Chromosomal breakage following treatment of CHO‐K1 Cells in Vitro With U‐68,553B is due to Induction of Undercondensation of Heterochromatin

  title={Chromosomal breakage following treatment of CHO‐K1 Cells in Vitro With U‐68,553B is due to Induction of Undercondensation of Heterochromatin},
  author={R L Yu and C. S. Aaron and Roger G. Ulrich and Arul Thilagar and P V Kumaroo and Y. Wang},
  journal={Environmental and Molecular Mutagenesis},
Preferential breakage of chromosomes af specific sites (so‐called “fragile sites”) has been observed to occur spontaneously, and has been induced by some metal salts and chemicals. Furthermore, a heterochromatic region of the long arm of the Chinese hamster ovary (CHO) M‐chromosome is known to be suceptible to a disproportionately high frequency of spontaneous breakage; unless there is physical displacement of chromatin the resulting achromatic lesions are not scored as structural aberrations… 
Sodium arsenite-induced chromosomal aberrations in the Xq arm of Chinese hamster cell lines.
An increased number of abnormal cells with pulverised chromosomes, decondensed chromatin, isochromosomes and hyperploidy in CHO9 and EM-C11 cell lines at all doses of SA is observed and a high degree of fragility of these regions is observed.
Localized Chromosomal Aberrations in the Heterochromatic q Arm of the X Chromosome in V79 Chinese Hamster Cells and the Implications for Industrial in vitro Cytogenetic Screening
Comparisons between different assays reveal significant discrepancies between the results obtained, and in vitro chromosomal aberration assay, in particular, has been criticized for leading to too many positive results.
Chromosomal Alterations


Induction of chromosomal damage in Chinese hamster ovary cells by soluble and particulate nickel compounds: preferential fragmentation of the heterochromatic long arm of the X-chromosome by carcinogenic crystalline NiS particles.
It is proposed that when cells are treated with high levels of NiCl2 in an attempt to achieve the cellular levels of nickel produced by NiS phagocytosis, this overloading results in cytotoxic responses rather than the preferential fragmentation of heterochromatin observed with particles.
Comparison of the localization of chromosome damage induced by calcium chromate and nickel compounds.
Results are interesting because nickel(II), which is thought to be the ultimate carcinogen of nickel compounds, binds poorly to DNA, is weakly mutagenic, but induces chromosome damage, probably because of its interaction with nuclear proteins in heterochromatin.
Parallel distribution of sister chromatid exchanges and chromosome aberrations
The results presented here indicate that two different hydrocarbon carcinogens, DMBA and 7,8,12-trimethylbenz(a)-anthracene (TMBA), induce aberrations localised in the same chromosomal regions of the rat bone marrow cells and that the targets for chromosome aberration and for SCE are identical; in other words, both phenomena are related.
Distribution of mitomycin C induced breaks on human chromosomes.
Findings indicate that the C-bands are aggregated in the cell and/or that such an aggregation is induced by mitomycin C.
Induction of sister chromatid exchanges at common fragile sites.
Results show that common fragile sites are hot spots not only for chromosomal lesions such as gaps but also for SCE formation, as measured by sister chromatid exchanges.
Fragile sites are targets of diverse mutagens and carcinogens.
The expression of so many similar fragile sites following exposure of cultured cells to diverse mutagens, and the high correlation of these sites with cancer chromosome breakpoints and oncogenes, suggests that they can be general targets of mutagenic action.
Development of a standard protocol for in vitro cytogenetic testing with Chinese hamster ovary cells: comparison of results for 22 compounds in two laboratories.
A sensitive in vitro test protocol that was applicable to large-scale chemical screening and yielded comparable results in two laboratories and by testing up to a maximum dose, limited by solubility and/or toxicity, should detect a high proportion of clastogens and SCE inducers.
Chromosome aberrations and sister chromatid exchanges in chinese hamster ovary cells: Evaluations of 108 chemicals
Results from the testing of 108 coded chemicals in Chinese hamster ovary (CHO) cells for the induction of chromosome aberrations and sister chromatid exchanges (SCEs) are presented. All chemicals
Heterochromatin heterogeneity in Chinese hamster sex bivalents.
The heterochromatin in the homologous regions of the sex chromosomes allows the formation of a chiasma in the sex bivalent of Chinese hamster spermatocytes, and the heterogeneity found in theseheterochromatic regions may help to establish a more precise relationship between heterochromeatin and recombination.