English

The Effect of Carbon Source and Phytohormones on the in vitro Growth of Euglena Gracilis

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Creator (cre): Trzaskalski, Natasha, Thesis advisor (ths): Emery, Neil, Degree committee member (dgc): Balch, Gordon, Degree committee member (dgc): Gueguen, Celine, Degree granting institution (dgg): Trent University
Abstract:

Microalgae are a promising source of valuable compounds relevant to biofuels, biomaterials, nutraceuticals as well as animal and human nutriment. Unfortunately, low cell density and slow growth result in reduced economic feasibility. Heterotrophic cell culturing using an organic carbon source in lieu of light has proven to be an effective alternative to photobioreactors; however, further improvement may be possible with the addition of growth promoting phytohormones. In this thesis, growth and endogenous hormone profiles in heterotrophic cultures of Euglena gracilis were evaluated using glucose and ethanol as carbon sources. Cytokinin (CK) and abscisic acid (ABA) were quantified by HPLC-ESI-MS/MS and compared to culture growth dynamics. Exogenous phytohormones treatments were also conducted to determine if they may mitigate nutrient reduction and improve growth. Phytohormones CK and ABA were purified and analyzed at seven points along the growth curve in small scale (250 mL flasks, 100 mL working volume) cultures. Among the key findings was that ethanol cultures undergoing exponential growth, primarily synthesize freebase cytokinins (FBCKs) and methylthiol-cytokinins (MeSCKs), while not producing detectable levels of ABA. In exogenous studies, dry biomass was positively influenced with the addition of exogenous ABA; however, the most notable result revealed the ability of transZ to alleviate nutrient reduction. These findings suggest a communication network in algal culture using FBCKs and MeSCKs, as well as the potential for exogenous hormone supplementation to increase growth rates and overall biomass productivity.

Author Keywords: abscisic acid, cytokinin, Euglena gracilis, heterotrophy, phytohormones

2018

Estimating mineral surface area and acid sensitivity of forest soils in Kitimat, British Columbia

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Creator (cre): Levasseur, Patrick, Thesis advisor (ths): Watmough, Shaun, Degree committee member (dgc): Aherne, Julian, Degree committee member (dgc): Eimers, Catherine, Degree committee member (dgc): Whitfield, Colin, Degree granting institution (dgg): Trent University
Abstract:

In 2012, the Rio Tinto aluminum smelter in Kitimat, British Columbia increased sulphur dioxide (SO2) emissions from 27 to 42 tonnes/day. An initial study was conducted to investigate the effect of the increased sulphur (S) deposition on forest soils. A key uncertainty of the initial study was mineral surface area estimations that were applied to critical load calculations. The current study investigates the effect of organic matter (OM) removal techniques on mineral surface area and the ability to predict mineral surface area using pedotransfer functions (PTFs). Mineral surface area was measured on bulk soil samples using BET gas-adsorption. Organic matter was removed from soil samples prior to surface area measurements using a sodium hypochlorite treatment (NaOCl), loss on ignition (LOI) and no treatment. Removal techniques were found to affect surface area measurements; decreasing in the order of LOI> untreated> NaOCl. Particle-size based PTFs developed from other regions were not significantly correlated with measured surface area. A regionally-specific particle-size based function had stronger predictive value of surface area measurements (adjusted R2=0.82). The PTF that best reflected surface area measurements of bulk soil for the Kitimat area used particle-size data as well as kaolinite, the most abundant clay mineral in the region. Surface area values estimated using the particle-size PTF were applied to the PROFILE model to calculate weathering rates. Weathering rates were then input to critical load calculations using steady-state mass balance. These estimates predicted that none of the 24 measured sites are receiving SO2 deposition in exceedance of their critical load.

Author Keywords: acid deposition, critical loads, mineral surface area, mineral weathering, pedotransfer functions, PROFILE

2018

'This is where the poetry comes out': Examining the Peterborough Poetry Slam as resistant space-making

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Creator (cre): Baldwin, Melissa, Thesis advisor (ths): Chazan, May, Degree committee member (dgc): Chivers, Sally, Degree granting institution (dgg): Trent University
Abstract:

Since 1984, poetry slams have emerged as a politicized expressive movement of performing the personal and political through poetry competitions. Slams are also discursively spatialized, often represented as "spaces" that are "safe," "inclusive," etc. In this thesis, I investigate how, why, and to what effect the Peterborough Poetry Slam produces, consolidates, and challenges such "resistant spaces." Drawing on interviews and participant observation, I consider how the slam's reiterative practices facilitate its space-making by encouraging performances that resist, reimagine, and sometimes inadvertently reify dominant societal norms. I argue that this space-making is imperfect yet productive: though not resistant space in any straightforward or static way, the slam continuously produces possibilities to challenge norms and confront power. This thesis contributes to scholarship on performative space and creative resistance movements. In an era when political resistance to power structures is often silenced, this research offers insights of potential significance to other resistant space-makings.

