Life Sciences Commons^™

Characterization Of Plant-Spider Mite Interactions And Establishment Of Tools For Spider Mite Functional Genetic Studies, Nicolas Bensoussan

Electronic Thesis and Dissertation Repository

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most polyphagous herbivores feeding on cell contents of over 1100 plant species including more than 150 crops. However, despite its important pest status and a growing understanding of the molecular basis of its interactions with plant hosts, knowledge of the way mites interface with the plant while feeding and the plant damage directly inflicted by mites is lacking. Likewise, while the use of the reverse genetic tools in plants facilitated our understanding of the establishment of defense mechanisms against spider mite herbivory, such tools are lacking for …

Characterization Of Acaricide Resistance, Plant-Mediated Rnai Against Two-Spotted Spider Mites (Tetranychus Urticae Koch), And Assessing Off- And Non-Target Effects, Hooman Hosseinzadeh Namin

Electronic Thesis and Dissertation Repository

The two-spotted spider mite (TSSM), Tetranychus urticae (Koch), is one of the most damaging agricultural pests in the world. It feeds on over 150 crops, causing considerable yield losses in greenhouses and agricultural fields. Currently, using synthetic acaricides is the main method to control TSSM. However, it can develop resistance to acaricides with repeated exposure, and typically resistance can occur within two to four years. To understand the underlying mechanisms of spider mite adaptation to acaricides is an essential part of resistance management strategy. The resistance ratio of the pyridaben-selected strain compared with the pre-selection strain was estimated at greater …

The Effect Of Diet On Midgut And Resulting Changes In Infectiousness Of Acmnpv Baculovirus In Trichoplusia Ni, Elizabeth Chen

Electronic Thesis and Dissertation Repository

The cabbage looper, Trichoplusia ni, a global generalist lepidopteran pest, has developed resistance to many synthetic and biological insecticides, requiring effective and environmentally acceptable alternatives. One possibility is the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). This baculovirus is highly infectious for T. ni, with potential as a biocontrol agent, however, its effectiveness is strongly influenced by dietary context. In this study, microscopy and transcriptomics were used to examine how the efficacy of this virus was affected when T. ni larvae were raised on different diets. Larvae raised on potato host plants had lower chitinase and chitin deacetylase transcript levels …

Intracellular Signalling Crosstalk In The Differentiation Of F9 Cells Into Extraembryonic Endoderm, Tina Nicole Cuthbert

Electronic Thesis and Dissertation Repository

Mouse F9 cells differentiate into primitive extraembryonic endoderm (PrE) with retinoic acid (RA) treatment, resulting in up-regulation of Gata6, which when translated directly activates Wnt6. Canonical Wnt signalling is required for PrE differentiation, and this, like most developmental processes, requires input from one or more additional pathways, including hedgehog (Hh). The Hh pathway is regulated by GATA6, and crosstalks positively/negatively with Wnt signalling. Ihh up-regulation in F9 cells accompanies PrE induction, but a role for GATA6 or Hh pathway activation in obligatory Wnt/ß-catenin signalling is not known. To address this, I show that RA induces Ihh and altered expression of …

Functional Characteristics Of Four Novel Lone Atrial Fibrillation-Linked Connexin40 Mutants, Mahmoud Noureldin

Electronic Thesis and Dissertation Repository

Atrial fibrillation (AF) is the most common form of cardiac arrhythmia. Recently, four novel heterozygous Cx40 mutations, K107R, L223M, Q236H, and I257L were identified in 4 of 310 unrelated AF patients. To study possible alterations associated with these mutants, we studied their localization and function using gap junction (GJ)-deficient model cells. Cell pairs expressing Q236H alone or together with wildtype Cx43 showed a significantly lower coupling conductance. Impaired GJ function and dominant negative action on Cx43 of this mutant are consistent with previous findings on the majority of AF-linked Cx40 mutants. The remaining three novel AF-linked mutants did not show …

Inhibition Of Pannexin 1 Reduces Tumorigenic Properties Of Human Melanoma, Taylor J. Freeman

