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Molecular And Genetic Analysis Of A Conserved Transcription Factor With A Role In Promoting The Completion Of Cytokinesis In Schizosaccharomyces Pombe, Bidhan Chakraborty

Electronic Thesis and Dissertation Repository

The fission yeast Schizosaccharomyces pombe activates regulatory networks that promote the faithful execution of cytokinesis in response to drugs that perturb the cytokinesis machinery. In order to identify novel components of these networks, a screen for mutants hyper-sensitive to the actin depolymerizing drug LatrunculinA (LatA) was previously performed. This screen identified a transcription factor, Pap1p, which is orthologous to the mammalian stress activated transcription factor, AP-1. Through molecular and genetic analysis, I showed that the deletion mutant of pap1 is sensitive to LatA and that it cannot maintain the integrity of the actomyosin ring upon LatA treatment leading to cytokinesis …

Characterization Of The Alternative Oxidase From The Psychrophilic Green Alga Chlamydomonas Sp. Uwo241, Michael Sj Inman

Electronic Thesis and Dissertation Repository

The alternative oxidase (AOX) was studied in the psychrophilic green alga Chlamydomonas sp. UWO241. AOX is the sole component of the alternative pathway of mitochondrial electron transport and is present in all plant and algal species. In silico analysis of the deduced protein sequence of the cloned AOX cDNA showed that the UWO241 protein has lower amounts of proline and higher amounts of lysine and tryptophan compared to the AOX sequence of the mesophilic alga C. reinhardtii. These changes have been seen in other studies of cold-adapted enzymes. Interestingly, unlike C. reinhardtii, AOX transcript abundance in UWO241 …

Effects Of Excitation Pressure On Variegation And Global Gene Expression In Arabidopsis Thaliana, Rainer Bode

Electronic Thesis and Dissertation Repository

I assessed the effects of photosystem II excitation pressure on chloroplast biogenesis and leaf sectoring in the Arabidopsis thaliana variegated mutants im, spotty, var1, var2, chs5 and atd2. The plants were grown under varying degrees of excitation pressure induced by growth at increasing irradiance at different temperatures and the extent of variegation was quantified throughout the plant’s development. I found that the degree of variegation was positively correlated with excitation pressure, regardless of whether high light or low temperature was used to induce increased excitation pressure in all the mutants tested. This was irrespective of …

Foraging Ecology, Sexual Selection, And Divergence In Sunfish (Lepomis Spp.), Scott F. Colborne

Electronic Thesis and Dissertation Repository

The origins of novel traits and their contribution to biodiversity have long been of interest to biologists. My research focused on the links between foraging ecology and both natural and sexual selection, and how these mechanisms interact to shape the phenotypic diversification of natural populations. Using bluegill (Lepomis macrochirus) and pumpkinseed sunfish (Lepomis gibbosus), I examined three major questions: 1) how are diet and morphological variation related to alternative reproductive tactics in bluegill; 2) are sexual selection and disruptive selection driving divergence between foraging ecomorphs in pumpkinseed; and 3) how are human-induced changes to prey communities …

Computational Molecular Coevolution, Russell J. Dickson

Electronic Thesis and Dissertation Repository

A major goal in computational biochemistry is to obtain three-dimensional structure information from protein sequence. Coevolution represents a biological mechanism through which structural information can be obtained from a family of protein sequences. Evolutionary relationships within a family of protein sequences are revealed through sequence alignment. Statistical analyses of these sequence alignments reveals positions in the protein family that covary, and thus appear to be dependent on one another throughout the evolution of the protein family. These covarying positions are inferred to be coevolving via one of two biological mechanisms, both of which imply that coevolution is facilitated by inter-residue …

Role Of Carotenoid Cleavage Dioxygenases In Volatile Emissions And Insect Resistance In Arabidopsis, Shailu Lakshminarayan

Electronic Thesis and Dissertation Repository

In Arabidopsis thaliana, carotenoid degradation by enzymatic oxidative cleavage is catalyzed by nine CCD and NCED enzymes; this cleavage produces an array of terpenoid products that are collectively known as apocarotenoids, which include volatile and non-volatile compounds. Previous studies on CCD1 revealed that its overexpression in A. thaliana enhances β-ionone emission and reduces damage caused by flea beetles. In consideration of these findings, I generated CCD4 and CCD8 Arabidopsis overexpression lines. Further, I characterized these overexpression lines on the basis of their carotenoid content and their volatile profiles. Surprisingly, accumulation of key carotenoids in the leaves was observed in both …

Characterizing The Human Vaginal Microbiome Using High-Throughput Sequencing, Jean Megan E. Macklaim

Electronic Thesis and Dissertation Repository

The human vaginal microbiome undoubtedly has a significant role in reproductive health and for protection from infectious organisms. Recent efforts to characterize the bacterial species of the vagina using molecular techniques have uncovered an unexpected diversity. Using high-throughput sequencing I sought to describe the structure and function of the vaginal microbiome under different physiological states including healthy, bacterial vaginosis (BV), post-menopausal vaginal atrophy, and acute vulvovaginal candidiasis (VVC).