Author Keywords: Nogojiwanong Peterborough, performative space, poetry slam, resistance, space-making, spoken word

2017

The Thin Line Between Hell and Here: Dystopian Fiction under Neoliberalism

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Creator (cre): Turkmen, Sezen, Thesis advisor (ths): Holdsworth, David, Degree committee member (dgc): Mitchell, Liam, Degree granting institution (dgg): Trent University
Abstract:

The end of the Cold War and the global triumph of neoliberalism were accompanied by the evolution of certain themes in dystopian fiction. According to some of its advocates, such as Francis Fukuyama, neoliberalism's success signified the "end of history," understood as ideological evolution, since the decline of communism left Western liberal democracies without any major opposition in terms of global governing and discursive practices. This thesis critically compares neoliberal rhetoric concerning invisible power, the end of history, technology, freedom of consumption and the commodification of human relationships with the ideologies represented in four neoliberal dystopian works of fiction, namely Black Mirror, Feed, The Circle, and The Fat Years. These examples create a "one-dimensional" dystopian subject who is rendered incapable of possessing the utopian imagination necessary to organize political resistance, precisely as a result of the governance and discourse of neoliberalism.

Author Keywords: dystopia, dystopian fiction, dystopian subjectivity, neoliberalism, post cold war fiction, subjectivity

2017

Phytohormone-enhanced heavy metal responses in Euglena gracilis: Ni, Pb and Cd uptake and associated hormone and metabolome profiles

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Creator (cre): Nguyen, Hai, Thesis advisor (ths): Emery, R.J. Neil, Degree committee member (dgc): Saville, Barry, Degree committee member (dgc): Kisiala, Anna, Degree granting institution (dgg): Trent University
Abstract:

Phytohormones, Cytokinin (CK) and Abscisic acid (ABA), are best known for controlling plant growth and stress responses; but they also mediate various developmental perspectives in alga. Yet, their mode of action in algal adaptive strategies to heavy metal responses, their involvement in orchestration of phytohormone crosstalk remain largely unknown and a molecular framework of phytohormone-controlled heavy metal uptake is absent. I found that three metals known globally to contaminate aquatic ecosystems, nickel (Ni), lead (Pb), and cadmium (Cd), cause changes in the levels of endogenous CKs, ABA, auxins, and gibberellins (GAs) in the green alga Euglena gracilis. Exogenous ABA or CK (trans-zeatin) alleviated metal toxicity through improved metal uptake efficiency and the regulation of the endogenous CKs activity profiles and GAs activity. This new evidence suggests that E. gracilis possesses functional phytohormone signals and metabolic pathways that are under metal stress response. Exogenously applied ABA or CK provoked the coordinated activation of metal uptake, likely via enhanced accumulation of metal binding compounds (i.e., proline, glycine, cysteine containing peptides), which are effective for metal sequestration. Using untargeted metabolomics analysis and functional annotation, this thesis further established that, CK and ABA modified pathways and metabolites, which were mainly involved in metal acclimation and resistance. These modified metabolites that were under the influence of phytohormones in algal cells growing under metal stress conditions were associated with: lipid pathways, riboflavin metabolism, biosynthesis of cofactors/vitamin, and carbohydrate metabolism. Bioactive secondary compounds (e.g., terpenoids, alkaloids, flavonoids, carotenoids) were also modified in algal cells treated with phytohormones. The present study highlights that ABA and CKs are important regulators of algal metal accumulation/acclimation strategies based on increased metal uptake, enhanced CK metabolism, regulation of hormonal crosstalk and regulation of some core cellular metabolism pathways, all of which improve metal uptake efficiency. Finally, our results suggest that ABA and CK form a novel strategy for metal bioremediation techniques and for sourcing microalgal value-added metabolites.

Author Keywords: abscisic acid, cadmium, cytokinin, Euglena gracilis, lead, nickel

2021

Potential for Greenhouse Gas Emissions from Sediments of Agricultural Streams and Lake Erie

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Creator (cre): Dyczko, Jessica, Thesis advisor (ths): Xenopoulos, Marguerite A, Degree committee member (dgc): Eimers, Catherine, Degree committee member (dgc): Dillon, Peter, Degree granting institution (dgg): Trent University
Abstract:

This thesis examines how dissolved organic matter quantity and quality and nutrients influence the flux potential of greenhouse gases (GHG) from sediments collected from streams across southern Ontario as well as Lake Erie. Sediments were collected and incubated in a laboratory setting where headspace gases and interstitial waters were analyzed. Results demonstrated that nutrients (dissolved organic carbon (DOC), total dissolved phosphorous (TDP) and total dissolved nitrogen (TDN)) were commonly significant predictors of CO2, CH4, and N2O fluxes, but spatial discrepancies were observed for the significance of DOM quality and sedimentary characteristics. Land use was not found to be directly related to gas flux potential. Different relationships were observed between the streams and lake, and between the basins of Lake Erie. Overall, results from this study suggest that sediments from freshwater systems have the potential to be sources of GHG, the degree of which depends on nutrient concentrations and DOM structure from watershed inputs.

