Strain-specificity of mutational types in the Ames Test
Different strains
of his- Salmonella
bacteria are used to
test for different types of mutagenic activity. For example, Aflatoxin
B1 is a mycotoxin produced by fungal growth on
a variety of crop plants. Besides being among the most potent
toxins, Aflatoxin is also a mutagen that binds to G bases and induces apurinic sites in DNA.
The TA100 and TA1538
are his- Salmonella
bacterial strains
sensitive to reversion
mutations by base substitutions and frameshifts,
respectively. In the experiment above, increasing concentration
of Aflatoxin induces
larger numbers of substitution mutations in the TA100 strain [upper plot], but
not frameshift mutations in the TA1538
strain [lower plot], as predicted.