Electronic Thesis and Dissertation Repository

Pannexin 1 (PANX1) is a channel-forming glycoprotein that allows the passage of important signaling molecules, including ATP. We examined PANX1 levels in a panel of human melanomas and evaluated its potential as an effective target for melanoma therapy. We are the first to report endogenous PANX1 levels in multiple human melanoma cell lines, patient-derived melanoma biopsies, and primary melanoma cells. Treatment with two PANX1 channel blockers, Carbenoxolone (CBX) and Probenecid (PBN), on A375 and A375-MA2 melanoma cells significantly reduced cell growth and migration, and increased the production of melanin, a marker for a melanocytic-like phenotype. Daily treatment with CBX or …

Nuak1 Has Tumor Suppressive Activity In Epithelial Ovarian Cancer, Parima Saxena

Electronic Thesis and Dissertation Repository

NUAK1, a downstream substrate of the stress metabolism regulator Liver kinase B1 (LKB1), has been implicated as an oncogene and tumor suppressor, with distinct roles in cell cycle, senescence and cell adhesion. Epithelial ovarian cancer (EOC) spheroids remain dormant during intraperitoneal metastasis with reduced proliferation and metabolism to survive metabolically harsh conditions, possibly implicating a role of NUAK1 in EOC spheroid biology. I hypothesize that NUAK1 is regulated by LKB1 to promote dormancy in EOC. I demonstrate that NUAK1 expression and phosphorylation is regulated by LKB1 in EOC cell lines. NUAK1 is largely under-expressed in many established and new ascites-derived …

Cellular/Molecular Analysis Of Interspecies Sterile Male Hybrids In Drosophila, Rachelle L. Kanippayoor

Electronic Thesis and Dissertation Repository

Over time, genetic differences can accumulate between populations that are geographically separated. This genetic divergence can lead to the evolution of reproductive isolating mechanisms that reduce gene flow between the populations and, upon secondary contact, result in distinct species. The process of speciation is, thus, what accounts for the multitude of species that contribute to the rich biodiversity on Earth. Interspecies hybrid sterility is a postzygotic isolating mechanism that affects the development of hybrids, rendering them sterile. A notable trend, known as Haldane's Rule, describes that heterogametic individual (e.g. males in Drosophila) are more susceptible to sterility than homogametic …

Alternative Splicing And Extra-Telomeric Role Of Telomerase Reverse Transcriptase Isoforms In Human Embryonic Stem Cells, Joohwan Kim

Electronic Thesis and Dissertation Repository

Human telomerase, a ribonucleoprotein complex consisting of a catalytic subunit (hTERT) and a RNA template component (TERC), prevents telomere attrition in human embryonic stem cells (hESCs) providing these cells with prolonged replicative capacity. Interestingly, hTERT has several alternatively spliced isoforms, most of which are catalytically inactive. One alternative splicing event involving a complete loss of exons 7 and 8 results in a catalytically inactive isoform called β-hTERT. The β-hTERT is highly expressed in certain cancer types and hESCs. Full-length hTERT (FL-hTERT) is known to translocate from nuclei to mitochondria when cells are exposed to either chronic (oxygen tension) or acute …

Cerebral Lactate Metabolism And Memory: Implications For Alzheimer's Disease, Richard Andrew Harris

Electronic Thesis and Dissertation Repository

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by amyloid plaques that are comprised of aggregated amyloid-beta peptides. These toxic proteins promote mitochondrial dysfunction and neuronal cell death. A shift in metabolism away from oxidative phosphorylation and toward aerobic glycolysis, with the concomitant production of lactate, affords neurons a survival advantage against amyloid-beta toxicity. Recent evidence now suggests that aerobic glycolysis in the brain plays a critical role in supporting synaptic plasticity, learning, and memory. However, the role of aerobic glycolysis and lactate metabolism in AD-mediated cognitive decline is unknown. My objective was to test the hypotheses that aerobic glycolysis …

Characterizing Ferroportin Trafficking In Macrophages During Phagocytosis, Tayler J. Farrell