Author Keywords: dissolved organic matter, greenhouse gases, Lake Erie, nutrients, sediment, streams

2020

Critical Topographies of two films: Aura, Temporality, and Place in El Sol del Membrillo and Rivers and Tides

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Creator (cre): Allwood, Mark, Thesis advisor (ths): Bordo, Jonathan, Thesis advisor (ths): Holdsworth, David, Degree committee member (dgc): Egan, Kelly, Degree committee member (dgc): Junyk, Ihor, Degree granting institution (dgg): Trent University
Abstract:

The following thesis is a work in Critical Topography that choses as its site of study two documentary films. The films being studied are El Sol del Membrillo by Victor Erice and Rivers and Tides by Thomas Riedelsheimer. My approach to critical topography in the thesis is twofold: first, I have traced the topical motifs that have appeared to me as I looked at the two films; second, I have translated the films into writing –with the purpose of creating a sourcebook for my analysis- thus bounding the visual content of the films into the delineated space of the written word. I have sought in my analysis to make visible the numerous conceptual, aesthetic, and philosophical notions that are repeated in each film. These notions include materiality, formal operations, temporality, memory, and failure. All of which are ideas that find expression - despite their significant differences - in both documentary films.

Author Keywords: Art, Critical Topography, Film Studies, Land Art, Painting, Time

2016

Time, Being, and the Image

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Creator (cre): Potempski, Jacob, Thesis advisor (ths): Angelova, Emilia, Degree committee member (dgc): Egan, Kelly, Degree committee member (dgc): Penney, James, Degree committee member (dgc): Junyk, Ihor, Degree granting institution (dgg): Trent University
Abstract:

The three projects that make up this dissertation try to articulate an ontological idea of art; which is to say, they all approach art, or the imagination (as in project two), from the standpoint of a philosophical question concerning the sense of being. The ontological question is elaborated in terms of a theory of the spatial-temporal structure of the aesthetic or sensible realm. This kind of ontology contrasts with a more traditional metaphysical one, where the sense of being is sought within the purely intelligible realm, a realm that transcends the sensible. In projects one and two, the contrast is developed in terms of the Nietzschean/Heideggerian critique of metaphysics, and through the work of Jean-Luc Nancy, who appropriates this critique. In project three, it is developed in terms of Bergson and Deleuze's critique of objective time, or of any attempt to define being and time in terms of what is static and unchanging. Art is central for the ontology at stake here, and the ontology is one of art, because it is a matter of questioning the spatial-temporal being of the sensible, and not the being of the purely intelligible; and because art (as I try to show) is itself essentially concerned with revealing this ontological dimension of the sensible.

Author Keywords: Aesthetics, Art, Being, Fragment, Image, Time

2016

Modelling Depressive Symptoms in Emerging Adulthood: Intergenerational Risk and the Protective Role of Trait Emotional Intelligence

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Creator (cre): Snetsinger, Samantha Wynne, Thesis advisor (ths): Parker, James, Degree committee member (dgc): Keefer, Kateryna, Degree committee member (dgc): Carter, Bruce, Degree granting institution (dgg): Trent University
Abstract:

Depression during the transition into adulthood is a growing mental health concern, with overwhelming evidence linking the developmental risk for depressive symptoms with maternal depression. In addition, there is a lack of research on the protective role of socioemotional competencies in this context. This study examines independent and joint effects of maternal depression and trait emotional intelligence (TEI) on the longitudinal trajectory of depressive symptoms during emerging adulthood. A series of latent growth models was applied to three biennial cycles of data from a nationally representative sample (N=933) from the Canadian National Longitudinal Survey of Children and Youth. We assessed the trajectory of self-reported depressive symptoms from age 20 to 24 years, as well as whether it was moderated by maternal depression at age 10 to 11 and TEI at age 20, separately by gender. The results indicated that mean levels of depression declined during the emerging adulthood in females, but remained relatively stable in males. Maternal depressive symptoms significantly positively predicted depressive symptoms across the entire emerging adulthood in females, but only at age 20-21 for males. In addition, likelihood of developing depressive symptoms was attenuated by higher global TEI in both females and males, and additionally by higher interpersonal skills in males. Our findings suggest that interventions for depressive symptoms in emerging adulthood should consider development of socioemotional competencies.

Author Keywords: Depression, Depressive Symptoms, Emerging Adulthood, Intergenerational Risk, Longitudinal, Trait Emotional Intelligence

2020