Application of RNA-Seq in Ecotoxicogenomics: Exploring the Effects of Ibuprofen Exposure on Rainbow Trout and C
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Application of RNA-Seq in Ecotoxicogenomics: Exploring the Effects of Ibuprofen Exposure on Rainbow Trout and C. elegans by Lorraine Lok-Lun Yu Brown B.Sc., University of British Columbia, 2007 Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in the Department of Molecular Biology and Biochemistry Faculty of Science Lorraine Lok-Lun Yu Brown 2013 SIMON FRASER UNIVERSITY Fall 2013 Approval Name: Lorraine Lok-Lun Yu Brown Degree: Master of Science Title of Thesis: Application of RNA-Seq in Ecotoxicogenomics: Exploring the Effects of Ibuprofen Exposure on Rainbow Trout and C. elegans Examining Committee: Chair: Nicholas Harden Professor Fiona Brinkman Senior Supervisor Professor William Davidson Supervisor Professor Steven Jones Supervisor Professor Christopher Kennedy Internal Examiner Professor Department of Biological Sciences Date Defended/Approved: December 16, 2013 ii Partial Copyright Licence iii Ethics Statement iv Abstract RNA-Seq was applied in this ecotoxicogenomics study to investigate the effects of ibuprofen in two species, rainbow trout (Oncorhynchus mykiss), a fish routinely used in ecotoxicology tests, and Caenorhabditis elegans, a well-studied nematode with immense genomics information. Exposure to environmentally relevant levels of ibuprofen resulted in gene expression changes relating to stress, prostaglandin synthesis, reproduction and development in both species. In fish, we observed sex-dependent differences in vitellogenin and prostaglandin synthase gene expression, highlighting the importance of genetic sex determination of juvenile fish used in bioassays. In worms, we saw a decrease in progeny production count. Our results suggest that ibuprofen may have negative impacts on reproduction in both species but requires further investigation. This study demonstrated the benefits and challenges of using RNA-Seq in ecotoxicology and the value of studying diverse species, including traditional models and more microscopic organisms, to better understand toxicant impact on an entire ecosystem. Keywords: RNA-Seq; rainbow trout; C. elegans; ibuprofen; toxicogenomics v Dedication To my family vi Acknowledgements First and foremost, I would like to thank my supervisor, Dr. Fiona Brinkman, for taking a chance on me and for being willing to branch out to a field (environmental toxicology) that was somewhat new to her when I first started. I am truly grateful for her support, guidance, and patience. Without her, all of this would not be possible. Thank you to Graham van Aggelen for always encouraging me to pursue my goals. Thank you to my committee members, Dr. Willie Davidson and Dr. Steven Jones, for providing constructive feedback and guidance. Thank you to Dr. Heather Osachoff, for being a positive role model for me and for inspiring me to pursue a graduate degree. Thank you to the Brinkman Lab staff members and students: Bhav Dhillon, Amir Foroushani, Erin Gill, Emma Griffiths, Matthew Laird, Raymond Lo, David Lynn, Mike Peabody, Thea Van Rossum, Geoff Winsor, and Matthew Whiteside. Thank you to the staff at Environment Canada: Norm Berke, Joy Bruno, Craig Buday, Michelle Linssen- Sauvé, Georgina Lush, Grant Schroeder, and Rachel Skirrow. Also thank you to all the co-op students and volunteers who have helped me with this project: Ishai Kones, Richard Chea, and Melanie Pylatuk. I am grateful for the funding provided by SFU via Graduate Student Fellowships. Finally, thank you to Aron, for his endless support and encouragement; my parents, Kin Kong and Wai Fan, and my sister, Rosa, for their unconditional love and support. vii Table of Contents Approval .......................................................................................................................... ii Partial Copyright Licence ............................................................................................... iii Ethics Statement ............................................................................................................ iv Abstract ........................................................................................................................... v Dedication ...................................................................................................................... vi Acknowledgements ....................................................................................................... vii Table of Contents .......................................................................................................... viii List of Tables ................................................................................................................... x List of Figures.................................................................................................................. x List of Acronyms ............................................................................................................ xii Chapter 1. Introduction ............................................................................................... 1 Introduction to the Research Problem and Objectives ..................................................... 1 Next Generation Sequencing: RNA-Seq .......................................................................... 2 Overview ................................................................................................................ 2 Template preparation ............................................................................................. 2 Sequencing and imaging (Illumina example) .......................................................... 3 Data analysis .......................................................................................................... 3 Benefits and challenges of RNA-Seq ...................................................................... 7 Recent applications of RNA-Seq in environmental toxicogenomics ........................ 9 Ibuprofen: A Non-Steroidal Anti-Inflammatory Drug ....................................................... 12 Overview of NSAIDs and their mode of action ...................................................... 12 Presence of ibuprofen in the environment ............................................................ 12 Known effects of ibuprofen on non-target organisms ............................................ 13 The endocrine system and endocrine disruption ................................................... 14 Vitellogenesis in endocrine disruption ................................................................... 16 Background Information of Test Species ....................................................................... 16 Rainbow trout (Oncorhynchus mykiss) ................................................................. 16 Caenorhabditis elegans ........................................................................................ 17 Research Objectives ..................................................................................................... 18 Chapter 2. Effects of Ibuprofen Exposure in Rainbow Trout ................................. 19 Acknowledgements ....................................................................................................... 19 Introduction ................................................................................................................... 20 Materials and Methods .................................................................................................. 21 Exposure bioassays and tissue collection ............................................................. 21 Water quality parameters and chemistry analysis ................................................. 22 RNA and DNA extraction ...................................................................................... 22 RNA-Seq .............................................................................................................. 22 QPCR ................................................................................................................... 24 Genetic sex identification ...................................................................................... 25 Results .......................................................................................................................... 26 Water quality parameters and chemistry analysis ................................................. 26 Genetic sex of test fish ......................................................................................... 27 viii RNA-Seq .............................................................................................................. 28 RNA-Seq gene expression ................................................................................... 29 Functional gene set enrichment analysis .............................................................. 35 qPCR gene expression ......................................................................................... 37 Discussion ..................................................................................................................... 39 General gene expression changes ....................................................................... 39 qPCR validation .................................................................................................... 40 Stress response ................................................................................................... 41 Prostaglandin biosynthesis pathway ....................................................................