Development of new tester strains derived from E. coli WP2uvrA for the determination of mutational specificity.
We have developed a set of multipurpose tester strains (WP3101 to WP3106) derived from E. coli WP2uvrA for the detection and classification of mutagens. Six kinds of F' plasmid (lacI, lacZ, proAB+) in strains CC101-CC106, each of which carried a different lacZ allele, were transferred to a delta(lac-pro) derivative of WP2uvrA. Assays for transitions and transversions are based upon Lac+ reversion of a specific mutation located within the lacZ gene on an F' plasmid in strains WP3101-WP3106. In addition, the trpE65(ochre) allele in the same strains is available for Trp+ reversion assays. Using the new tester strains, we investigated the mutational specificities of various chemical mutagens. Base analog mutagens and alkylating mutagens induced specific types of base substitutions. G:C-->A:T transitions and G:C-->T:A transversions predominated in mutagenesis induced by 4-nitroquinoline 1-oxide. Only a slight increase in G:C-->T:A transversions was observed in cells treated with 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2), although the potent mutagenicity of AF-2 was detected in a concurrent Trp+ reversion assay in the same strain. Sodium azide, on the other hand, was negative in the Trp+ reversion assay but specifically induced G:C-->A:T transitions. Present finding suggested that target sites for AF-2- and azide-induced lesions may largely depend on sequence context.
Ohta
T
T
School of Life Science, Tokyo University of Pharmacy and Life Science, Japan. ohta@ls.toyaku.ac.jp
Watanabe-Akanuma
M
M
Tokishita
S
S
Shiga
Y
Y
Yamagata
H
H
D015112:4-Nitroquinoline-1-oxide / Q000633:toxicity; D001374:Azacitidine / Q000633:toxicity; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D007763:Lac Operon / Q000187:drug effects / Q000235:genetics; D009152:Mutagenicity Tests / Q000379:methods*; D010957:Plasmids / Q000187:drug effects* / Q000235:genetics; D017354:Point Mutation; D019810:Sodium Azide / Q000633:toxicity
D015112:4-Nitroquinoline-1-oxide; D019810:Sodium Azide; D001374:Azacitidine