Life Sciences Commons^™

Fungi Associated With Common Buckthorn (Rhamnus Cathartica) In Southern Ontario, Nimalka M. Weerasuriya

Electronic Thesis and Dissertation Repository

Common buckthorn (Rhamnus cathartica) is a competitive Eurasian woody shrub currently invading North America. Buckthorn thickets reduce native diversity and may reduce mycorrhizal diversity through the release of allelochemicals. Two aspects of buckthorn’s invasional biology are explored: 1) identifying fungi associating with buckthorn, and 2) determining buckthorn’s allelochemical impacts on arbuscular mycorrhizae in forest soils and an open-greenhouse experiment.

Twenty-three fungi were found growing on buckthorn, including Armillaria mellea s.l., Hypoxylon fuscum, H. perforatum, Nectria cinnabarina, and Cylindrobasidium evolvens. Data from invaded and uninvaded sugar maple (Acer saccharum) soils revealed that arbuscular …

First-Order Statistical Speckle Models Improve Robustness And Reproducibility Of Contrast-Enhanced Ultrasound Perfusion Estimates, Matthew R. Lowerison

Electronic Thesis and Dissertation Repository

Contrast-enhanced ultrasound (CEUS) permits the quantification and monitoring of adaptive tumor responses in the face of anti-angiogenic treatment, with the goal of informing targeted therapy. However, conventional CEUS image analysis relies on mean signal intensity as an estimate of tracer concentration in indicator-dilution modeling. This discounts additional information that may be available from the first-order speckle statistics in a CEUS image. Heterogeneous vascular networks, typical of tumor-induced angiogenesis, lead to heterogeneous contrast enhancement of the imaged tumor cross-section.

To address this, a linear (B-mode) processing approach was developed to quantify the change in the first-order speckle statistics of B-mode cine …

Mhc Class Iiβ Diversity As A Correlate Of Neutral-Locus Similarity And Diversity, And A Predictor Of Overwinter Return, In Song Sparrows (Melospiza Melodia), Matthew J. Watson

Electronic Thesis and Dissertation Repository

Abstract

The major histocompatibility complex (MHC) is a family of genes involved with recognizing pathogens and mounting an immune response. Parasite-mediated selection often favours heterozygosity at MHC because MHC-diverse individuals recognize a wider range of pathogens. Because migratory birds encounter many pathogens, I hypothesized that MHC diversity predicts overwinter and juvenile survivorship in song sparrows (Melospiza melodia). I found no correlation between MHC diversity and neutral-locus (microsatellite) heterozygosity, suggesting that measures of neutral and adaptive genetic diversity provide complementary rather than redundant information. However, pairwise similarity at MHC predicted pairwise similarity at microsatellite loci. In contrast to my hypothesis, MHC …

Mosaic Expression Of Atrx In The Mouse Central Nervous System Causes Memory Deficits, Renee J. Tamming, Jennifer R. Siu, Yan Jiang, Marco A. M. Prado, Frank Beier, Nathalie G. Berube

Anatomy and Cell Biology Publications

The rapid modulation of chromatin organization is thought to play a crucial role in cognitive processes such as memory consolidation. This is supported in part by the dysregulation of many chromatin-remodelling proteins in neurodevelopmental and psychiatric disorders. A key example is ATRX, an X-linked gene commonly mutated in individuals with syndromic and nonsyndromic intellectual disability. The consequences of Atrx inactivation for learning and memory have been difficult to evaluate because of the early lethality of hemizygous-null animals. In this study, we evaluated the outcome of brain-specific Atrx deletion in heterozygous female mice. These mice exhibit a mosaic pattern of ATRX …

Microbial Repopulation Following In Situ Star Remediation, Gavin Overbeeke

Electronic Thesis and Dissertation Repository

In situ STAR (Self-sustaining Treatment for Active Remediation) is an emerging remediation technology which uses smouldering combustion to destroy nonaqueous phase liquid (NAPL) contamination in the subsurface. Since STAR smouldering travels through contaminated soils slowly (~0.5 to 5 m/day) and subjects them to high temperatures (400–1000°C), it is expected that this technology will thoroughly dry and sterilize the zones which it treats. Further, soils surrounding the treatment zone which are not smouldered will be heated, although not smouldered, by virtue of their proximity to STAR, impacting microbial communities within them. Therefore, the objectives of this work are to quantify the …

