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Zhang R, Wu Q, Qi X, Wang X, Zhang X, Song C, Peng Y, Crump D, Zhang X. Using In Vitro and Machine Learning Approaches to Determine Species-Specific Dioxin-like Potency and Congener-Specific Relative Sensitivity among Birds for Brominated Dioxin Analogues. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:16056-16066. [PMID: 34761675 DOI: 10.1021/acs.est.1c05951] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
There is a paucity of experimental data regarding dioxin-like toxicity of polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs) and non-ortho polybrominated biphenyls (PBBs). In this study, avian aryl hydrocarbon receptor 1 (AHR1)-luciferase reporter gene assays were used to determine their species-specific dioxin-like potencies (DLPs) and congener-specific interspecies relative sensitivities in birds. The results suggested that DLPs of the brominated congeners for chicken-like (Ile324_Ser380) species did not always follow World Health Organization toxicity equivalency factors of their chlorinated analogues. For ring-necked pheasant-like (Ile324_Ala380) and Japanese quail-like (Val324_Ala380) species, the difference in DLP for several congeners was 1 or even 2 orders of magnitude. Moreover, molecular docking and molecular dynamics simulation were performed to explore the interactions between the brominated congeners and AHR1-ligand-binding domain (LBD). The molecular mechanics energy (EMM) between each congener and each individual amino acid (AA) residue in AHR1-LBD was calculated. These EMM values could finely characterize the final conformation of species-specific AHR1-LBD for each brominated congener. Based on this, mechanism-driven generalized linear models were successfully built using machine learning algorithms and the spline approximation method, and these models could qualitatively predict the complex relationships between AHR1 conformations and DLPs or avian interspecies relative sensitivity to brominated dioxin-like compounds (DLCs). In addition, several AAs conserved among birds were found to potentially interact with species-specific AAs, thereby inducing species-specific interactions between AHR1 and brominated DLCs. The present study provides a novel strategy to facilitate the development of mechanism-driven computational prediction models for supporting safety assessment of DLCs, as well as a basis for the ecotoxicological risk assessment of brominated congeners in birds.
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Affiliation(s)
- Rui Zhang
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China
| | - Qiuxuan Wu
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China
| | - Xiaoyi Qi
- Department of Gynecology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, China
- Department of Gynecology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, China
| | - Xiaoxiang Wang
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
- Yuanshang Technology Co., Ltd., Shenzhen 518126, China
| | - Xuesheng Zhang
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China
| | - Chao Song
- Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China
- Laboratory of Quality & Safety Risk Assessment for Aquatic Products on Environmental Factors (Wuxi), Ministry of Agriculture, Wuxi 214081, China
| | - Ying Peng
- Research and Development Center for Watershed Environmental Eco-Engineering, Beijing Normal University, Zhuhai 519087, China
| | - Doug Crump
- Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa K1A 0H3, Canada
| | - Xiaowei Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
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Ha K, Xia P, Crump D, Saini A, Harner T, O’Brien J. Cytotoxic and Transcriptomic Effects in Avian Hepatocytes Exposed to a Complex Mixture from Air Samples, and Their Relation to the Organic Flame Retardant Signature. TOXICS 2021; 9:toxics9120324. [PMID: 34941758 PMCID: PMC8704741 DOI: 10.3390/toxics9120324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/09/2021] [Accepted: 11/20/2021] [Indexed: 11/30/2022]
Abstract
Assessing complex environmental mixtures and their effects is challenging. In this study, we evaluate the utility of an avian in vitro screening approach to determine the effects of passive air sampler extracts collected from different global megacities on cytotoxicity and gene expression. Concentrations of a suite of organic flame retardants (OFRs) were quantified in extracts from a total of 19 megacities/major cities in an earlier study, and levels were highly variable across sites. Chicken embryonic hepatocytes were exposed to serial dilutions of extracts from the 19 cities for 24 h. Cell viability results indicate a high level of variability in cytotoxicity, with extracts from Toronto, Canada, having the lowest LC50 value. Partial least squares (PLS) regression analysis was used to estimate LC50 values from OFR concentrations. PLS modeling of OFRs was moderately predictive of LC50 (p-value = 0.0003, r2 = 0.66, slope = 0.76, when comparing predicted LC50 to actual values), although only after one outlier city was removed from the analysis. A chicken ToxChip PCR array, comprising 43 target genes, was used to determine effects on gene expression, and similar to results for cell viability, gene expression profiles were highly variable among the megacities. PLS modeling was used to determine if gene expression was related to the OFR profiles of the extracts. Weak relationships to the ToxChip expression profiles could be detected for only three of the 35 OFRs (indicated by regression slopes between 0.6 and 0.5 when comparing predicted to actual OFR concentrations). While this in vitro approach shows promise in terms of evaluating effects of complex mixtures, we also identified several limitations that, if addressed in future studies, might improve its performance.
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Affiliation(s)
- Kelsey Ha
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada;
- National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, ON K1A 0H3, Canada; (P.X.); (J.O.)
| | - Pu Xia
- National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, ON K1A 0H3, Canada; (P.X.); (J.O.)
| | - Doug Crump
- National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, ON K1A 0H3, Canada; (P.X.); (J.O.)
- Correspondence: ; Tel.: +1-(613)-998-7383
| | - Amandeep Saini
- Air Quality Processes Research Section, Environment and Climate Change Canada, Toronto, ON M3H 5T4, Canada; (A.S.); (T.H.)
| | - Tom Harner
- Air Quality Processes Research Section, Environment and Climate Change Canada, Toronto, ON M3H 5T4, Canada; (A.S.); (T.H.)
| | - Jason O’Brien
- National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, ON K1A 0H3, Canada; (P.X.); (J.O.)
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