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Changing The Substrate Specificity Of Arogenate Dehydratases (Adts) From Arabidopsis Thaliana., Megan Es Smith-Uffen

Electronic Thesis and Dissertation Repository

Phenylalanine (Phe), an essential aromatic amino acid, serves as a precursor for protein synthesis and a variety of secondary metabolites in plants. Two pathways are known for Phe biosynthesis. In the first, prephenate dehydratases (PDTs) convert prephenate to phenylpyruvate, which is transaminated to Phe. In the second, prephenate is transaminated to arogenate, which is converted to Phe by arogenate dehydratases (ADTs). ADTs and PDTs are structurally very similar, as are their substrates. Six ADTs (ADT1-ADT6) have been identified in Arabidopsis thaliana. ADT1 and ADT2 can recognize both prephenate and arogenate as substrates whereas ADT3-ADT6 are solely arogenate-accepting. Twenty ADT domain-swapping …

Social Immunity And The Expression Of Immune-Related Genes In The Eastern Subterranean Termite, Qi Gao

Electronic Thesis and Dissertation Repository

Individuals living within social groups may benefit from the efficiencies of division of labour, but on the other hand render themselves vulnerable to socially transmitted disease. This cost to social living should promote cooperative barriers to disease transmission, especially in eusocial taxa where spatial and genetic proximity to nestmates are characteristically pronounced. Though studies of the immunity at multiple levels in social species are becoming more common, little is known about how their sociality is deployed to resist contagion. By exposing the Eastern subterranean termite Reticulitermes flavipes to entomopathogenic fungi, I studied their immune responses at multiple levels. At the …

Two Spotted Spider Mite (Tetranychus Urticae) Selection To Arabidopsis Thaliana, Huzefa Ratlamwala

Electronic Thesis and Dissertation Repository

Spider mite feeding on A. thaliana induces the production of indole glucosinolates (IGs), plant secondary metabolites that negatively affect mite performance. In this study I conducted selection experiments on A. thaliana with varying levels of IGs, to determine if mites could adapt to IGs and other defense compounds. After 12 months, mites reared on host with IGs performed significantly better on A. thaliana than mites maintained on beans. However, an adaptation cost was detected between selected mite lines and their ancestral host. The qRT-PCR data on different mite lines revealed that the detoxification genes previously identified may only be involved …

Nitrogen Fixation By The Cyanobacterium Nostoc Punctiforme In Response To Variation In Nitrogen Availability, Temperature, And Atmospheric Co2 Concentrations, Danielle A. Griffith

Electronic Thesis and Dissertation Repository

The predominant input of available nitrogen (N) in boreal forest ecosystems originates from moss-associated cyanobacteria, which fix unavailable atmospheric N₂, contribute to the soil N pool, and thereby support forest productivity. Although increases in N availability, temperature, and atmospheric CO₂ concentrations are expected in Canada’s boreal region over the next century, little is known about the combined effects of these factors on N₂ fixation by axenic cyanobacteria or the associated mechanisms. I assessed changes in N₂ fixation by Nostoc punctiforme under different global environmental change scenarios and examined correlations between the response and changes in …

The Role Of Lactate Dehydrogenase B In Aerobic Glycolysis-Mediated Resistance To Ab Toxicity, Tyler Tam

Electronic Thesis and Dissertation Repository

Alzheimer’s disease is a progressive, neurodegenerative disorder characterized by the accumulation of amyloid β (Aβ) plaques in affected brain regions. Strong evidence indicates that Aβ exerts neurotoxic effects by promoting mitochondrial dysfunction and ROS production, leading to widespread oxidative damage and activation of pro-apoptotic mechanisms. Past investigations suggest that neuronal resistance to Aβ toxicity is partly mediated by a Warburg Effect-like metabolism, in which cells exhibit elevated glycolytic activity and lactate production, while limiting mitochondrial respiration. Elevated lactate dehydrogenase A (LDHA) activity, which catalyzes lactate production from pyruvate, has been demonstrated to counter Aβ-induced oxidative stress and neurotoxicity, however the …

