Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using an O-acetyltransferase-overexpressing strain Salmonella typhimurium NM2009 we measured the activities for metabolic activation of several carcinogenic arylamines to genotoxic products by rat liver microsomal cytochrome P-450 enzymes, and compared them with the activities obtained in the original tester strain Salmonella typhimurium TA1535/pSK1002 or the O-acetyltransferase-defective strain Salmonella typhimurium NM2000. Since all of the tester strains had introduced the umuC'-'lacZ gene, we could detect the genotoxic activities by measuring bacterial beta-galactosidase activity resulting from the DNA damage. In the O-acetyltransferase-defective strain NM2000 most of the arylamines tested showed weak responses in inducing umu gene expression after metabolic activation by liver microsomes. The strain NM2009, on the other hand, was found to be highly sensitive towards a variety of aromatic amines, and these activities were greater than those seen in the original tester strain S. typhimurium TA1535/pSK1002. The chemicals which marked responses in strain NM2009 include 2-aminoanthracene, 6-aminochrysene, 2-aminofluorene, 2-acetylaminofluorene, 3-methoxy-4-aminoazobenzene, O-aminoazotoluene, Glu-P-1, Trp-P-2, A alpha C, MeA alpha C, MeIQ, MeIQx and IQ. Of these procarcinogens tested MeIQ, MeIQx and IQ also showed strong cytotoxic effects in S. typhimurium NM2009 after metabolic activation by liver microsomes. Only PhIP was the substrate showing similar responses in strains TA1535/pSK1002 and NM2009. The results with the reconstituted monooxygenase system containing purified cytochrome P-450 enzymes support the above findings obtained with the liver microsomal enzyme system. Thus, the usefulness of the newly developed strain NM2009 for the detection of reactive metabolites of several carcinogenic aromatic amines after metabolism by the liver microsomal cytochrome P-450-linked monooxygenase system has been ascertained.
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PMID:Use of a newly developed tester strain Salmonella typhimurium NM2009 for the study of metabolic activation of carcinogenic aromatic amines by rat liver microsomal cytochrome P-450 enzymes. 138 50

A highly sensitive umu test system for the detection of carcinogenic/mutagenic aromatic amines has been developed utilizing a new tester strain, Salmonella typhimurium NM2009, possessing an elevated O-acetyltransferase (O-AT) level. NM2009 was constructed by subcloning the bacterial O-AT gene into a plasmid vector pACYC184 and introducing the plasmid into the original strain S. typhimurium TA1535/pSK1002 harboring an umuC'-'lacZ fusion gene. The system is based on the ability of DNA-damaging agents (genotoxins) to induce umuC gene expression and monitored by measuring the cellular beta-galactosidase activity evoked by the fusion gene. Twenty-two aromatic amine compounds including arylamines, aminoazo dyes, and heterocyclic aromatic amines were tested for inducibility of DNA damage after metabolic activation by rat liver S9 in strain NM2009 and the sensitivity was compared with those of the parent strain TA1535/pSK1002 and the O-AT-defective strain NM2000. NM2009 had about 400 times higher O-AT activity than the parent strain. It was found that NM2009 was much more sensitive to aromatic amines than other strains to induce umuC gene expression after metabolic activation; the chemicals which were extremely sensitive in strain NM2009 include 2-aminoanthracene, 2-aminofluorene, 2-acetylaminofluorene, benzidine, 6-aminochrysene, 2,4-diaminotoluene, 2,6-diaminotoluene, 1-naphthylamine, o-tolidine, 3-MeO-AAB, o-aminoazotoluene, Glu-P-1, Trp-P-1, MeA alpha C, A alpha C, MeIQ, MeIQx, and IQ. In contrast, Trp-P-2 and PhIP showed almost similar sensitivities in three tester strains used in this study. These results suggest that strain NM2009 with high O-acetyltransferase activity is very useful to detect the genotoxic activities of potential mutagenic aromatic amine compounds, which require metabolic activation via the cytochrome P-450/acetyltransferase system.
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PMID:Development of high sensitive umu test system: rapid detection of genotoxicity of promutagenic aromatic amines by Salmonella typhimurium strain NM2009 possessing high O-acetyltransferase activity. 788 66

