AMES TEST

(USED TO SCREEN CARCINOGENS AND MUTAGENS )
                                       Discovered by Bruce Ames

• Histidine auxotroph (mutated ones)Salmonella typhimurium were taken which requires presence of histidine to grow.
• It is mixed with rat liver enzymes and plated in a media which is devoid of histidine .
• Liver enzymes are required to detect the mutagens that are converted to carcinoogenic form by the liver .
• Test chemical (mutagenic) is then added to the medium .
• Control plates lack the test chemical shows a small number of bacterial cells or colony growing without histidine .
• Plated innoculated with mutagens (test chemical )show a larger number of revertants which implies the auxotroph converted to prototrophs by the presence of histidine which acts as a selectable marker .

(ALL CARCINOGENS ARE MUTAGENS BUT ALL MUTAGENS ARE NOT CARCINOGENS)

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