title: A forward mutation assay using ampicillin-resistance in Escherichia coli designed for investigating the mutagenicity of biological samples.
abstract: The development of a bacterial mutation assay using forward mutation to ampicillin-resistance is described. It is a technically simple assay using Escherichia coli D494uvrB transformed with a multi-copy mutator plasmid pGW1700. Mutation is detected by an increase in the frequency of ampicillin-resistant colonies following treatment of bacteria with the test material during logarithmic growth. The determination of viable counts allows a correction factor to be applied to compensate for the effects of sample-induced growth enhancement or toxicity on the bacterial population. The assay has been tested with a range of reference mutagens. It is particularly sensitive to base-pair substitution mutagens, detecting these at doses equal to or less than those detected in the Salmonella/microsome assay or the SOS Chromotest. The assay also detects frameshift mutagens but with lower sensitivity than the Salmonella/microsome assay.
mesh_terms: D015112:4-Nitroquinoline-1-oxide / Q000494:pharmacology; D000668:Ampicillin Resistance / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D005020:Ethyl Methanesulfonate / Q000494:pharmacology; D009152:Mutagenicity Tests / Q000379:methods*; D009154:Mutation; D010957:Plasmids
chemical_list: D015112:4-Nitroquinoline-1-oxide; D005020:Ethyl Methanesulfonate