Dual-Active Genome-Editing Reagents, Jason M. Wolfs

Electronic Thesis and Dissertation Repository

Manipulation of complex genomes has many beneficial downstream applications in agriculture and human gene therapy. Precise genome-editing requires the introduction of a specific DNA double-stand break at a locus of interest, in turn inducing host DNA repair pathways to cause gene knockout through non-homologous end-joining or gene repair using homologous recombination and donor template. No matter the application, the field has depended on a few reagents to introduce precise double-strand breaks in host genomes. LAGLIDADG homing endonucleases or meganucleases harness the natural properties of these rare-cutting enzymes to target precise sequences in a complex genome. Other successful reagents are derived …

Sleep Spindles And Intellectual Ability: Epiphenomenon Or Directly Related?, Zhuo Fang, Valya Sergeeva, Laura B. Ray, Adrian M. Owen, Stuart M. Fogel

Anatomy and Cell Biology Publications

Sleep spindlesshort, phasic, oscillatory bursts of activity that characterize non-rapid eye movement sleepare one of the only electrophysiological oscillations identified as a biological marker of human intelligence (e.g., cognitive abilities commonly assessed using intelligence quotient tests). However, spindles are also important for sleep maintenance and are modulated by circadian factors. Thus, the possibility remains that the relationship between spindles and intelligence quotient may be an epiphenomenon of a putative relationship between good quality sleep and cognitive ability or perhaps modulated by circadian factors such as morningness-eveningness tendencies. We sought to ascertain whether spindles are directly or indirectly related to cognitive …

Mt1-Mmp Mediates The Migratory And Tumourigenic Potential Of Breast Cancer Cells Via Non-Proteolytic Mechanisms, Mario Cepeda

Electronic Thesis and Dissertation Repository

Membrane Type-1 Matrix Metalloproteinase (MT1-MMP) is a multifunctional protease that affects cell function via proteolytic and non-proteolytic mechanisms such as promoting degradation of the extracellular matrix (ECM) or augmentation of cell migration and viability, respectively. MT1-MMP has been implicated in metastatic progression ostensibly due to its ability to degrade ECM components and to allow migration of cells through the basement membrane. Despite in vitro studies demonstrating this principle, this knowledge has not translated into the use of MMP inhibitors (MMPi) that inhibit substrate catalysis as effective cancer therapeutics, or been corroborated by evidence of in vivo ECM degradation mediated by …

Discovery Of Novel Diagnostic Biomarkers On Prostate Tumor Microparticles For Discriminating Between Low And High Risk Prostate Cancer And Improving Prostate Cancer Screening, Sabine Brett

Electronic Thesis and Dissertation Repository

There are few protein-based biomarkers to accurately distinguish between patients with low risk prostate cancer from those with high risk disease in a non-invasive manner. Prostate specific antigen (PSA) is used for clinical follow-up of prostate cancer; however, it is not effective as a screening tool. As a result, many men with non-life threatening disease having to undergo unnecessary and painful biopsies. Therefore, there is a dire need for minimally invasive platforms for monitoring patients with clinically significant prostate cancer. Prostate cell microparticles (PCMPs) released by prostate epithelial cells into plasma are a potential source of biomarkers specific for prostate …

Regulation Of Human 69-Kda Choline Acetyltransferase Protein Stability And Function By Molecular Chaperones And The Ubiquitin-Proteasome System, Trevor M. Morey

