Biological Sciences - Theses, Dissertations, and other Required Graduate Degree Essays

Receive updates for this collection

Investigating potential growth, behavioural, and reproductive effects of nestling exposure to methylmercury in Zebra Finches (Taeniopygia guttata)

Date created: 
2016-08-11
Abstract: 

Methylmercury is a widespread contaminant that has been shown in multiple studies to cause behavioural and reproductive effects on piscivorous birds. Previously, it was thought that non-aquatic birds (such as passerines) were not at risk for methylmercury toxicity. However, in recent years high blood mercury levels have been found in free-living passerines. In the current study, zebra finch (Taeniopygia guttata) chicks were treated with methylmercury during the nestling stage of early development to simulate exposure from food provisioning by the parents. Despite a dose response relationship shown in the blood mercury analyses, no effects of dose were found for growth, development, or behaviour of the chicks. No long-term effects were seen on male courtship and song or female reproductive success. The lack of treatment effects in these experiments indicates that the nesting stage may be less sensitive in passerines, possibly due the sequestration of mercury into growing feathers.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Tony Williams
John Elliott
Department: 
Science: Biological Sciences Department
Thesis type: 
(Project) M.E.T.

Elucidating the mechanism of action of a small molecule proteostasis regulator with potential relevance for treatment of the lysosomal storage disease, mucopolysaccharidosis I

Date created: 
2016-06-24
Abstract: 

The lysosomal storage disease Mucopolysaccharidosis I, involving lysosomal deficiency of α-L-iduronidase (IDUA), is often characterized by extensive ER-associated degradation (ERAD) of missense mutant IDUAs, folding variants which often retain residual activity. Compound X-372, identified from a plant cell-based screen of 1,040 FDA-approved drugs, enhanced the post-ER transport of ERAD-prone P533R-IDUA. Here, dose response studies of compound treatment on Nicotiana tabacum BY2 protoplasts, expressing human wild-type and ERAD-prone R383H-IDUA, not only validated the rescuing effect of X-372, but also indicated this effect occurred via augmenting a general cellular process. Microarray analysis and subsequent quantitative PCR validation of candidate genes showed that the therapeutic effect of X-372 was linked to augmented sulfur assimilation. Reduced glutathione - a product of the sulfur assimilation pathway that is also a potent cellular antioxidant – is a target for future studies to identify the specific means by which X-372 enhances the post-ER transport of ERAD-prone folding mutants.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Allison Kermode
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Microtubule associated protein END BINDING 1b: functional domain deletions and root responses to mechanical stimuli

Author: 
Date created: 
2016-05-16
Abstract: 

The microtubule-associated protein EB1b inhibits root responses to mechanical stimulation. The goal of this study was to understand more clearly how EB1b regulates these responses. Loss of EB1b did not alter root elongation rates in response to mechanical cues. However, overexpressing EB1b had an inhibitory effect on root elongation. Mutant eb1b-1 Arabidopsis plants expressing truncated EB1b proteins, with and without GFP fusions, were generated. Truncations included both N-terminal (microtubule-binding) and C-terminal (protein-interaction) domains. Transgenic mutants expressing a truncated version of EB1b missing part of the C-terminal domain were analyzed. The responses of these mutant roots to mechanical stimulation was similar to untransformed eb1b-1 mutants. Since previous analyses have shown that responses of mutants expressing full-length EB1b are equivalent to wild type, this result indicates that the EB1b C-terminus is required for normal regulation of root responses to mechanical cues and that interactions between EB1b and other, non-tubulin proteins is involved.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Sherryl Bisgrove
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Genetic analysis of the role of the OsARF11 gene in rice development

Date created: 
2016-07-25
Abstract: 

Based on sequence similarity to the well-studied Arabidopsis thaliana MP/ARF5 gene, we hypothesized that the Oryza sativa Auxin Response Factor 11 (OsARF11) gene is a prime candidate for auxin-signaling mediated development in rice. Here we describe characterizations of two independent insertion mutants in the OsARF11 gene. Our results reveal that homozygous plants of both allelic mutants have reduced shoot and root growth and produce fewer seeds compared to wild type plants grown under the same growth conditions. In addition, the number of leaf veins per leaf and per unit leaf width is reduced, as is the width of leaf mid veins. Taken together, the results demonstrate for the first time that OsARF11 contributes to plant growth, fecundity, and the regulation of leaf vein patterning in rice. The results also suggest that OsARF11 may be a suitable target for breeding on these traits.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Jim Mattsson
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Habitat-specific breeding performance and cavity dynamics of Lewis's Woodpeckers (Melanerpes lewis) in British Columbia

