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Comparative investigations with different bacterial strains
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33 Y. Agnet, J.L. Dorange and P. Dupuy, Station de Technologic des Produits V6g6taux, Dijon (France) Mutagenicity of peracetic acid on Salmonella typhimurium The mutagenicity of peracetic acid (PAA) on Salmonella typhimurium has been studied with hydrogen peroxide (HP) as a reference mutagen. The type of induced mutation has been identified by the spot test method performed for the selection of point, frameshift and deletion mutants. The mutagenicities of both peroxides have been compared on the forward marker (resistance to ethionine) the mutagenesis being performed either on the plate or in a liquid buffer. It comes o u t of this study that both PAA and HP induce mainly deletions, HP being more efficient than PAA. For the lower concentrations, cells are protected against these peroxides by superoxide dismutase and catalase. The 500 fold ratio between the concentrations of HP and PAA producing a similar biological effect indicates that cells are more efficiently protected against HP. This is likely due to the fact that PAA is decomposed via a 02radicals liberation : these radicals have to be converted by superoxide dismutase into HP which is further decomposed by catalase. Once the cell protection is overcome (5 g/1 HP, 20 mg/1 PAA) the differences in the survival suggest that induced genetic damage by HP would be partly repaired whereas the one induced by PAA would not. According to its chemical structure, PAA is able to link itself to DNA whereas HP is not. This property is proposed as an hypothesis to explain the differences of mutagenicity between PAA and HP and further between organic peroxides which have been tested up to now. Nevertheless, whatever may happen after the induction of a DNA damage, the observed mutagenicity of HP exceeds that of PAA.
34 G. RShrborn and U. Buckel, Institut ffir Humangenetik und Anthropologie, DiSsseldorf (Federal Republic of Germany} Further investigations on frequency of chromosome aberrations in bone marrow cells of Chinese hamsters after cyclophosphamide or caffeine or cyclophosphamide and caffeine treatment In our investigations we checked the question whether caffeine may act synergistically with alkylating agents such as cyclophosphamide. Four experimental series were performed: t w o with caffeine alone (dose 200 mg/kg and 35 mg/ kg), another one with cyclophosphamide alone {dose 40 mg/kg), and a third and fourth one with caffeine plus cyclophosphamide (dose 200 mg/kg + 40 mg/ kg and 35 mg/kg + 40 mg/kg respectively} at the same time. Chromosome preparations of bone marrow cells were made 6 and 24 h after the second treatment (application interval 24 h). Caffeine alone was not mutagenic. It increased, however, the high mutagen-
33 Y. Agnet, J.L. Dorange and P. Dupuy, Station de Technologic des Produits V6g6taux, Dijon (France) Mutagenicity of peracetic acid on Salmonella typhimurium The mutagenicity of peracetic acid (PAA) on Salmonella typhimurium has been studied with hydrogen peroxide (HP) as a reference mutagen. The type of induced mutation has been identified by the spot test method performed for the selection of point, frameshift and deletion mutants. The mutagenicities of both peroxides have been compared on the forward marker (resistance to ethionine) the mutagenesis being performed either on the plate or in a liquid buffer. It comes o u t of this study that both PAA and HP induce mainly deletions, HP being more efficient than PAA. For the lower concentrations, cells are protected against these peroxides by superoxide dismutase and catalase. The 500 fold ratio between the concentrations of HP and PAA producing a similar biological effect indicates that cells are more efficiently protected against HP. This is likely due to the fact that PAA is decomposed via a 02radicals liberation : these radicals have to be converted by superoxide dismutase into HP which is further decomposed by catalase. Once the cell protection is overcome (5 g/1 HP, 20 mg/1 PAA) the differences in the survival suggest that induced genetic damage by HP would be partly repaired whereas the one induced by PAA would not. According to its chemical structure, PAA is able to link itself to DNA whereas HP is not. This property is proposed as an hypothesis to explain the differences of mutagenicity between PAA and HP and further between organic peroxides which have been tested up to now. Nevertheless, whatever may happen after the induction of a DNA damage, the observed mutagenicity of HP exceeds that of PAA.
34 G. RShrborn and U. Buckel, Institut ffir Humangenetik und Anthropologie, DiSsseldorf (Federal Republic of Germany} Further investigations on frequency of chromosome aberrations in bone marrow cells of Chinese hamsters after cyclophosphamide or caffeine or cyclophosphamide and caffeine treatment In our investigations we checked the question whether caffeine may act synergistically with alkylating agents such as cyclophosphamide. Four experimental series were performed: t w o with caffeine alone (dose 200 mg/kg and 35 mg/ kg), another one with cyclophosphamide alone {dose 40 mg/kg), and a third and fourth one with caffeine plus cyclophosphamide (dose 200 mg/kg + 40 mg/ kg and 35 mg/kg + 40 mg/kg respectively} at the same time. Chromosome preparations of bone marrow cells were made 6 and 24 h after the second treatment (application interval 24 h). Caffeine alone was not mutagenic. It increased, however, the high mutagen-