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Mutagenicity and DNA adduct formation of nitrodibenzopyranone isomers
228 mutation site between NMU and NBU showed that the length of alkyl chain changed the selectivity of mutated sites.
genesis is not simple; we should consider other factors such as the position ofDNA adduct formation and cell proliferation.
84 Arimochi, H., T. Kinouchi, K. Kataoka, Y. Ohnishi, Department of Bacteriology, School of Medicine, The University of Tokushima, 3-18-15, Kuramoto, Tokushima, Tokushima 770, Japan
85 Watanabe, T. a'b, M. Kohan b, L. Ball c, T. Hirayama", J. Lewtas b, ~Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607, Japan, ~U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA, CUniversity of North Carolina, Chapel Hill, NC 27599, USA
Analysis of DNA adduets formed in target and non-target organs of animals treated with 1-nitropyrene The tumorigenic response of animals treated with 1-nitropyrene (l-NP) depends on their age, sex, organ, strain and species. To elucidate the relationship between tumorigenicity and DNA adduct levels, we administered I-NP to rats and mice according to established protocols used in the l-NP-induced carcinogenesis experiments. DNA was extracted l¥om target and non-target organs of each animal 24 h after the last injection and adduct levels were assayed by the 32p_postlabeling method. In target organs except for those of A / J mice, two major adducts, N-(deoxyguanosin-8-yl)-l-aminopyrene (dG-C8-AP), a DNA adduct of a reduced metabolite of I-NP, and an unidentified adduct, were detected. The levels of both adducts in the target organs such as the injection site and the mammary gland of female CD rats and the liver of the male CD-I mouse were significantly higher than those in nontarget organs such as the liver of the female CD rat, the lung of the male CD-1 mouse and the liver and lung of the male B6C3FI mouse. The level of the unidentified adduct in the liver of the male CD-I mouse was significantly higher than that in the livers of female CD-I and B6C3FI mice, where it is a non-target organ, while the level of the dG-C8-AP adduct was lower in the male CD-I mouse livers than in the female CD-I and B6C3FI mouse cases. These results suggest that the unidentified adduct is more important for l-NP-induced carcinogenesis in these animals. However, the unidentified DNA adduct was not detected in target organs in the A / J mouse, and differences in adduct levels between target and non-target organs were not consistent. Therefore the mechanism of 1-NP-induced carcino-
Mutagenicity and DNA adduct formation of nitrodibenzopyranone isomers The mutagenicity of 2-, 3- and 4-nitro-6H-dibenzo[b,d]pyran-6-one (NDBP) isomers was investigated in Salmonella tester strains by an Ames plateincorporation (PI) and a microsuspension (MS) assays. All of the NDBPs were mutagenic in every strain in both assays. In the absence of $9 mix, TA98 was the strain most sensitive to the mutagenicity of NDBPs. The activity of NDBPs was reduced in TA98NR and TA98/1,8-DNP 6 strains relative to TA98. Mutagenic potency of NDBPs in TA98 without $9 mix in the MS assay (2-NDBP 104300 rev.//zg, 3-NDBP 23500 rev./ktg, and 4-NDBP 15 300 rev.//~g) was much higher than that in the P1 assay (2-NDBP 38 rev./p~g, 3-NDBP 162 rev.//~g, and 4-NDBP 7 rev.//zg). Although additional $9 mix increased the mutagenicity of NDBPs in the PI assay, the mutagenic potency of NDBPs in the MS assay using strain TA98 and TAI00 was decreased by the addition of $9 mix. DNA adduct formation with NDBPs was investigated using a calf thymus DNA in vitro system with either $9 or xanthine oxidase (XO) activation. DNA adducts were analyzed by 32P-postlabeling. All of the NDBPs formed DNA adducts with XO activation, and most of the adducts observed by butanol extraction were nuclease PI sensitive suggesting C8 guanine adducts. In the presence of high concentration $9 mix, only 3-NDBP formed DNA adducts that were nuclease P1 resistant. The chromatographic differences suggest that the DNA adducts formed from nitro-reduction by XO are different from the $9 activated DNA adducts.
genesis is not simple; we should consider other factors such as the position ofDNA adduct formation and cell proliferation.