Author: 
Date created: 
2016-06-28
Abstract: 

Lewis’s Woodpeckers (Melanerpes lewis) are Threatened in Canada and rely on pre-existing cavities for nesting. I studied how cavity density, competition, and predators influence Lewis’s Woodpecker breeding performance across three habitats in British Columbia, and investigated the broad-scale patterns of nest tree persistence and reuse over time. I found that Lewis’s Woodpecker breeding performance was high in riparian cottonwood habitat, moderate in live pine, and lowest in crown-burned pine habitat. Cavity density explained habitat-based breeding performance. Nest tree persistence was generally high, but declined over time, and while nest tree reuse varied dramatically across years, there was no consistent temporal pattern. Our results suggest that 1) resource managers should use regionally-specific data for managing Lewis’s Woodpecker populations, and 2) cavities may be a limiting factor for the recovery of Lewis’s Woodpecker populations in Canada, particularly in regions where nest tree persistence is lower and may not support recruitment.

Document type: 
Thesis
File(s): 
Senior supervisor: 
David Green
Nancy Mahony
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Contributions to the foraging ecology of house flies, Musca domestica L.

Date created: 
2016-05-26
Abstract: 

Attract-and-kill tactics for control of house flies (Musca domestica) often use foraging cues as attractants. To investigate foraging resources for indoor attraction of house flies, I tested the response of flies to various human foods and a floral resource. In two-choice laboratory bioassays, only dandelion flowers and dandelion honey attracted flies. Analytical attempts to capture the essential semiochemicals from these resources failed, highlighting the need to develop alternative approaches. Another potentially effective foraging cue is the “fly factor”, the phenomenon that food currently or previously fed on by flies attracts more flies than the same type of food kept inaccessible to flies. In two-choice laboratory bioassays, I demonstrate that the fly factor exists in house flies. Of the mechanisms tested potentially causing the fly factor, only fly feces and regurgitate attract flies. Attraction of flies to fly feces and regurgitate indicates that flies sense airborne semiochemicals emanating from these sources.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Gerhard Gries
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.P.M.

The habitat association of bats in the South Okanagan Valley, British Columbia, Canada: Radar-acoustic surveys to assess the use of vineyards by insectivorous bats (Vespertilionidae)

Date created: 
2016-04-15
Abstract: 

British Columbia’s South Okanagan has an expanding wine industry and supports the greatest diversity of bats in Canada. I surveyed bat activity in six matched pairs of vineyards and adjacent natural sagebrush habitats during the summer of 2013 using a unique radar-acoustic system, which I described and evaluated. By evaluating the characteristics of radar tracks and combining radar and acoustic data, I was able to compare bat activity over the habitats. Target parameters (height, speed, and relative size measured as Signal-to-Noise Ratio) had similar distributions in both habitats. There was no statistical difference between habitats in mean target track length per unit area or in the mean number of acoustic ‘individual bat passes’, nor did these measures differ between surveys in early (bat pregnancy and parturition), middle (lactation) and late summer (pup fledging). My results suggest that the amount of bat activity over vineyards and natural habitats is similar; however the use of habitat by bat species differs.

Document type: 
Thesis
Senior supervisor: 
Ronald Ydenberg
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Patterns in winter site fidelity and polycyclic aromatic hydrocarbon exposure risk in Barrow’s goldeneye (Bucephala islandica) in the Pacific Northwest

Date created: 
2016-04-08
Abstract: 

Species inhabiting coastal areas can serve as indicators of marine pollution. Hydrocarbons occur naturally in marine ecosystems and wildlife have evolved detoxification systems to manage hydrocarbon exposure. Human activities may increase hydrocarbons in the environment, to the extent that they may be detrimental to biota. Elevated hydrocarbon exposure can be measured directly as increased concentrations in some species, or through biomarkers of active detoxification systems. I found that cytochrome P4501A induction in liver tissue of Barrow’s goldeneyes (Bucephala islandica) and polycyclic aromatic hydrocarbon (PAH) concentration in their winter prey, blue mussels (Mytilus spp.) were correlated across coastal sites in British Columbia, despite generally low PAH concentrations. Using satellite telemetry, I determined that winter movements of Pacific goldeneyes were small, indicating that biomarkers reflected local hydrocarbon levels. These results indicate that the mussel – goldeneye system is useful for evaluating contemporary marine hydrocarbon contamination and recovery endpoints in the event of spills.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Ronald Ydenberg
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

