Related Experiment Video
Updated: May 11, 2026

Immunofluorescence Microscopy of γH2AX and 53BP1 for Analyzing the Formation and Repair of DNA Double-strand Breaks
Published on: November 3, 2017
Probability of double-strand breaks in genome-sized DNA by γ-ray decreases markedly as the DNA concentration
Shunsuke F Shimobayashi1, Takafumi Iwaki, Toshiaki Mori
1Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan. shimobayashi@chem.scphys.kyoto-u.ac.jp
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.
Related Concept Videos
Fixing Double-strand Breaks
Fixing Double-strand Breaks
Homologous Recombination
Overview of DNA Repair
Chemically...
Mutations
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
DNA Damage can Stall the Cell Cycle

