Plasmid DNA damage by heavy ions at spread-out Bragg peak energies
- 120 Downloads
Interaction of ionizing radiation with plasmid DNA can lead to formation of single strand breaks, double strand breaks and clustered lesions. We have investigated the response of the synthetic plasmid pBR322 in aqueous solution upon irradiation with 12C ions under spread-out Bragg peak conditions (densely ionizing) and with 137Cs γ-photons (sparsely ionizing) as a function of dose. To evaluate the relevance of indirect effects, i.e. influences of diffusion limited radical induced DNA damage triggered by water radiolysis, the experiments were performed at various concentrations of the radical scavenger mannitol. Agarose gel electrophoresis was employed to quantify the DNA damage. At low scavenger concentration for a given dose DNA damage is higher for γ-photons than for 12C. For the latter, the microscopic dose distribution is inhomogeneous, with very high dose deposited along the few tracks through the solution. This is in agreement with the concept that scavengers efficiently reduce damage for γ-photons, implying that the underlying damage mechanism is single strand break induction by OH radicals. For 12C induced damage, the fraction of SSB and DSB that is unaffected by radical scavengers and thus due to direct effect is quantified.
KeywordsLinear Energy Transfer Single Strand Break Open Circular Supercoiled Plasmid Mannitol Concentration
Unable to display preview. Download preview PDF.
- 1.W.A. Bernhard, D.M. Close, in Physics and Chemistry Basis of Biotechnology, edited by A. Mozurnder, Y. Hatano (Marcel Dekker, Inc., New York, 2004), pp. 434–473 Google Scholar
- 2.H.A. Schwarz, J. Phys. Chem. 75, 1069 (1928) Google Scholar
- 4.C. von Sonntag, The Chemical Basis for Radiation Biology (Taylor and Francis, London, 1987) Google Scholar
- 14.T. Elsässer, M. Krämer, M. Scholz, Int. J. Radiat. Oncol. Biol. Phys. 71, 866 (2008) Google Scholar
- 19.M.J. van Goethem, M. Niemantverdriet, P. van Luijk, R.C. Coppes, to be submitted Google Scholar
- 35.W. Mondelaers, P. Lahorte, in Charged Particle and Photon Interactions with Matter Chemical, Physicochemical and Biological Consequences with Applications, edited by M. De Cuyper, J.W.M. Bulte (Kluwer Academic Publishers, the Netherlands, 2001), pp. 254–265 Google Scholar