Journal Article

A new <i>Salmonella typhimurium</i> NM5004 strain expressing rat glutathione S-transferase 5–5: use in detection of genotoxicity of dihaloalkanes using an SOS/<i>umu</i> test system

Yoshimitsu Oda, Hiroshi Yamazaki, Ricarda Thier, Brian Ketterer, F.Peter Guengerich and Tsutomu Shimada

in Carcinogenesis

Volume 17, issue 2, pages 297-302
Published in print February 1996 | ISSN: 0143-3334
Published online February 1996 | e-ISSN: 1460-2180 | DOI: https://dx.doi.org/10.1093/carcin/17.2.297
A new Salmonella typhimurium NM5004 strain expressing rat glutathione S-transferase 5–5: use in detection of genotoxicity of dihaloalkanes using an SOS/umu test system

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The Escherichia coli mu operon was subcloned into a pKK233–2 vector containing rat glutathione S-transferase (GST) 5–5 cDNA and the plasmid thus obtained was introduced into Salmonella typhimurium TA1535. The newly developed strain S.typhimurium NM5004, was found to have 52-fold greater GST activity than the original umu strain S.typhimurium TA1535/pSK1002. We compared sensitivities of these two tester strains, NM5004 and TA1535/pSK1002, for induction of umuC gene expression with several dihaloalkanes which are activated or inactivated by GST 5–5 activity. The induction of umuC gene expression by these chemicals was monitored by measuring the cellular β-galactosidase activity produced by umuC'lacZ fusion gene in these two tester strains. Ethylene dibromide, 1-bromo-2-chloroethane, 1, 2-dichloroethane, and methylene dichloride induced umuC gene expression more strongly in the NM5004 strain than the original strain. 4-Nitro-quinoline 1-oxide and N-methyl-N'-nitro-N-nitrosoguanidine were found to induce umuC gene expression to similar extents in both strains. In the case of 1-nitropyrene and 2-nitrofluorene, however, NM5004 strain showed weaker umuC gene expression responses than the original TA1535/pSK1002 strain. 1,2-Epoxy-3-(4'-nitrophenoxy)propane, a known substrate for GST 5–5, was found to inhibit umuC induction caused by 1-bromo-2-chloroethane. These results indicate that this new tester NM5004 strain expressing a mammalian GST theta class enzyme may be useful for studies of environmental chemicals proposed to be activated or inactivated by GST activity.

Journal Article.  0 words. 

Subjects: Clinical Cytogenetics and Molecular Genetics

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