title: Probability of double-strand breaks in genome-sized DNA by γ-ray decreases markedly as the DNA concentration increases.
abstract: By use of the single-molecule observation, we count the number of DNA double-strand breaks caused by γ-ray irradiation with genome-sized DNA molecules (166 kbp). We find that P1, the number of double-strand breaks (DSBs) per base pair per unit Gy, is nearly inversely proportional to the DNA concentration above a certain threshold DNA concentration. The inverse relationship implies that the total number of DSBs remains essentially constant. We give a theoretical interpretation of our experimental results in terms of attack of reactive species upon DNA molecules, indicating the significance of the characteristics of genome-sized giant DNA as semiflexible polymers for the efficiency of DSBs.
authors: Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan. shimobayashi@chem.scphys.kyoto-u.ac.jp
authors: Shunsuke F
authors: SF
authors: Shimobayashi
authors: Takafumi
authors: T
authors: Iwaki
authors: Toshiaki
authors: T
authors: Mori
authors: Kenichi
authors: K
authors: Yoshikawa
mesh_terms: D017122:Bacteriophage T4 / Q000235:genetics / Q000528:radiation effects; D004247:DNA / Q000737:chemistry / Q000235:genetics*; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D004307:Dose-Response Relationship, Radiation; D004926:Escherichia coli / Q000235:genetics / Q000528:radiation effects; D005720:Gamma Rays; D006801:Humans; D008954:Models, Biological; D011336:Probability
chemical_list: D004269:DNA, Bacterial; D004279:DNA, Viral; D004247:DNA