Final answer:
The Ames test uses a special strain of Salmonella to detect increased mutation rates caused by exposure to potential mutagens, indicating possible carcinogenic risks. It includes the use of rat liver extract to simulate human metabolism and provides a quicker, less costly alternative to animal testing.
Step-by-step explanation:
The Ames test is a biological assay utilized to evaluate the mutagenic potential of chemical compounds. Developed by Bruce Ames in the 1970s, this test has become a fundamental method for screening potential environmental mutagens, particularly those that may be carcinogenic. The core of this test involves a strain of Salmonella typhimurium that cannot produce the amino acid histidine due to a genetic mutation. When exposed to a potential mutagen, if the mutation rate increases, it may indicate carcinogenic risk since more bacteria would revert to being able to produce histidine on their own.
Including a rat liver extract in the assay simulates mammalian metabolism, which is critical since many compounds are not mutagenic until metabolized. The outcome leads to a comparison of the number of histidine-positive revertants in both the presence and absence of the tested compound. Subsequent to the indication of mutagenicity by the Ames test, further verification through additional testing, including animal models, is typically pursued to establish carcinogenicity.
The Ames test provides a cheaper and faster alternative to animal testing methods, which are not only cost-intensive but also time-consuming. The use of bacteria makes the initial screening for hazardous chemicals more accessible and less ethically contentious in comparison to immediate use of vertebrate animal models.