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D7 strain of Saccharomyces cerevisiae: a sensitive tool for genetic risk detection
207 II.1A.2 Bronzetti, G., C. Bauer, C. Corsi, E. Cundari, R. Del Carratore, M. Paolini, R. Nieri and G. Cantelli-Forti 1, Istituto di Mutagenesi e Differenziamento del CNR, via Svezia 10, 56100-Pisa, and i Istituto di Farmacologia, Universith, Via Irnerio 38, Bologna (Italy) D7 strain of Saccharomyces cerevisia~ a sensitive tool for genetic risk detection
The diploid strain D7 of Saccharomyces cerevisiae allows to determine simultaneously 3 genetic effects: mitotic crossing-over, mitotic gene conversion and point (reverse) mutation. The genetic activity on this tester strain of ultraviolet radiation (UV), chlorinated ethylenes (1,1-dichloroethylene, 1,2-dichloroethylene cis and trans, trichloroethylene and perchloroethylene), icanthone, ethyl methanesulfonate (EMS), nitrous acid, Pr toxin, 3,4-epoxycycloexene was examined both "in vitro" and " in vivo" and the results were plotted. The purpose of this work was to determine the relation between molecular structure and activity of the genotoxic potency of this series of compounds through the comparison of the 3 genetic effects induced. UV and HNO 2 showed the highest potency in comparison with the other compounds examined. In addition these compounds and UV induced mitotic gene conversion and cross-over more actively than point reverse mutation. 1,1-Dichloroethylene was the most active of the chlorinated compounds examined. Research supportedjointlyby Italian MPI and CNR (ContractNos. 82.02119.56 and 520/83/8209326).
II.1A.3 De Flora, S., P. Zanacchi, A. Camoirano, C. Bennicelli and G.S. Badolati, Institute of Hygiene, University of Genoa, 16132-Genoa (Italy) A bacterial DNA-repair assay yielding a 6-billion-fold range of genotoxic potency
A simple and rapid liquid micromethod procedure was used in order to assess, both with and without $9 mix, the minimum inhibitory concentration (MIC) of 150 compounds of various chemical classes or complex mixtures in E. coli strains WP2 (repair-proficient), WP67 (uvrA- polA-) and CM871 (uvrArecA- lexA-). The genotoxic potency was calculated by relating the difference and ratio of MICs in repair-proficient and -deficient bacteria to nmoles of compounds. The same compounds were also assayed in the Ames reversion test with S. thyphimurium TA1535, TA1537, TA1538, TA98, TA100 and partly TA97. The results were overlapping in the 2 tests for 96 chemicals (71.1%) (59 positive and 37 negative). 9 compounds (6.7%) were detected only in the reversion test and 30 (18.3% of organics and 38.5% of inorganics) only in the DNA-repair test, half of them undergoing a complete loss of activity in the presence of $9 mix. With very few exceptions, CM871 was considerably more sensitive than WP67. Some of the compounds damaging E. coli DNA but negative for the above 5 Salmonella strains were found later to revert TA97 or TA102. Although the experimental protocol intentionally included a number of nonmutagenic carcinogens or noncarcinogenic mutagens, the overall accuracy was 65.3% in the reversion test and 72.0% in the DNA-repair test. The genotoxic potency varied over a 4.4 × 107-fold range in the Ames test and over a 6 × 109-fold range in the DNA-repair test, with a significant correlation between potencies within the majority of chemical classes. As also confirmed by assaying complex mixtures, the 2 bacterial
The diploid strain D7 of Saccharomyces cerevisiae allows to determine simultaneously 3 genetic effects: mitotic crossing-over, mitotic gene conversion and point (reverse) mutation. The genetic activity on this tester strain of ultraviolet radiation (UV), chlorinated ethylenes (1,1-dichloroethylene, 1,2-dichloroethylene cis and trans, trichloroethylene and perchloroethylene), icanthone, ethyl methanesulfonate (EMS), nitrous acid, Pr toxin, 3,4-epoxycycloexene was examined both "in vitro" and " in vivo" and the results were plotted. The purpose of this work was to determine the relation between molecular structure and activity of the genotoxic potency of this series of compounds through the comparison of the 3 genetic effects induced. UV and HNO 2 showed the highest potency in comparison with the other compounds examined. In addition these compounds and UV induced mitotic gene conversion and cross-over more actively than point reverse mutation. 1,1-Dichloroethylene was the most active of the chlorinated compounds examined. Research supportedjointlyby Italian MPI and CNR (ContractNos. 82.02119.56 and 520/83/8209326).
II.1A.3 De Flora, S., P. Zanacchi, A. Camoirano, C. Bennicelli and G.S. Badolati, Institute of Hygiene, University of Genoa, 16132-Genoa (Italy) A bacterial DNA-repair assay yielding a 6-billion-fold range of genotoxic potency
A simple and rapid liquid micromethod procedure was used in order to assess, both with and without $9 mix, the minimum inhibitory concentration (MIC) of 150 compounds of various chemical classes or complex mixtures in E. coli strains WP2 (repair-proficient), WP67 (uvrA- polA-) and CM871 (uvrArecA- lexA-). The genotoxic potency was calculated by relating the difference and ratio of MICs in repair-proficient and -deficient bacteria to nmoles of compounds. The same compounds were also assayed in the Ames reversion test with S. thyphimurium TA1535, TA1537, TA1538, TA98, TA100 and partly TA97. The results were overlapping in the 2 tests for 96 chemicals (71.1%) (59 positive and 37 negative). 9 compounds (6.7%) were detected only in the reversion test and 30 (18.3% of organics and 38.5% of inorganics) only in the DNA-repair test, half of them undergoing a complete loss of activity in the presence of $9 mix. With very few exceptions, CM871 was considerably more sensitive than WP67. Some of the compounds damaging E. coli DNA but negative for the above 5 Salmonella strains were found later to revert TA97 or TA102. Although the experimental protocol intentionally included a number of nonmutagenic carcinogens or noncarcinogenic mutagens, the overall accuracy was 65.3% in the reversion test and 72.0% in the DNA-repair test. The genotoxic potency varied over a 4.4 × 107-fold range in the Ames test and over a 6 × 109-fold range in the DNA-repair test, with a significant correlation between potencies within the majority of chemical classes. As also confirmed by assaying complex mixtures, the 2 bacterial