Life Sciences Commons^™

Population And Evolution Dynamics In Predator-Prey Systems With Anti-Predation Responses, Yang Wang

Electronic Thesis and Dissertation Repository

This thesis studies the impact of anti-predation strategy on the population dynamics of predator-prey interactions. This work includes three research projects.

In the first project, we study a system of delay differential equations by considering both benefit and cost of anti-predation response, as well as a time delay in the transfer of biomass from the prey to the predator after predation. We reveal some insights on how the anti-predation response level and the biomass transfer delay jointly affect the population dynamics; we also show how the nonlinearity in the predation term mediated by the fear effect affects the long term ...

Hiv-1 Drug Resistance To Integrase Strand Transfer Inhibitors In Hiv-1 Non-B Subtypes, Emmanuel Ndashimye

Electronic Thesis and Dissertation Repository

Human immunodeficiency syndrome (HIV-1) has infected over 75 million people and over 35 million have succumbed to virus related illnesses. Despite access to a variety of antiretroviral therapy (ART) options, ART programs have been disproportionally spread in the world with low-and middle-income countries (LMICs) facing challenges to access the most potent ART options. With less potent ART remaining in use in LMICs, HIV-1 drug resistance (HIVDR) presents a growing challenge in LMICs. Since approval of the first-generation integrase strand transfer inhibitor (INSTIs), Raltegravir (RAL) in 2007, INSTIs remain the best choice as a backbone of ART. Access to second generation ...

Post-Activation Potentiation Induced By Concentric Contractions At Three Speeds In Humans, Alexander Zero

Electronic Thesis and Dissertation Repository

Post-activation potentiation (PAP) is the acute enhancement of contractile properties following a short duration (<10s) high intensity contraction. Compared with isometric contractions, little is known about the PAP response induced by concentric conditioning contractions (CCs) and the effect of contractile speeds. In the dorsiflexors of 10 participants, twitch responses were measured following 5s of maximal effort concentric CCs at each of 10, 20 and 50°/s. Concentric PAP responses were compared to a maximal isometric voluntary contraction (MVC) matched for contraction time. Additionally, concentric CCs were compared to isometric CCs matched for mean torque, contraction area and time. The principal finding was that the PAP response following maximal concentric CCs was independent of contractile speed and, there was no difference in the PAP response between concentric CCs and an isometric MVC. Maximal contractions, regardless of contraction modality, likely produce sufficient Ca²⁺ to induce a full PAP response, and thus there was no difference between speeds or contraction type. Concentric CCs had significantly larger peak twitch torque than their isometric torque matches (49-58%), and faster maximal rates of torque development at the three speeds (62-77%). However, these responses are likely related to greater muscle activation (EMG), and not contraction modality per se. Thus, PAP responses following maximal concentric CCs are not affected by velocity and responses are not different from an isometric MVC. This indicates maximal CCs ...

Ischemic Stroke Thrombus Characterization Through Quantitative Magnetic Resonance Imaging, Spencer D. Christiansen

Electronic Thesis and Dissertation Repository

Stroke is a pervasive, devastating disease and remains one of the most challenging conditions to treat. In particular, risk of recurrence is dramatically heightened after a primary stroke and requires urgent preventative therapy to effectively mitigate. However, the appropriate preventative therapy depends on the underlying source of the stroke, known as etiology, which is challenging to determine promptly. Current diagnostic tests for determining etiology underwhelm in both sensitivity and specificity, and in as much as 35% of cases etiology is never determined. In ischemic stroke, the composition of the occluding thrombus, specifically its red blood cell (RBC) content, has been ...

