DNA Strand Breakage in Chinese Hamster V79 Cells Caused by Low Levels of Incorporated [³H] and [¹⁴C]thymidine

Summary

A sensitive alkali-unwinding assay was used to measure DNA strand breakage in Chinese hamster V79 cells caused by low-level incorporation of methyl-labelled [³H] and [¹⁴C] thymidine, and to estimate the effective dose per disintegration relative to low doses of gamma-irradiation. Damage equivalent to 0·0035 ± 0·0006 and 0·0014 ± 0·0005 Gy was observed for each ³H and ¹⁴C disintegration respectively. These values agree well with those expected from the estimated nuclear radiation dose delivered by the beta particles if a relative biological effect (r.b.e.) of 1·0 is assumed, and suggest that strand-breakage produced by these isotopes is determined by the nuclear radiation dose delivered by the beta particles.

• DNA damage
• radiosotopes
• low doses
• strand breaks
• beta particles