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 umuC'-'lacZ fusion gene. The induction of umuC gene expression could be monitored by measuring the cellular beta-galactosidase 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-overexpression 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/pSK1002 strain. Among six strains tested, NM3009 showed the highest sensitivity toward such chemicals as 1-nitronaphthalene, 2-nitrofluorene, 3,7-dinitrofluoranthene, 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 umuC 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.
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PMID:Highly sensitive umu test system for the detection of mutagenic nitroarenes in Salmonella typhimurium NM3009 having high O-acetyltransferase and nitroreductase activities. 849 Dec 15

Human NAT1 and NAT2 genes were subcloned into pACYC184 vector and the plasmids thus obtained were introduced into Salmonella typhimurium O-acetyltransferase-deficient strain NM6000 (TA1538/1, 8-DNP/pSK1002), establishing new strains NM6001 and NM6002, respectively. We compared the sensitivities of these two strains with those of NM6000 towards carcinogenic nitroarenes and aromatic amines in the SOS/umu response. The induction of umuC gene expression by these chemicals in the presence and absence of the S9 fraction was assayed by measuring the cellular beta-galactosidase activity expressed by the umuC"lacZ fusion gene in the tester strains. 2-Nitrofluorene and 2-aminofluorene induced umuC gene expression more strongly in the NM6001 strain than in the NM6002 strain. In contrast, induction of umuC gene expression by 1, 8-dinitropyrene, 6-aminochrysene and 2-amino-3,5-dimethylimidazo[4, 5-f]quinoline was weaker in the NM6001 strain than in the NM6002 strain. 1-Nitropyrene, 2-amino-6-methyl-dipyrido[1,2-a:3', 2'-d]imidazole, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole, 3-amino-1-methyl-5H-pyrido[4,3-b]indole, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and 2-amino-3-methyl-9H-pyrido[2,3-b]indole were found to induce umuC gene expression at similar extents in both strains. These results suggest that the newly developed strains can be employed for the studies on mechanisms of genotoxicity of a variety of nitroarenes and aromatic amines, along with the assessment of cancer risk to humans.
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PMID:Role of human N-acetyltransferases, NAT1 or NAT2, in genotoxicity of nitroarenes and aromatic amines in Salmonella typhimurium NM6001 and NM6002. 1035 91

In the present study, we developed a rapid umu-microplate test system that uses the nitroreductase- and O-acetyltransferase-overproducing Salmonella typhimurium strain NM3009 and the O-acetyltransferase-overproducing S. typhimurium strain NM2009 to detect genotoxic activity in small volume samples. The assay was used to test the genotoxicity of several standard mutagens and environmental samples. Exponentially growing cultures of NM3009, NM2009, and the parental strain TA1535/pSK1002 were incubated in 96-well microplates with test chemicals both in the presence and in the absence of rat liver S9. The relative beta-galactosidase activities were then determined colorimetrically using either chlorophenol red-beta-D-galactopyranoside (CPRG) or O-nitrophenyl-beta-D-galactopyranoside (ONPG) as a measure of umuC gene induction activity. The sensitivities of NM3009 without S9 mix and NM2009 with S9 mix to nitroarenes and aromatic amines were up to 24- to 75-fold higher than those of the parent strain. Induction of umuC gene expression was detected more readily with CPRG than ONPG. The umu-microplate assay also detected genotoxicity in organic extracts of particulate matter from air samples collected in Osaka City, Japan. The pattern of the responses suggested that the genotoxic activity of the particulate extract was due primarily to nitrated polycyclic aromatic hydrocarbons. Our results indicate that the umu-microplate assay may be a useful way of carrying out rapid screens for genotoxicity in small-volume environmental samples.
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PMID:Use of a high-throughput umu-microplate test system for rapid detection of genotoxicity produced by mutagenic carcinogens and airborne particulate matter. 1474 41