A comparison of the ability of frog and rat S-9 to activate promutagens in the Ames test.
A mutagenesis assay employing the frog, Rana pipiens, is currently under development [McKinnell et al, 1979]. A question that must be answered is whether the frog is metabolically capable of activating a large number of promutagens. The Ames assay offers a simple means of comparing the metabolism of mutagens by different animal species. The Ames response obtained with frog-liver S-9 was compared to the response with rat-liver S-9, using the following compounds: Benzo(a)pyrene, 7,12-dimethylbenz(a)anthracene, 2-amino-fluorene, azobenzene, Sudan II, dibutylnitrosamine, hydrazine sulfate, hydroxyethylhydrazine, cyclophosphamide, 1,2-dichloroethane, tris(2,3 dibromopropyl)phosphate, diallate, quinoline, quercetin, aflatoxin B 1, emodin, and safrole. Of these compounds, activation by rat S-9 was observed for all except hydrazine sulfate and safrole. All except Sudan II, 1,2-dichloroethane, quinoline, and safrole gave positive Ames responses with frog S-9. In general, the responses with frog S-9 were quantitatively lower than those obtained with Aroclor-induced rat S-9; however, the optimum procedure for frog-liver induction has not been determined. The response to dichloroethane is very sensitive  to the amount of activating enzyme present; it might be positive with optimally induced frog S-9. Thus, only two of the 15 compounds positive with rat S-9 were definitely missed when tested with frog S-9. We feel that the frog assay appears to be promising from the standpoint of false-negatives.
D000818:Animals; D002273:Carcinogens / Q000494:pharmacology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008099:Liver / Q000378:metabolism*; D008297:Male; D009152:Mutagenicity Tests; D009153:Mutagens / Q000494:pharmacology*; D011894:Rana pipiens; D051381:Rats; D012486:Salmonella typhimurium / Q000187:drug effects; D013045:Species Specificity
D002273:Carcinogens; D009153:Mutagens