Cytogenetic assays of chemical clastogens using mammalian cells in culture.

A protocol is described for cytogenetic assays of chemical mutagens using mammalian cells in vitro. The system employs continuous drug treatment (3 concentrations) for up to 8 h and recovery-cell populations after pulse treatments with a high dose. Both direct fixation (for recording spindle anomalies in anaphase) and colcemid-hypotonic fixation (for reading metaphase chromosome aberrations) are used in order to estimate the effects of an agent as a mitotic poison and as a clastogen respectively. Some DNA intercalating dyes (acridine orange, quinacrine mustard, neutral red) were found to be highly clastogenic whereas others (quinacrine dihydrochloride, 33258 Hoechst) are not.