The Ames test

Hello, today I am going to be talking to you and blogging about the ames test. Before coming into this toxicology class, I really had no idea what the ames test even was. I even sat through your lecture and I was still puzzled by this concept. Does AMES stand for something? Or is Ames the name of the person who invented the test.  Well I am doing research so I am writing this as I go.  

 Let us begin, During the 1960s the biologist Bruce Ames developed a test that still carries his name and that is still used as a relatively inexpensive way to assess the mutagenic potential of many chemical compounds. The procedure uses the bacteria Salmonella typhimurium.

The dictionary definition of the Ames test is: a screening test for possible carcinogens using strains of Salmonella typhimurium that are unable to synthesize histidine; if the test substance produces mutations that regain the ability to synthesize histidine, the substance is carcinogenic.

Was To widely used method that uses bacteria to test whether a given chemical can cause mutations in the DNA of the test organism. If we want to be more formal and scientific. The ames test is a biological assay to assess the mutagenic potential of chemical compounds. A positive test proves that the chemical you are testing is mutagenetic thus meaning that this could act s a carcinogen. This is the case because cancer is somewhat linked to mutation. This test serves as a quick and easy assay to determine the carcinogenic potential of a compound because.

                The ames test uses several different types of bacteria. The methods of this testing tests the capability of the tested substance in creating mutations that result in a return to prototrophic state, so that the cells can grow.

                Mutagens identified by the Ames test are also possible carcinogens, and early studies by Ames showed that 90% of known carcinogens may be identified with this test. Later studies however showed identification of 50–70% of known carcinogens. The test was used to identify a number of compounds previously used in commercial products as potential carcinogens.  Examples include tris(2,3-dibromopropyl)phosphate, which was used as a flame retardant in plastic and textiles such as children's sleepwear, and furylfuramide which was used as an antibacterial additive in food in Japan in 1960s and 1970s. Furylfuramide in fact had previously passed animal test, but more vigorous tests after its identification in the Ames test showed it to be carcinogenic. Their positive tests resulted in those chemicals being withdrawn from use in consumer products.

The Ames test can detect mutagens that work directly to alter DNA. In humans, however, many chemicals are promutagens, agents that must be activated to become true mutagens. Activation, involving a chemical modification, often occurs in the liver as a consequence of normal liver activity on unusual substances. Bacteria such as S. typhimurium do not produce the enzymes required to activate promutagens, so promutagens would not be detected by the Ames test unless they were first activated. An important part of the Ames test also involves mixing the test compound with enzymes from rodent liver that convert promutagens into active mutagens. These potentially activated promutagens are then used in the Ames test. If the liver enzymes convert the agent to a mutagen, the Ames test will detect it, and it will be labeled as a promutagenic agent.

To learn more about this test, click on the links below.  

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