The mouse bone marrow micronucleus assay can be used to distinguish aneugens from clastogens

The occurrence of aneuploidy can be measured in several assays. However, none of them have been sufficiently validated. The bone marrow micronucleus test may be considered as a method for aneuploidy detection. In this work, micronuclei were induced by two aneugens, vincristine sulfate (0.1 mg/kg) and nocodazole (80 mg/kg), and two clastogens ethylmethanesulfonate (EMS) (300 mg/kg) and cyclophosphamide (60 mg/kg). Three criteria have been examined in order to distinguish micronuclei induced by aneugens and clastogens: the area of the micronuclei, the percentage of micronuclei with C-band-positive material and the DNA content of the micronuclei. C-band-positive micronuclei were found in 47% of the micronuclei for vincristine sulfate, 58% for nocodazole, 17% for EMS and 20% for cyclophosphamide. Areas of micronuclei showed a significant difference when induced by aneugens or by clastogens. Finally, the DNA content of micronuclei also showed a totally different distribution pattern when comparing the aneugen vincristine sulfate with the clastogen EMS. The three methods analysed could thus all make a difference between micronuclei induced by aneugens and those induced by clastogens.