The International Scientific Association For Probiotics And Prebiotics (Isapp) Consensus Statement On Fermented Foods, Maria L. Marco, Mary Ellen Sanders, Michael Gänzle, Marie Claire Arrieta, Paul D. Cotter, Luc De Vuyst, Colin Hill, Wilhelm Holzapfel, Sarah Lebeer, Dan Merenstein, Gregor Reid, Benjamin E. Wolfe, Robert Hutkins

Microbiology & Immunology Publications

An expert panel was convened in September 2019 by The International Scientific Association for Probiotics and Prebiotics (ISAPP) to develop a definition for fermented foods and to describe their role in the human diet. Although these foods have been consumed for thousands of years, they are receiving increased attention among biologists, nutritionists, technologists, clinicians and consumers. Despite this interest, inconsistencies related to the use of the term ‘fermented’ led the panel to define fermented foods and beverages as “foods made through desired microbial growth and enzymatic conversions of food components”. This definition, encompassing the many varieties of fermented foods, is ...

Sexual Dimorphism In Response To Repetitive Bouts Of Acute Exercise In Rodents With Type 1 Diabetes Mellitus, Jordan C. Larocque

Electronic Thesis and Dissertation Repository

The purpose of this study was to examine sex-specific differences in the blood glucose (BG) response to recurrent aerobic exercise in type 1 diabetes. Specifically, we examined the role of peak estrogen (E2) concentrations during proestrus on BG response to prolonged aerobic exercise. To do so, nineteen Sprague-Dawley rats were assigned to four exercised groups: control female (CXF; n = 5), control male (CXM; n = 5), diabetic female (DXF, n = 5) and diabetic male (DXM, n = 4). Diabetes was induced in DX groups via subcutaneous injection of low dose streptozotocin. After four days of exercise, liver glycogen and BG responses were ...

Recognizing Parasport Impacts: Ripples, Waves, And Echoes, Adam J. Purdy

Electronic Thesis and Dissertation Repository

Major Games such as the 2015 Parapan American Games in Toronto (TO2015) generate the potential to bring awareness to sport participation opportunities for people with impairment (Chalip et al, 2017). In the post-games era, it is important to examine the ways in which sport program managers recognize the outcomes of games-related leveraging initiatives. Teleconference interviews were conducted with twelve program managers in the Greater Toronto Area. The study followed an interpretive descriptive methodology and employed a theoretical construct of recognition as a novel approach to assess the legacy and social impacts of hosting parasport games. A form of thematic analysis ...

Effects Of Gene-Environment Interactions On The Evolution Of Social Behaviours, Vonica J. Flear

Electronic Thesis and Dissertation Repository

Inclusive fitness models in sociobiology emphasize the importance of relatedness, R, and synergy, S when exploring the evolution of social behaviours. Very few models explicitly consider ‘role’, or environmental stimuli, influencing the expression of behaviours, and none consider genetic-environment interactions where genotype predisposes individuals to certain roles. I propose a third key variable for inclusive fitness models, Q, which describes the overlooked potential bias in the genetic composition of individuals exposed to an environmental stimulus – here referred to as ‘role’. I describe a model built from Price’s formula which can be presented in a ‘Hamilton’s Rule’ format. I ...

Evaluating Anesthetic Protocols For Non-Human Primate Functional Neuroimaging, Megha Verma

Electronic Thesis and Dissertation Repository

Functional magnetic resonance imaging (fMRI) is a non-invasive technique that can be used to measure a proxy of neural activity in vivo with high spatial specificity. One subject can be followed for a long period of time to assess changes in functional brain organization. However, fMRI is extremely sensitive to motion. The challenges of training non-human primates to reduce motion in an MRI scanner motivate the study of anesthesia which is commonly used to substitute for this training. In this thesis, I compare three different commonly used anesthetic protocols: isoflurane, propofol-fentanyl in combination, and fentanyl alone, to test which of ...

