The cytotoxic effects of organophosphorus compound dichlorvos and of its commercial formulations Nuvan — 50 and Nogos — 50, both produced and in use in Yugoslavia, were comparatively studied. Saccharomyces cerevisiae N 123 yeast strain served as a test organism. Yeasts were incubated in a complete nutrient medium containing the pesticide in a concentration range from 0.125 to 12.0 mg/ml of active substance. The cytotoxic effect was determined as the degree of inhibited cell division during and after 26-hour incubation at 28°C. According to results the original form of dichlorvos is more toxic than the two commercial formulations, and so is Nuvan-50 compared to Nogos-50. In our experimental conditions no increase of tolerance of the microorganism to the pesticide or the reversibility of the effect after treat ment with high pesticide concentrations could be establi shed. It may be concluded that the effect of the active sub stance, dichlorvos, is modified in formulations more in terms of intensity rather than in the mode of action.
2 Figures and Tables
Fig. 1. Growth curves of yeast cells at different concentrations of a) dich lorvos, b) Nuvan-50, c) Nogos-50: 0-controls, ▼-4mg/mL., d -2 mg/mL, ■-1 mg/mL, A -0.5 mg/mL, A-0.25 mg/mL, V -0.125 mg/mL
Fig. 2. Growth curves of yeast cells in the medium free of pesticidg after pretreatment in the presence of a) dichlorvos, b) Nuvan-50, c) Nogos-50 in concentrations: 0-controls, Y -4 mg/mL, d -2 mg/mL, ■ - ! mg/mL
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