Development of a comprehensive test battery is necesary for the evaluation and detection of aneugenic chemicals. The chromosome couting method was used in the present study. The aneugenic ability of
cadmium choride (1.0, 2.0 and 4.0x10(-3) mM),
cadmium sulfate (3. 3, 6.7x10(-5) and 1.3x10(-4) mM),
potassium dichromate (2.5, 5. 0x10(-4) and 1.0x10(-3) mM) and cacodilic
acid (1.25, 2.5 and 5. 0x10(-2) mM) were analysed using MRC-5 cells which have a modal diploid number of 2 n=46 with a spontaneous
aneuploid or
polyploid cells not higher than 13% and 8%, respectively.All compounds induced significant increments of
aneuploid cells in relation to negative controls. The frequency of
aneuploid cells increased in all treatments with
cadmium chloride.
Cadmium sulfate induced significant increments of
aneuploid cells with the two higher doses. All the doses of
potassium dichromate increased the frequency of
aneuploid cells although to a lesser degree than the other compounds. In these cases, differences were in the borderline of statistical significance (p<0.05). Moreover, a low number of cells could be analysed in treatments with the highest dose due to the decrease in the mitotic index. Results obtained are coincident with previous reports using the same methodology in the sense that induced
aneuploidy was mainly evidenced by the increase of hypodiploid but not hyperdiploid cells. In addition, anaphase-telophase analysis of the effects of the same doses of these
metal compounds in CHO cells showed significant increments of lagging chromosomes and increased frequencies of kinetochore positive micronuclei in MRC-5 cells. These findings could be considered as an indication that the main cause of unequal chromosome separation is the failure of kinetochores to attach the spindle apparatus either by alteration of its
protein components or by the altered chromatid separation in anaphase.