Immune Function And Infection Status Is Related To Migration Distance And Phases Of The Annual Cycle In Song Sparrows (Melospiza Melodia), Tosha R. Kelly

Electronic Thesis and Dissertation Repository

Life history theory predicts animals adjust immune investment based on their risk of encountering familiar and unfamiliar parasites. Although long-distance migrants may encounter a greater diversity of parasites than short-distance migrants, the energetic costs of migration may constrain immune investment. However, few studies have investigated the relationship between migration distance and immunity. I used stable isotope analysis to estimate the wintering latitude, and thus migration distance, of song sparrows (Melospiza melodia). I assessed whether migration distance was related to the incidence of infection with a blood-borne parasite, parasite load, and immune function. The incidence of infection increased with …

Early Mechanisms Of Retinal Degeneration In The Harlequin Mouse, Eric Dolinar

Electronic Thesis and Dissertation Repository

Retinal diseases are personally debilitating and expensive, yet many early disease mechanisms leading to their onset and progression remain poorly understood. The harlequin mouse is a model of human mitochondrial dysfunction and parainflammation leading to subsequent cerebellar and retinal degeneration. Diagnosis of retinal degeneration can be tracked in vivo and is associated with AIF dysfunction. Here, retinal dysfunction in the harlequin mouse was first quantified using electroretinography followed by assay of blood-retinal-barrier integrity and transcriptome alterations in young adulthood. Nonmetric multidimensional scaling of oscillatory potentials provided a novel, comprehensive assessment of inner-retinal health and can detect shifts in OP parameters. …

Seed Tuber Treatments With Pseudomonas Spp. To Reduce Potato Common Scab Incidence And Severity, Muna Basahi

Electronic Thesis and Dissertation Repository

Potato common scab is a tuber- or soil-borne disease caused by several species in the genus Streptomyces. The objective of this study was to study the treatment of seed tubers with Pseudomonas spp. as a means to reduce common scab incidence and severity, and improve seed tuber quality and marketability. All four Pseudomonas spp. tested inhibited Streptomyces SS-1; PEI-1 and AL-1 in vitro.

In laboratory trials, treatments of seed tubers with Pseudomonas strains A25, A145, and A153, significantly reduced in the number of pathogenic Streptomyces in comparison to untreated tubers within five weeks (P<0.05). Seed tuber treatments with A25 and A153 significantly reduced scab incidence and severity in Russets Burbank and Prospect, respectively. This study also demonstrated the use of TaqMan qPCR detecting the txtAB gene analysis as …

Islet Regenerative Properties Of Ex Vivo Expanded Hematopoietic Progenitor Cells, Ayesh K. Seneviratne

Electronic Thesis and Dissertation Repository

Human umbilical cord blood (UCB) progenitor cells with high aldehyde dehydrogenase activity (ALDH^hi), can stimulate endogenous islet regeneration after transplantation into mice with steptozotocin (STZ)-induced diabetes. However, UCB ALDH^hi cell are extremely rare, and expansion will be required to develop cell-mediated strategies to treat patients with diabetes. To increase the number of progenitor cells available for clinical application, we expanded ALDH^hi UCB cells under clinically applicable, serum-free hematopoietic-restricted conditions. 6 day expansion resulted in a 15-fold increase in total cell number, and a 3-fold increase in the number of HPC retaining high ALDH (ALDH^hi HPC) …

Identifying The Role Of Non-Native Species In The Enhanced Trophic Transfer Of Mercury In The Food Web Of Lake Erie, A North American Great Lake, Kaylin M.S. Liznick

Electronic Thesis and Dissertation Repository

Increasing mercury (Hg) concentrations in top predatory fish is concerning for human and wildlife health. This study examined the amount of Hg available to the food web of Lake Erie, and explored the role that two recently established non-native species, dreissenid mussels and round goby, have played in the trophic transfer of Hg to sport fish. A comprehensive sampling of total Hg (THg) and methylmercury (MeHg) within Lake Erie water, sediment and seston with high temporal and spatial resolution describes environmental concentrations. In addition, biotic THg and MeHg are quantified in benthic invertebrates and three fish species. A steep spatial …

