Scientific Background
Salmonella strains with specific genetic
modifications are used in the Ames Test, they are unable to grow
without the amino acid histidine (his- genotype). Only Salmonella
strains that have undergone a genetic mutation, i.e. a mutagenic
reversion to histidine prototrophy can survive and grow in absence of
histidine (his genotype). Thus, only in the presence of mutagenic
compounds, an increase in back-mutations occur to this his genotype.
The Salmonella colonies which are growing on agar plates or in liquid
media, are called “revertants”. An increased number of revertants in
relation to the strain-specific spontaneous mutation rates obtained with
the solvent control is a clear indication for a mutagenic test
substance. See also OECD TG471.
Many mutagenic compounds are only mutagenic upon metabolization. The
Salmonella strains which do not have a metabolic system are therefore
exposed to a test compound in the presence of microsomal fraction S9 of a
rat liver homogenate.
Ames- Micro6- Macro1-
Service Analytics Genotoxicity
Test Principle
Bacteria are exposed to different
concentrations of a test sample (11 mg / strain), as well as a positive
and a negative control in a medium containing limited quantities of
histidine (S. typhimurium) to support approximately two cell
divisions. The cultures in each condition (negative control, test
samples and positive controls) are poured in 6 well plates. The cells
are exposed to the compound in absence and presence of S9. Rat liver
post mitochondrial S9 fraction mimics the effect of the chemical after
metabolization. Within three days, cells that have undergone a genetic
reversion event to amino acid prototrophy will grow and form colonies.
The revertant counts will be compared to those grown in the solvent
(negative) control wells. A dose-dependent and significant increase in
the number of revertant colonies upon exposure to test sample relative
to the solvent controls indicates that the sample is mutagenic. A
sterility plate for S9 and buffer is used a contamination control.
Service analytics under GLP and non GLP conditions is available, please contact info@xenometrix.ch.
Characteristics
- Quality controlled products: all products included in the kit are quality controlled according to OECD TG471
- Certificate of Analysis provided for all strains, S9, positive controls, media
- Standardized procedure including all products necessary, except S9 Cofactor Solutions and Plastic Ware
- Shipped at Room Temperature from external Storage in Germany or from Switzerland
- On site or digital training, technology transfer respectively, is available
- Technical support
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