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Shao Y, Schiwy A, Glauch L, Henneberger L, König M, Mühlenbrink M, Xiao H, Thalmann B, Schlichting R, Hollert H, Escher BI. Optimization of a pre-metabolization procedure using rat liver S9 and cell-extracted S9 in the Ames fluctuation test. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 749:141468. [PMID: 32827816 DOI: 10.1016/j.scitotenv.2020.141468] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 08/01/2020] [Accepted: 08/02/2020] [Indexed: 06/11/2023]
Abstract
Many environmental pollutants pose a toxicological hazard only after metabolic activation. In vitro bioassays using cell lines or bacteria have often no or reduced metabolic activity, which impedes their use in the risk assessment. To improve the predictive capability of in vitro assays, external metabolization systems like the liver S9 fraction are frequently combined with in vitro toxicity assays. While it is typical for S9 fractions that samples and testing systems are combined in the same exposure system, we propose to separate the metabolism step and toxicity measurement. This allows for a modular combination of metabolic activation by enzymes isolated from rat liver (S9) or a biotechnological alternative (ewoS9R) with in vitro bioassays that lack metabolic capacity. Benzo(a)pyrene and 2-aminoanthracene were used as model compounds to optimize the conditions for the S9 metabolic degradation/activation step. The Ames assay with Salmonella typhimurium strains TA98 and TA100 was applied to validate the set-up of decoupling the S9 activation/metabolism from the bioassay system. S9 protein concentration of 0.25 mgprotein/mL, a supplement of 0.13 mM NADPH and a pre-incubation time of 100 min are recommended for activation of samples prior to dosing them to in vitro bioassays using the regular dosing protocols of the respective bioassay. EwoS9R performed equally well as Moltox S9, which is a step forward in developing true animal-free in vitro bioassays. After pre-incubation with S9 fraction, chemicals induced bacteria revertants in both the TA98 and the TA100 assay as efficiently as the standard Ames assay. The pre-incubation of chemicals with S9 fraction could serve for a wide range of cellular in vitro assays to efficiently combine activation and toxicity measurement, which may greatly facilitate the application of these assays for chemical hazard assessment and monitoring of environmental samples.
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Affiliation(s)
- Ying Shao
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany; Key Laboratory of the Three Gorges Reservoir Eco-environment, Ministry of Education, Chongqing University, Shazheng street 174, Shapingba, 400044 Chongqing, China.
| | - Andreas Schiwy
- Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany; Department of Evolutionary Ecology and Ecotoxicology, Goethe University, Max-von-Laue-Str. 13, 60438 Frankfurt/Main, Germany
| | - Lisa Glauch
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Luise Henneberger
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Maria König
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Marie Mühlenbrink
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Hongxia Xiao
- Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany
| | - Beat Thalmann
- EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany
| | - Rita Schlichting
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Henner Hollert
- Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany; Department of Evolutionary Ecology and Ecotoxicology, Goethe University, Max-von-Laue-Str. 13, 60438 Frankfurt/Main, Germany
| | - Beate I Escher
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany; Eberhard Karls University of Tübingen, Environmental Toxicology, Centre for Applied Geosciences, 72074 Tubingen, Germany
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