Electronic Thesis and Dissertation Repository

The enzyme choline acetyltransferase (ChAT) mediates synthesis of the neurotransmitter acetylcholine required for cholinergic neurotransmission. ChAT mutations are linked to congenital myasthenic syndrome (CMS), a rare neuromuscular disorder. One CMS-related mutation, V18M, reduces ChAT enzyme activity and cellular protein levels, and is located within a highly-conserved N-terminal proline-rich motif at residues ₁₄PKLPVPP₂₀. It is currently unknown if this motif regulates ChAT function. In this thesis, I demonstrate that disruption of this proline-rich motif in mouse cholinergic SN56 cells reduces both the protein levels and cellular enzymatic activity of mutated P17A/P19A- and V18M-ChAT. The cellular loss …

The Effect Of Age On Social Behaviour In Drosophila Melanogaster And The Progeny Of Aged Parents, Dova Brenman

Electronic Thesis and Dissertation Repository

Recent studies have linked neuropsychiatric disorders to older parents. These disorders often include changes in social behaviours like the social spacing between neighbouring individuals, which can be modeled in organisms such as Drosophila melanogaster. I investigated the effects of aging on the social space between neighbouring D. melanogaster and how aging impacts the next generation. To achieve this, I used the social space assay and found that individuals become less social with age and that this effect is passed on to the first generation only. Additionally, accelerating the physiological process of aging via increased rearing temperatures or exposure to …

The Mixed Source Chinook Salmon Fishery In Lake Huron: A Comparison Of Spawning And Foraging Habitat Use By Naturalized And Hatchery Fish, Stephen A.C. Marklevitz

Electronic Thesis and Dissertation Repository

Chinook salmon (Oncorhynchus tshawytscha) were introduced into the Great Lakes to restore top-down control of the food web and create new recreational fisheries. Soon after introduction, naturalized spawning populations became established, and with continued stocking of hatchery fish, created a mixed source fishery. My research provides new ecological information about the contributions of naturalized fish to the mixed source Chinook salmon fishery in Lake Huron. I examined spawning and foraging habitat use by naturalized and hatchery Chinook salmon using multiple methods to identify sources of individual fish (external tags, hatchery fin clips, and otolith microchemistry). In the Sydenham …

Tti2 In Pikk Biosynthesis And Its Use In Identifying Missense Suppressor Trnas, Kyle S. Hoffman

Electronic Thesis and Dissertation Repository

Protein biosynthesis is an essential process for all cells. It involves the translation of genetically encoded information into peptides, folding and assembly of peptides into three-dimensional molecules and complexes, and post-translational modification. Molecular chaperones facilitate protein folding so that a native state is achieved. Misfolded proteins and aggregates are toxic within the cell and accumulate due to stress conditions, mutations, and cell aging. Moreover, essential proteins rely on chaperones and co-chaperones for their regulation and activity.

The TTT complex, consisting of Tel2, Tti1, and Tti2, is considered an Hsp90 co-chaperone with specificity for phosphatidylinositol 3-kinase-related kinases (PIKKs). I show that …

Maternal Nutrient Restriction In Pregnant Guinea Pigs And The Impact On Fetal Growth And Brain Development, Andrew Ghaly

Electronic Thesis and Dissertation Repository

Maternal nutrient restriction (MNR) in guinea pigs results in placental structural abnormalities that reduce nutrient transport contributing to fetal growth restriction (FGR). However, whether brain weights are similarly reduced, or preserved by “brain sparing” mechanisms, and whether energy levels are depleted leading to membrane failure and overt injury remains unknown. Guinea pig sows were fed ad libitum (Controls) or 70% of the control diet pre-pregnant switching to 90% at mid-pregnancy (MNR). Animals were necropsied near term for fetal growth measures and fetal brains were assessed for markers of necrotic cell injury, apoptotic cell injury, endoplasmic reticulum stress, and altered development …

An Evaluation Of Challenges And Opportunities For Western Heads East [2017], Felicia Krausert, Reshel Perera,, Spencer Yeung, Jacinta Mwachiro, Bob Kigen, Elizabeth Pham

Business and Social Enterprise

Western Heads East (WHE) is “a collaboration between Western staff, students, faculty, and African partners using probiotic food to contribute to health and sustainable development”. The primary objective of this program is to establish a sustainable grassroots social enterprise using the health benefits of probiotic yoghurt in order to improve health of Tanzanian community while empowering local women to become business owners and entrepreneurs. This report investigates the challenges, opportunities, local conditions and previous works to recommend a potential intervention that could support the sustainability and the intended value of probiotic yoghurt kitchens.

