Host: The Japan Radiation Research Society
Clustered DNA damage is a specific form of DNA damage induced by ionizing radiation, and it is thought to be mainly involved in radiation effect to any biological systems. We previously reported that it showed a clear inverse correlation between the yields of clustered DNA damage and LET of the ionizing radiation in DNA molecules irradiated in vitro. For demonstration of this correlation in cell, we analyzed yields of clustered DNA damage in cells irradiated with gamma-rays (0.2 keV/μm) and various accelerated ion particle beams including carbon (13 keV/μm), silicon (55 keV/μm), and iron ions (200 keV/μm), in the present study. Logarithmic growing chinese hamster ovary-AA8 cells were irradiated with respective radiations and embedded into agarose plug gels. After treatment with proteinase K, the plugs were subjected in static field gel electrophoresis for analysis of the clustered DNA damage. Surviving rate of the irradiated cells were also estimated by colony formation assay. Cell survivals decreased with an increase in LET. On the other hand, the yields of clustered DNA damage also decreased with an increase in LET, showing a correlation similar to the results observed in vitro, as our previous report. These results suggest that additional critical factors engage in severity of higher LET radiations, such as physiological processing of clustered DNA damage in vivo.
