Abstract
In order to clarify the characteristics of DNA damage induced by neutron irradiation, the induction and repair of DNA double strand breaks (DNA-dsb) were investigated in CHO-K1 cells and xrs5 cells (Ku-80 deficient mutant). Both the cells were incubated according to the ordinary procedures, and then exposed to neutron (approximately 2Gy/50 min) in the D2O neutron irradiation facilities of Kyoto University Reactor. The control cells were also irradiated with 60Co gamma-ray (approximately 2Gy/2min). At the scheduled time after irradiation, the cells were fixed with 4% formalin and stained immunochemically with gamma-H2AX or 53BP1 antibody. Number of DNA-dsb was determined by counting the gamma-H2AX or 53BP1 foci. One hour after 2Gy irradiation, the numbers of gamma-H2AX and 53BP1 foci were not so much different between neutron and gamma-ray irradiation. Considering the duration of irradiation, it seems to be the number of induced DNA-dsb may be larger in neutron irradiation. The numbers of gamma-H2AX or 53BP1 foci were much larger in the xrs5 cells than in the CHO-K1 cell, regardless of neutron or gamma-ray irradiation. This may suggest that the repair of DNA-dsb induced by neutron was also impaired in xrs5 cells, as well known in gamma-ray irradiation.
