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Chromosome Aberrations in Normal and Ataxia-Telangiectasia Cells Exposed to Heavy IonsAlthough cells derived from Ataxia Telangiectasia (AT) patients are known to exhibit abnormal responses to ionizing radiations, its underlying mechanism still remains unclear. Previously, the authors reported that at the same gamma-irradiation dose AT cells show higher frequencies of misrepair and deletions compared to normal human fibroblast cells. In this study, we investigated the effects of heavy ions beams on chromosomal aberrations in normal and AT cells. Normal and AT fibroblast cells arrested at G0/G1 phase were irradiated with 2 Gy of X-rays, 490 MeV/u Silicon (LET 55 keV/m), 500 MeV/u Iron (LET 185 keV/m) and 200 MeV/u Iron (LET 440 keV/m) particles, and then cells were allowed to repair for 24 hours at 37 degrees before subculture. Calyculin-A induced PCC method was employed to collect G2/M chromosomes and whole DNA probes 1 and 3 were used to analyze chromosomal aberrations such as color-junctions, deletions, simple exchanges (incomplete and reciprocal exanges) and complex-type exchanges. The percentages of aberrant cells were higher when normal and AT cells were exposed to heavy ions compared to X-rays, and had a tendency to increase with increasing LET up to 185 keV/m and then decreased at 440 keV/m. When the frequency of color-junctions per cell was compared after X-ray exposure, AT cells had around three times higher frequency of color-junctions (mis-rejoining) than normal cells. However, at 185 keV/m there was no difference in the frequency of color-junctions between two cell lines. It was also found that the frequency of simple exchanges per cell was almost constant in AT cells regardless LET levels, but it was LET dependent for normal cells. Interestingly, the frequency of simple exchanges was higher for AT cells when it was compared at 185 keV/m but AT cells had more complex-type exchanges at the same LET levels. Heavy ions are more efficient in inducing chromosome aberrations in normal and AT cells compared to X-rays, and the aberration types between normal and AT fibroblast appeared different probably due to difference in the ATM gene function.
Document ID
20070022354
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Kawata, T.
(Chiba Univ. Chiba, Japan)
Ito, H.
(Chiba Univ. Chiba, Japan)
Liu, C.
(Chiba Univ. Chiba, Japan)
Shigematsu, N.
(Keio Univ. Tokyo, Japan)
George, K.
(Wyle Labs., Inc. Houston, TX, United States)
Cucinotta, F. A.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 23, 2013
Publication Date
July 13, 2007
Subject Category
Life Sciences (General)
Meeting Information
Meeting: 18th Annual NASA Space Radiation Investigators'' Workshop
Location: Rohnert Park, California
Country: United States
Start Date: July 13, 2007
End Date: July 15, 2007
Sponsors: Universities Space Research Association
Distribution Limits
Public
Copyright
Other

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