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Demonstrating laboratory proficiency in bacterial mutagenicity assays for regulatory submission. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2019; 848:403075. [DOI: 10.1016/j.mrgentox.2019.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 05/30/2019] [Accepted: 07/11/2019] [Indexed: 11/18/2022]
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Levy DD, Zeiger E, Escobar PA, Hakura A, van der Leede BJM, Kato M, Moore MM, Sugiyama KI. Recommended criteria for the evaluation of bacterial mutagenicity data (Ames test). Mutat Res 2019; 848:403074. [PMID: 31708073 DOI: 10.1016/j.mrgentox.2019.07.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 07/11/2019] [Indexed: 10/26/2022]
Abstract
A committee was constituted within the International Workshop on Genetic Toxicology Testing (IWGT) to evaluate the current criteria for a valid Ames test and to provide recommendations for interpretation of test results. Currently, determination of a positive vs. a negative result is made by applying various data evaluation procedures for comparing dosed plates with the concurrent solvent control plates. These evaluation procedures include a requirement for a specific fold increase (2- or 3-fold, specific to the bacterial strain), formal statistical procedures, or subjective (expert judgment) evaluation. After extensive discussion, the workgroup was not able to reach consensus recommendations in favor of any of these procedures. There was a consensus that combining additional evaluation criteria to the comparison between dosed plates and the concurrent solvent control plates improves test interpretation. The workgroup recommended using these additional criteria because the induction of mutations is a continuum of responses and there is no biological relevance to a strict dividing line between a positive (mutagenic) and not-positive (nonmutagenic) response. The most useful additional criteria identified were a concentration-response relationship and consideration of a possible increase above the concurrent control in the context of the laboratory's historical solvent control values for the particular tester strain. The workgroup also emphasized the need for additional testing to resolve weak or inconclusive responses, usually with altered experimental conditions chosen based on the initial results. Use of these multiple criteria allowed the workgroup to reach consensus on definitions of "clear positive" and "clear negative" responses which would not require a repeat test for clarification. The workgroup also reached consensus on recommendations to compare the responses of concurrent positive and negative controls to historical control distributions for assay acceptability, and the use of control charts to determine the validity of the individual test.
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Affiliation(s)
- Dan D Levy
- US Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD, 20740, USA.
| | - Errol Zeiger
- Errol Zeiger Consulting, Chapel Hill, NC, 27514, USA
| | | | - Atsushi Hakura
- Tsukuba Drug Safety, Eisai Co., Ltd., Tsukuba, Ibaraki, 300-2635, Japan
| | - Bas-Jan M van der Leede
- Non-Clinical Safety, Janssen Research & Development, a Division of Janssen Pharmaceutica N.V., Beerse, Belgium
| | - Masayuki Kato
- CMIC Pharma Science Co., Ltd., Hokuto, Yamanashi, Japan
| | | | - Kei-Ichi Sugiyama
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, Kawasaki, Kanagawa, 210-9501, Japan
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Prival MJ. The unusual effect of pKM101 on the mutagenicity of acetaldehyde oxime in Salmonella typhimurium. Mutat Res 2003; 537:201-8. [PMID: 12787823 DOI: 10.1016/s1383-5718(03)00087-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Acetaldehyde oxime was found to induce more revertants in Salmonella typhimurium strain TA1535 than in TA100 in the absence of S9 metabolic activation. TA100 was originally constructed from TA1535 by the addition of the plasmid pKM101, carrying mucAB which generally enhances sensitivity to the mutagenic effects of chemicals. The role of pKM101 in lowering the sensitivity to acetaldehyde oxime was explored by: (1) increasing the incubation time of the selective agar plates from 2 to 3 days; (2) using a new strain, isogenic to TA100, constructed by introducing pKM101 into the TA1535 isolate used in these experiments; (3) by testing a strain constructed by inserting into TA1535 a plasmid carrying mucAB but otherwise unrelated to pKM101. Each of these alterations increased the number of revertants per plate in the presence of acetaldehyde oxime, indicating that the apparent nonmutagenicity of this chemical in TA100 is due to multiple factors.
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Affiliation(s)
- Michael J Prival
- Division of In Vitro and Biochemical Toxicology (HFS-25), U.S. Food and Drug Administration, 8301 Muirkirk Road, Laurel, MD 20708, USA.
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