The Functional Significance of Variation in Hematological Traits that Determine Aerobic Capacity

Date created: 
2016-03-29
Abstract: 

A principal aim of evolutionary physiology is to understand how physiological variation affects the fitness and distribution of organisms. Physiological traits underlie performance, behavior, and life histories and exhibit variation at every taxonomic level. Studies within and between species can reveal whether variation in a physiological trait is currently, and/or was historically, functionally significant. Intraspecific variation is regarded as the raw material on which selection acts, and studying it in relation to measures of fitness can help identify the targets of selection that underlie life history strategies. Comparing interspecific variation with ecological factors can help clarify whether the physiological variation was either shaped by adaptation in response to different selective pressures or influenced differences in habitat and life histories.Traits related to energy expenditure are believed to play a principal role in shaping the evolution of life histories. Hematocrit, the percent of red blood cells per unit volume of blood is a measure of an individual’s oxygen carrying potential and therefore is pivotal in determining endurance. Given that birds show extensive variation in hematocrit within and between species and that flight imposes high energetic costs, variation in hematocrit in birds is likely to be functionally significant. I used observational, experimental, and comparative approaches to investigate the functional significance of intraspecific and interspecific hematocrit variation in birds. Intraspecific hematocrit variation could influence fitness if it plays a role in regulating eggshell colouration or by limiting physical endurance, thereby shaping reproductive decisions. Experimental manipulation of hematocrit in free-living European starlings provided no evidence that hematocrit variation affects eggshell coloration. However, natural and experimental variation in hematocrit influenced fitness measures, suggesting that hematocrit variation, if heritable, is acted upon by natural selection. Comparative analyses indicated that hematocrit variation across passerines was related to habitat altitude, latitude and migration, suggesting adaptive or exaptive significance. Overall, the results suggest that variation in hematocrit within and between avian species is functionally significant. Such studies can help to understand population dynamics, demography, biodiversity, and responses to climate change.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Julian Christians
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.

Inhibition of Caffeine Metabolism in Humans by Furanocoumarin-Containing Plant Extracts: In Vivo and In Vitro Studies

Date created: 
2016-04-25
Abstract: 

Caffeine is found at high concentrations in tea, coffee, soft drinks and energy drinks. Daily consumption of caffeinated beverages is considered to be safe but adverse health effects and deaths have been reported in sensitive or overdosed individuals. A variety of furanocoumarin bioactive has been identified in fruits, spices and herbs from plants in the Apiaceous and Rutaceae families. Since caffeinated beverages are often consumed with food, and both are metabolized by the same CYP1A2 enzyme, we hypothesized metabolic inhibition between caffeine and furanocoumarin-containing food or herbs are common in humans. The goals of this thesis were: (a) to compare the pharmacokinetics of caffeine in humans before and after pre-treatment with a furanocoumarin-containing herb, (b) to elucidate the mechanism(s) of caffeine-herb interaction using in vitro incubations containing pure furanocoumarins and human liver microsomes (HLMs), and (c) to predict in vivo herb-caffeine interactions for humans based on in vitro caffeine metabolism data and in vivo furanocoumarin inhibitor concentrations in the liver.Chapter 1 of this thesis is a brief introduction of caffeine and furanocoumarin-containing food and herbs. In chapter 2, major furanocoumarin bioactives in 29 food and herbs are identified and quantified using gas chromatography mass spectrometry and high performance liquid chromatography. Chapter 3 describes the pharmacokinetics of caffeine in humans after administering 200 mg of caffeine orally before and after pre-treatment with an herbal extract. Caffeine clearance in the volunteers decreased 33.7-77.3% with concomitant increases in area-under-the-concentration-time curve after oral consumption of Ammi majus L., Angelica archangelica L., Angelica pubescens Maxim, Cnidium monnieri (L.) Cusson, or Ruta graveolens L. Chapter 4 provides the experimental evidence for irreversible adduct formation between 14C-labeled 8-methoxypsoralen and HLMs. Moreover, the observed caffeine-herb interaction in humans is best explained by mechanism-based inhibition of CYP1A2 enzyme. Chapter 5 demonstrated the use of in vitro-in vivo drug-drug interaction models and an integrated furanocoumarin dose/concentration to predict in vivo furanocoumarin-caffeine herb interaction in humans. Chapter 6 summarizes the conclusions of this thesis. The experimental and modeling approaches described in this study are also useful in predicting in vivo interactions between prescription drugs and dietary supplements or functional food.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Francis Law
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.