Host: The Japan Radiation Research Society, Chairman of the 52nd Annual Meeting, Toshiteru Okubo (Radiation Effects Research Foundation)
DNA is considered to be the critical target for cell killing by ionizing radiation. Therefore it is expected that the photoionization of phosphorus in DNA may cause some specific biological effects. However, at the 45th Annual Meeting of the Japan Radiation Research Society, we reported the similar enhancement of cell lethality of photoionization of phosphorus for both normal and DNA repair deficient cell lines including non-homologous repair deficient or homologous recombination repair deficient cell lines. Here, we will report the gamma-H2AX induction by k-shell photoionization of phosphorus in wild type mammalian cells.
Exponentially growing L5178Y cells (derived from mouse leukemia) were irradiated by monochromatic X-rays at 2.153 keV (K-shell resonance absorption peak of phosphorus) and 2.146 keV (off peak) at the Beam Line-27A in KEK-PF. The amount of gamma-H2AX per cell after 20 min incubation, detected by flowcytometry increased linearly with increasing dose for the both energy of X-rays. The dose enhancement ratio was about 1.5 and was similar to that for cell inactivation.
