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通过凝胶电泳扫描法测试了γ射线辐射下ｐＢＲ３２２超螺旋ＤＮＡ的单链断裂（ＳＳＢ）和双链断裂（ＤＳＢ）与辐射剂量的关系，验证了ＳＳＢ的产生方式，发现ＤＳＢ的形成与ＤＮＡ溶液中自由基清除效能σ有关：一方面，αＤＳＢ与βＤＳＢ的比随σ的增大而非线性增大；另一方面，σ＜１０８ｓ－１时，αＤＳＢ可由单自由基传递机制产生，而σ＞２×１０８ｓ－１时，αＤＳＢ则主要通过ＬＭＤＳ机制形成。另外，发现组成βＤＳＢ的两互补链上ＳＳＢ的距离ａ几乎不受自由基清除效能的影响。
The relationship between single-stranded breakage (SSB) and double-stranded breakage (DSB) of pBR322 supercoiled DNA by γ-irradiation and radiation dose was tested by gel electrophoresis scanning. The production of SSB was verified. The formation of DSB and DNA solution On the one hand, the ratio of αDSB to βDSB increases nonlinearly with the increase of σ; on the other hand, αDSB can be generated by the single radical transfer mechanism when σ <108s-1, while σ> 2 × 108s-1, αDSB is mainly formed by the LMDS mechanism. In addition, it was found that the distance a of the SSBs on the two complementary strands constituting the βDSB was hardly affected by the free radical scavenging activity.