Unique response of double-stranded oligonucleotides containing a single 8-oxo-7,8-dihydroguanine to gamma rays in the frozen aqueous state at 77 K.
Two kinds of double-stranded oligonucleotides containing a single 8-oxo-7,8-dihydroguanine were labeled with (32)P at their 5' ends and exposed to gamma rays in the frozen aqueous state at 77 K, where both direct and quasi-direct effects of ionizing radiation predominate. Analysis of the oligonucleotides with 20% denaturing polyacrylamide gel electrophoresis revealed no difference in the immediate induction of strand breaks between oligonucleotides containing 8-oxo-7,8-dihydroguanine and their corresponding oligonucleotides with normal guanine, but piperidine-sensitive damage was induced more frequently in the former than in the latter. Sequence analysis of irradiated oligonucleotides showed that not only 8-oxo-7,8-dihydroguanine but also its neighboring bases and the cytosine residue that is paired to it became piperidine-sensitive in both oligonucleotides. These results suggest that 8-oxo-7,8-dihydroguanine, its neighboring bases and the opposite cytosine are candidates for radiation damage hot spots.
Kuwabara
M
M
Laboratory of Radiation Biology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
D003080:Cold Temperature; D004249:DNA Damage; D004591:Electrophoresis, Polyacrylamide Gel; D005720:Gamma Rays; D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry*; D006801:Humans; D009841:Oligonucleotides / Q000737:chemistry / Q000528:radiation effects*; D010880:Piperidines / Q000737:chemistry; D014867:Water / Q000737:chemistry
D009841:Oligonucleotides; D010880:Piperidines; D014867:Water; C024829:8-hydroxyguanine; D006147:Guanine