84 Arimochi, H., T. Kinouchi, K. Kataoka, Y. Ohnishi, Department of Bacteriology, School of Medicine, The University of Tokushima, 3-18-15, Kuramoto, Tokushima, Tokushima 770, Japan
85 Watanabe, T. a'b, M. Kohan b, L. Ball c, T. Hirayama", J. Lewtas b, ~Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607, Japan, ~U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA, CUniversity of North Carolina, Chapel Hill, NC 27599, USA
Analysis of DNA adduets formed in target and non-target organs of animals treated with 1-nitropyrene The tumorigenic response of animals treated with 1-nitropyrene (l-NP) depends on their age, sex, organ, strain and species. To elucidate the relationship between tumorigenicity and DNA adduct levels, we administered I-NP to rats and mice according to established protocols used in the l-NP-induced carcinogenesis experiments. DNA was extracted l¥om target and non-target organs of each animal 24 h after the last injection and adduct levels were assayed by the 32p_postlabeling method. In target organs except for those of A / J mice, two major adducts, N-(deoxyguanosin-8-yl)-l-aminopyrene (dG-C8-AP), a DNA adduct of a reduced metabolite of I-NP, and an unidentified adduct, were detected. The levels of both adducts in the target organs such as the injection site and the mammary gland of female CD rats and the liver of the male CD-I mouse were significantly higher than those in nontarget organs such as the liver of the female CD rat, the lung of the male CD-1 mouse and the liver and lung of the male B6C3FI mouse. The level of the unidentified adduct in the liver of the male CD-I mouse was significantly higher than that in the livers of female CD-I and B6C3FI mice, where it is a non-target organ, while the level of the dG-C8-AP adduct was lower in the male CD-I mouse livers than in the female CD-I and B6C3FI mouse cases. These results suggest that the unidentified adduct is more important for l-NP-induced carcinogenesis in these animals. However, the unidentified DNA adduct was not detected in target organs in the A / J mouse, and differences in adduct levels between target and non-target organs were not consistent. Therefore the mechanism of 1-NP-induced carcino-
Mutagenicity and DNA adduct formation of nitrodibenzopyranone isomers The mutagenicity of 2-, 3- and 4-nitro-6H-dibenzo[b,d]pyran-6-one (NDBP) isomers was investigated in Salmonella tester strains by an Ames plateincorporation (PI) and a microsuspension (MS) assays. All of the NDBPs were mutagenic in every strain in both assays. In the absence of $9 mix, TA98 was the strain most sensitive to the mutagenicity of NDBPs. The activity of NDBPs was reduced in TA98NR and TA98/1,8-DNP 6 strains relative to TA98. Mutagenic potency of NDBPs in TA98 without $9 mix in the MS assay (2-NDBP 104300 rev.//zg, 3-NDBP 23500 rev./ktg, and 4-NDBP 15 300 rev.//~g) was much higher than that in the P1 assay (2-NDBP 38 rev./p~g, 3-NDBP 162 rev.//~g, and 4-NDBP 7 rev.//zg). Although additional $9 mix increased the mutagenicity of NDBPs in the PI assay, the mutagenic potency of NDBPs in the MS assay using strain TA98 and TAI00 was decreased by the addition of $9 mix. DNA adduct formation with NDBPs was investigated using a calf thymus DNA in vitro system with either $9 or xanthine oxidase (XO) activation. DNA adducts were analyzed by 32P-postlabeling. All of the NDBPs formed DNA adducts with XO activation, and most of the adducts observed by butanol extraction were nuclease PI sensitive suggesting C8 guanine adducts. In the presence of high concentration $9 mix, only 3-NDBP formed DNA adducts that were nuclease P1 resistant. The chromatographic differences suggest that the DNA adducts formed from nitro-reduction by XO are different from the $9 activated DNA adducts.