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Understanding Mechanisms Underlying Changes In Parental Care Behaviour In Response To Perceived Paternity In Sunfish, Emma Churchman

Electronic Thesis and Dissertation Repository

Parental care is essential for the survival of many young animals but presents significant costs to the caring parent. To mitigate these costs, parental care systems have evolved to optimize survival and fitness. According to parental investment theory, care allocation is influenced by the offspring’s value, which is often linked to their relatedness to the parent. In this thesis, I explore how hormones and gene expression influence parental care, focusing on bluegill sunfish (Lepomis macrochirus) and the hybrids they produce with pumpkinseed sunfish (Lepomis gibbosus). By manipulating direct and indirect paternity cues – swapping eggs between …

Elucidating The Relationships Between Spider Size, Joint Stiffness, And The Mechanical Frequency Response Of The Body, Reese L. Gartly

Electronic Thesis and Dissertation Repository

Spiders use vibrations to sense their surroundings. It has been suggested that the vibration perception in spiders may be altered by the mechanics of the body. I studied the biomechanics of spiders, at the level of leg joints and the whole body. To study joints, I quantified the allometry of leg joint stiffness in spiders. I found that the stiffness of spider joints increased nearly isometrically with increasing body mass, partly by having shorter and thicker leg segments and also by other unknown means. Using these data, I developed empirically validated biomechanical models which predicted the effects of mechanics on …

Sex Comparisons Of External, Anatomical And Methodological Factors On Motor Unit Firing Behavior, Michael James Marsala

Electronic Thesis and Dissertation Repository

Motor unit (MU) recruitment and firing rate (MUFR) modulation are the primary factors governing force control. Differences in the anatomical distributions of α-motoneurons, muscle properties, and perception of fatigue between males and females may cause sexually dimorphic MU firing behaviors. The purpose of this dissertation was to further examine external, anatomical, and methodological factors that may influence observations of sex-related differences in neuromuscular function. In chapter 2, sex differences in how mental fatigue may influence MU firing behaviors were examined. Mental fatigue did not significantly alter MU firing behavior, maximal force, or force tracing ability in either males or females. …

Investigating Task-Free Functional Connectivity Patterns In Newborns Using Functional Near-Infrared Spectroscopy, Homa Vahidi

Electronic Thesis and Dissertation Repository

Robust functional connectivity in sensorimotor resting-state network (RSN) has been linked to positive neurodevelopmental outcomes in neonates. In the current study, we aimed to map the developmental trajectory of sensorimotor RSN in awake neonates using functional near-infrared spectroscopy (fNIRS). We acquired fNIRS resting-state data from 41 healthy newborns (17 females, gestational age range=36+0 to 42+1 weeks) within the first 48 hours after birth. At the group level, we observed robust positive connectivity in numerous channel-pairs across the sensorimotor network, especially in the left hemisphere. Next, we examined the relationship between functional connectivity, gestational age and postnatal age, while controlling for …

Differential Migration Timing And The Form And Function Of Avian Wings, Jessica E. Deakin

Electronic Thesis and Dissertation Repository

A common differential migration strategy in birds is protandry, whereby males arrive earlier than females. The probable causes of protandry are well studied from the perspective of innate and physical environmental cues, but the influence of the social environment and wing morphology are less known. Theoretical models propose that sex ratio influences protandry; male-biased sex ratios are predicted to advance timing in males due to increased intrasexual competition. To empirically test this, I investigated the spring migration traits of male Yellow-rumped Warblers Setophaga coronata under differing sex ratios. An integrated automated telemetry approach was used, where locomotor movement of captive …

Neural Responses To Magnetic Orientation Information In Songbirds, Madeleine Ir Brodbeck

Electronic Thesis and Dissertation Repository

Effective navigation and orientation is essential for animals to survive. The study of migratory birds provides insights into these processes, particularly through mechanisms like the geomagnetic compass, which uses Earth's magnetic field for directional information. A brain region in songbirds relevant to this is cluster N, known for its potential role in processing geomagnetic information. Notably, cluster N appears exclusive to nocturnally migratory birds, being active solely at night, and lesion studies reveal that an intact cluster N is necessary for geomagnetic compass orientation. However, given the scarcity of empirical data concerning cluster N, substantial questions persist regarding its function. …

Acetylation Regulates Thioredoxin Reductase Activity And Oligomerization, David E. Wright