There are two main end users for …

Does Cold Activate The Drosophila Melanogaster Immune System?, Golnaz Salehipour-Shirazi, Laura V Ferguson, Brent J Sinclair

Biology Publications

Cold exposure appears to activate aspects of the insect immune system; however, the functional significance of the relationship between cold and immunity is unclear. Insect success at low temperatures is shaped in part by interactions with biotic stressors, such as pathogens, thus it is important to understand how and why immunity might be activated by cold. Here we explore which components of the immune system are activated, and whether those components differ among different kinds of cold exposure. We exposed Drosophila melanogaster to both acute (2h, -2°C) and sustained (10h, -0.5°C) cold, and measured potential (antimicrobial peptide expression, phenoloxidase activity, …

Cold Tolerance Of Third-Instar Drosophila Suzukii Larvae., Ruth Jakobs, Banafsheh Ahmadi, Sarah Houben, Tara D Gariepy, Brent J Sinclair

Biology Publications

Drosophila suzukii is an emerging global pest of soft fruit; although it likely overwinters as an adult, larval cold tolerance is important both for determining performance during spring and autumn, and for the development of temperature-based control methods aimed at larvae. We examined the low temperature biology of third instar feeding and wandering larvae in and out of food. We induced phenotypic plasticity of thermal biology by rearing under short days and fluctuating temperatures (5.5-19°C). Rearing under fluctuating temperatures led to much slower development (42.1days egg-adult) compared to control conditions (constant 21.5°C; 15.7days), and yielded larger adults of both sexes. …

Do Large Carnivores And Mesocarnivores Have Redundant Impacts On Intertidal Prey?, Justin P. Suraci, Michael Clinchy, Liana Y. Zanette

Biology Publications

The presence of large carnivores can affect lower trophic levels by suppressing mesocarnivores and reducing their impacts on prey. The mesopredator release hypothesis therefore predicts prey abundance will be higher where large carnivores are present, but this prediction assumes limited dietary overlap between large and mesocarnivores. Where dietary overlap is high, e.g., among omnivorous carnivore species, or where prey are relatively easily accessible, the potential exists for large and mesocarnivores to have redundant impacts on prey, though this possibility has not been explored. The intertidal community represents a potentially important but poorly studied resource for coastal carnivore populations, and one …

Immune Profiles Vary Seasonally, But Are Not Significantly Related To Migration Distance Or Natal Dispersal, In A Migratory Songbird, Tosha R. Kelly, Heather L. Macgillivray, Keith A. Hobson, Scott A. Macdougall-Shackleton, Elizabeth A. Macdougall-Shackleton

Biology Publications

A central tenet of ecoimmunology is that an organism’s environment shapes its optimal investment in immunity. For example, the benefits of acquired (relatively pathogen-specific) versus innate (non-specific) immune defences are thought to vary with the risk of encountering familiar versus unfamiliar pathogens. Because pathogen communities vary geographically, individuals that travel farther during seasonal migration or natal dispersal are predicted to have higher exposure to novel pathogens, and lower exposure to familiar pathogens, potentially favoring investment in innate immunity. During the breeding season, migratory animals’ exposure to familiar pathogens should increase, potentially favoring investment in acquired immunity. We hypothesized that song …

The Fear Factor: Impacts Of Perceived Predation Risk And Competition On Fall Field Crickets (Gryllus Pennsylvanicus), Ruilin Guo

