电离辐射诱导的DNA双链断裂

DNA DOUBLE-STRAND BREAK INDUCED BY IONIZING RADIATION

利用γ射线和不同LET的碳离子辐照小鼠B16黑色素瘤细胞、Hela细胞、V79中国仓鼠肺细胞和人肝癌SMMC -7721细胞的DNA ,采用脉冲场凝胶电泳结合荧光扫描技术研究了DNA双链断裂(DSB)片段的分布。结果发现DSB片段是非随机分布的 ,而且这种分布与DNA序列有关。原因可能在于沉积的能量直接或间接沿DNA链迁移 ,链上相对较弱的化学键优先产生反应 ,并最终导致链的断裂 ,从而引起断裂的不均匀分布。

The DNA samples of melanoma B16, Hela, V79 and hepatoma SMMC-7721 cells were exposed to γ-rays or carbon ions of various LETs. The pulsed field gel electrophoresis and fluorescent scanning were applied to measure the distribution of DSB fragments. The results show that the distribution of DSB fragments is non-random, but concerned with DNA sequence. The energy deposited by the particles can transfer directly or indirectly along DNA strand and the bonds of high affinity and low ionization potential respond firstly. As a result, the strand breaks and uneven distribution of breaks is formed.