Chemically induced micronucleus formation in V79 cells - comparison of three different test approaches

The in vitro micronucleus test (MNT) is a useful assay for the detection of mutagenic events on both the chromosomal and the genomic level, The main d isadvantage for introducing the in vitro MNT into official test guidelines seems to be the disparity of existing protocols. To contribute to the aim o f standardisation, three different methodological approaches of the in vitr o MNT with V79 cells were compared: the standard assay using an asynchronic ally growing mixed cell population, the cytokinesis block (CB) assay and a modified MNT, the so-called mitotic shake-off (MSO) method. V79 cells were thus treated with two known aneugens (colcemide and griseofulvin) and two c lastogens (mitomycin C and cyclophosphamide) over various time periods. The cultures of the CB assay were additionally exposed to cytochalasin B (Cyt- B), an inhibitor of cell, but not of nucleus division. After treatment, the cells were harvested and analysed for the appearance of micronuclei (MN). All three assays yielded positive results for all test substances. These re sults support the suitability of the MNT with V79 cells with regard to the ability to detect the genotoxic potential of both clastogens and aneugens i ndependent of the test protocol applied, Thus, all three methods are approp riate for MN detection, but due to the fact that the application of Cyt-B h as no advantages for a cell line like V79 in which nearly all cells undergo a normal cell cycle, its use is not recommended. (C) 1999 Elsevier Science B.V. All rights reserved.