Electronic Thesis and Dissertation Repository

The Thioredoxin (Trx) system provides the cell with robust defense against oxidative stress and regulates the function of nearly every cellular process through the reduction-oxidation (redox) regulation of proteins. The Trx system is involved in the development of many diseases ranging from cancer to cardiovascular disorders. Thioredoxin reductase (TrxR) is the key enzyme in the Trx system and contains the 21^st genetically encoded amino acid, selenocysteine (Sec). There were multiple experimentally identified TrxR acetylation sites with an unknown effect on TrxR activity. My thesis tested the hypothesis that programmed protein acetylation will enhance the activity of TrxR1. I used …

Short-Term Versus Long-Term Effects Of Nitrogen Addition And Warming On Ecosystem N Dynamics In A Grass-Dominated Temperate Old Field, Benjamin F. A. Souriol

Electronic Thesis and Dissertation Repository

Increased atmospheric nitrogen (N) deposition and climate warming are both anticipated to influence the ecosystem N dynamics of northern temperate ecosystems substantially over the next century. Nevertheless, in field experiments with N addition and warming treatments, temporal scale can play an important role in determining the extent of treatment effects on N dynamics, and it is unclear to what extent the results of short-term studies can be extrapolated to responses over longer time scales. I compared the short-term versus long-term effects of N addition and warming on net N mineralization, N leaching, and N retention in a grass-dominated old field. …

Smartphones For Smart Eating: Evaluating The Effectiveness Of Smartphone Applications On Improving Adolescent Food Knowledge, Heather A. Jantzi

Electronic Thesis and Dissertation Repository

Many Canadian adolescents have unhealthy eating habits which are risk factors for developing chronic diseases later in life. Food literacy plays a role in healthy eating habits but teens in Ontario currently lack sufficient nutrition education learning opportunities in home and school environments. Across health research, smartphones have been utilized as a novel medium to promote learning and alter behaviour. This thesis seeks to understand the effectiveness of smartphone applications at improving food knowledge in adolescents through (i) a systematic review of published interventions, and (ii) by investigating the efficacy of a novel location-based smartphone application. Findings from this thesis …

Changes In Peatland Soil Fauna Biomass Alter Food Web Structure And Function Under Warming And Hydrological Changes, Trevor L. Pettit

Electronic Thesis and Dissertation Repository

Short-term climate perturbations affect both predator and prey species that comprise soil communities, and alter carbon flux. I used a mesocosm experiment to model the effects of experimentally-imposed temperature and moisture conditions that simulate potential future conditions during climate perturbations, on peatland soil food web flux and soil carbon sequestration after three-weeks of experimentally imposed conditions, and then again after an additional three-week recovery under control conditions. I compared system resistance and resilience, and modelled carbon (C) and nitrogen (N) fluxes throughout the mesocosm experiment. There was a lack of resistance of the soil food web to perturbation shown by …

White Matter Connectome Associations With Reading Functions In Children, Chenglin Lou

Electronic Thesis and Dissertation Repository

This thesis investigated associations between the white matter connectome and reading in children with a wide range of reading abilities. It is well established that the connectome supports the interplay among brain regions and connections within an integrated system. In this dissertation, I examine the hypothesis that it could therefore represent multiple mapping processes among reading components and further explain variations in reading performance. Such associations between the organization of the connectome and reading skills have not been well explored. This thesis aimed to address this issue by considering both the relationship between connectome measures and standardized reading performance out …

Investigating The Roles Of The Dorsal And Ventral Striatum In Humor Comprehension And Appreciation Throughout Health, Aging, And Parkinson’S Disease, Maggie Prenger

Electronic Thesis and Dissertation Repository

Humor processing is thought to involve two distinct components. The first, humor comprehension, involves detecting and resolving incongruities that are present within a humorous stimulus. This is related to cognitive processes such as ambiguity resolution, response inhibition, working memory, and cognitive flexibility, functions that are mediated in part by the dorsal portion of the striatum (DS). Humor appreciation, on the other hand, refers to the subjective amusement and mirth that one experiences in response to a joke. This is related to reward processing, which implicates the ventral portion of the striatum (VS). Across three separate studies, we investigated the involvement …

The Combined Effects Of Physical Exercise And Cognitive Training On Gait Speed And Primary Motor Cortex Metabolism In Individuals With Mild Cognitive Impairment: A 1h-Mrs Analysis, Jack Thomas Emsey Elkas

