Hepatic Proteome and Toxic Response of Early-Life Stage Rainbow Trout (Oncorhynchus Mykiss) to the Aquatic Herbicide, Reward®
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Hepatic proteome and toxic response of early-life stage rainbow trout (Oncorhynchus mykiss) to the aquatic herbicide, Reward® by Lisa McCuaig Bachelor of Environmental Engineering, British Columbia Institute of Technology, 2014 Project Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Environmental Toxicology in the Department of Biological Sciences Faculty of Science © Lisa McCuaig 2018 SIMON FRASER UNIVERSITY Summer 2018 Copyright in this work rests with the author. Please ensure that any reproduction or re-use is done in accordance with the relevant national copyright legislation. Approval Name: Lisa McCuaig Degree: Master of Environmental Toxicology Title: Hepatic proteome and toxic response of early-life stage rainbow trout (Oncorhynchus mykiss) to the aquatic herbicide, Reward® Examining Committee: Chair: Felix Breden Professor Vicki Marlatt Senior Supervisor Assistant Professor Chris Kennedy Supervisor Professor Heather Osachoff Supervisor Senior Risk Assessment Officer/Biologist Ministry of Environment Climate Change Strategy Jennifer Cory Internal Examiner Professor Date Defended/Approved: May 7, 2018 ii Ethics Statement iii Abstract The objective of this study was to examine the acute toxicity and sub-lethal effects of the commercial formulation of diquat dibromide, Reward® Landscape and Aquatic Herbicide, on multiple early-life stages of rainbow trout exposed to environmentally relevant concentrations. The continuous exposure 96 h LC50 derived for juvenile feeding fry aged 85 d post-hatch was 9.8 mg/L. Rainbow trout eyed embryos and juvenile feeding fry were also exposed to concentrations of Reward® ranging from 0.12 to 10 mg/L during two 24 h pulse exposures separated by 14 d of rearing in fresh water to mimic the manufacturers instructions for direct applications to water bodies. Effects on growth and development were evident at 9.25 mg/L during the embryo/alevin exposures, but not in feeding juveniles, indicating a higher sensitivity of the early life stage fish. Quantitative proteomic assessment and subnetwork enrichment analyses were conducted on hepatic proteins for both life stages to evaluate protein expression changes after 0.37 mg/L diquat via Reward® exposure. Unique cellular process expression profiles for pre-feeding swim-up fry and for feeding juvenile fish were observed, reflecting differences between the two life stages in sub-cellular responses after diquat dibromide exposure. Hepatic proteome effects were more dramatic in the pre-feeding swim-up fry with 315 proteins significantly different between the control and fish exposed to Reward®, while in the later life stage feeding fry, only 84 proteins were significantly different after Reward® exposure. This study is the first to report the sub-cellular and whole organism level effects of diquat dibromide in a commercial formulation and demonstrates that numerous changes at the protein level occur at environmentally relevant concentrations based on aquatic application rates. Keywords: Reward®; Proteomics; Diquat dibromide; Rainbow trout; Sub-network enrichment analysis iv Acknowledgements I acknowledge the support and guidance of my senior supervisor, Dr. Vicki Marlatt, and committee members, Dr. Chris Kennedy and Dr. Heather Osachoff. This research was funded by a grant to Dr. Vicki Marlatt received from the National Contaminants Advisory Group within Fisheries and Ocean Canada. Thank you to Bruce Leighton at SFU Alcan Centre for his husbandry assistance. Special thank you to the Marlatt Lab for the many volunteer hours dissecting fish and for their support and friendship. v Table of Contents Approval .......................................................................................................................... ii Ethics Statement ............................................................................................................ iii Abstract .......................................................................................................................... iv Acknowledgements ......................................................................................................... v Table of Contents ........................................................................................................... vi List of Tables .................................................................................................................viii List of Figures................................................................................................................. ix List of Acronyms .............................................................................................................. x Glossary ......................................................................................................................... xi Chapter 1. Introduction .............................................................................................. 1 1.1. Pesticides in Canada ............................................................................................. 1 1.2. Reward® Landscape and Aquatic Herbicide .......................................................... 2 1.2.1. Chemical Properties and Environmental Fate ................................................ 3 1.2.2. Diquat Toxicity in Plants and Non-Target Animals ......................................... 5 1.3. Rainbow trout (Oncorhynchus mykiss) .................................................................. 8 1.4. Proteomics as an Ecotoxicological Tool ................................................................. 9 1.5. Research Objectives ........................................................................................... 11 1.6. Tables ................................................................................................................. 12 1.7. References .......................................................................................................... 13 Chapter 2. .................................................................................................................... 18 2.1. Methods .............................................................................................................. 18 2.1.1. Chemicals .................................................................................................... 18 2.1.2. Animals........................................................................................................ 19 2.1.3. Exposure Apparatus .................................................................................... 19 2.1.4. In Vivo Rainbow Trout Exposures to Reward® ............................................. 19 Acute lethality 96 h rainbow trout exposure to Reward® ......................................... 19 Pre feeding early-life stage pulse dose exposure to Reward® ................................ 20 Juvenile feeding life stage pulse dose exposure to Reward® .................................. 22 2.1.5. Fish Euthanization and Tissue Collection .................................................... 23 2.1.6. Hepatic Tissue Protein Extractions .............................................................. 23 2.1.7. Protein Quantification .................................................................................. 24 2.1.8. Pathway Analysis ........................................................................................ 26 2.1.9. Statistical Analysis ....................................................................................... 26 2.2. Results ................................................................................................................ 27 2.2.1. Water quality and pesticide exposures ........................................................ 27 2.2.2. Acute Lethality Toxicity Test ........................................................................ 28 2.2.3. Pre Feeding Early Life Stage Pulse Dose Exposure to Reward® ................. 28 Proteomics ............................................................................................................. 29 Pathway Analysis ................................................................................................... 30 2.2.4. Juvenile Feeding Life Stage Pulse Dose Exposure to Reward® ................... 31 vi Proteomics ............................................................................................................. 32 Pathway Analysis ................................................................................................... 33 2.3. Discussion ........................................................................................................... 34 2.3.1. Reward® Effects on Growth, Development and Survival .............................. 34 2.3.2. Proteome Response and Underlying Subnetworks after Pulse Dose Reward® Exposure ................................................................................................................... 36 2.4. Conclusion and Future Work ............................................................................... 41 2.5. Tables ................................................................................................................. 43 2.6. Figures ................................................................................................................ 50 2.7. References .......................................................................................................... 66 Appendix A. Supplemental Information ................................................................