Spatial Distribution and Yield of DNA Double-Strand Breaks Induced by 3-7 MeV Helium Ions in Human Fibroblasts

Abstract Rydberg, B., Heilbronn, L., Holley, W. R., Lobrich, M., Zeitlin, C., Chatterjee, A. and Cooper, P. K. Spatial Distribution and Yield of DNA Double-Strand Breaks Induced by 3–7 MeV Helium Ions in Human Fibroblasts. Radiat. Res. 158, 32–42 (2002). Accelerated helium ions with mean energies at the target location of 3–7 MeV were used to simulate α-particle radiation from radon daughters. The experimental setup and calibration procedure allowed determination of the helium-ion energy distribution and dose in the nuclei of irradiated cells. Using this system, the induction of DNA double-strand breaks and their spatial distributions along DNA were studied in irradiated human fibroblasts. It was found that the apparent number of double-strand breaks as measured by a standard pulsed-field gel assay (FAR assay) decreased with increasing LET in the range 67–120 keV/μm (corresponding to the energy of 7–3 MeV). On the other hand, the generation of small and intermediate-size DNA fragments (0.1–100 kbp) increa...