Optimal levels of S9 fraction in the Ames and fluctuation tests: apparent importance of diffusion of metabolites from top agar
- 1 January 1980
- journal article
- research article
- Published by Oxford University Press (OUP) in Carcinogenesis: Integrative Cancer Research
- Vol. 1 (4) , 337-346
- https://doi.org/10.1093/carcin/1.4.337
Abstract
For activation of 2-acetylaminofluorene (AAF) there is an optimal level of rat liver S9 fraction which is considerably lower in the fluctuation test than in the Ames test. The optimal level of S9 is not markedly affected by the dose of AAF used, nor by the ratio of S9 to bacteria [Salmonella typimurium], nor by the presence of soft agar. The difference between Ames and fluctuation tests appears to be due to diffusion of some substance or substances from the top agar layer in the Ames test. Diffusion of the co-factors NADP and glucose-6-phosphate is not responsible for the difference in S9 optima, nor is diffusion of soluble S9 constituents although this may considerably affect the performance of the S9 mix. Diffusion of non-mutagenic metabolites of AAF from the Ames test top agar may be responsible for the difference in S9 optima. Lipophilic non-mutagenic metabolites may accumulate in the microsomes and inhibit further activation. When the metabolites are able to diffuse away, a higher level of S9 will be optimal. The model is consistent with some other phenomena of S9 activation.This publication has 10 references indexed in Scilit:
- ACETYLORNITHINASE OF ESCHERICHIA COLI: PARTIAL PURIFICATION AND SOME PROPERTIESPublished by Elsevier ,2021
- Critical importance of microsome concentration in mutagenesis assay with V79 Chinese hamster cellsMutation Research - Fundamental and Molecular Mechanisms of Mutagenesis, 1979
- Some factors determining the concentration of liver proteins for optimal mutagenicity of chemicals in the salmonella/microsome assayMutation Research - Fundamental and Molecular Mechanisms of Mutagenesis, 1979
- Comutagenicity, competitive enzyme substrates, and in vitro carcinogenicity assaysMutation Research/Environmental Mutagenesis and Related Subjects, 1978
- Microbial assays for mutagenicity: A modified liquid culture method compared with the agar plate system for precision and sensitivityMutation Research/Environmental Mutagenesis and Related Subjects, 1978
- Mutagen screening by a simplified bacterial fluctuation test: Use of microsomal preparations and whole liver cells for metabolic activationMutation Research - Fundamental and Molecular Mechanisms of Mutagenesis, 1977
- Factors for efficiency of the Salmonella/microsome mutagenicity assayChemico-Biological Interactions, 1977
- Mutagenicities of N-nitrosamines on salmonellaMutation Research - Fundamental and Molecular Mechanisms of Mutagenesis, 1977
- Comparative mutagenicity of N-nitrosamines in a semi-solid and in liquid incubation system in the presence of rat or human tissue fractionsMutation Research - Fundamental and Molecular Mechanisms of Mutagenesis, 1976
- Use of a simplified fluctuation test to detect low levels of mutagensMutation Research/Environmental Mutagenesis and Related Subjects, 1976