Associations Between Hypothalamic-Pituitary-Adrenal Axis System Gene Variants And Cortisol Reactivity In Preschoolers: Main Effects And Gene-Environment Interactions, Haroon I. Sheikh

Electronic Thesis and Dissertation Repository

Exposure to stressful events during early development has consistently been shown to produce long lasting effects on the hypothalamic-pituitary-adrenal (HPA) axis, which may increase vulnerability to mood and anxiety disorders. Recently reported genetic association studies indicate that these disorders may be influenced, in part, by gene-environment interactions (GxE) involving polymorphisms within the corticotrophin-releasing hormone and monoaminergic system genes. However, little is known about how genetic variants and life stress work to shape children’s neuroendocrine reactivity and emerging symptoms. Therefore, the aim of this thesis is to examine main effects of candidate genes and GxE on the neuroendocrine stress response and …

The Apl5 Subunit Of The Ap3 Adaptor Protein Complex Is Required For Cytokinesis Checkpoint Function In Schizosaccharomyces Pombe, Joy Wang

Electronic Thesis and Dissertation Repository

This study investigates the role of Apl5p in the complex regulatory network of Schizosaccharomyces pombe, which ensures the faithful and reliable completion of cytokinesis. This network, referred to as the cytokinesis checkpoint, ensures successful cell division upon perturbances to the cytokinetic machinery (e.g. disruption of the actin cytoskeleton). Apl5p has been identified as a putative regulator of the cytokinesis checkpoint based on the hyper-sensitivity of apl5D mutants to the actin depolymerizing drug, Latrunculin A. Apl5p is an essential subunit of the conserved AP3 adaptor complex, which is suspected to be involved in vesicular trafficking. Thus, I hypothesized that Apl5p …

Testing For Positive Edge Responses In A Fragmented Landscape In The Eastern Tiger (Papilio Glaucus) And The Spicebush (P. Troilus) Swallowtail Butterflies, Jenna C. Siu

Electronic Thesis and Dissertation Repository

Landscape changes such as habitat fragmentation and habitat loss are contributing to a global decline in biodiversity. While habitat fragmentation research has mainly focused on species that avoid edges, or the boundaries between different landcover types (negative edge response), a hypothesized resource distribution model predicts that species that require complementary resources in different landcovers will be most abundant at edges (positive edge response). Adults of Eastern Tiger (Papilio glaucus) and Spicebush (P. troilus) swallowtail butterflies require forests for oviposition sites and meadows for nectar resources. I examined the relative abundance and flight orientation of both species …

Ubiquitin-Mediated Degradation Via Ups And Lysosome, Qizhi Sun

Electronic Thesis and Dissertation Repository

Ubiquitination plays a fundamental role in determining protein fate. Once ubiquitinated, the cargo is directed to the proteasome for partial or complete degradation or lysosome for complete degradation. Failing to eliminate these cargos results in the accumulation of toxic proteins that contribute to neurodegenerative and immunological diseases, cancer and other human maladies. Thus, identifying proteins subject to ubiquitin-mediated degradation and characterizing the mechanisms governing these processes underscores their importance to human health. The calcium/calmodulin-dependent serine protein kinase (CASK) is one such protein that is required for brain development. However, mutations that cause CASK to accumulate are correlated to X-linked mental …

Population Genetic Structure In The Pitcher Plant Flesh Fly Fletcherimyia Fletcheri, John R. O'Leary

Electronic Thesis and Dissertation Repository

The study of population genetic structure in the pitcher plant flesh fly, Fletcherimyia fletcheri, is an important step in bettering our understanding of dispersal abilities, gene flow, and behavior in the species. In this paper, an extended sampling of populations across Algonquin Provincial Park was performed to elucidate an effective scale of genetic differentiation in F. fletcheri. Genetic differentiation between sites was compared to interceding landscape composition, and digital dispersal models were developed, testing the hypothesis that F. fletcheri uses aquatic tributaries for dispersal between peatlands. Data were collected on 613 specimens from 15 populations, and population differentiation …

