Contact person
Francisco Salva Serra
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Mutagenicity testing
Certain chemical compounds are mutagenic; they can alter DNA and lead to severe diseases like cancer. When working with novel substances, it is essential to assess their mutagenic potential. At RISE, we offer a simplified bacterial reverse mutation test (Ames test), which is a cost-effective initial screening assay to detect mutagenic compounds.
Aim
The purpose of the Ames test is to identify whether a substance has mutagenic potential, i.e. the ability to cause genetic changes. The test is used as a first step in the risk assessment of chemical compounds. By using specific bacterial strains, it is possible to quickly and cost-effectively detect the ability of substances to induce mutations.
Method
The bacterial reverse mutation test uses strains of Salmonella typhimurium and/or Escherichia coli to determine whether a compound is mutagenic. The strains carry specific point mutations that prevent them from synthetising an essential amino acid. As a result, they can only grow if that amino acid is present in the growth medium. The test detects reverse mutations that restore the bacteria’s ability to synthetise the amino acid. The revertant bacteria are detected by their ability to grow in medium lacking that amino acid.
At RISE, we offer a simplified version of the method described in the OECD Test Guideline No. 471 (Bacterial Reverse Mutation Test) of the OECD Guidelines for the Testing of Chemicals. This version uses two S. typhimurium strains: TA98, which carries a frameshift mutation, and TA100, which carries a base-pair substitution. Both mutations are in the histidine operon, making the strains unable to produce histidine.
The test involves exposing the strains to six concentrations of the test compound, both with and without a metabolic activator. The bacteria are then incubated in a histidine-free medium. A dose-dependent increase in the number of revertant colonies indicates that the compound is mutagenic under the test conditions.
Deliveries
Methods and results are presented in a written report.
