Mechanism of DNA Damage by Tritium―Fluorescence Microscope Observation of Double-Strand Breaks and Simulation

Abstract

In this article, we have introduced both experimental and simulation efforts aimed at elucidating the mechanism of tritium-induced DNA damage. Quantitative evaluation of double-strand breaks (DSBs) of DNA molecules using a fluorescence microscope revealed that DSBs occur more rapidly in high concentration tritiated water (5 MBq/cm³) than in non-tritiated water, though no acceleration of DSBs was observed at 1.3 kBq/cm³. As a result of molecular dynamics (MD) simulation of DNA, it was clarified that the hydrogen bond disappeared and the double helix structure collapsed due to the removal of hydrogen atoms in the amino group of guanine. In addition, it was found from reactive force field (ReaxFF) MD simulation of polyethylene that it is possible to analyze rearrangement of chemical bonds in detail. In the future, we plan to analyze the breakage phenomenon of DNA strands due to β decay of substituted tritium by ReaxFF MD simulation.