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ST: Strahlen- und Medizinphysik
ST 8: Strahlenphysik: Strahlenbiophysik II
ST 8.4: Fachvortrag
Mittwoch, 9. März 2005, 14:45–15:00, TU HL1
AFM studies of particle induced DNA damage. — •Katarzyna Psonka1,2, Ewa Gudowska-Nowak1,2, Gisela Taucher-Scholz2, and Stephan Brons2 — 1Marian Smoluchowski Institute of Physics, Jagiellonian University, Cracow, Poland — 2Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany
DNA double strand breaks (DSBs) are the critical lesions induced by ionizing radiation. Their production is determined by the spatial distribution of ionization events, which itself depends on the physical properties of energy deposition and the chemical environment of DNA. High linear energy transfer (LET) radiation produces more severe and less repairable lesions as compared to low LET radiation, most likely due to the induction of multiple DSBs in close proximity. DNA fragmentation resulting from such clustered lesions is difficult to be analyzed by conventional methods, even using DNA in solution. We used atomic force microscopy (AFM) to investigate the DSB production in plasmid DNA by analyzing the DNA fragments induced by Ni ions (E=3.5 MeV/u). Based on the selected step length, the uncertainty produced by this procedure was 20 nm (60 bp). Access to the fraction of the smallest fragments was restricted due to the limited resolution with the lower detection limit approx. 100 nm. Fragment distributions induced by high LET radiation were found to be shifted towards smaller fragment sizes compared to those obtained for X-rays. Our first results provide an experimental indication of the correlated production of DSBs after particle radiation (in terms of a compound Poisson process).