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Differential effect of β-naphthoflavone on promutagen activation capabilities of S9 from rat and mouse livers
236 II.2C.7 Rapir, V., and M. Latinovir, 'Boris Kidrir' Institute of Nuclear Sciences, 11000 Belgrade (Yugoslavia)
Differential effect of [3-naphthoflavone on promutagen activation capabilities of $9 from rat and mouse livers Since it was recommended to find a safe substitute for Aroclor as an inducer of liver metabolic activation system, we studied the promutagen activation by fl-naphthoflavone (NF) in two animal species. Male Wistar rats and C57BIL mice were i.p. treated with N F at a dose of 80 m g / k g 2 days before sacrifice. $9 liver fractions were used for activation of B[a]P and 2-AAF in S. typhimurium assay (TA97 and TA1538). Cytochrome P450, cytochrome b 5 and cytochrome c reductase were determined in microsomal fraction. The results of the Ames test show that N F pretreatment of both species increases metabolic transformation of B[a]P. In contrast, N F markedly inhibited activation of 2-AAF to mutagens when rat $9 was used, while mouse $9 highly enhanced 2-AAF mutagenesis. The same results were obtained when microsomal fractions were used instead of $9. The effects of N F on microsomal enzymes were the same in both species: content of cytochrome P450 and cytochrome b 5 increased while cytochrome c reductase activity slightly decreased. Although N F pretreatment results in enhancement of cytochrome P450 content in both species, metabolic transformation of 2-AAF is almost completely inhibited in Wistar rats.
II.2C.8 Wottawa, A., Institut for Biologie, Forschungszentrum Seibersdorf, A-2444 Seibersdorf (Austria)
Influence of ethanol as fuel component on genetic toxicity of gasoline exhaust Four different cars were operated simulating normal traffic conditions in several experiments. In each experiment exhaust was produced using normal gasoline as well as gasoline with addition of 5% (v/v) ethanol. Gases were absorbed in saline and DMSO and particles were collected on filter discs. In different short-term tests the genetic activities of the exhaust fractions obtained with and without addition of ethanol to the fuel were compared. The liquid fractions were strongly toxic to E. coli and Salmonella typhimurium and in higher dilutions only weak mutagenicity was detected in the Ames test. The particle fractions (dissolved in DMSO) were active in the Ames test, with 3 markers of E. coli 343/113, in the prophage induction test and suppressed semiconservative DNA synthesis of human fibroblasts. Influence on DNA repair was only weak and reproducibility was not satisfactory. In all experiments ethanol addition to the fuel reduced the genetic activity of the exhaust samples. II.2C.9 Hubbard, S.A., C.M. Hunt, T. McDonald and J.W. Bridges, Robens Institute of Industrial and Environmental Health and Safety, University of Surrey, Guildford, GU2 5XH, Surrey (Great Britain)
Factors influencing the mutagenic activity of benzola ]pyrene-coated alumina particles Simultaneous exposure to particles and chemically reactive vapours may result in binding or deposition of a chemical onto the particle surface. This may alter the biological activity of a particle if it is inhaled and
Differential effect of [3-naphthoflavone on promutagen activation capabilities of $9 from rat and mouse livers Since it was recommended to find a safe substitute for Aroclor as an inducer of liver metabolic activation system, we studied the promutagen activation by fl-naphthoflavone (NF) in two animal species. Male Wistar rats and C57BIL mice were i.p. treated with N F at a dose of 80 m g / k g 2 days before sacrifice. $9 liver fractions were used for activation of B[a]P and 2-AAF in S. typhimurium assay (TA97 and TA1538). Cytochrome P450, cytochrome b 5 and cytochrome c reductase were determined in microsomal fraction. The results of the Ames test show that N F pretreatment of both species increases metabolic transformation of B[a]P. In contrast, N F markedly inhibited activation of 2-AAF to mutagens when rat $9 was used, while mouse $9 highly enhanced 2-AAF mutagenesis. The same results were obtained when microsomal fractions were used instead of $9. The effects of N F on microsomal enzymes were the same in both species: content of cytochrome P450 and cytochrome b 5 increased while cytochrome c reductase activity slightly decreased. Although N F pretreatment results in enhancement of cytochrome P450 content in both species, metabolic transformation of 2-AAF is almost completely inhibited in Wistar rats.
II.2C.8 Wottawa, A., Institut for Biologie, Forschungszentrum Seibersdorf, A-2444 Seibersdorf (Austria)
Influence of ethanol as fuel component on genetic toxicity of gasoline exhaust Four different cars were operated simulating normal traffic conditions in several experiments. In each experiment exhaust was produced using normal gasoline as well as gasoline with addition of 5% (v/v) ethanol. Gases were absorbed in saline and DMSO and particles were collected on filter discs. In different short-term tests the genetic activities of the exhaust fractions obtained with and without addition of ethanol to the fuel were compared. The liquid fractions were strongly toxic to E. coli and Salmonella typhimurium and in higher dilutions only weak mutagenicity was detected in the Ames test. The particle fractions (dissolved in DMSO) were active in the Ames test, with 3 markers of E. coli 343/113, in the prophage induction test and suppressed semiconservative DNA synthesis of human fibroblasts. Influence on DNA repair was only weak and reproducibility was not satisfactory. In all experiments ethanol addition to the fuel reduced the genetic activity of the exhaust samples. II.2C.9 Hubbard, S.A., C.M. Hunt, T. McDonald and J.W. Bridges, Robens Institute of Industrial and Environmental Health and Safety, University of Surrey, Guildford, GU2 5XH, Surrey (Great Britain)
Factors influencing the mutagenic activity of benzola ]pyrene-coated alumina particles Simultaneous exposure to particles and chemically reactive vapours may result in binding or deposition of a chemical onto the particle surface. This may alter the biological activity of a particle if it is inhaled and