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| Measurement of DNA Breakage and Breakage Repair In Mice Spleen Cells Induced by Ionizing Radiation |
| WANG Qin, YUE Jing-yin, LI Jin, et al |
| Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300192, China |
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Abstract Objective To investigate the radioresistance mechanism of IRM-2 mice through measuring DNA single-strand break (SSB) and double-strands break (DSB) as well as their repair.Methods Pulsed-field gel electrophoresis was used to measure DSB and SSB in IRM-2 mice and their parental mice ICR/JCL and 615 mice after exposure to different doses of γ-ray at different postirradiation time.Results The initial DNA damages, ie the quantities of DSB and SSB in unirradiation IRM-2 mice were less serious than that of their parental mice ICR/JCL and 615 mice (P<0.01).The percentage of DSB and SSB in IRM-2 mice was significantly lower than that of ICR/JCL and 615 mice after exposure to various doses of γ-ray (P<0.01 and P<0.05).There were not statistic differences in DSB and SSB repair between IRM-2 mice and their parental mice after exposure to 2Gy radiation.The DNA damage repair rate induced by 4Gy and 8Gy radiation in IRM-2 mice was rapid, ie the repair rate of SSB and DSB after 0.5h and 1h postirradiation in IRM-2 mice was higher than that of their parental mice (P<0.01 and P<0.05).And remaining damages after repair in IRM-2 mice were lower than that of ICR/JCL and 615 mice.Conclusion The DNA damages in IRM-2 mice were lower than that of their parental mice after exposure to ionizing radiation.Moreover, the repair rate of SSB and DSB was higher than that of their parental mice, which perhaps were the radioresistance causes of IRM-2 mice.Therefore IRM-2 mice are naturally resistant to DNA damages induced by ionizing radiation.
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Received: 21 July 2006
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