GENOTOXIC ACTIVATION OF HYDRAZINE, 2 DIALKYLHYDRAZINES, THIOUREA AND ETHYLENE THIOUREA IN THE SOMATIC W W+ ASSAY OF DROSOPHILA-MELANOGASTER/

Genotoxic activation of hydrazine (HZ), two symmetrical dialkylhydrazi nes, namely, 1,2dimethylhydrazine and 1,2-diethylhydrazine (SDMH and S DEH), thiourea (TU) and ethylene thiourea (ETU) has been evaluated by means of the w/w + somatic assay of Drosophila. Both low bioactivation insecticide-susceptible (IS) and high biotransformation insecticide-r esistant (IR) strains were used. The combined application of insectici de-susceptible and insecticide-resistant strains should, in principle, detect somatic cell recombinagens in the Drosophila melanogaster in v ivo w/w + assay. The IS strain was more susceptible to toxicity induce d by the test chemicals than the IR stocks. Its performance in the bio transformation of the chemicals tested was rather poor. TU was inactiv e in all strains. With the active compounds, spot frequencies increase d approximately linearly with dose for each spot type. SDEH gave a str ong positive result in all three female genotypes exposed. HZ, ETU and SDMH were overall weakly positive in the IR strain Haag-79 (HG-R). In terestingly, ETU was clearly positive in the IR Hikone-R (HK-R) strain . A comparison of the recombinagenic potencies between the active and the weakly positive compounds, and among strains, showed pronounced ge notype-dependent differences between the low and the high bioactivatio n strains. The ability of Drosophila to express several procarcinogens in relation to insecticide-resistance after activation catalyzed by C YP450 enzymes is discussed. (C) 1997 Elsevier Science B.V.