Partial 16S rRNA gene sequencing revealed that healthy, asymptomatic women most often have vaginal biotas dominated by Lactobacillus iners or L. crispatus. In contrast, BV is a heterogeneous, highly diversified condition …

The Hippocampus Participates In A Pharmacological Rat Model Of Absence Seizures, Justin Andrew Arcaro

Electronic Thesis and Dissertation Repository

The thalamocortical network is responsible for the generation of spike-and-wave discharges (SWDs) in absence epilepsy. Recent studies suggest a potential involvement of the hippocampus, which may explain the variability in the extent of cognitive deficits among patients with absence epilepsy. I hypothesize that the hippocampus may become entrained in spike-and-wave discharges following thalamocortical activation. The gamma-butyrolactone (GBL) rat model of absence seizures was used in this thesis. Following GBL injection, SWDs of 4 to 6 Hz developed in the spontaneous local field potentials (LFPs) recorded by depth electrodes in the thalamus, neocortex and hippocampus. Synchronization of hippocampal, thalamic and neocortical …

Exploring The Structure And Biochemistry Of Oxidation-Mediated Inhibitation Of The Peptidyl-Prolyl Isomerase Pin1, Brendan T. Innes

Electronic Thesis and Dissertation Repository

Pin1 is a phosphorylation-dependent peptidyl-prolyl isomerase that has been shown to be neuroprotective in aging-related neurodegenerative diseases such as Alzheimer's disease (AD). However, it is not active in AD brain, and a recent proteomic screen of Mild Cognitive Impairment (MCI) brain samples revealed that Pin1 is oxidized in the brains of these pre-AD patients. This suggests that this oxidation may be the cause of the loss of the neuroprotective Pin1 function in AD. The Pin1 active site contains a functionally critical cysteine residue (Cys113) with a low predicted pKa, making it highly susceptible to oxidation. We hypothesize that Pin1 is …

Cold-Activation Of The Drosophila Melanogaster Immune System, Golnaz Salehipourshirazi

Electronic Thesis and Dissertation Repository

Evidence of immune response enhancement after cold exposure suggests that cold activates the insect immune system. I investigated whether the immune response of Drosophila melanogaster is activated by cold exposure in the absence of pathogens. To explore if different kinds of cold affect the immune response differently, I included acute and chronic cold exposure. I cold-exposed flies, and then examined up-regulation of immune-related genes. In addition, I measured hemocyte concentration, phenoloxidase activity, and woundinduced melanization. Acute cold exposure increased hemocyte concentration and woundinduced melanization. Chronic cold did not change hemocyte concentration, phenoloxidase activity or melanization in flies. Acute and chronic …

The Role Of Choline Acetyltransferase Variants In Alzheimer's Disease Models, Shawn Albers

Electronic Thesis and Dissertation Repository

The primate specific 82-kDa choline acetyltransferase (ChAT) isoform is found in the nuclei of cholinergic neurons, with a disruption in the subcellular localization in aging and AD brain samples# The functional significance of this protein is poorly understood. Previous studies have revealed a potentially protective role for 82-kDa ChAT, mediated through a reduction in amyloid-!1-42 (A!1-42) release in APP/PS1 double transgenic primary cortical neurons. Here we examine the effect of 82-kDa ChAT expression in transgenic neurons, on the amyloidogenic processing of amyloid precursor protein (APP) and A! production. In this study we demonstrate 82-kDa ChAT transcriptionally increases golgi- localized "-ear-containing …

Reaching For The Light: The Prioritization Of Conspicuous Visual Stimuli For Reflexive Target-Directed Reaching, Daniel K. Wood

Electronic Thesis and Dissertation Repository

The degree to which something stands out against the background of its environment communicates important information. The phenomenon of camouflage is a testament of the degree to which visual salience and probability of survival tend to overlap. Salient stimuli often elicit fast, reflexive movements in order to catch prey or avoid a predator. The overarching goal of the work presented in this thesis is to investigate how the physical salience of visual stimuli influence the programming and execution of reaching movements. I approached this question by recording kinematics and muscle responses during reaching movements. Broadly, this thesis investigates the effect …

Increasing Atmospheric Nitrogen Deposition: Implications For Tallgrass Prairie Restoration, Jennifer M. Mcphee

