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The long term impact of ionising radiation on living systems

Abstract : All life on earth has adapted to an environment where there is a small, persistent, radiation background interacting with cells. Unlike evaluating the clearly harmful effects of high radiation doses, understanding the effects of this low persistent radiation dose on living systems is incredibly difficult. We have attempted to study whether background radiation is an important factor in evolution by conducting identical evolution experiments with Escherichia coli in the Clermont-Ferrand Particle Physics Laboratory and the Modane Underground Laboratory. Despite a 7.3 fold difference in the rate of interactions between the radiation background and cells between the two environments, no significant difference was found in the competitive fitness of the cell populations grown at each location. Using simulations, we showed that the rate at which ionising radiation interacts with cells is one hundred times less frequent than E. coli’s mutation rate in our experimental conditions, supporting the contention that natural radiation has no strong evolutionary effect. To further support this conclusion, we developed a mechanistic simulation for DNA damage as part of the Geant4-DNA project. Using this application, we irradiated a model of an E. coli genome, showing that for electron irradiation > 10 keV, the double strand break yield can be reasonably estimated to be between 0.006 – 0.010 DSB Gy-1 Mbp-1, depending upon the modelling of radical scavenging. This is in agreement with experimental data, further highlighting the small role natural ionising radation plays as a cause of mutations.
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  • HAL Id : tel-01626614, version 1

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Nathanael Lampe. The long term impact of ionising radiation on living systems. Nuclear Experiment [nucl-ex]. Université Clermont Auvergne [2017-2020], 2017. English. ⟨NNT : 2017CLFAC011⟩. ⟨tel-01626614⟩

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