Electronic Thesis and Dissertation Repository

Mild cognitive impairment (MCI) is a transitional stage before dementia. Altered gait in MCI has been associated with progression to dementia. Using magnetic resonance spectroscopy, a relationship between primary motor cortex (M1) neurochemistry and dual task gait speed has been reported in MCI. Interventional research suggests exercise, cognitive training, and vitamin D supplementation may benefit MCI, yet the combined effect of these treatments on gait speed and M1 metabolism is unknown. Participants with MCI (N=75) were assigned to one of five intervention arms and dual task cost on gait speed and M1 metabolism was assessed before and five months after …

The Sympathetic Neural Control Of The Circulation At Rest And During Exercise: Effects Of Age, Biological Sex, And Sex Hormones, Andrew W. D'Souza

Electronic Thesis and Dissertation Repository

The overall objective of this dissertation was to determine the impact of age, sex, and sex hormones on the discharge behaviours of muscle sympathetic action potentials (APs) as well as the corresponding changes in peripheral vasoconstriction and blood pressure at rest and during exercise. The microneurographic technique was employed to record multi-unit muscle sympathetic nerve activity (MSNA), with a continuous wavelet transform applied post-hoc to evaluate APs within the recorded neurogram. Study One examined the impact of aging on the central and peripheral arcs of the sympathetic baroreflex under resting conditions. This study revealed that middle-aged-to-older adults demonstrated heightened sympathetic …

Non-Renal Alterations Of Drug Disposition In Chronic Kidney Disease, Nicholas Tonial

Electronic Thesis and Dissertation Repository

Chronic kidney disease (CKD) results in profound changes to non-renal drug elimination pathways including hepatic drug metabolism and hepatic transport mediated excretion. This results in complex pharmacological changes to drug disposition in the setting of kidney dysfunction. Four million Canadians are affected by CKD and the average CKD patient takes 14 medications daily with up to 40% experiencing adverse drug reactions at some point in their disease progression. Better elucidation of these changes in the setting of CKD is required to properly dose medications to provide therapeutic benefits while minimizing toxicity. This thesis aimed to better understand the impact kidney …

Recovery From Social Isolation In Drosophila: The Role Of Dopamine And The Autism-Related Gene Nlg3., Ryley T. Yost

Electronic Thesis and Dissertation Repository

Within a group, individuals establish their preferred distance from each other, or social space, a form of social behaviour. The resulting distance depends on the exchange of social cues from others that needs to be perceived and integrated within the organism’s neural circuitry. In humans, social spacing can be impaired in neuropsychiatric disorders such as autism and schizophrenia. When organisms are subject to social isolation, profound changes in social behaviour are observed in a variety of species from insects to mammals, including social space. However, the genetic and molecular mechanisms modulating a behavioural response to isolation and possible recovery remain …

The Effect Of Dietary Thiaminase On Cardiac Function And Morphology In Lake Trout (Salvelinus Namaycush), Peter Baker

Electronic Thesis and Dissertation Repository

Thiamine deficiency from the consumption of invasive, high-thiaminase prey fishes is considered to be a major barrier for lake trout restoration in the Great Lakes. In fishes, an understudied aspect of thiamine deficiency is its effect on cardiac function. I examined the effects of dietary thiaminase on cardiac function and morphology in lake trout, specifically as they relate to thermal tolerance. Two hatchery strains of lake trout (Seneca and Slate) were raised on a control or thiaminase diet for nine months. The thiaminase diet was associated with significant ventricle enlargement, impaired cardiac function, and reduced thermal tolerance; these effects were …

Postexercise Executive Function And Cortical Hemodynamics During The Different Phases Of The Menstrual Cycle, Priyanka Persaud

Electronic Thesis and Dissertation Repository

Resting cerebral blood flow (CBF) is increased during the luteal (LUT) phase of the menstrual cycle; however, it is unclear whether this change impacts a postexercise executive function (EF) benefit. Female participants (N=16) performed three experimental sessions: a V̇O_2peak task and 20-min single bouts of moderate intensity aerobic exercise (i.e., 80% of lactate threshold) during their follicular (FOL) and luteal (LUT) menstrual cycle phases. A separate group of male participants (N=21) additionally completed a V̇O_2peak test and a 20-min exercise intervention. Middle cerebral artery velocity (MCAv) was measured during exercise via transcranial Doppler ultrasound to estimate CBF and …

Addressing The Impact Of Time-Dependent Social Groupings On Animal Survival And Recapture Rates In Mark-Recapture Studies, Alexandru M. Draghici