Is Motor Excitability Modulated By Isochronous Rhythms?, Syed Z. Raza

Electronic Thesis and Dissertation Repository

Humans perceive and synchronize to regularity in auditory temporal sequences. Auditory regularity activates motor areas, but how the timing of motor responses relates to the regularity is unclear. Thus, we examined whether motor excitability, an index of motor activity, fluctuated to an isochronous sequence and characterized the timing of these fluctuations. Participants heard isochronous tones followed by a short silence, during which they imagined the tones continuing. Using single pulse transcranial magnetic stimulation (TMS), we indexed excitability throughout the sequence. Cosine models were fit to constructed excitability timecourses to quantify periodicity of the excitability fluctuations. Motor excitability did not fluctuate ...

The Role Of Gsk3 Alpha And Beta In Embryonic Craniofacial Development, Harman Jassar

Electronic Thesis and Dissertation Repository

Background: The GSK-3 genes (Gsk3a and Gsk3b) have been known to affect many cellular processes and signaling pathways some of which are implicated in the growth and development of the craniofacial skeleton.

Aim: The purpose of this study was to assess the effect of chondrocyte-specific deletion of Gsk3a and Gsk3b on the size of the mandible and craniofacial skeleton in embryonic mice.

Materials & Methods: Mice were bred to generate cartilage-specific Gsk3a and Gsk3b KO mice. On embryonic day 18.5 (E18.5) the offspring were gathered by caesarian section. Whole mount skeletal staining was completed on the specimens using Alcian ...

Impact Of Extremely Low-Frequency Magnetic And Electric Stimuli On Vestibular-Driven Outcomes, Nicolas Bouisset

Electronic Thesis and Dissertation Repository

The vestibular system is extremely sensitive to electric fields (E-fields). Indeed, vestibular hair cells are graded potential cells and this property makes them very susceptible to small membrane potential modulations. Studies show that extremely low-frequency magnetic fields (ELF-MF) induced E-fields impact postural control in which the vestibular system plays an important role. However, the knowledge of whether this is indeed a vestibular specific effect is still pending.

Considering its crucial role and the specific neurophysiological characteristics of its hair cells, the vestibular system emerges as an ELF-MF likely target

The three studies presented in this thesis aimed to further address ...

Investigating The Impact Of Environmentally Relevant Imidazole Concentrations On The Antifungal Susceptibility And Community Composition Of Soil Fungi, Farhaan Kanji

Electronic Thesis and Dissertation Repository

Miconazole and clotrimazole are environmentally-persistent drugs that are entrained into crop soils through the application of biosolids. There is concern that environmental exposure to such azole antifungals, which inhibit fungal growth by disrupting the production of the fungal cell membrane component ergosterol, promotes resistance in clinically or agriculturally relevant fungi. Thus, either environmentally-relevant or excessive levels of these drugs were applied to microplots over ten years and compared with drug-free plots. Overall, ergosterol quantification, plates counts, and identification of >250 fungal isolates showed lower fungal counts and species richness in plots receiving excessive drug amounts. In addition, fungi from treated ...

The Genetic Determinants Of Complex Lipid And Lipoprotein Phenotypes, Jacqueline S. Dron

Electronic Thesis and Dissertation Repository

Cardiovascular disease (CVD) is the primary cause of death globally and is estimated to cause one-third of deaths in Canada. Each year, millions of Canadians are affected by CVD despite ongoing efforts to reduce risk through lifestyle modifications and pharmacological therapies. With the expected rise in CVD prevalence due to the obesity epidemic, we need to better understand the genetic basis of heritable, modifiable risk factors, including levels of high-density lipoprotein (HDL) cholesterol and triglyceride, for insights into future therapeutic treatments and risk prediction. Through the use of a targeted next-generation sequencing panel designed specifically to study lipid and metabolic ...

Perspectives Of Canadian University Coaches On Integrating Sport Psychology And Mental Performance Consultants In Varsity Programs, Federico Cisneros Sánchez

Electronic Thesis and Dissertation Repository

Recently, sport psychology has become a more popular resource for athletes and coaches when looking to increase performance. It is unknown how many Canadian universities utilize sport psychology services in their athletic programs. Semi-structured interviews were conducted with coaches of Canadian university varsity teams to learn about their opinions on sport psychology and mental performance consultants (MPCs). The research was approached from a pragmatic perspective. Results showed that MPCs are important to enhance performance and provide mental health resources. MPCs provide athletes with personal and leadership development, mental skills training, and mental health support. MPCs can also be a resource ...

