Abstract
There is increasing evidence that aneuploidy during mitosis may be a factor in the etiology of somatic malignancy. The analysis of alterations in anaphase-telophase of mitosis is a useful test for evaluating the aneuploidogenic and clastogenic ability of chemicals. Several metals have been found to be carcinogenic to humans and animals. However, the underlying mechanisms remain unclear. In the present study the aneugenic and clastogenic abilities of cadmium sulfate, potassium dichromate and nickel chloride were analyzed using the anaphase-telophase test. Chinese hamster ovary (CHO) cells cultured for two cycles were treated with the desired compound for 8 h before cell harvesting. The frequency of cells with chromatin bridges, lagging chromosomes and lagging chromosomal fragments was scored. The mitotic index was determined by counting the number of mitotic cells per 1,000 cells on each coverslip and was expressed as a percentage of the number of mitotic plates. Statistical comparisons were done using the "G" method. Correlation and regression analyses were performed to evaluate variations of the mitotic index. Chromium and cadmium were clastogenic and aneugenic and increased the frequencies of the three types of aberrations scored; nickel had only aneugenic activity because it increased the frequency of lagging chromosomes. These results indicate that the anaphase-telophase test is sufficiently sensitive to detect dose-response relationships that can distinguish clastogenic and/or aneugenic activities and that the results obtained using the anaphase-telophase test were similar to those obtained by chromosome counting.
Highlights
Aneuploidy is a serious health problem, the experimental methodology used to investigate the condition has not been completely validated
The objective of this study is to analyze the aneugenic and clastogenic abilities of cadmium sulfate, potassium dichromate and nickel chloride using the anaphase-telophase test, and to validate, if possible, the usefulness of such analysis to distinguish between these two mentioned kinds of genetic damage
Cadmium sulfate increased the frequencies of chromatid bridges, lagging fragments and lagging chromosomes (Table I), this was significantly different from the untreated controls only at the highest dose (G = 9.71, P < 0.01 for lagging chromosomes; G = 6.88, P < 0.01 for lagging fragments; G = 8.41, P < 0.01 for chromatin bridges)
Summary
Aneuploidy is a serious health problem, the experimental methodology used to investigate the condition has not been completely validated. The tests currently used to detect aneugenic compounds include chromosome counting in diploid cell lines (Danford, 1984, 1985; Dulout and Natarajan, 1987) and the fluorescence in situ hybridization (FISH) (van Diemen et al, 1995; Dulout et al, 1996; Natarajan et al, 1996). An alternative ancillary test system is the analysis of alterations in the anaphasetelophase of cultured mitotic cells (Dulout and Olivero, 1984; Seoane and Dulout, 1994). This test is very simple and can be performed in any cytogenetic laboratory with cell culture facilities. Lagging chromosomes are presumably produced by alterations at the level of the kinetochore
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