The Contribution of the Nuclear Reaction ¹H(n, γ)²D to the Yield of DNA Single Strand Breaks in Cultured Mammalian Cells Irradiated by Thermal Neutrons

Summary

The yield of single strand breaks (ssb) in DNA of the HeLa S-3 cells after thermal neutron irradiation was examined using the alkaline sucrose gradient method. The contribution of the ¹H(n, γ)²D reaction to the yield of ssb was determined by substituting D₂O for H₂O in the irradiated medium. Calculation shows that when cells are irradiated in the H₂O medium, the per cent contribution of the contaminating γ-rays, the nuclear reaction ¹H(n, γ)²D and the other nuclear reactions is 31, 44 and 25 per cent respectively assuming additivity of effects. The estimated number of ssb induced by the nuclear reaction ¹H(n, γ)²D was at least 4·4 times greater than that by ⁶⁰Co γ-rays at the same absorbed dose. Two possible interpretations are discussed to explain the high efficiency of the ¹H(n, γ)²D reaction for ssb induction.

• thermal neutrons
• DNA single strand breaks
• D₂0
• ¹H(n, γ)²D reaction
• HeLa S-3 cells