Increased levels of 8-hydroxy-2′-deoxyguanosine in Drosophila larval DNA after irradiation with 364-nm laser light but not with X-rays

Tomoe Negishi, Kazuaki Kawai, Ritsuo Arakawa, Shoichi Higashi, Takanori Nakamura, Masakatsu Watanabe, Hiroshi Kasai, Kazuo Fujikawa

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Exposure to UVA light causes damage to cellular components such as DNA and membrane lipids. We showed previously that UVA irradiation can induce mutations in Drosophila larvae and that the major lesions responsible for mutations were not thymidine dimers when wavelengths tested became longer. The use of a longer wavelength with UVA laser apparatus (364 nm) has made it possible to test the effects of this powerful light in biological organisms. In the present study, we irradiated third instar larvae of the urate-null Drosophila mutant strain y v ma-l, which is sensitive to oxidative stress, and compared the effects of 364 nm light irradiation with the effects of X-rays. To assay viability, some of the larvae were kept at 25°C until they eclosed in order to obtain a measure of viability. The remaining larvae were used to measure the amount of 8-hydroxydeoxyguanosine (8-OHdG), an indicator of oxidative DNA damage. The amount of 8-OHdG increased and viability decreased in response to increased UV dose in both the y v ma-l and wild-type strains. With irradiation of 600 kJ m-2, 8-OHdG/106dG was 7.2 ± 3.2 and 6.2 ± 2.0 in y v ma-l and wild-type strains, respectively, whereas the respective levels were 2.2 ± 0.6 and 2.3 ± 0.8 without irradiation. Our results indicated that irradiation with a 364-nm laser light caused significant oxidative damage in Drosophila larval DNA; however, induction of the damage was not prohibited by urate. To the best of our knowledge, this is the first report of a study in whole animals that shows increased levels of 8-OHdG in response to 364-nm UVA. X-ray ionizing radiation is also thought to generate reactive oxygen species in irradiated cells. We found that the amount of 8-OHdG in DNA following X-ray radiation remained unchanged in both strains, though survival rates were affected. X-ray-generated oxidative damage in Drosophila cells was followed by cell death but not DNA base oxidation, and the damage was suppressed by urate. The overall results suggest significant differences in the major in vivo oxidative damage caused by 364-nm light and X-rays.

Original languageEnglish
Pages (from-to)658-663
Number of pages6
JournalPhotochemistry and Photobiology
Issue number3
Publication statusPublished - 2007
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry


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