中文摘要：

目的分析XRCC修复基因在IRM-2近交系小鼠辐射抗性产生中的作用。方法用Northern杂交方法，比较IRM-2小鼠及其亲本ICR/JCL及615小鼠不同剂量γ射线照射后不同时间XRCC1及XRCC5修复基因mRNA表达水平。结果对照组IRM-2小鼠XRCC1及XRCC5基因mRNA水平明显高于其亲本对照组小鼠（P〈0．01及P〈0．05）。当接受1，2及4Gy照射后，亲本小鼠XRCC1及XRCC5基因mRNA水平均有不同程度升高，但显著变化出现在照射后2h（P〈0．05）。IRM-2小鼠在较低剂量1，2Gy时变化不明显，只在相对较高的4Gy剂量组照射后1h，XRCC1及XRCC5基因mRNA水平显著升高（P〈0．05及P〈0．01）。结论IRM-2小鼠的这两种修复基因基础表达处于高水平，当受到较大剂量照射后，XRCC5基因高表达参与DNA双链断裂修复，这可能是其辐射抗性的主要原因之一。

英文摘要：

Objective To investigate the role of XRCC repair genes in radioresistance of IRM-2 inbred mice. Methods Northern hybridization was used to measure mRNA expression of XRCC1 and XRCC5 genes in IRM-2 mice and their parental mice ICR/JCL and 615 after exposure to different doses of γ-ray radiation at different postirradiation time. Results The levels of XRCCI and XRCC5 mRNA expression in control IRM-2 mice were higher significantly than those in their control parental mice（ P 〈 0.01 and P 〈 0.05）. The mRNA expression of XRCC genes in ICR/JCL and 615 mice all increased to some extent after exposure 1, 2 and 4Gy radiation. But the levels were significantly higher at 2h postirradiation（ P 〈 0.05）. The levels of XRCC mRNA expression in IRM-2 mice did not increase significantly compared with the control mice after exposure 1 and 2Gy radiation. But the levels of XRCC1 and XRCC5 mRNA expression increased markedly at4Gy lh postirradiation（P 〈0.05 and P〈0.01）. Conclusion The basal levels of XRCC1 and XRCC5 mRNA expression in IRM-2 mice were high. The high level of XRCC5 mRNA expression was involved in the repair of DNA double strand breaks induced by higher dose radiation , which perhaps was one of radioresistance causes of IRM-2 mice.