In Vitro Effects of Gamma Radiation from 60Co and 137Cs on Plasmid DNA

Abstract

The effects of gamma radiation from 60 Co and 137 Cs on DNA in aqueous solution are studied experimentally. Using an improved plasmid purification protocol and improved electrophoretic gel analysis techniques provided results with relatively small uncertainties. The results are compared with both theoretical and experimental results. In particular, the results obtained here are discussed in the light of recent discussion on supposed differences of the effects induced by gamma radiation from 60 Co and 137 Cs. We find that the effects of both types of gamma radiation are similar.Keywords Double-strand breaks . Single-strand breaks . Scavenger-derived radicals . Ionizing radiation . pBSKS + DNA . Gamma effects Irradiation of purified DNA molecules has been extensively used during the last decades for studying the interaction of ionizing radiation with DNA [1-13]. The results obtained in such in vitro experiments are, in many aspects, in qualitative agreement with those from irradiation of cells and tissues. For instance, the increase of cell apoptosis as a function of the delivered dose resembles, qualitatively, the increase of SSB (single strand break) and J Biol Phys (2007) 33:155-160

Effects of Solar Particle Event Proton Radiation on Parameters Related to Ferret Emesis

“…(20)] and for the LDR experiment, 0.8 MeV. The RBE of 60 Co and 137 Cs photons is defined by the International Commission on Radiation Protection (ICRP) as 1 (21) and this is supported by experimental observations of DNA damage (22). Therefore, the experimentally observed differences in emesis observed in our experiments cannot be explained by the difference in RBE between the LDR and HDR exposures.…”

Calculation of direct effects of 60Co gamma rays on the different DNA structural levels: A simulation study using the Geant4-DNA toolkit

“…To obtain the direct strand break yields in experimental studies, there are two approaches: (1) using dry DNA in which the hydration layer surrounding the DNA is removed and therefore, contribution of the indirect effects of water radiolysis products is not considered [57][58][59] and (2) using OH radical scavengers to eliminate the indirect contribution of radiation-induced DNA damage [13,14]. Table 2 shows experimental data for DSB yield using different techniques in comparison with the result of the present study for secondary electron spectrum of 60 Co gamma rays.…”

“…DNA lesions can be produced either by the direct ionization of DNA components (direct effects) or the indirect action of free radicals produced in the surrounding environment of DNA (indirect effects) [8,9]. DNA damage from direct effects have been straightly measured and reported in theoretical and experimental studies, especially in the case of strand breaks [10][11][12][13][14]. In addition, in the case of low-LET ionizing radiations such as X-rays and gamma rays with energies less than 10 MeV, energy deposition is made mainly by secondary electrons and these electrons play an important role in DNA damage induction [15][16][17].…”

Monte Carlo Modeling of DNA Lesions and Chromosomal Aberrations Induced by Mixed Beams of Alpha Particles and X-Rays

“…According to theoretical predictions, 1 Gy of X-rays causes about 1000 SSB [29] and 50 DSB [30] per nucleus. Experimental data indicate that radiation causes about 923 SSB [31], and the ratio between SSB and DSB is equal to 25 [32]. Taking into account the uncertainties of performed simulations, it can be assumed that the simulated mean values of SSB and DSB are in line with experimental data and calculations performed with independent MC tools.…”