2017 Undergraduate Awards

Fear is a powerful force. The perceived threat of predation and competition can cause behavioural and physiological changes that ultimately affect fitness. Fear of predation may result in decreased foraging, increased hiding, or energetically-costly defense mechanisms, while intraspecific competition may lead to risky mating efforts. I investigated the impact of perceived predation and competition on the growth, behaviour, and fecundity of fall field crickets (Gryllus pennsylvanicus). This study is the first to manipulate both perceived predation and competition while measuring multiple impacts, allowing a holistic perspective. Using four treatments of control, predation, competition, and predation+competition, I exposed juvenile crickets to …

Impact Of Age On Cerebrovascular Dilation Versus Reactivity To Hypercapnia., Nicole S Coverdale, Mark B Badrov, J Kevin Shoemaker

Kinesiology Publications

This study quantified the effect of age on cerebrovascular reactivity and cerebrovascular conductance while accounting for differences in grey matter volume in younger (YA: n = 12; 24 ± 4 years, six females) and older adults (OA: n = 10; 66 ± 7 years; five females). Cerebral blood flow velocity (CBFV; transcranial Doppler) in the middle cerebral artery (MCA), MCA cross-sectional area (CSA), intracranial volumes (magnetic resonance imaging), and mean arterial pressure (MAP; Finometer), were measured under normocapnic and hypercapnic (6% carbon dioxide) conditions. Cerebral blood flow (CBF) was quantified from CBFV and MCA CSA and normalized to grey matter …

Covert Narrative Capacity: Mental Life In Patients Thought To Lack Consciousness, Lorina Naci, Mackenzie Graham, Adrian M. Owen, Charles Weijer

Anatomy and Cell Biology Publications

Despite the apparent absence of external signs of consciousness, a significant proportion of behaviorally nonresponsive patients can respond to commands by willfully modulating their brain activity. However, little is known about the mental life of these patients. We discuss a recent innovative approach, which sheds light on the preserved cognitive capacities of these patients, including executive function, theory of mind, and the experience of affective states. This research represents a fundamental shift in our understanding of these patients, and has important implications for both their continued treatment and care. Moreover, this research marks out avenues for future inquiry into the …

Pearls And Perils Of Pupillometry Using A Webcam, Mason Kadem, Rhodri Cusack

Undergraduate Honors Posters

Current methods to measure infants’ cognitive repertoire (i.e., collection of cognitive abilities) are limited. Previous testing paradigms required acquisition of non-age contextualized responses, and relied on measures that involved acquisition of other functions (e.g., language, motor). In addition to response limitations, cognitive functions may be difficult to observe in infants due to the difficulty in infant recruitment. Online testing has increased infant recruitment efforts and physiological responses have bypassed the motor, behavioural and linguistic limitations of infants. Recently, it has been shown that heart rate measures can be acquired through a webcam. Another feasible and reliable physiological measure is pupillometery, …

Real-Time Interactive Tractography Analysis For Multimodal Brain Visualization Tool: Multixplore, Saeed M. Bakhshmand, Sandrine De Ribaupierre, Roy Eagleson

Anatomy and Cell Biology Publications

Most debilitating neurological disorders can have anatomical origins. Yet unlike other body organs, the anatomy alone cannot easily provide an understanding of brain functionality. In fact, addressing the challenge of linking structural and functional connectivity remains in the frontiers of neuroscience. Aggregating multimodal neuroimaging datasets may be critical for developing theories that span brain functionality, global neuroanatomy and internal microstructures. Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) are main such techniques that are employed to investigate the brain under normal and pathological conditions. FMRI records blood oxygenation level of the grey matter (GM), whereas DTI is able …

The Roles Of Insulin-Like Growth Factors In Mesenchymal Stem Cell Niche, Amer Youssef, Doaa Aboalola, Victor K. M. Han

Anatomy and Cell Biology Publications

Many tissues contain adult mesenchymal stem cells (MSCs), which may be used in tissue regeneration therapies. However, the MSC availability in most tissues is limited which demands expansion in vitro following isolation. Like many developing cells, the state of MSCs is affected by the surrounding microenvironment, and mimicking this natural microenvironment that supports multipotent or differentiated state in vivo is essential to understand for the successful use of MSC in regenerative therapies. Many researchers are, therefore, optimizing cell culture conditions in vitro by altering growth factors, extracellular matrices, chemicals, oxygen tension, and surrounding pH to enhance stem cells self-renewal or …

