Ames test

The Ames test is a more important test method for rapid screening of chemical carcinogens. The Ames test is a rapid identification of the carcinogenicity of chemicals, new pesticides and new food additives. It is widely used as a screening method for carcinogens and can detect the carcinogenicity of many substances. The Ames test genetically bred a variant of Salmonella typhimurium that does not produce histidine by itself. This strain cannot grow in histidine-free medium. Basic Information Specialist classification: Oncology examination classification: biochemical examination Applicable gender: whether men and women apply fasting: not fasting Tips: Before the examination, the diet is light and alcohol is prohibited. Check for an empty stomach in the morning. Normal value Non-toxic, no mutagenic health chemicals, new pesticides and new food additives. Clinical significance Biological genetic mutations are considered the key to cancer formation. Therefore, the carcinogenic activity of certain microorganisms is determined by chemical substances. Precautions Note that some substances are not mutagens themselves, but such "pre-mutagenic agents" often enter the animal body and undergo biochemical modification to become mutagens. To compensate for this deficiency, a rat liver extract containing an enzyme (such as a hydroxylase, etc.) capable of converting such a "pre-mutagenic agent" into a mutagen should be added to the test system. Inspection process Genetically, a variant of Salmonella typhimurium that does not produce histidine by itself is grown in a histidine-free medium. If this strain is cultured with a chemical carcinogen, the DNA (deoxyribonucleic acid) can be mutated again and restored to a prototype capable of producing histidine (wild type), that is, in a histidine-free medium. Can grow. This characteristic change is used to test the presence or absence of mutagenicity of the chemical, and the carcinogenicity can be determined based on the number of colonies grown. For example: a sample containing a suspected "triad" such as aflatoxin, dimethylaminoazobenzene (cream yellow) or "reaction stop", added to the rat liver homogenate, kept for a while, inhaled into the filter paper, and then The filter paper is placed in the center of the above plate. After culture, there are three cases: if there is no large number of colonies on the plate, it means that the sample does not contain mutagen; if there is a suppression circle around the paper, it is a large number of colonies outside, indicating that a certain sample is in the sample. The concentration of the agent is very high; if a large number of colonies are around the paper, the concentration of the mutagen is appropriate. Not suitable for the crowd no. Adverse reactions and risks no.

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