Mechanisms of Formation
of DNA Strand Breaks Induced by γ-Rays
SHAO Chun-Lin and YU Zeng-Liang
( Institute of Plasma Physics, the Chinese Academy of Sciences, PO Box
1126, Hefei 230031, China )
SAITO Masahiro
( Research Reactor Institute, Kyoto University, Osaka 5900494, Japan
)
Abstract Dose responses of DNA single-
and double-strand breaks (SSB and DSB) of pBR322 irradiated with g-rays were measured by gel
electrophoresis scanning, and the production process of SSB was tested. Results
showed that the formation of DSB was related to the free radicals scavenging
capacity s of mannitol dissolved in DNA
solution. The ratio of aDSB to βDSB non-linearly
increased with increasing s. On the other hand, aDSB was induced by the single radical
transfer mechanism as s<108 s-1,
it could, however, be formed by the LMDS mechanism as s>2×108s-1.
Moreover, the distance for two SSBs forming a DSB in complementary strands was
not obviously influenced by the scavenging capacity.
Key words g-rays; pBR322; single strand break; double
strand break
Corresponding author:
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