Salmonella typhimurium Ames test

Eisenstark et al. (15A11), nearly a decade before Ames 1973 presentation on the use of Salmonella typhimurium to test for mutagenicity, described the high mutagenicity obtained with NNAs in tests with Salmonella typhimurium. Several potent NNAs became positive standards, e.g., A-methyl-A -nitro-A-nitrosoguanidine in the Ames test with Salmonella typhimurium. 

In the Ames mutagenicity assay, an extract of bloodroot tested weakly positive in Salmonella typhimurium (Ames assay) with metabolic activation, while no mutagenic activity of the compound sanguinarine was observed with or without metabolic activation. No mutagenic activity was observed in E. colt in the unscheduled DNA synthesis assay in rat hepatocytes (Frankos et al. 1990). 

Physicochemical properties requked include melting/boiling point, vapor pressure, solubiUty, and flammabiUty/explosion characteristics. The toxicological studies include acute toxicity tests, oral, inhalation, and dermal skin and eye kritation skin sensiti2ation subacute toxicity, oral, inhalation, and dermal and mutagenicity tests. In vitro reverse mutation assay (Ames test) on Salmonella typhimurium and/or E.scherichia coli and mammalian cytogenic test. In vivo mouse micronucleus test. 

Acute oral toxicity (rat)3 Ames mutagenicity screening test (Salmonella typhimurium)... 

Much toxicological data are available on this red pigment acute oral toxicity in mice, 90-day subchronic toxicological study, acute dermal irritation and corrosion, acute eye irritation and corrosion, anti-tumor effectiveness, micronucleus test in mice, AMES test Salmonella typhimurium reverse mutation assay), estimation of antibiotic activity, and results of estimation of five mycotoxins. A new patent on Arpink Red was filed in 2001 with claims of anti-cancer effects of the anthraquinone derivatives and apphcations in the food and pharmaceutical fields. 

Some toxicity studies were performed analyzing Bfx and Fx mutagenic effects [240-242], For example, Bfx and Bfz nitro-substituted were tested for mutagenicity in Salmonella typhimurium (S. typhimurium) TA 98 and TA 100 strains with and without metabolic activation (Ames test). All the Bfx (10/10) and some of the Bfz (9/15) are mutagenic without activation. Other study has demonstrated benzofuroxan (128, Fig. 20) is mutagenic in the Luria and Del-brueck s fluctuation test, with Klebsiella pneumoniae, and in the Ames test. In another study it has been found that compound 137 (Fig. 21) is not mutagenic to S. typhimurium. 

The mutagenic potential of diisopropyl methylphosphonate was investigated using the Ames assay. The compound was obtained from two different sources and tested on Salmonella typhimurium strains TA-1535, TA-1537, TA-1538, TA-98, and TA-100, both with and without S-9 activation. The compound did not demonstrate mutagenic activity in any of the assays (Hart 1980). Diisopropyl methylphosphonate was also negative for gene mutation in Saccharomyces cerevisiae (Hart 1980). 

Genotoxic Effects. The Ames test with Salmonella typhimurium with and without s9 liver fractions from male Syrian golden hamsters or Sprague-Dawley rats indicates that hydrogen sulfide is not a mutagen (EPA 1984). A summary of genotoxicity studies is presented in Table 2-3. 

Mutagenicity tests are usually carried out in vitro and in vivo, often using both prokaryotic and eukaryotic organisms. A well-known example is the Ames test, which assesses the ability of a drug to induce mutation reversions in E. coli and Salmonella typhimurium. 

The Ames Salmonella typhimurium microsome reverse mutation test (ability to produce point gene mutations of a base pair). 

Assays for Gene Mutations Salmonella Typhimurium reverse mutation assay (Ames test, / ... 

The Ames salmonella-microsome test is a principal sensitive mutagen screening test. Compounds are tested on the mutants of Salmonella typhimurium for reversion from a histidine requirement back to prototrophy. A positive result is seen by the growth of revertant bacteria (which do not require an external histidine source). A microsomal activation system should be included in this assay. The use of five different bacterial test strains are generally required. 

Professor Bruce Ames, a biochemist at the University of California at Berkeley is one of the pioneers of this type of short-term testing. The Ames Test, as it is called, is now widely used, typically as one of several short-term tests that constitute a series of tests, or battery. A battery is thought necessary because no single test is adequate to detect all types of genotoxicity. The Ames Test involves the use of mutant strains of a common bacterium. Salmonella typhimurium, that back-mutate to their normal state in the presence of a mutagenic chemical or metabolite. Many other bacterial and mammalian cell systems have been made available for this type of testing. 

Ecoflex (powder) was tested for its mutagenic potential on the basis of its ability to induce point mutations in several bacterial strains Salmonella typhimurium and Escherichia coll) in a reverse mutation assay (Ames test), according to OECD guideline 471. Results revealed that the polyester is not mutagenic to bacteria. 

The bacterial and mammalian cell assays for gene mutation were developed to measure statistically significant increases in the numbers of mutant colonies derived from rare events many millions of exposed cells must be plated out to allow the assessment of mutation frequency. The Salmonella typhimurium reverse mutation assay ( Ames test) is carried out in a variety of different mutant strains selected to identify the various classes of mutation. The test generates many hundreds of Petri dishes for counting and is not practical for profiling. 

Safety of Enterosgel preparation in terms of mutagenic action has been shown in the tests for induction of chromosome aberrations in bone marrow cells, in cultured human peripheral blood lymphocytes, and in the Ames test for induction of reversible gene mutations in Salmonella typhimurium. 

In some areas, the use of in vitro systems has been successful. For example, the use of in vitro tests for the detection of genotoxicity is now well established. These tests include the well-known Ames test, which relies on detecting mutations in bacteria (such as Salmonella typhimurium). These are useful early screens for detecting potential genotoxicity. 

Top) Toxicity of various resveratrol concentrations against Salmonella typhimurium tester strain TA-102 in a histidine-containing medium. (Bottom) Antimutagenic effect of resveratrol concentrations in a modified Ames test employing strain TA-102 and hydrogen peroxide. 

FIGURE 25-19 Ames test for carcinogens, based on their mutagenicity. A strain of Salmonella typhimurium having a mutation that... 

In the Ames test the following Salmonella typhimurium strains were used TA 1535 and TA 100, which are sensitive to... 

Ames Test The Ames test, developed by Bruce Ames and his coworkers at the University of California, Berkeley, depends on the ability of mutagenic chemicals to bring about reverse mutations in Salmonella typhimurium strains that have defects in the histidine biosynthesis pathway. These strains will not grow in the absence of histidine but can be caused to mutate back to the wild type, which can synthesize histidine and hence can grow in its absence. The postmitochondrial supernatant (S-9 fraction), obtained from homogenates of livers of rats previously treated with PCBs in order to induce certain cytochrome P450 isoforms, is also included in order to provide the activating enzymes involved in the production of the potent electrophiles often involved in the toxicity of chemicals to animals. 

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