| Project/Area Number |
14570299
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Hygiene
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| Research Institution | OKAYAMA UNIVERSITY |
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Principal Investigator |
WANG Da-hong Okayama University, Graduate School of Medicine and Dentistry, Assistant, 大学院・医歯学総合研究科, 助手 (90294404)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAOKA Kiyonori Okayama University, Medical School, Professor, 医学部, 教授 (00314683)
SANO Kuniaki Okayama University, Graduate School of Medicine and Dentistry, Assistant, 大学院・医歯学総合研究科, 助手 (00294405)
TSUTSUI Ken Okayama University, Advanced Science Research Center, Professor, 自然生命科学研究支援センター, 教授 (70108158)
KIRA Shohei Okayama University, Graduate School of Medicine and Dentistry, Professor, 大学院・医歯学総合研究科, 教授 (50033212)
MASUOKA Noriyoshi Okayama University, Graduate School of Medicine and Dentistry, Associate Professor, 大学院・医歯学総合研究科, 助教授 (20116502)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2003: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2002: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | Catalase mutant E coli strains / Acatalasemic mice / Hypocatalasemic mice / Catalase mutant genes / Hydrogen peroxide / Cytotoxicity / Antioxidants / Inorganic heavy metal compounds / アカタラセラミクスマウス / ヒポカタラセミクマウス / カタラーゼ阻害剤 / ニトロベンゼン / DNA酸化損傷 |
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| Research Abstract |
This research was aimed at developing a risk assessment method for potential hazards by using catalase mutant strains. At first, we successfully constructed catalase mutant E coli strains by transforming plasmids encoding the catalase cDNA from catalase mutant mice (Cs^b, Cs^c) and its corresponding wild type (Cs^a) into catalase-deficient Escherichia coli UM255. There was a significant difference in catalase activities among each catalase-deficient E. coli mutant. The level of catalase in Csa appeared higher than that in the others, the catalase level in Cs^c was 65.1% of Cs^a, Cs^b was 61.7%, and UM 255 was 8.8% of Cs^a. Susceptibility to H_2O_2 showed a clear dose dependency with negative correlation to catalase activity levels. The susceptibility order was UM255>Cs^b>Cs^c>Cs^a. To assess the cytotoxicity of the chemicals, we employed colony-forming efficiency test and zones of inhibition test, the results demonstrated that survival of catalase-deficient E. coli mutants was signific
… More
antly reduced by treatment of hydroquinone, pyrogallol and L-Dopa in a dose-dependent manner and the cell viabilities underexposure to these chemicals were also different significantly among each catalase mutant strain, showing the following orders : Cs^a>Cs^c>Cs^b>UM255. The cytotoxicities induced by hydroquinone, pyrogallol and L-Dopa were also confirmed by zone of inhibition test, in which UM255 was the most susceptible, showing the largest zone of growth inhibition surrounding the paper disc, followed by Cs^b, Cs^c and Cs^a. The toxicities of these chemicals were completely blocked by catalase and ascorbic acid in a concentration-dependent relation. Treatment by some heavy metals (Hg, Cr, Cd, As, Ni, Fe, Cu) also significantly reduced the survival of these strains in a dose-dependent manner, suggesting H_2O_2 was increasingly produced in the process of hydroquinone cytotoxicity and catalase played a protective role in inhibiting the cell damage. The results support the usefulness of these newly established strains for hazard identification of oxidative chemicals in a risk assessment process. Less
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