在允许修复潜在致死性损伤的条件下，研究了缺氧条件下诱导的DSB的重新连接，并与有氧细胞中诱导的DSB的重新连接进行了比较。与有氧细胞中诱导的DSB的双相重新连接动力学相反，缺氧细胞中诱导的DSB的重新连接动力学因二次DSB的形成而变得复杂。这些二次DSB在细胞照射后的培养过程中出现，推测是作用于除DSB之外的辐射诱导损伤的修复过程的结果。这些二次DSB可能至少部分解释了以下发现：与有氧条件相比，在缺氧条件下照射的细胞中存在更大比例的不可重新连接的DSB。因此，在DSB重新连接过程中，剩余DSB产量的氧增强比在下降。
