['346', '1983,', '1985).', 'In', 'fact,', 'the', 'TA98/1,8-DNP,', 'strain.', 'which', 'is', 'deficient', 'in', 'OAT,', 'is', 'not', 'susceptible', 'to', 'the', 'mutagenic', 'action', 'of', '2-hydroxy-AF', '(McCoy', 'et', 'al.,', '1933).', 'OAT', 'has', 'been', 'partially', 'purified', 'from', 'the', 'extracts', 'of', 'S.', 'typhimurium', 'TA98', 'and', 'was', 'shown', 'to', 'have', 'a', 'broad', 'substrate', 'specificity', 'to', 'various', 'mutagenic', 'N-hydroxyarylamines', 'such', 'as', '2-hy-', 'droxy-AF', 'and', 'N-hydroxy-Glu-P-1', '(Saito', 'et', 'al,', '1985).', 'The', 'enzyme', 'has', 'both', 'OAT', 'and', 'NAT', 'actiy-', 'ity', 'but', 'has', 'no', 'N,O-acetyltransferase', 'activities.', 'We', 'have', 'cloned', 'the', 'OAT', 'gene', 'of', 'S.', 'typhimurium', 'TA1538', 'into', 'plasmid', 'pBR322', 'by', 'screening', 'the', 'cloned', 'gene', 'which', 'increases', 'the', 'kill-', 'ing', 'and', 'mutagenic', 'sensitivity', 'of', 'the', 'host', 'strain,', 'TA1538/1,8-DNP,', 'to', '2-NF.', 'The', 'strains', 'harboring', 'the', 'plasmids', 'carrying', 'the', 'gene', 'had', 'about', '50', 'times', 'higher', 'N-hydroxy-Glu-P-1', 'OAT', 'activity', 'and', 'iso-', 'niazid', 'NAT', 'activity', 'than', 'did', 'the', 'control', 'strain', '(Table', '2).', 'The', 'high', 'level', 'of', 'enzyme', 'activity', 'is', 'probably', 'due', 'to', 'gene', 'dosage', 'effects', 'of', 'the', 'cloned', 'gene', 'on', 'multicopy', 'plasmids.', 'We', 'have', 'subcloned', 'the', 'gene', 'into', 'the', 'Scal', 'site', 'of', 'another', 'pBR322', 'plasmid', 'and', 'transformed', 'the', 'pKM101-containing', 'strains', 'TA98', 'and', 'TA100', 'with', 'the', 'subcloned', 'plasmid.', 'The', 'TA98', 'and', 'TA100', 'strains', 'were', 'cho-', 'sen', 'because', 'they', 'are', 'the', 'most', 'widely', 'used', 'for', 'bacterial', 'mutagenicity', 'tests', 'and', 'also', 'because', 'the', 'possession', 'of', 'the', 'pKM101', 'plasmid', 'is', 'absolutely', 'required', 'for', 'detecting', 'the', 'mutagenicity', 'of', 'some', 'nitroarenes', 'such', 'as', 'l-nitronaphthalene', 'and', '5-', 'nitroguinoline', '(Karpinsky', 'et', 'al.,', '1982;', 'Scribner', 'et', 'al.', '1979).', 'The', 'resulting', 'transformants,', 'YG1024', 'and', 'YG1029,', 'had', 'about', '100', 'times', 'higher', 'N-hy-', 'droxy-Glu-P-1', 'OAT', 'activity', 'and', 'isoniazid', 'NAT', 'activity', 'than', 'did', 'the', 'control', 'strain', 'and', 'were', 'ex-', 'tremely', 'sensitive', 'to', 'the', 'mutagenic', 'actions', 'of', 'typi-', 'cal', 'arylhydroxylamines,', 'nitroarenes', 'and', 'aromatic', 'amines', '(Table', '3).', 'Of', 'the', '10', 'chemicals', 'tested,', 'only', '4-NQO', 'was', 'an', 'exception', 'in', 'that', 'neither', 'YG1024', 'nor', 'YG1029', 'was', 'more', 'sensitive', 'to', 'this', 'chemical', 'than', 'were', 'their', 'control', 'strains.', 'It', 'is', 'reported', 'that', '4-hydroxyquinoline', 'l-oxide,', 'the', 'N-hydroxy', 'de-', 'rivative', 'of', '4-NQO,', 'is', 'activated', 'by', 't-RNA', 'syn-', 'thetase', 'in', 'Escherichia', 'coli', 'to', 'covalently', 'modify', 'DNA', '(Tada', 'and', 'Tada.', '1975).', 'We', 'have', 'previously', 'established', 'derivatives', 'of', 'TA98', 'and', 'TA100,', 'i.e,', 'YG1021', 'and', 'YG1026,', 'both', 'of', 'which', 'possess', 'elevated', 'nitroreductase', 'levels', '(Watanabe', 'et', 'al,', '1989).', 'YG1021', 'and', 'YG1026', 