The effect of cytochalasin-B concentration on the frequency of micronuclei induced by four standard mutagens. Results from two laboratories.
In a previous collaborative work, we have recently shown that the cytochalasin-B (Cyt-B) concentration used in the human lymphocytes cytokinesis-block micronucleus (CBMN) assay is an important variable in the baseline micronuclei (MN) frequency as well as in the percentage of binucleated cells obtained. Now we have investigated how Cyt-B concentration modulates the MN frequency induced in whole blood human lymphocyte cultures by two clastogens (ethyl methanesulphonate and mitomycin-C) and two aneugens (colchicine and vincristine sulphate). The experimental design includes six donors, two concentrations of Cyt-B (3 and 6 micrograms/ml), two concentrations of the four chemicals tested and the exchange of slides between laboratories. The statistical analysis of the results shows: (i) non-significant differences in the MN frequencies and in the toxicity results between scorers from each laboratory, except for 0.06 microM colchicine at 3 micrograms/ml Cyt-B; (ii) an induction of MN by all genotoxic agents tested, the frequencies being lower with 6 than with 3 micrograms/ml Cyt-B, in control and aneugen-treated cultures; and (iii) significant differences between Cyt-B concentrations in several treatments, obtaining lower MN frequencies and higher values for nuclear division index and % binucleated cells when 6 micrograms/ml Cyt-B was used. Bearing in mind these results as well as the toxicity data showing that 6 micrograms/ml Cyt-B is much more effective in blocking cytokinesis, we can conclude that the use of 3 micrograms/ml Cyt-B may overestimate the induced frequency of MN.
Departament de Genètica i de Microbiologia, Edifici C, Universitat Autonoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain.
J
J
Surrallés
A
A
Antoccia
A
A
Creus
F
F
Degrassi
F
F
Peris
C
C
Tanzarella
N
N
Xamena
R
R
Marcos
D000328:Adult; D016477:Artifacts; D002478:Cells, Cultured; D003078:Colchicine / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005020:Ethyl Methanesulfonate / Q000494:pharmacology; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects*; D008297:Male; D015162:Micronucleus Tests / Q000379:methods*; D016685:Mitomycin / Q000494:pharmacology; D009153:Mutagens / Q000494:pharmacology; D014750:Vincristine / Q000494:pharmacology
D009153:Mutagens; D003571:Cytochalasin B; D016685:Mitomycin; D014750:Vincristine; D005020:Ethyl Methanesulfonate; D003078:Colchicine