1995 Fiscal Year Final Research Report Summary
Molecular mechanisms of proton and x-ray mutagenesis
| Project/Area Number |
06454634
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
環境影響評価(含放射線生物学)
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
YAMAMOTO Kazuo Tohoku University Graduate school of science Professor, 大学院理学研究科, 教授 (20093536)
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| Co-Investigator(Kenkyū-buntansha) |
ONO Tetsuya Tohoku University School of Medicine Professor, 医学部, 教授 (00107509)
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| Project Period (FY) |
1994 – 1995
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| Keywords | transgenic mouse / proton / alpha-ray / x-ray / active oxygen / supF gene / tonB gene / lacZ gene |
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| Research Abstract |
A plasmid, pZ189, was treated with active oxygen species and radiation, and mutagenesis in the supF gene was determined by DNA sequencing. In these cases, more than 80% of the mutations were single base substitutions, the most frequent base change being G : C->C : G and G : C->T : A transversions. Active oxygen species resulted in increased formation of 8-hydroxydeoxyguanosine in pZ189 DNA.Thus, major components of radiation mutagenesis were concluded to be formation of active oxygens due to radiation indirect effect to water molecule in the environment.
We next analyzed the DNA sequence changes in x-ray-induced mutations in the endogenous tonB gene of Escherichia coli strain. In this case, we did not find significant increase of deletion formation among tonB mutants. Thus, our results did not agree with previous notion that x-ray is a chromosome deletion inducer.
Using transgenic mouse that has E.coli lacZ gene as a transgene, we examined the DNA sequence changes in x-ray induced mutagenesis in mouse. Mutagenic spectrum was similar to that of spontaneous mutation. Deletion mutation was not detected in this case which may be due to experimental system or the fact that x-ray does not induce deletion in vivo.
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