Salmonella typhimurium, histidine, auxotrophs

Prokaryotic organisms Salmonella typhimurium (histidine auxotrophs) Gene mutation + - Simmon and Shepherd 1978a... 

Salmonella typhimurium from auxotrophism histidine-dependent) to prototrophism (non-histidine-dependent). When mutated Salmonella typhimurium is exposed to a mutagen, mutation to the non-histidine-dependent form takes place in a proportion of the bacterial population. 

This assay employs a number of different strains of Salmonella typhimurium mutants that are histidine auxotrophs. The first tester strains developed and tested on extracts of diesel and ambient POM in the mid to late 1970s included TA1535, which responds to base-pair substitution chemical mutagens (e.g., /f -propiolac-tone), and TA1537 and TA1538, which respond to frameshift mutagens, e.g., BaP and other PAHs. 

Tosk, J., Schmeltz, I. Hoffmann. D. (1979) Hydrazines as mutagens in a histidine-requiring auxotroph of Salmonella typhimurium. Mutat. Res., 66. 247-252... 

Geiger LE, Neal RA. 1981. Mutagenicity testing of 2,3,7,8-tetrachlorodibenzo-p-dioxin in histidine auxotrophs of Salmonella typhimurium. Toxicol Appl Pharmacol 59 125-129. 

Ames test Test used to determine whether a particular substance is mutagenic, based on its ability to induce mutations in auxotrophic bacteria. A strain of the bacterium Salmonella typhimurium having a mutation that disables an enzyme necessary for histidine utilization is exposed to the substance in question and plated on a medium lacking histidine. A reversion mutation that activates the mutant enzyme causes the cells to grow on this medium. 

Studies with histidine auxotrophs of Salmonella typhimurium showed that mixing extracts of a strain unable to produce compound III with that of a strain capable of producing III, but unable to convert it to the aminoribosylimidazolecarboxamide phosphate and imidazoleglycerol phosphate, carried the reaction to completion with the formation of both of these compounds. 

Ames test analy chem A bioassay that uses a set of histidine auxotrophic mutants of Salmonella typhimurium for detecti ng mutagenic and possibly carcinogenic compounds. amz, test ... 

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