| Project/Area Number |
07680577
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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 |
環境影響評価(含放射線生物学)
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
TACHIBANA Akira KYOTO UNIVERSITY,RADIATION BIOLOGY CENTER,RESEARCH ASSOCIATE, 放射線生物研究センター, 助手 (20188262)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Masao KYOTO UNIVERSITY,RADIATION BIOLOGY CENTER,PROFESSOR, 放射線生物研究センター, 教授 (20013857)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1996: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1995: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | radioadaptive response / radiation-induced mutation / DNA double strand break repair / mouse cells / mouse Hprt gene / deletion mutation / HPRT遺伝子 |
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| Research Abstract |
The DNA double strand break (dsb) has been implicated as the critical lesion induced by ionizing radiation leading to chromosome aberrations, mutations and cell death. We have attempted to refine the measurement and analysis of the rejoining of dsbs with the use of nuclear extracts applied to defined plasmid molecules carrying specific enzymatically-induced dsb. The plasmid pZEr0-2 containing the ccdB gene under the control of the lac gene promotor was used as a substrate. The ccdB gene is lethal to E.coli on being overexpressed, which makes it easy to select plasmids with the mutated ccdB gene caused by mis-rejoining. We have compared the activities of extracts from an ataxia-telangiectasia cell line (AT2KYSV) with those from a normal cell line (N2KYSV).
The extract from AT2KYSV cells showed much higher frequency of mis-rejoining than the N2KYSV extract. Sequence analysis of the mutant plasmids revealed deletion mutations which occurred mostly between short direct repeats (3-6 basepairs). This feature resembles breakpoint junctions in deletion mutations, indicating that this in vitro system reflects the deletion formation mechanism in vivo. We are currently investigating the radioadaptive response using this in vitro system.
To analyze mutations at the mouse Hprt locus in radioadaptive response, we first tried to determine the sequence of the gene. We have determined the sequences of exons 2,3,6,7,8, and 9 and the surrounding sequences of each exon, but not yet for exons 4 and 5.
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