Double-strand breaks in genome-sized DNA caused by photo-irradiation, gamma-rays and ultrasound

摘要

We evaluated double-strand breaks (DSBs) in genome-sized DNA (T4 DNA; 166 kbp) caused by photo-irradiation, gamma-rays and ultrasound through a single DNA observation by fluorescence microscopy in a quantitative manner. Based on experimental results, DSBs were induced by two-step mechanism for the photo-irradiation. On the other hands, one-step mechanism led to DSBs for the irradiations of gamma-ray and ultrasound. Regarding the effect of ultrasound, it was found that DSBs were generated above a threshold power. It is suggested that the experimental methodology of single DNA observation serves as a useful tool for studying DSBs of genome-sized DNA.