Pathway‐Extended Gene Expression Signatures Integrate Novel Biomarkers That Improve Predictions Of Patient Responses To Kinase Inhibitors, Ashis Bagchee‐Clark, Eliseos J. Mucaki, Tyson Whitehead, Peter Rogan

Biochemistry Publications

Cancer chemotherapy responses have been related to multiple pharmacogenetic biomarkers, often for the same drug. This study utilizes machine learning to derive multi‐gene expression signatures that predict individual patient responses to specific tyrosine kinase inhibitors, including erlotinib, gefitinib, sorafenib, sunitinib, lapatinib and imatinib. Support vector machine (SVM) learning was used to train mathematical models that distinguished sensitivity from resistance to these drugs using a novel systems biology‐based approach. This began with expression of genes previously implicated in specific drug responses, then expanded to evaluate genes whose products were related through biochemical pathways and interactions. Optimal pathway‐extended SVMs ...

Targeting Cd5 To Enhance Immune T Cell Activation And Function In Treatment Of Solid Tumours, Faizah Alotaibi

Electronic Thesis and Dissertation Repository

CD5 is a member of scavenger receptor cysteine-rich superfamily that is expressed primarily on T cells. It can attenuate T-cell receptor signaling and impair cytotoxic T lymphocyte (CTL) activation and is a therapeutic targetable tumour antigen expressed on leukemic T and B cells. However, the potential therapeutic effect of functionally blocking CD5 to increase T cell anti-tumour activity against tumours (including solid tumours) has not been explored. CD5^- solid tumours in CD5 knockout mice display increased in anti-tumour immunity. Hence, blocking CD5 function may have a potential therapeutic effect by enhancing CTL function. Here, I assessed CD5 levels in T ...

The Impact Of Impacts: Repetitive Head Impact Exposure In Canadian University Football Players, Jeffrey S. Brooks

Electronic Thesis and Dissertation Repository

Due to the physical nature of the game and repeated head impacts between players each play, the sport of football has one of the highest incidence rates of concussion. With nearly two million participants, this incidence rate translates to a reserved estimate of 100,000 concussions per year due to the contact nature of the sport. Injury thresholds have proven difficult to establish, so American football concussion research has shifted focus to measuring the accumulation of repetitive head impacts. As there are numerous rule differences between Canadian and American football, head impact exposure may present differently for Canadian players. Accordingly ...

Examining The Structure Of Symbolic Number Representations In The Parietal Cortex: An Rsa Study, Aymee Alvarez Rivero

Electronic Thesis and Dissertation Repository

Previous studies using fMRI adaptation to investigate the neural substrate of symbolic number processing have found ratio-dependent responses in regions of the parietal cortex, suggesting that number symbols are coded by overlapping neuronal populations: the larger the ratio between two numerals, the more their representation overlap. The current study analyzed the distributed patterns of activation associated with numerals presented during this task. I could not find substantial evidence supporting the ratio-dependent structure of the similarity space predicted by the univariate adaptation analyses. I also failed to find evidence in favor of the alternative model that similarities were driven by lexical ...

Pathway-Extended Gene Expression Signatures Integrate Novel Biomarkers That Improve Predictions Of Patient Responses To Kinase Inhibitors, Jem Bagchee-Clark, Eliseos J. Mucaki, Tyson Whitehead, Peter Rogan

Biochemistry Publications

Cancer chemotherapy responses have been related to multiple pharmacogenetic biomarkers, often for the same drug. This study utilizes machine learning to derive multi-gene expression signatures that predict individual patient responses to specific tyrosine kinase inhibitors, including erlotinib, gefitinib, sorafenib, sunitinib, lapatinib and imatinib. Support Vector Machine learning was used to train mathematical models that distinguished sensitivity from resistance to these drugs using a novel systems biology-based approach. This began with expression of genes previously implicated in specific drug responses, then expanded to evaluate genes whose products were related through biochemical pathways and interactions. Optimal pathway-extended support vector machines predicted responses ...

