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Highly sensitive umu test system for the detection of mutagenic nitroarenes in Salmonella typhimurium NM3009 having high O‐acetyltransferase and nitroreductase activities
Author(s) -
Oda Yoshimitsu,
Yamazaki Hiroshi,
Watanabe Mosahiko,
Nohmi Takehiko,
Shimada Tsutomu
Publication year - 1993
Publication title -
environmental and molecular mutagenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1
H-Index - 87
eISSN - 1098-2280
pISSN - 0893-6692
DOI - 10.1002/em.2850210407
Subject(s) - acetyltransferase , strain (injury) , nitroreductase , plasmid , ames test , salmonella , chemistry , subcloning , gene , chloramphenicol acetyltransferase , enterobacteriaceae , microbiology and biotechnology , biology , gene expression , escherichia coli , bacteria , genetics , biochemistry , reporter gene , acetylation , anatomy
A highly sensitive umu test system for the detection of genotoxic activities of a variety of mutagenic nitroarenes has been developed using a new tester strain, Salmonella typhimurium NM3009 having high O‐acetyltransferase (O‐AT) and nitroreductase (NR) activities. The NM3009 was constructed by subcloning both the O‐AT and NR genes into plasmid vector pACYC184, and the resulting plasmid was introduced into the parent tester strain S. typhimurium TA1535/pSK1002 harboring an umu C‘‐’lac Z fusion gene. The induction of umu C gene expression could be monitored by measuring the cellular β‐galoctosidase activity produced by fusion gene. The purpose of the study was to evaluate whether the newly developed strain NM3009 is highly sensitive toward nitroarene compounds. The sensitivity of the strain NM3009 was compared with those of the parent TA1535/pSK1002 strain, the NR‐overexpressing strain NM1011, the NR‐deficient strain NM1000, the O‐AT‐over‐expressing strain NM2009, and the O‐AT‐defective strain NM2000. The newly developed NM3009 strain had about 13‐fold and 3‐fold higher activities for N ‐AT and NR, respectively, than the original S. typhimurium TA1535/pS1002 strain. Among six strains tested, NM3009 showed the highest sensitivity toward such chemicals as 1‐nitronaphthalene, 2‐nitrofluorene, 3,7‐dinitro‐fluoranthene, 3‐nitrofluoranthene, 5‐nitroacenaphthene, 2‐nitronaphthalene, 1‐nitropyrene, 1,6‐dinitropyrene, 3,9‐dinitrofluoranthene, 4,4′‐dinitrobiphenyl, 1,8‐dinitropyrene, m ‐dinitrobenzene, 2,4‐dinitrotoluene, and 1,3‐dinitropyrene. We have also found that the order of sensitivities to induce umu C gene expression toward a variety of nitroarenes was NM3009 > NM2009 > NM1011 > TA1535/pSK1002 > NM2000 > NM1000. These results suggest that the newly developed tester strain NM3009 is of great use for the detection of genotoxic activities of numerous carcinogenic and mutagenic chemicals including nitroarenes, which require NR and/or O‐AT for the activation. © 1993 Wiley‐Liss, Inc.