Electronic Thesis and Dissertation Repository

Mark-recapture (MR) models typically assume that individuals under study have independent survival and recapture outcomes. One such model of interest is known as the Cormack-Jolly-Seber (CJS) model. In this dissertation, we conduct three major research projects focused on studying the impact of violating the independence assumption in MR models along with presenting extensions which relax the independence assumption. In the first project, we conduct a simulation study to address the impact of failing to account for pair-bonded animals having correlated recapture and survival fates on the CJS model. We examined the impact of correlation on the likelihood ratio test (LRT), …

Effects Of 11-Kt And Prolactin On Gene Expression, Parental Care Behaviour And Immune Response In Male Bluegill Sunfish., Adriano A P Da Cunha

Electronic Thesis and Dissertation Repository

Parental care is very critical for reproduction in species that provide it. Hormones such as prolactin and androgens play a crucial role in parenting and reproductive behaviours. In mammals and birds, prolactin’s role in parental care is well-established; it stimulates milk production and stimulates attachment to newborns by its release in the preoptic area of the hypothalamus (POA), among other functions. Androgens, on the other hand, are commonly associated with male secondary sex characteristics, territoriality, and aggressiveness in mammals and birds. There are similar reports of prolactin and androgen effects in fish, but there are fewer studies. I investigated if …

The Neural Control Of Force Production In Response To Directional Force Challenges, Joshua W. Cohen

Electronic Thesis and Dissertation Repository

Maintenance of upright standing posture is fundamental to human mobility and requires muscular control of the body’s centre of mass over the base of support. Force production, necessary for standing, is achieved by neural activation of populations of motor units (MUs). The possibility of preferentially activating different MUs within or across synergists has been debated in the motor control literature. Accordingly, the overall objective of this dissertation was to examine the neural control of standing balance in response to different directional force challenges. High Density Surface-Electromyography (HD-sEMG) was used to observe the location of muscle activity, and signal decomposition techniques …

Maturation Of Default Mode Network Functional Connectivity Strength In Utero And The Association With Subcortical Macrostructure: Mapping Brain Ontogeny Supporting Early Cognitive Processing, Susana Correa

Electronic Thesis and Dissertation Repository

The third trimester of gestation is scarcely studied despite this being a key window for the development of learning and memory systems. In a prospective cohort study, 30 pregnant women participated in one or two fetal MR imaging sessions between 28- and 39 weeks of gestational age. Activation time courses were extracted from the default mode (DMN), medial temporal lobe (MTL), and thalamocortical (TCN) networks of the fetal brain. Generalized estimating equations were used to examine the association between the DMN-MTL, DMN-TCV connectivity strength, and subcortical volumes. Increased functional connectivity strength between the DMN-MTL networks was negatively associated with smaller …

Plantar Flexor Dynamic Contractile Rates Are Not Dependent On Calcaneal Tendon Stiffness, Sohum Kulkarni

Electronic Thesis and Dissertation Repository

The ability to rapidly generate muscular torque and velocity is important in specialized activities and daily tasks of living. Tendon stiffness is one factor in the neuromuscular system that influences musculoskeletal torque transmission. Previous studies have reported weak-to-moderate correlations between tendon stiffness and rate of torque development (RTD). However, these correlations have been reported only for isometric contractions which may not be relevant to contractions involving joint rotation (i.e., dynamic). The purpose was to investigate the effect of calcaneal tendon stiffness on the dynamic rates of torque (RTD) and velocity (RVD) development in plantar flexor muscles. Young adult males (n=13) …

Novel 129xe Magnetic Resonance Imaging And Spectroscopy Measurements Of Pulmonary Gas-Exchange, Alexander M. Matheson

Electronic Thesis and Dissertation Repository

Gas-exchange is the primary function of the lungs and involves removing carbon dioxide from the body and exchanging it within the alveoli for inhaled oxygen. Several different pulmonary, cardiac and cardiovascular abnormalities have negative effects on pulmonary gas-exchange. Unfortunately, clinical tests do not always pinpoint the problem; sensitive and specific measurements are needed to probe the individual components participating in gas-exchange for a better understanding of pathophysiology, disease progression and response to therapy.

