Kinetochore analysis of micronuclei allows insights into the actions of colcemid and mitomycin C.
We have induced micronuclei in two strains of diploid human fibroblasts with a known aneugen, colcemid, and a known clastogen, mitomycin C. Using immunofluorescence to detect the presence of kinetochores in micronuclei, we were able to demonstrate a 26.8-fold increase in fluorescence-positive micronuclei (aneuploidy) in colcemid-treated cells. However, colcemid also induced an increase in kinetochore-negative micronuclei. Our findings support previous reports that suggest colcemid may induce chromosome breakage in addition to its major aneugenic effect. The frequency of kinetochore-negative micronuclei (chromosome breakage) in mitomycin C-treated cells rose an average of 7.9-fold in the two test strains, a clear reflection of its clastogenic action. However, a 4-fold increase in the kinetochore-positive fraction was seen. We conclude that the fibroblast micronucleus assay, coupled with kinetochore immunofluorescence, provides a useful screening approach for genotoxic agents. The delineation of the precise mechanism by which an agent perturbs the rates of chromosomal breakage or lag may require more detailed analysis.
Rudd
N L
NL
Department of Paediatrics, University of Calgary, Alb., Canada.
Williams
S E
SE
Evans
M
M
Hennig
U G
UG
Hoar
D I
DI
D000782:Aneuploidy; D002869:Chromosome Aberrations; D003703:Demecolcine / Q000494:pharmacology*; D005069:Evaluation Studies as Topic; D005347:Fibroblasts / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D006801:Humans; D048629:Micronuclei, Chromosome-Defective / Q000187:drug effects*; D016685:Mitomycin; D008937:Mitomycins / Q000494:pharmacology*; D009152:Mutagenicity Tests
D008937:Mitomycins; D016685:Mitomycin; D003703:Demecolcine