Yields of SSB and DSB induced in DNA by Al(K) ultrasoft X-rays and alpha-particles: comparison of experimental and simulated yields.
OBJECTIVE
To compare experimental yields of single strand breaks (SSB) and double strand breaks (DSB) induced in plasmid DNA in aqueous solution by alpha-particles and Al(K) ultrasoft X-rays (USX) with the corresponding yields, generated via computer simulations, for a range of mean diffusion distances of the hydroxyl radical (*OH).


METHODS
Aerobic, aqueous solutions of plasmid DNA were irradiated at 277K with 238Pu alpha-particles or USX in the presence of 10(-4) to 0.33 mol dm(-3) Tris and the yields of SSB and DSB determined by gel electrophoresis. Computer simulations, using Monte Carlo track-structure codes for 1.5keV electrons (CPA100) and 3.2MeV alpha-particle track segments (PITS), were used to obtain yields of DNA SSB and DSB at different *OH scavenger conditions.


RESULTS
The experimental yield of SSB and DSB induced by AlK USX and SSB induced by alpha-particles and the dependences on the mean diffusion distance of the *OH are in reasonable agreement with the corresponding simulated yields and their corresponding dependences. However, for DSB induced by alpha-particles, a significant systematic difference exists between the simulated and experimental yields over the full *OH scavenging range, with the simulated yields being a factor of two to three greater than the experimental values.


CONCLUSIONS
That the simulated yields of strand breaks are generally in reasonable agreement with those determined experimentally over a wide range of *OH scavenging capacities, increases confidence in the use of these simulations as a valuable source of quantitative, mechanistic information on DNA damage induced at very low radiation doses.
Fulford
J
J
MRC Radiation and Genome Stability Unit, Harwell, Oxfordshire, OX11 ORD, UK.
Nikjoo
H
H
Goodhead
D T
DT
O'Neill
P
P
D000512:Alpha Particles; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004277:DNA, Single-Stranded / Q000528:radiation effects*; D017665:Hydroxyl Radical; D014965:X-Rays
D004277:DNA, Single-Stranded; D017665:Hydroxyl Radical; D004247:DNA