碳离子束辐照对质粒DNA的损伤效应

为了证明DNA双链断裂(DSB)片段分布与DNA序列有关的假设,采用32keV／μm的^12C^6 离子和45ke V／μm的^13C^6 离子分别辐照pUCl8质粒,结合限制性内切酶处理,进行琼脂糖凝胶电泳,分析DNA断裂和片段分布。结果表明,除了由一个DSB导致的线性DNA带外,还出现了一条新的、小分子量线性DNA带;限制性内切酶处理后,有另一条线性DNA带产生。证明重离子辐照诱导的DSB是非随机分布的,DNA分子上存在对电离辐射相对敏感的位点。

Damage of Plasmid DNA Induced by Carbon Ion Beam

To verify our hypothesis of the correlation between DNA sequence and the nonrandom distribution of DNA doublestrand break (DSB), pUC18 was irradiated by 32keV/μm12C6+ ions or 45keV/μm13C6+ ions. Agarose gel electrophoresis and restriction endonuclease were employed to analysis the DNA beaks and their distribution. Dose response and the distribution of DNA fragments were obtained. Besides the linear DNA band induced by one DSB, another linear DNA band was found. After treatment with restriction endonuclease, a new linear DNA band emerged. It is testified that the distribution of DSB fragments is nonrandom. This implies that there may be relatively sensitive sites to ionizing radiation in DNA molecules.