Evidence for nonrandom rejoining of chromatid breaks and its relation to the origin of sister-chromatid exchanges |
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| Authors: | G Olivieri J G Brewen |
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| Affiliation: | 1. Department of Environmental Sciences, COMSATS University Islamabad, Abbottabad Campus 22060, Pakistan;2. Department System-Ecotoxicology, Helmholtz Centre for Environmental Research – UFZ, Permoserstraße 15, 04318 Leipzig, Germany;3. Department of Environmental Sciences, COMSATS University Islamabad, Vehari Campus, Pakistan;4. Department of Civil Engineering, COMSATS University Islamabad, Abbottabad Campus 22060, Pakistan;5. Department of Civil and Environmental Engineering, University of Alberta, Canada;1. Service de pneumologie, hôpital André-Mignot, centre hospitalier de Versailles, 177, rue de Versailles, 78155 Le Chesnay, France;2. Service d’anatomopathologie, hôpital André-Mignot, 78150 Le Chesnay, France |
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| Abstract: | Studies were made of the relative frequencies of sister-strand exchanges, isochromatid deletions, and symmetrical and asymmetrical interchanges involving daughter endoreduplicated chromosomes (diplochromosomes) in tritiated thymidine-labeled aneuploid Chinese hamster and diploid human cells. It was found that the reunion of broken ends in the endoreduplicated chromosomes was not random and that the ratio of symmetrical to asymmetrical interchanges was about the same as the ratio of sister-strand exchanges to isochromatid deletions. These data are interpreted to mean that sister-strand exchanges may be radiation-induced exchanges resulting from isolocus breaks that do not rejoin in the expected random fashion. The very high frequency of interchanges in daughter endoreduplicated chromosomes is taken as evidence in support of the site hypothesis of Wolff and Atwood (see ref. 19). |
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