In vivo Xenon-129 gas-exchange magnetic resonance imaging (¹²⁹Xe gas-exchange MRI) has the potential to overcome these challenges. When participants inhale hyperpolarized ¹²⁹Xe gas, it …

Molecular Characterization Of The Antiviral Properties Of The Small Herc Family Of Proteins, Ermela Paparisto

Electronic Thesis and Dissertation Repository

Although viruses are obligate intracellular parasites, they have their own evolutionary trajectory, their genomes are in a constant battle to overcome the defenses of the host. This thesis investigates the role of the small HERC family of proteins in the battle against two deadly viruses: Human Immunodeficiency Virus -1 (HIV) and Zaire ebolavirus (EBOV). Although their discovery occurred decades ago, little knowledge is available about the small HERC family, their functions, and modes of interactions with other cellular proteins. In the first chapter, the structural evolution of the small HERC family and related functional changes that have occurred over time …

Sarcopenia In Head And Neck Cancer: A Prognostic Analysis, Nedeljko Jovanovic

Electronic Thesis and Dissertation Repository

Introduction: In head and neck cancer (HNC), loss of skeletal muscle mass (SMM), or sarcopenia, is a strong prognostic factor for outcomes. However, inconsistencies in its assessment limit our understanding of the relationship between sarcopenia and nutrition-related outcomes. This project evaluated the significance of sarcopenia as described in the literature and as demonstrated in a cohort of HNC patients.

Methods: A scoping review was first conducted followed by a retrospective cohort study with data collected from 194 oropharyngeal carcinoma patients treated with definitive radiation/chemoradiation. Sarcopenia was assessed from computed tomography (CT) imaging at the third cervical vertebra (C3) and the …

A Comparison Of Methods To Identify The Mean Response Time Of Ramp-Incremental Exercise For Exercise Prescription, Nikan Behboodpour

Electronic Thesis and Dissertation Repository

Introduction: The oxygen uptake (V̇O₂) vs power output (PO) relationship from ramp incremental exercise (RAMP) is used to prescribe aerobic exercise. As PO increases, there is a delay in V̇O₂ that contributes to a misalignment of V̇O₂ from PO making precise prescription of exercise PO untenable. Three methods of determining Mean Response Time (exponential modeling (MRT_EXP), linear modeling (MRT_LIN), and the steady-state method (MRT_SS)) were compared and evaluated for their accuracy at predicting the V̇O₂ associated with two PO below estimated lactate threshold (q_LT) and one …

Nitrogen Transfer From Cover Crops To The Subsequent Grain Crop And The Influence Of Variability In Winter Conditions, Spencer Heuchan

Electronic Thesis and Dissertation Repository

Cover crops, which are used to provide ground cover after the harvest of the grain crop, can potentially improve the sustainability of agroecosystems by reducing nutrient losses. However, few data are available to document the extent to which cover crops improve both the retention of soil nitrogen (N) and the transfer of this N to the grain crop. The efficiency of this N transfer may be further influenced by variation in winter soil temperature; for example, reduced snow cover can increase the frequency and intensity of soil freezing, which can affect the survival of cover crops and the timing of …

The Effect Of Postural Perturbations On Cardiovascular And Skeletal Muscle Function In Healthy Adults, Patrick Siedlecki

Electronic Thesis and Dissertation Repository

Maintenance of standing balance is vital to daily living. Traditionally, perspectives on maintaining balance are achieved through the study of visual, vestibular and somatosensory inputs on motor outputs. While evidence suggests cardiovascular regulation also functions to assist postural control during orthostatic stress, how the cardiovascular system responds to postural perturbations is not well established. This dissertation includes four studies that investigated the effects of postural perturbations on the cardiovascular system and skeletal muscle responses in healthy adults. All of the studies involved exposing standing participants to surface-translation perturbations at different velocities, with known or unknown timing, and occurred while spontaneously …

Gene Regulatory Context Of Honey Bee Worker Sterility, Rahul Choorakkat Unnikrishnan

Electronic Thesis and Dissertation Repository

Honey bee workers deactivate their ovaries and are functionally sterile when a queen is present in the colony. I adopt a bioinformatics approach to up-date a model transcriptional regulatory network (TRN) to study gene-regulatory processes that regulate fecundity in workers. On splitting the network, I obtained nine clusters and each cluster conformed to properties associated with real-world networks. Two of the nine clusters are enriched for 'sterility genes' and contained single well-connected hub genes (GB44769, ftz-f1). The genes in the two clusters were functionally enriched for nucleic acid binding (GO:0003676) and nucleotide binding (GO:0000166). I identified homologous genes for …