7177-16-3P AID: 2112 | 15/05/2013
RID: 2498 | 14/06/2013The liver extract was added to each sample because sometimes compounds only become mutagenic when processed by the enzymes in the vertebrate liver. So, although the exposure to these compounds in humans may cause cancer, they would not give a positive result in a bacterial mutation assay.
Ames found that there is strong correlation between the ability of compounds to cause cancer and their ability to cause mutations. He said that the measurement of mutation rates in bacterial systems would be an effective model for evaluating the mutagenicity of compounds as a first level of detection of potential carcinogens.
It became clear that not all carcinogens were themselves mutagenic. Rather, some carcinogens' metabolites produced in the body are mutagenic agents.
Typically these metabolites are produced in the liver and the enzymatic reactions that convert the carcinogen into the bioactive metabolites did not take place in bacteria.