INDUCTION AND REPAIR OF DNA STRAND BREAKS IN CULTURED MAMMALIAN-CELLS FOLLOWING FAST-NEUTRON IRRADIATION

Induction and repair of DNA breaks following irradiation with NIRS cyclotron neutrons were studied in cultured mammalian cells (L5178Y) in comparison to those following γrays. The yield of the total single-strand breaks, 3'OH terminals and sites susceptible to S1 endonuclease following fast neutrons was found to be approximately 50 per cent of that following γirradiation. On the other hand, the yield of double-strand breaks was slightly higher after fast neutrons than after γrays. The percentage of the total single-strand breaks remaining unrejoined at 3 hours after post-irradiation incubation was found to be distinctly higher after the fast neutrons than after γrays. The neutron-induced damage appears to carry a higher proportion of alkali-labile lesions compared to γrays. It was concluded that the increase in the yield of double-strand breaks and of unrejoinable breaks is responsible for a high r.b.e. of the cyclotron neutrons. © 1979 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.