Cell Inactivation and DNA Single- and Double-strand Breaks in Cultured Mammalian Cells Irradiated by a Thermal Neutron Beam

Summary

The effects on the cellular viability and induction and repair kinetics of DNA strand breaks in HeLa cells were examined after exposure to a thermal neutron beam and compared with those after γ-irradiation. The thermal neutron survival curve had no initial shoulder. The relative biological effectiveness (r.b.e.) value of the neutron beam was determined to be 2·2 for cell killing (ratio of D₀ values), 1·8 and 0·89 for single strand breakage (ssb) by alkaline sedimentation and alkaline elution respectively, and for double strand breakage (dsb) 2·6 by neutral elution. No difference was observed between thermal neutrons and γ-rays in the repair kinetics of ssb and dsb. It is suggested that the effect induced by the intracellular nuclear reaction, ¹⁴N(n,p)¹⁴C is mainly responsible for the high r.b.e. values observed.

• thermal neutron beam
• DNA strand break
• r.b.e.
• repair kinetics
• HeLa cells