Within-Wing Isotopic (Δ2h, Δ13c, Δ15n) Variation Of Monarch Butterflies: Implications For Studies Of Migratory Origins And Diet, Keith A. Hobson, Tessa Plint, Eligio García Serrano, Xiomara Mora Alvarez, Isabel Ramirez, Fred J. Longstaffe

Earth Sciences Publications

Increasingly, stable isotope measurements are being used to assign individuals to broad geographic origins based on established relationships between animal tissues and tissue-specific isoscapes. In particular, the eastern North American population of the monarch butterfly (Danaus plexippus) has been the subject of several studies using established δ²H and δ¹³C wing-tissue isoscapes to infer natal origins of migrating and overwintering individuals. However, there has been no study investigating potential variance that can derive from sub-sampling different regions of the wings, especially those regions differing in pigmentation (orange versus black). Within-wing isotopic (δ²H, …

Stable Isotope Investigation Of The Migratory Behavior Of Silverhaired Bats (Lasionycteris Noctivagans) In Eastern North America, Erin E. Fraser, Darin Brooks, Fred J. Longstaffe

Earth Sciences Publications

We investigated the migratory movements of silver-haired bats (Lasionycteris noctivagans) across the eastern extent of the species’ range. We conducted stable hydrogen isotope analysis of fur samples (δ²H_fur) from museum specimens collected across latitudes and at all times of the year. We first used these data to estimate the timing of fur replacement and to develop a model associating δ²H_fur with that of local precipitation (δ²H_precip) at the location where fur replacement occurred. We then used this model to 1) identify individuals that had migrated …

Origins Of Thalamic And Cortical Projections To The Posterior Auditory Field In Congenitally Deaf Cats., Blake E Butler, Nicole Chabot, Andrej Kral, Stephen G Lomber

Psychology Publications

Crossmodal plasticity takes place following sensory loss, such that areas that normally process the missing modality are reorganized to provide compensatory function in the remaining sensory systems. For example, congenitally deaf cats outperform normal hearing animals on localization of visual stimuli presented in the periphery, and this advantage has been shown to be mediated by the posterior auditory field (PAF). In order to determine the nature of the anatomical differences that underlie this phenomenon, we injected a retrograde tracer into PAF of congenitally deaf animals and quantified the thalamic and cortical projections to this field. The pattern of projections from …

Are There Place Cells In The Avian Hippocampus?, David F Sherry, Stephanie L Grella, Mélanie F Guigueno, David J White, Diano F Marrone

Psychology Publications

Birds possess a hippocampus that serves many of the same spatial and mnemonic functions as the mammalian hippocampus but achieves these outcomes with a dramatically different neuroanatomical organization. The properties of spatially responsive neurons in birds and mammals are also different. Much of the contemporary interest in the role of the mammalian hippocampus in spatial representation dates to the discovery of place cells in the rat hippocampus. Since that time, cells that respond to head direction and cells that encode a grid-like representation of space have been described in the rat brain. Research with homing pigeons has discovered hippocampal cells, …

Resting State Functional Network Disruptions In A Kainic Acid Model Of Temporal Lobe Epilepsy., Ravnoor Singh Gill, Seyed M Mirsattari, L Stan Leung

Physiology and Pharmacology Publications

We studied the graph topological properties of brain networks derived from resting-state functional magnetic resonance imaging in a kainic acid induced model of temporal lobe epilepsy (TLE) in rats. Functional connectivity was determined by temporal correlation of the resting-state Blood Oxygen Level Dependent (BOLD) signals between two brain regions during 1.5% and 2% isoflurane, and analyzed as networks in epileptic and control rats. Graph theoretical analysis revealed a significant increase in functional connectivity between brain areas in epileptic than control rats, and the connected brain areas could be categorized as a limbic network and a default mode network (DMN). The …