DNA double-strand breaks induced by high-energy neon and iron ions in human fibroblasts. I. Pulsed-field gel electrophoresis method
- Lawrence Berkeley Lab., CA (United States)
The relative effectiveness of high-energy neon and iron ions for the production of DNA double-strand breaks was measured in one transformed and one nontransformed human fibroblast cell line using pulsed-field gel electrophoresis. The DNA released from the gel plug (fraction of activity released: FAR) as well as the size distribution of the DNA entering the gel were used to compare the effects of the heavy-ion exposure with X-ray exposure. Both methods gave similar results, indicating similar distributions of breaks over megabase-pair distances for the heavy ions and the X rays. The relative biological effectiveness (RBE) compared to 225 kVp X rays of initially induced DNA double-strand breaks was found to be 0.85 for 425 MeV/u neon ions (LET 32 keV/{mu}m) and 0.42-0.55 for 250-600 MeV/u iron ions (LET 190-350 keV/{mu}m). Postirradiation incubation showed less efficient repair of breaks induced by the neon ions and the 600 MeV/u iron ions compared to X rays. Survival experiments demonstrated RBE values larger than one for cell killing by the heavy ions in parallel experiments (neon: RBE = 1.2, iron: RBE = 2.3-3.0, based on D{sub 10} values). It is concluded that either the initial yield of DNA double-strand breaks induced by the high-energy particles is lower than the yield for X rays, or the breaks induced by heavy ions are present in clusters that cannot be resolved with the technique used. These results are confirmed in the accompanying paper. 48 refs., 5 figs., 2 tabs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 70227
- Journal Information:
- Radiation Research, Journal Name: Radiation Research Journal Issue: 2 Vol. 139; ISSN 0033-7587; ISSN RAREAE
- Country of Publication:
- United States
- Language:
- English
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