Genotoxic ability of cadmium, chromium and nickel salts studied by kinetochore staining in the cytokinesis-blocked micronucleus assay

The aneugenic and clastogenic ability of cadmium chloride(II), cadmium sulf ate(II), nickel chloride(II), nickel sulfate(ll), chromium chloride(III) an d potassium dichromate(IV) have been evaluated through kinetochore-stained micronucleus test. Traditional genotoxicity assays evaluate DNA damage, gen e mutations and chromosome breakage. However, these tests are not adequate to detect aneugenic agents that do not act directly on DNA. Staining kineto chores in the cytokinesis-blocked micronucleus assay is a useful way to dis criminate between clastogens and aneuploidogens and may allow a rapid ident ification of aneuploidy-inducing environmental compounds. Human diploid fibroblasts (MRC-5) were employed. All compounds increased mi cronuclei frequency in a statistically significant way. However, increases in kinetochore-positive micronuclei frequencies were higher than in kinetoc hore-negative ones. The present work demonstrates the genotoxic ability of the cadmium and chromium salts studied. Aneugenic as well as clastogenic ab ility could be observed with this assay. Nickel salts, as it was expected b ecause of their known weak mutagenicity, showed lower genotoxic effects tha n the other metal salts studied. As the test employed only allows the detec tion of malsegregation, it is proposed that this mechanism is at least one of those by which the tested metal salts induced aneuploidy. On the other h and, Visualization of kinetochores in all experiments suggests that the com pounds studied did not act by damaging these structures. (C) 2001 Elsevier Science B.V. All rights reserved.