Abstract The premature chromosome condensation (PCC) technique was used to investigate chromosomal damage, repair, and misrepair in the G1 phase of a human/hamster hybrid cell line that contains a single human chromosome. Plateau-phase cell cultures were exposed to either x-rays or a 425 MeV/u beam of neon ions near the Bragg peak where the LET is 183 keV/μm. An in situ hybridization technique coupled to fluorescent staining of PCC spreads confirmed the linearity of the dose response for initial chromatin breakage in the human chromosome to high doses (1600 cGy x-ray or 1062 cGy Ne). On Giemsa-stained slides, initial chromatin breakage in the total genome and the rejoining kinetics of these breaks were determined. As a measure of chromosomal misrepair, ring PCC aberrations were also scored. Ne ions were about 1.5 x more effective per unit dose compared to x-rays at producing the initially measured chromatin breakage. 90% of the x-ray-induced breaks rejoined in cells incubated at 37°C after exposure. In contrast, only 50% of Ne-ion-induced breaks rejoined. In the irradiated G1 cells, ring PCC aberrations increased with time apparently by first order kinetics after either x-ray or Ne exposures. However, far fewer rings formed in Ne-irradiated cells after a dose giving a comparable initial number of chromatin breaks. Following x-ray exposures, the yield of rings formed after long repair times (6 to 9 hrs) fit a quadratic dose-response curve. These results indicate quantitative and qualitative differences in the chromosomal lesions induced by low- and high-LET radiations.


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    Title :

    Repair and misrepair of heavy-ion-induced chromosomal damage


    Contributors:
    Goodwin, E. (author) / Blakely, E. (author) / Ivery, G. (author) / Tobias, C. (author)

    Published in:

    Publication date :

    1989-01-01


    Size :

    7 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English



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