Electronic Thesis and Dissertation Repository

Macrophages are important mediators of innate immunity and nutritional immunity via modulation of essential nutrients like iron during bacterial infection. Ferroportin (Fpn), an iron-exporting protein, is found on the plasma membrane of macrophages and, if not modulated during phagocytosis, would transport iron into phagosomes and supply phagocytosed bacteria with iron. Interestingly, the fate of Fpn during phagocytosis and bacterial infection remains unknown. We generated a Fpn-GFP fusion protein and, using fluorescence microscopy, demonstrated that, during phagocytosis in RAW264.7 macrophages, Fpn is removed from phagosomes containing IgG-coated beads or Staphylococcus aureus. Further, Fpn is present on Rab5-containing phagosomes but absent …

Investigation Of Chitosan-Based Hydrogels As A Cell Delivery Platform For Adipose-Derived Stem/Stromal Cell Transplantation To Promote Angiogenesis In Ischemic Tissues, Jobanpreet Singh Dhillon

Electronic Thesis and Dissertation Repository

Stem cell transplantation is under investigation to stimulate angiogenesis in patients with peripheral artery disease. To develop a cell-delivery platform that enhances cell retention and function post-transplantation, the response of human adipose-derived stem/stromal cells (ASCs) encapsulated within N-methacrylate glycol chitosan (MGC) hydrogels with or without integrin-binding RGD or IKVAV motifs was explored. ASC viability was enhanced in the MGC and MGC-RGD hydrogels relative to the MGC-IKVAV group under hypoxic (2% O­₂) culture conditions, with cell spreading and higher metabolic activity noted in MGC-RGD at 14 days. Analysis of angiogenic gene expression revealed similar patterns between all hydrogel …

P32. Altered Sensory Processing In Response To Novel Dreadd-Induced Inactivation Of Gaba In Pedunculopontine Tegmental Nucleus, Niveen Fulcher

Western Research Forum

Niveen Fulcher¹, Cleusa De Oliveira², & Susanne Schmid^1,2

¹Schulich School of Medicine & Dentistry, University of Western Ontario

²Anatomy and Cell Biology, University of Western Ontario

Altered sensory processing in response to novel DREADD-induced inactivation of GABA in pedunculopontine tegmental nucleus

Background: Sensory processing deficits are associated with certain psychiatric illnesses, such as schizophrenia and autism spectrum disorder (ASD). Sensory filtering and sensorimotor gating are evolutionarily conserved preattentive responses that filter and block redundant sensory stimuli that would otherwise overwhelm our brains. To date, underlying mechanisms of these deficits are undefined. Prepulse …

P23. Elucidation Of The Signaling Pathway Of Mertk, Kyle Taruc

Western Research Forum

Background

Mer Tyrosine Kinase (MERTK) is a receptor which mediates efferocytosis – removal of apoptotic cells by phagocytes such as macrophages. MERTK plays a critical role in homeostasis, with mutations in MERTK associated with the development and progression of atherosclerosis, the buildup of cholesterol-laden plaque in the sub-arterial space. Indeed, one MERTK allele is associated with 66% (heterozygous) to 75% (homozygous) protection from atherosclerosis, while other alleles and SNP’s pre-dispose to atherosclerosis and autoimmunity. Complications resulting from atherosclerosis, including heart attack and stroke, are currently the second leading cause of mortality in Canada. Despite the importance of MERTK in atherosclerosis …

Pulmonary Surfactant Fortified With Cath-2 As A Novel Therapy For Bacterial Pneumonia, Brandon J. Baer

Western Research Forum

Background: Bacterial pneumonia is a leading cause of death worldwide, with high mortality rates persisting even after antibiotic treatment. Current treatments for pneumonia involve administration of antibiotics, however after the bacteria are killed they release toxic substances that induce inflammation and lung dysfunction. Host defense peptides represent a potential solution to this problem through their ability to down regulate inflammation. However, effective delivery to the lung is difficult because of the complex branching structure of the airways. My study addresses this delivery problem by using exogenous surfactant, a pulmonary delivery vehicle capable of improving spreading of these peptides throughout the …

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 …