Drosophila melanogaster stock consisting of meiotic recombination deficient (Rec-) double mutant mei-9a mei-41D5 males and Rec+ females was exposed at the larval stage to an aromatic amine or a polycyclic aromatic hydrocarbon. After emergence as adult flies, the males and the females were scored separately. When the treatment caused a dose-dependent reduction in the male to female ratio from the control level; the experiment was repeated with a larval stock consisting of Rec+ males and Rec+ females under comparable conditions. A preferential killing effect upon Rec- larvae was taken as evidence of DNA damaging effect of the test compound. Among 16 compounds tested, 1-AP, B(a)P, 2-AF, DAF, 4-AAF, 2-AAF, 1-AA, 2-AA, DMA, B(a)A and DMBA were registered as positive; Py and 3-MC were weakly positive; and B(e)P, Fluo and Ant were negative. The selective killing effects of the compounds in each of the pyrene, fluorene and anthracene series varied drastically as a function of structure in a way similar to that reported for the genotoxicity in Drosophila and the carcinogenicity in rodents. The Drosophila DNA repair assay will serve as a simple adjunct to the already available means for studying the genotoxic potency of aromatic amines and polycyclic aromatic hydrocarbons.
