A sensitive umu test system for the detection of mutagenic nitroarenes in Salmonella typhimurium NM1011 having a high nitroreductase activity.
A sensitive umu test system for the detection of mutagenic nitroarenes has been developed using a new tester strain Salmonella typhimurium NM1011 having a high nitroreductase activity. The new strain was constructed by subcloning the bacterial nitroreductase gene into a plasmid pACYC184 and introducing the plasmid into the original strain S. typhimurium TA1535/pSK1002 harboring a fusion gene umuC'-'lacZ (pSK1002). Thus, the tester strain enabled us to monitor the genotoxic activities of various nitroarene compounds by measuring the beta-galactosidase activity in the cells. The sensitivity of strain NM1011 was compared with that of the parent tester strain S. typhimurium TA1535/pSK1002 or a nitroreductase-deficient strain S. typhimurium NM1000 with respect to the induction of umuC gene expression by 17 mutagenic nitroarenes. The newly developed strain with high nitroreductase activity had about 3 times higher nitrofurazone-reductase activity than the parent strain and was highly sensitive to the compounds 2-nitrofluorene, 1-nitronaphthalene, 2-nitronaphthalene, 1-nitropyrene, m-dinitrobenzene, 4,4'-dinitrobiphenyl, 3-nitrofluoranthene, 3,7-dinitrofluoranthene, 3,9-dinitrofluoranthene, 5-nitroacenaphthene and 2,4-dinitrotoluene. By contrast, the enzyme-deficient strain did not show any considerable response to 2-nitrofluorene, m-dinitrobenzene, 1-nitronaphthalene, 2-nitronaphthalene, 1-nitropyrene, 4,4'-dinitrobiphenyl, 3-nitrofluoranthene, 3,7-dinitrofluoranthene, 2,4-dinitrotoluene and 5-nitroacenaphthene. These results suggest that the newly developed tester strain with high nitroreductase activity is very useful for the detection of potent mutagenic nitroarene compounds.
Oda
Y
Y
Osaka Prefectural Institute of Public Health, Japan.
Shimada
T
T
Watanabe
M
M
Ishidate
M
M
Nohmi
T
T
D003001:Cloning, Molecular; D015245:Deoxyribonuclease BamHI / Q000378:metabolism; D005798:Genes, Bacterial; D009152:Mutagenicity Tests; D009574:Nitro Compounds / Q000633:toxicity*; D009601:Nitroreductases / Q000235:genetics / Q000378:metabolism*; D013014:SOS Response, Genetics / Q000235:genetics; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D012680:Sensitivity and Specificity
D009574:Nitro Compounds; D009601:Nitroreductases; D015245:Deoxyribonuclease BamHI