Isolation and characterization of an isogenic set of Salmonella typhimurium strains analogous to the "Ames" tester strains.
The standard Ames tester strains of Salmonella typhimurium contain a number of genetic differences at loci other than his. The fact that these strains contain independently isolated uvrB-bio-gal deletions and rfa mutations implies that these are likely to vary from strain to strain. Since the strains were isolated from different parental stocks of S. typhimurium LT-2, they differ in their ability to metabolize arabinose. Other, unknown differences may exist because the isolation of some of the strains involved ultraviolet and chemical mutagenesis. We have isolated a set of isogenic S. typhimurium strains that contain the relevant genetic markers of the standard Ames tester strains. These strains all contain the same uvrB-bio-gal deletion and the same rfa mutation; they differ only in the nature of their his mutations and in the presence or absence of the plasmid pKM101. We have assessed the responsiveness of these strains to a number of mutagens and conclude that their mutagenic specificities are the same as those of the corresponding Ames strains: TA98, TA100, TA1535, TA1537 and TA1538. Therefore, the specificity of the standard Ames strains with respect to these mutagens is a result solely of the differences in the nature of their his mutations and the effects of pKM101.
Popkin
D J
DJ
Genetic Toxicology Branch, Food and Drug Administration, Washington, DC 20204.
Davis
V M
VM
Prival
M J
MJ
D004305:Dose-Response Relationship, Drug; D005838:Genotype; D009152:Mutagenicity Tests / Q000379:methods*; D009153:Mutagens / Q000494:pharmacology; D010641:Phenotype; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics*
D009153:Mutagens