1995 Fiscal Year Final Research Report Summary
Analysis of damage to human genes for estimating the carcinogenicity of environmental chemicals
| Project/Area Number |
06557028
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Hygiene
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
KAWANISHI Shosuke Kyoto Univ., Fac.of Med. lecturer, 医学研究科, 講師 (10025637)
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| Co-Investigator(Kenkyū-buntansha) |
SUGIYAMA Hiroshi Kyoto Univ., Fac.of Eng.associate professor, 工学研究科, 助教授 (50183843)
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| Project Period (FY) |
1994 – 1995
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| Keywords | human gene / Ame's test / carcinogen / active oxygen species / DNA damage / NADH / Mn / transition metal |
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| Research Abstract |
Pulsed-field gel electrophoresis (PFGE) has emerged as a powerful tool for the study of high-molecular weight DNA.PFGE is generally used for detection of cellular DNA double-strand breaks. In addition, we have designed an experimental protocol which allows the detection of DNA single-strand breaks plus alkali-labile sites by PFGE.In this study, we have investigated damage to cellular and isolated DNA by Ames-test negative carcinogens in the presence of metal ions using both PFGE and DNA sequencing techNique. Active species causing DNA damage were investigated by the ESR-spin trapping method. We have shown that in the presence of Cu (II), Ames-test negative carcinogens (benzene metabolites, o-phenylphenol metabolites, caffeic acid, pentachlorophenol metabolites, tryptophan metabolites) caused damage to isolated DNA through H2O2 formation. PFGE showed that Ames-test negative carcinogens induced DNA strand breaks in cultured human cells in the presence of Mn (II). With alkali treatment, DNA single-strand breaks were observed. The strand breakage was increased by 3-aminotriazol (a catalase inhibitor) and decreased by catalase, indicating the involvement of H2O2. The DNA damage was decreased by o-phenanthroline, indicating the involvement of transition metal ion. These results suggest that in the presence of Mn (II) or Cu (II), Ames-test negative carcinogens produce H2O2, which is activated by transition metals to cause damage to DNA in vitro and probably in cultured cells.
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