Transgenic Plants As Novel Bioreactors To Produce Human Protein, Nadiyah Alqazlan

Electronic Thesis and Dissertation Repository

Plants have emerged in the past decade as a suitable alternative to the current production systems for recombinant pharmaceutical proteins. This project aims to develop plants as a green bioreactor for large-scale and cost-effective production of human therapeutic proteins. Several binary plant expression vectors were designed and constructed to express a human protein. The constructed plant expression vectors were transferred to Agrobacterium prior to plant transformation. By using Agrobacterium-mediated plant transformation, both transient expression in N. benthamiana plants and stable expression of the human protein in Nicotiana tabacum cv.81V9 were achieved. Immunoassays such as Western blot and ELISA (the enzyme-linked …

Signaling Events During Extraembryonic Endoderm Differentiation, Jason Taek Ki Hwang

Electronic Thesis and Dissertation Repository

Mouse F9 cells differentiate into primitive endoderm (PrE) when treated with retinoic acid (RA) and into parietal endoderm (PE) following subsequent treatment with dibutyryl cAMP. Wnt6 is up-regulated in PrE cell, and although it is sufficient to induce differentiation by signaling through the canonical WNT/β-catenin pathway, the mechanism by which the Wnt6 gene is regulated is not known. In addition to WNT signaling, PrE differentiation is accompanied by an increase in reactive oxygen species (ROS). ROS have been implicated in regulating the canonical WNT/β-catenin signaling pathway through Nucleoredoxin (NRX), but whether they are sufficient to induce extraembryonic endoderm in vitro …

Sirna Targeting Of Thymidylate Synthase, Thymidine Kinase 1 And Thymidine Kinase 2 As An Anticancer Therapy: A Combinatorial Rnai Approach, Christine Di Cresce

Electronic Thesis and Dissertation Repository

Thymidylate synthase (TS) is the only de novo source of thymidylate (dTMP) for DNA synthesis and repair. Drugs targeting TS protein are a mainstay in cancer treatment but off-target effects and toxicity limit their use. Cytosolic thymidine kinase (TK1) and mitochondrial thymidine kinase (TK2) contribute to an alternative dTMP-producing pathway, by salvaging thymidine from the tumour milieu, and may modulate resistance to TS-targeting drugs. We have previously shown that TS antisense molecules (oligodeoxynucleotides, ODNs, and small interfering siRNA, siRNA) sensitize tumour cells, both in vitro and in vivo, to TS targeting drugs. As both TS and TKs contribute to cellular …

Effects Of Microrna156 On Flowering Time And Plant Architecture In Medicago Sativa, Banyar Aung

Electronic Thesis and Dissertation Repository

MiR156 regulates plant biomass production through regulation of members of Squamosa-Promoter Binding Protein-Like (SPL) genes. In this study, I investigated function of miR156 in Medicago sativa (alfalfa). Alfalfa plants overexpressing alfalfa miR156 and Lotus japonicus miR156 were generated, and the miR156 cleavage targets were validated. In silico analysis showed that some alfalfa sequence reads (~ 60 bp) are similar to miR156 precursors but the hairpin secondary structure could not be produced from these sequences. Of the five predicted target SPLs genes, three (SPL6, SPL12 and SPL13) contain miR156 cleavage sites and their expression …

Growth Of The Marine Fish-Killing Phytoflagellate, Heterosigma Akashiwo Under Emerging Coastal Regimes: Temperature, Eutrophication And Ocean Acidification, Cayla M. Bronicheski

Electronic Thesis and Dissertation Repository

Coastal oceans are fundamental to human economies, nutrition and recreation. Anthropogenic stressors have led to the acceleration of the nitrogen cycle, the accumulation of inorganic carbon in the earth’s atmosphere, the loss of UV-scavenging upper atmospheric ozone and the overall accumulation of deep elements from the earth’s crust to surface exposure. These changes have caused ocean acidification and eutrophication events in coastal waters and the impacts of these events on primary production and ocean biodiversity are not yet fully understood.

This study examined the effects of predicted future ocean conditions (salinity, temperature, reduced seawater pH and modified nitrogen supplies), on …