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Ewald JD, Basu N, Crump D, Boulanger E, Head J. Characterizing Variability and Uncertainty Associated with Transcriptomic Dose-Response Modeling. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:15960-15968. [PMID: 36268973 DOI: 10.1021/acs.est.2c04665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Transcriptomics dose-response analysis (TDRA) has emerged as a promising approach for integrating toxicogenomics data into a risk assessment context; however, variability and uncertainty associated with experimental design are not well understood. Here, we evaluated n = 55 RNA-seq profiles derived from Japanese quail liver tissue following exposure to chlorpyrifos (0, 0.04, 0.1, 0.2, 0.4, 1, 2, 4, 10, 20, and 40 μg/g; n = 5 replicates per group) via egg injection. The full dataset was subsampled 637 times to generate smaller datasets with different dose ranges and spacing (designs A-E) and number of replicates (n = 2-5). TDRA of the 637 datasets revealed substantial variability in the gene and pathway benchmark doses, but relative stability in overall transcriptomic point-of-departure (tPOD) values when tPODs were calculated with the "pathway" and "mode" methods. Further, we found that tPOD values were more dependent on the dose range and spacing than on the number of replicates, suggesting that optimal experimental designs should use fewer replicates (n = 2 or 3) and more dose groups to reduce uncertainty in the results. Finally, tPOD values ranged by over ten times for all surveyed experimental designs and tPOD types, suggesting that tPODs should be interpreted as order-of-magnitude estimates.
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Affiliation(s)
- Jessica D Ewald
- Faculty of Agricultural and Environmental Sciences, McGill University, Ste-Anne-de-Bellevue H9X 3V9, Canada
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Ste-Anne-de-Bellevue H9X 3V9, Canada
| | - Doug Crump
- Ecotoxicology and Wildlife Health Division, National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa K1A 0H3, Canada
| | - Emily Boulanger
- Faculty of Agricultural and Environmental Sciences, McGill University, Ste-Anne-de-Bellevue H9X 3V9, Canada
| | - Jessica Head
- Faculty of Agricultural and Environmental Sciences, McGill University, Ste-Anne-de-Bellevue H9X 3V9, Canada
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Jeon YS, Crump D, Boulanger E, Soufan O, Park B, Basu N, Hecker M, Xia J, Head JA. Hepatic Transcriptomic Responses to Ethinylestradiol in Two Life Stages of Japanese Quail. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2022; 41:2769-2781. [PMID: 35975422 DOI: 10.1002/etc.5464] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/29/2022] [Accepted: 08/11/2022] [Indexed: 06/15/2023]
Abstract
Chemical risk assessment for avian species typically depends on information from toxicity tests performed in adult birds. Early-life stage (ELS) toxicity tests have been proposed as an alternative, but incorporation of these data into existing frameworks will require knowledge about the similarities/differences between ELS and adult responses. The present study uses transcriptomics to assess hepatic gene expression in ELS and adult Japanese quail following exposure to ethinylestradiol (EE2). Prior to incubation, ELS quail were dosed with measured EE2 concentrations of 0.54, 6.3, and 54.2 µg/g egg weight via air cell injection. Adult quail were fed a single dose of EE2 at nominal concentrations of 0, 0.5, and 5 mg/kg body weight by gavage. Liver tissue was collected from five to six individuals per dose group at mid-incubation for ELS quail and 4 days after dosing for adults. A total of 283 and 111 differentially expressed genes (DEGs) were detected in ELS and adult quail, respectively, 16 of which were shared across life stages. Shared DEGs included estrogenic biomarkers such as vitellogenin genes and apovitellenin-1. For the dose groups that resulted in the highest number of DEGs (ELS, 6.3 µg/g; adult, 5 mg/kg), 21 and 35 Kyoto Encyclopedia of Genes and Genomes pathways were enriched, respectively. Ten of these pathways were shared between life stages, including pathways involved with signaling molecules and interaction and the endocrine system. Taken together, our results suggest conserved mechanisms of action following estrogenic exposure across two life stages, with evidence from differential expression of key biomarker genes and enriched pathways. The present study contributes to the development and evaluation of ELS tests and toxicogenomic approaches and highlights their combined potential for screening estrogenic chemicals. Environ Toxicol Chem 2022;41:2769-2781. © 2022 SETAC.
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Affiliation(s)
- Yeon-Seon Jeon
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada
| | - Doug Crump
- Ecotoxicology and Wildlife Health Division, National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, Ontario, Canada
| | - Emily Boulanger
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada
| | - Othman Soufan
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada
- Computer Science Department, St. Francis Xavier University, Antigonish, Nova Scotia, Canada
| | - Bradley Park
- School of the Environment and Sustainability and Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada
| | - Markus Hecker
- School of the Environment and Sustainability and Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Jianguo Xia
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada
| | - Jessica A Head
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada
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