'Overview of Ames Test\r'

'The AMES tally as well known as bacterium reversed regeneration assay is used to evaluate the mutagenic properties of canvass articles. The shield was premier developed by Bruce Ames in 1974 (Krebsfaenger). The amino acid dependent strain of S. typhimurium and E. coli ar used in this experiment where in the absence seizure of the external histidine source, the cells pratnot stick to form colonies. Specifically these strains of Salmonella argon defective in 1. ) Repair of mutations (uvrB) and 2. A rfa mutation (eliminating a portion of lipolysaccharide (a coating of outer bacterial surface)). The rfa mutation here fulfills two purposes: 1. ) Helps Salmonella in development in presence of sodium desoxycholate or quartz violet. and 2. ) Increases the cell permeability allowing more mutagen to enter the cell. The privation of uvrB gene in the decreases the rate of repair machine of mutations occurring resulting in the increased incidences of occurring mutations. These auxo trophic strain cannot originate on the media without histidine and biotine (due to uvrB).If these organisms are allowed to grow on the media lacking some(prenominal) of these, the strain get converted to prototroph resulting the organisms to grow on the mutagenic chemicals to be time-tested in the media. If the chemical being tested is mutagenic, the organisms will grow as some substance are cap adequate to(p) of cause mutations in the cells at same site or at nearby sites resulting in restoring genes function and these mutations in the cells can revert back the gene take its function (Tejs).These revertant cells are then able to grow on the media which does not contain histdine as it can now synthesize histidine on its own. This mutation causes the cells to secernate continuously. If there is no further mutation occurring in the cell, the cells will die out like recipe cell. But if any further mutation occurs which allows the cells to grow for many generations, then the can cerous cells will be formed. The principle of Ames test is specifically based on the hypothesis that any substance that is mutagenic for the bacteria used in this test may too turn out to be carcinogenic (compound make cancer).The most important limiting points of the Ames test includes first an assumption that though Ames test is being tested on prokaryotic microorganisms, it will detect the mutagens or cancer causing agents in human beings. (Though this test uses rat liver enzymes, Ames test is not able to serve the perfect model for human beings. ) Secondly, mutagens lay down by this test might not be carcinogenic i. e. further test may be required. also all carcinogens are not mutagens ( i. e. Ames test is unable to find such agents eg: asbestos).Third, some nitrate containing compounds lie nitroglycerine can cause treacherously positive production by producing nitric oxide. ? plant Cited 1. Krebsfaenger, Niels. â€Å"AMES TEST: Bacterial Reversed Mutation judge. ” Genpharmtox, Assay Sheet AMES TEST. Gen Pharm Tox, n. d. Web. 21 Nov 2012. . 2. Tejs, Sebastian. â€Å"The Ames Test: A methodological Short Review. ” Environmental Biotechnology. Environmental Biotechnology, University of Warmia and Mazury, n. d. Web. 27 Nov 2012. . 3.\r\n'