'are', 'highly', 'sensitive', 'in', 'detecting', 'the', 'mutagenicity', 'of', '2-NF,', '1-NP', 'and', '2-NN', 'but', 'are', 'not', 'sensitive', 'to', 'the', 'mutagenic', 'actions', 'of', '1,8-DNP', 'and', '4-NQO.', 'Since', 'the', 'nitroreductase', 'does', 'not', 'participate', 'in', 'the', 'metabolic', 'activation', 'of', 'aromatic', 'amines,', 'these', 'strains', 'should', 'be', 'insensitive', 'to', 'the', 'mutagenic', 'aromatic', 'amines.', 'On', 'the', 'other', 'hand,', 'the', 'OAT-', 'overproducing', 'derivatives', 'YG1024', 'and', 'YG1029', 'were', 'very', 'sensitive', 'not', 'only', 'to', '2-NF,', '1-NP', 'and', '2-NN', 'but', 'also', 'to', '1,8-DNP', 'and', 'to', 'the', 'aromatic', 'amines,', '2-AF.', 'Glu-P-1', 'and', '2-AA.', 'Thus,', 'YG1024', 'and', 'YG1029', 'are', 'more', 'suitable', 'for', 'general', 'moni-', 'toring', 'of', 'the', 'mutagenic', 'nitroarenes', 'and', 'aromatic', 'amines', 'than', 'YG1021', 'and', 'YG1026.', 'We', 'recommend', 'the', 'use', 'of', 'these', 'newly', 'estab-', 'lished', 'derivatives,', 'YG1024', 'and', 'YG1029,', 'for', 'the', 'following', 'purposes.', '(1)', 'Sensitive', 'detection', 'of', 'mutagenic', 'nitroarenes', 'and', 'aromatic', 'amines.', 'The', 'mutagenic', 'nitroarenes', 'and', 'aromatic', 'amines', 'such', 'as', '1-NP,', '1,8-DNP', 'and', 'Glu-P-1', 'are', 'widely', 'distrib-', 'uted', 'in', 'the', 'environment.', 'The', 'strains', 'are', 'suitable', 'for', 'sensitive', 'monitoring', 'of', 'the', 'mutagenicity', 'of', 'these', 'compounds,', 'particularly', 'in', 'complex', 'mix-', 'tures', 'such', 'as', 'dietary', 'components', 'or', 'vehicle', 'ex-', 'haust.', 'In', 'fact,', 'YG1024', 'was', 'far', 'more', 'sensitive', 'to', 'the', 'mutagenicity', 'of', 'smokers’', 'urine', '(P.', 'Einisté,', 'personal', 'communication)', 'or', 'to', 'the', 'mutagenicity', 'of', 'condensates', 'of', 'river', 'water', '(K.', 'Nakamuro,', 'per-', 'sonal', 'communication)', 'than', 'was', 'TA98.', '(2)', 'Sensi-', 'tive', 'detection', 'of', 'mutagenic', 'metabolites', 'derived', 'from', 'nitroarenes', 'or', 'aromatic', 'amines,', 'and', 'to', 'ascer-', 'tain', 'the', 'possible', 'mechanism', 'by', 'which', 'the', 'muta-', 'gens', 'are', 'activated.', 'Josephy', 'et', 'al.', '(1989)', 'have', 'used', 'YG1006', '(=', 'TA1538/1,8-DNP(pYG121))', 'for', 'the', 'demonstration', 'of', 'prostaglandin', 'H_', 'synthase-de-', 'pendent', 'activation', 'of', 'benzidine.', 'YG1006', 'was', 'much', 'more', 'sensitive', 'to', 'benzidine', 'than', 'any', 'other', 'previous', 'tester', 'strain,', 'following', 'metabolism', 'of', 'the', 'aromatic', 'amine', 'by', 'hamster', 'hepatic', 'S9,', 'ram', 'semi-', 'nal', 'vesicle', 'microsomal', 'preparation', 'or', 'purified', 'prostaglandin', 'H', 'synthase.', '(3)', 'Primary', 'identifica-', 'tion', 'of', 'mutagenic', 'principles', 'of', 'complex', 'mixtures', 'which', 'are', 'mutagenic', 'towards', 'S.', 'yphimurium,', 'We', 'recommend', 'the', 'use', 'of', 'the', 'sensitive', 'strains', 'with', 'the', 'standard', 'strains', '(TA98', 'and', 'TA100)', 'and', 'the', 'resistant', 'strains', '(TA98/1,8-DNP,', 'and', 'TA100/', '1,8-DNP).', 'If', 'the', 'mixtures', 'contain', 'nitro-contain-', 'ing', 'chemicals', 'or', 'aromatic', 'amines', 'which', 'are', 'activated', 'by', 'OAT,', 'they', 'will', 'show', 'different', 'muta-', ' ', 'TEEEDVTECO?']