ANTIGENOTOXICITY STUDIES IN DROSOPHILA-MELANOGASTER

The fruit fly Drosophila melanogaster with its well developed array of genotoxicity test systems has been used in a number of studies on ant igenotoxicity of various compounds and mixtures. In recent years, the newly developed Somatic Mutation and Recombination Tests (SMART) have mainly been employed. These one-generation tests make use of the wing or eye imaginal disc cells in larvae and have proven to be very effici ent and sensitive. They are based on the principle that the loss of he terozygosity of suitable recessive markers can lead to the formation o f mutant clones of cells that are then expressed as spots on the wings or eyes of the adult flies. We have employed the wing spot test with the two markers multiple wing hairs (mwh, 3-0.3) and flare (flr, 3-38. 5), Three-day-old larvae, trans-heterozygous for these markers, are tr eated chronically or acutely by oral administration with the test comp ound(s) or complex mixtures. For antigenotoxicity studies, chronic co- treatments can be used, as well as separate pre-treatments with an ant igenotoxic agent followed by a chronic treatment with a genotoxin. Aft er eclosion, the wings of the adult flies are scored for the presence of single and twin spots. These spots can be due to different genotoxi c events: either mitotic recombination or mutation (deletion, point mu tation, specific types of translocation, etc.). The analysis of two di fferent genotypes (one with structurally normal chromosomes, one with a multiply inverted balancer chromosome) allows for a quantitative det ermination of the recombinagenic activity of genotoxins. Results of tw o separate studies are presented: (1) instant coffee has antirecombina genic but not antimutagenic activity in the wing spot test; and (2) as corbic acid and catechin are able to protect against in vivo nitrosati on products of methyl urea in combination with sodium nitrite. (C) 199 8 Elsevier Science B.V. All rights reserved.