1987 Fiscal Year Final Research Report Summary
Molecular mechanisms for X-ray induced mutagenesis, carcinogenesis and aging
| Project/Area Number |
60440106
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
放射線5生物学
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| Research Institution | Kyoto University |
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Principal Investigator |
IKENAGA Mituo Radiation Biology Center, Kyoto University, 放射線生物研究センター, 教授 (70025378)
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| Co-Investigator(Kenkyū-buntansha) |
ONO Tetsuya Radiation Biology Center, Kyoto University, 放射線生物研究センター, 助教授 (00107509)
OKADA Shigefumi Radiation Biology Center, Kyoto University, 放射線生物研究センター, 教授 (70010048)
UTSUMI Hiroshi Radiation Biology Center, Kyoto University, 放射線生物研究センター, 助教授 (20025646)
SASAKI Masao Radiation Biology Center, Kyoto University, 放射線生物研究センター, 教授 (20013857)
ISHIZAKI Kanji Radiation Biology Center, Kyoto University, 放射線生物研究センター, 助手 (70111987)
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| Project Period (FY) |
1985 – 1987
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| Keywords | X-rays / Mutation / cAMP receptor gene / Nucleotide sequence change / Cell transformation / Chromosome aberration / Aging / C-myc |
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| Research Abstract |
1. X-ray mutagenesis Cyclic-AMP receptor gene (crp gene) of E. coli, which is cloned on a plasmid pHA7, was irradiated with X-rays and used to transform E. coli pp47 (crp-minus strain).
The arised mutants which harbored crp-minus mutant plasmids were collected form agar plates. Plasmid DNA was isolated form each mutant, and the nucleotide sequence in the crp gene was determined by a chain termination method of Sanger. Among the 84 mutants analyzed, we found one GC to AT transition mutation, 7 transversion mutations either from GC to CG or to TA; 8 frameshift mutations involving changes in single base, namely, 5 deletion mutations and 3 insertion mutation.
2. X-ray induced cell transformation
The transformation of a near-diploid mouse cell line (m5S) by X-rays was studied in relation to chromosomal changes. Chromosome analysis revealed that 17 out of 24 morphological transformants showed a common chromosome change, a diminution of the C2-ter region of chromosome 13. The tumorigenicity in nude mice was associated with the further appearance of an extra chromosome segment, probably consisting of tandem repeats of active genes.
3. Aging
The degree of methylation at c-myc protp-oncogene was found to change during aging process of mice; hypermethylation was observed in the liver DNA.
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