The Influence of Physical Characteristics of Accelerated Heavy Ions on the Formation and Repair of DNA Double-Strand Breaks

The kinetics of formation and elimination of γH2AX/53ВР1 foci induced by accelerated 11 B, 20 Ne, and 15 N ions with different physical characteristics in human skin fibroblasts have been investigated. The results of the elimination kinetics for radiation-induced γH2AX/53BP1 foci (RIF) reveal that a decrease in the energy and an increase of the linear energy transfer (LET) of the particles reduce the efficiency of doublestrand break (DSB) repair. An investigation into the structure of RIF induced by accelerated 20 Ne and 11 B ions with various physical parameters shows significant differences in the nature of the RIF that is formed. It is found that 20 Ne ions with a high density of δ rays in tracks ( Z * 2 /β 2 = 1454) induce larger clustered γH2AX/53BP1 foci with a more complex structure than 11 B ions with a lower density of δ rays in tracks (Z* 2 /β 2 = 494), which indicates the formation of more severe complex damage to genetic structures, first and foremost, DNA DSBs.