Pathway-Extended Gene Expression Signatures Integrate Novel Biomarkers That Improve Predictions Of Patient Responses To Kinase Inhibitors, Ashis Jem Bagchee-Clark, Eliseos J. Mucaki, Tyson Whitehead, Peter Rogan

Biochemistry Publications

No abstract provided.

Understanding Physical Activity Behaviour In Ontario, Canada: A Cross-Sectional Cohort Analysis Of Carrot Rewards App Users, David D. Mchugh

Electronic Thesis and Dissertation Repository

Little device-measured data are available to describe the physical activity (PA) of rural-dwelling individuals living with chronic disease. PURPOSE: From accelerometer data collected using a smartphone app (‘Carrot Rewards’), we sought to provide mean daily step counts for app users in general and by age and gender for those living in rural/urban areas and those self-reporting a chronic disease or not. METHODS: This cross-sectional cohort study used device-assessed data from Ontario app users (i.e., PA data collected over a 7-day period for each user) who completed an in-app chronic disease survey from December 2018 to April 2019. A ...

Functional Characterization Of Vesicular Trafficking Genes In The Midgut Of Tetranychus Urticae Via Rna Interference, Sean Pham

Electronic Thesis and Dissertation Repository

The two-spotted spider mite Tetranychus urticae is a polyphagous agricultural pest of economic importance. Previous studies have established that reduced gene expression of COPB2, SNAP-α, and V-ATPase genes with RNAi and lowers both the survivorship and fecundity of T. urticae. A visible phenotype was also associated with changes to the digestive cells of the midgut after treatment. Serial sections of paraffin embedded RNAi treated mites to determine the changes caused by the transcriptional silencing of the three focal genes. COPB2 silencing leads to a significant increase in the number of juvenile digestive cells, while SNAP-α and V-ATPase silencing caused dysfunctional ...

Elucidating The Consequence And Cause Of Microrna Dysregulation In Amyotrophic Lateral Sclerosis (Als), Zachary C. E. Hawley

Electronic Thesis and Dissertation Repository

Amyotrophic Lateral Sclerosis (ALS) is a progressive motor neurodegenerative disorder with an average life expectancy of 2-5 years post-diagnosis. Common pathological features associated with ALS are the formation of cytoplasmic inclusions of intermediate filaments and RNA-binding proteins within motor neurons. The formation of intermediate filament cytoplasmic inclusions is believed to be driven by a loss of stochiometric expression between five neuronal intermediate filament proteins—NFL, NFM, NFH, INA and PRPH—where there is a selective suppression of the steady-state levels of NEFL, INA and PRPH mRNA. Further, three RNA-binding proteins—TDP-43, FUS and RGNEF—have been shown to co-aggregate with ...

Genetic Basis Of Hybrid Sterility Between Drosophila Pseudoobscura And D. Persimilis, Alannah J.P. Mattice

Electronic Thesis and Dissertation Repository

Speciation is the underlying process that leads to formation of new species, and therefore is the basis of biodiversity. Genes involved in each stage of speciation, such as those involved in interspecies sterility, remain elusive. Male hybrid sterility and postzygotic isolation between Drosophila pseudoobscura and D. persimilis was examined in this study through backcrossing of female hybrids into each parental line (introgression), selecting for a sterile sperm phenotype, needle-eye sperm. Sperm phenotypes did not separate through backcrossing; instead, males presented with multiple sperm phenotypes. A relationship between the phenotypes observed and the potential genes involved was examined through whole genome ...

