DNA-damaging potency and genotoxicity of aflatoxin M1 in somatic cells in vivo of Drosophila melanogaster.

Aflatoxin M1 (AFM1), a metabolic hydroxylation product of aflatoxin B1 (AFB1), and the parent compound were comparatively assayed for DNA-damaging potency and genotoxicity in vivo in Drosophila melanogaster using, respectively, the mei-9a mei-41D5 DNA repair test and the mwh/flr3 wing spot test. In the repair test, larval stock, consisting of meiotic recombination-deficient double mutant mei-9a mei-41D5 males and repair-proficient females, was exposed to the test agents, and the preferential killing of the mutant larvae was taken as evidence of the DNA-damaging effect. In this test, AFM1 was registered as a DNA-damaging agent with an activity approximately 3-fold lower than that of AFB1. In the wing spot test, where larval flies, trans-heterozygous for the somatic cell markers mwh and flr3, were treated and the wings were inspected at adulthood for spots manifesting the phenotypes of the markers, AFM1 exerted a genotoxic effect compatible to that of AFB1. Based on these results and other data, we predict that AFM1 may be genotoxic in mammalian in-vivo systems as well.