Iida, Y., Inanami, O., Inoue, H., Ohtsuka, E. and Kuwabara, M. 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 32P at their 5′ ends and exposed to γ 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.