Pan-Cancer Analysis Of Telomerase Reverse Transcriptase (Tert) Isoforms, Mathushan Subasri

Electronic Thesis and Dissertation Repository

Reactivation of the multi-subunit ribonucleoprotein telomerase is the primary telomere maintenance mechanism in cancer, but it is rate-limited by the enzymatic component, telomerase reverse transcriptase (TERT). While regulatory in nature, TERT alternative splice variant/isoform regulation and functions are not fully elucidated and are further complicated by their highly diverse expression. In this thesis, I characterized TERT expression across normal and neoplastic tissues using TCGA and GTEx RNA-sequencing data. In doing so, I demonstrated the global overexpression and splicing shift towards full-length TERT in neoplastic tissue. Furthermore, my studies identified tumour subtype expression differences possibly regulated by subtype-specific characteristics, detailed ...

Computational Unfolding Of The Human Hippocampus, Jordan M. K. Dekraker

Electronic Thesis and Dissertation Repository

The hippocampal subfields are defined by their unique cytoarchitectures, which many recent studies have tried to map to human in-vivo MRI because of their promise to further our understanding of hippocampal function, or its dysfunction in disease. However, recent anatomical literature has highlighted broad inter-individual variability in hippocampal morphology and subfield locations, much of which can be attributed to different folding configurations within hippocampal (or archicortical) tissue. Inspired in part by analogous surface-based neocortical analysis methods, the current thesis aimed to develop a standardized coordinate framework, or surface-based method, that respects the topology of all hippocampal folding configurations. I developed ...

Characterizing The Diversity Of The Eukaryotic Microbiome In Marine Crustacean Zooplankton., Rose-Lynne Savage

Electronic Thesis and Dissertation Repository

Understanding zooplankton productivity is critical for modeling marine food web function, of which one poorly known factor is the influence of zooplankton symbionts. Zooplankton protist symbiont diversity is underestimated due to the limited surveys and techniques previously used. Using 18S V4 metabarcoding, I characterized the eukaryotic microbiomes associated with crustacean zooplankton from the northern Strait of Georgia, BC. Apostome ciliates were most abundant in all hosts except for cyclopoid copepods, which were dominated by Syndiniales. Most symbiont lineages were more abundant in one or two hosts, suggesting some degree of host preference. Microbiome data also provided information on diet, confirming ...

Cognitive Resources Are Recruited Consistently Across People During Story Listening, Matthew T. Bain

Electronic Thesis and Dissertation Repository

Degraded speech encoding as a result of hearing loss increases cognitive load and makes listening effortful. Standard hearing assessment does not capture this cognitive impact of hearing impairment. Speech-in-noise testing measures intelligibility for isolated sentences that are typically not engaging and lack meaningful context. These materials may not capture the processes involved in everyday listening situations, in which people are often intrinsically motivated to comprehend the speech they are hearing. The current study explored a novel approach using natural, spoken stories. We first characterized time courses of executive load during story listening in young individuals with normal hearing using a ...

Reactive Oxygen Species Damage And Consequences For Mitochondrial Function In The Hibernating Thirteen-Lined Ground Squirrel, Ictidomys Tridecemlineatus, Brynne Duffy

Electronic Thesis and Dissertation Repository

Hibernators experience changes in blood flow, similar to ischemia-reperfusion injury, which may lead to oxidative damage. I hypothesized that suppression of mitochondrial metabolism during hibernation protects against such damage. I compared oxidative damage and antioxidant capacity in tissues and isolated liver mitochondria among summer, torpid, and interbout euthermic thirteen-lined ground squirrels (TLGS). I found less oxidative tissue damage during summer than hibernation, but no mitochondrial differences. I also compared metabolic activity of isolated mitochondria before and after five minutes of anoxia, followed by reoxygenation, among hibernation states and rats. Anoxia-reoxygenation decreased state-three respiration (ST3) in all groups, with rat mitochondria ...