AMES TEST - Introduction - Greenquat BT

PRINCIPLE OF THE TEST
The identification of substances capable of inducing mutations is crucial for the assessment of their safety, because they could damage the DNA of germline cells and induce tumors. Gene mutations are easily identifiable in bacteria because they can cause changes in the growth of bacteria dependent on the nutrients needed for growth. The Ames test is widely used to identify compounds that are capable of inducing gene mutations.

The analysis involves the use of five Salmonella strains that present different types of mutations that make the bacteria unable to synthesize the amino-acid histidine and therefore are not able to grow on selective media that do not contain histidine. If the compound induces a mutation in these specific genes, the function of the affected gene can be reintroduced, allowing the cells to synthesize the histidine and to grow on the selective medium (reversion test).
Salmonella strains have different mutations in the various genes of histidine operon and they are designed to respond to mutagenic compounds acting through different mechanisms.

Many of the test strains have several features that make them more sensitive for the detection of mutations, including responsive DNA sequences at the reversions sites, increased cell permeability to large molecules and elimination of DNA repair systems or enhancement of error-prone DNA repair processes.