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Monitoring Macrophage Immune Gene Expression Profiles as an Early Indicator System for Examining the Bioactivity of Oil Sands Process Affected Waters

  • Author / Creator
    Choo-Yin, Yemayá Yue
  • Oil sands process-affected waters (OSPW) are by-products of bitumen (i.e. oil) extraction from the oil sands located in northern Alberta. These large volumes of water are held in tailings ponds and cannot be released due to their potential toxic effects. Overall, tailings ponds and mining operations have changed the landscape immensely and industry is mandated to reclaim these sites to self-sustaining ecosystems. Consequently, OSPW must be remediated so that it can be safely released into the environment. Unfortunately, remediation efforts are hampered by the variability of constituents found in each OSPW source which restricts industry’s ability to implement common, effective, and accepted treatment strategies. Furthermore, while individual culprits of toxicity have been identified, such as naphthenic acids, very little is known about the interactive and dynamic effects of different components that likely influence each tailings pond’s toxicity potentials. These include, but are not limited to, inorganic constituents, microbial communities, and various environmental factors such as pond ageing and location. It is therefore necessary to examine and monitor the effects of OSPW with a focus on identifying the major toxic and/or bioactive impacts. To do this, my research aimed to further optimize an immune cell-based bioindicator system using a mouse macrophage cell line to rapidly and sensitively detect changes in inducible pro-inflammatory/antimicrobial genes following OSPW exposures. I focused on two OSPW sources: the first was collected from Lake Miwasin prior to the placement of a freshwater cap (termed OSPW #7). Lake Miwasin is a demonstration pit lake established Fall 2018 that contains large volumes of alum treated OSPW and is the focus of a large-scale monitoring program examining passive remediation efforts. After the addition of the freshwater cap, a second sample was collected from Lake Miwasin, which is termed OSPW #2 throughout the thesis. Following exposure of the cells to these different whole OSPW samples, I observed a rapid and significant basal upregulation of pro-inflammatory gene expression. In resting cells, OSPW #2 exposure induced an overall greater magnitude of response than OSPW #7, however, when I examined bacterial-stimulated macrophage gene expression activity, only OSPW #7 caused significant abrogation of antimicrobial gene expression. Overall, this suggests that each OSPW sample contained bioactive constituents that can activate or suppress antimicrobial responses depending on the activation state of the macrophages. Furthermore, when macrophages were exposed to the inorganic (IF) and organic (OF) fractions of each OSPW, bioactivity (i.e. changes to gene expression) segregated to the OF of OSPW #2 and the IF of OSPW #7. These results showed that OSPW-mediated bioactivity can be traced to specific fractions, which is an asset for identifying bioactive constituents. When the OSPW #2 IF and OF were reconstituted to examine potential interactions between the fractions, no clear gene expression profile changes were observed. However, following treatment of the cells with an untreated and alum treated OSPW, discrete bioactive responses were documented. Overall, my data suggests that macrophages can serve as sensitive cell-based biomonitoring tools that show unique gene expression profiles following exposure to different samples. Accordingly, this assay can be used as a bioindicator for OSPW-mediated biological effects and for examining changes in bioactivity that may aide in OSPW characterizations to help guide ongoing remediation efforts.

  • Subjects / Keywords
  • Graduation date
    Fall 2021
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/r3-12es-rj42
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.