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Humic acids in the form of potassium humate (KH), at concentrations exerting a strong inhibitory effect on the formation of N-methyl-N-nitrosourea (MNU) when present during the nitrosation of N-methylurea (MU) at pH 3, did not reduce the mutagenicity of preformed MNU in Tradescantia, clone 4430. The inhibitory effect of 20 mg/ml KH corresponds approximately(More)
Nitrosation of the carbamate insecticide propoxur at pH 3 and 37 degrees C was determined colorimetrically and found to be time- and sodium nitrite concentration-dependent. Nitrosated propoxur was mutagenic when exposed to the seeds of the higher plant Arabidopsis thaliana but the formation of nitrosopropoxur, the presumed mutagen, was inhibited by humic(More)
The data are analyzed on the bilateral asymmetry of the number of dorsal and scutellar chaeta observed under the action of methotrexate in Drosophila of wild strain. It was shown that the incidence of asymmetric specimens induced by methotrexate was abruptly increased as compared to the control. The asymmetry was found to have a statistically significant(More)
Fractions of humic acids (HA-K+) of molecular mass between 500 and 300 000 and exceeding 300 000 showed a very high nitrite depleting ability, whereas the fraction of HA-K+ with molecular mass lower than 500 had little or no such effect. Autoclaving HA-K+ (121 °C, 20 min) decreased the nitrite-depleting ability to about a half. This observation correlates(More)
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