7Li和12C离子致DNA链断裂的研究

选用HI-13串列加速器产生的不同传能线密度的⁷Li和¹²C重离子,以不同的剂量对纯化的质粒DNA水溶液进行了辐照.利用原子力显微镜对这两种重离子诱发的DNA损伤进行了纳米水平的结构分析,并用ScionImage分析软件完成了DNA碎片长度的测量.得到了DNA分子超螺旋、开环和线性三种形态随剂量的变化情况以及DNA碎片长度的分布函数,并用Tsallis熵统计理论对实验结果进行了拟合.

Investigation of DNA Strand Breaks Induced by 7Li and 12C Ions

Deoxyribonucleic acid (DNA) is an important biomacromolecule. It is a carrier of genetic information and a critical target for radiobiological effects. Numerous lesions have been identified in irradiated DNA. DNA double strand breaks (DSBs) are considered as the most important initial damage of all biological effects induced by ionizing radiation. In this experiment,DNA DSBs induced by heavy ions in the early period were investigated with atomic force microscopy (AFM). Choosing 7Li and 12 C heavy ions with different LET values delivered by HI 13 tandem accelerator respectively,purified plasmid DNA samples in aqueous solution were irradiated at different doses. AFM was used for nanometer level structure analysis of DNA damage induced by these two kinds of heavy ions. Measurement of the DNA fragment lengths was accomplished with the Scion Image analyzed software. Change laws of three forms of DNA,supercoil,open circular and linear form as dose increased were obtained. Distributed function of DNA fragment length was also obtained,and fitted with Tsallis entropy statistical theory.