Electronic Thesis and Dissertation Repository

Continued intensification of agriculture and combustion of fossil fuels will increase rates of atmospheric nitrogen (N) deposition over the next century. N is typically a limiting resource for terrestrial plants, and many species are adapted to low-N conditions. Increased N availability can affect both plant biomass and species composition, often favouring N-demanding, adventive species. These effects can be adverse in the context of ecological restoration, where the end product often relies on establishing a particular community composition. I used a field experiment in Norfolk County, Ontario, to examine how N addition affects species composition and plant productivity of a tallgrass …

The Effect Of Testosterone On The Spring Migratory Phenotype Of A North American Songbird (Zonotrichia Albicollis), Caitlin L. Vandermeer

Electronic Thesis and Dissertation Repository

In passerines, the endocrine modulators responsible for seasonal changes in migratory behaviour and physiology are unclear. Spring photoperiods alter androgen levels, influencing muscle mass and fat deposition rates to power migration, as well as enhance nocturnal migratory restlessness activity (Zugunruhe). My study compared physiological indicators and migratory restlessness in castrated and intact white-throated sparrows (Zonotrichia albicollis) following photoperiod and hormone manipulation. Nocturnal restlessness activity was highest in migratory intact males or migratory castrated males that received testosterone replacement. Liver mass decreased in all photostimulated migratory groups regardless of testosterone treatment. Likewise, oxidative enzyme activity was unrelated to testosterone, …

Regulation Of Eukaryotic Mcm2-7 Activity, Lance F. Dasilva

Electronic Thesis and Dissertation Repository

The transfer of genetic material from one cell generation to the next requires precise genome duplication. Aberrant DNA replication can lead to genomic instability and contribute to diseases arising from an unregulated cell cycle, such as cancer. Replicative DNA polymerases require a single-stranded (ssDNA) template from which to produce newly synthesized DNA. In eukaryotes, ssDNA is generated by the heterohexameric minichromosome maintenance 2 through 7 (Mcm2-7) replicative helicase that unwinds duplex DNA. Strict temporal separation of helicase loading and activation at multiple replication origins ensures once per cell cycle replication. The processes involved in activating Mcm2-7 to unwind DNA during …

Prenatal Programming Of Hepatic Glucose And Cholesterol Regulation In Male Rat Offspring By Chronic Intermittent Hypoxia, Waseem Iqbal

Electronic Thesis and Dissertation Repository

Obstructive sleep apnea (OSA) is a chronic disorder involving repetitive interruptions in breathing during sleep. Sufferers of OSA are exposed to chronic intermittent hypoxia (CIH), characterized by cyclical reductions in oxygen availability. A number of studies have established a link between OSA and various cardiovascular and metabolic comorbidities in adulthood, including hypertension, obesity, and type II diabetes. While the consequences of OSA in adults have been well described, the cross-generational impact of this condition and potential effects on fetal development are not known. Epidemiological and animal studies have demonstrated that physiological insults during pregnancy lead to diminished growth of offspring …

Contribution Of Trpm2 To Memory Loss In An Alzheimer's Mouse Model, Megan M. Chen

Electronic Thesis and Dissertation Repository

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by the progressive deterioration of memory and other intellectual abilities. Accumulation of amyloid-β (Aβ) peptide, the major contributor to the senile plaques central to AD, is thought to mediate neurotoxicity by inducing oxidative stress and calcium dysregulation. Transient Receptor Potential Melastatin type 2 (TRPM2) is a calcium permeable, non-selective cation channel activated under oxidative stress and ultimately induces cell death. The APPSWE/PSEN1ΔE9 double transgenic mouse model carries the human APPswe (Swedish mutations K594N/M595L) and PS1 mutations with a deletion in exon 9 (PS1-dE9), and is one of the most commonly used AD …

Tundra Swan (Cygnus Columbianus Columbianus) Habitat Selection During The Nonbreeding Period, Katelyn H. A. Weaver

Electronic Thesis and Dissertation Repository

Changes in availability and foraging profitability of agricultural and aquatic habitats have the potential to greatly influence population dynamics of waterfowl. Therefore, the purpose of my research was to understand habitat selection by Tundra Swans during the nonbreeding period and to explore the scale-dependency of these relationships. Habitat selection was influenced by seasonal changes in nutritional requirements and food availability; Tundra Swans selected open water and agriculture in winter, wetlands were weakly selected during migration when open water was strongly selected (especially during autumn), and there was a 2-fold increase in use of agriculture from autumn to spring. It appears …

Song As An Honest Indicator Of Developmental Stress In Song Sparrows, Kimberly L. Schmidt

Electronic Thesis and Dissertation Repository

The Developmental Stress Hypothesis proposes that the honesty of birdsong is maintained by costs incurred during development, such that song in adulthood reflects exposure to early-life stressors. The purpose of this thesis was to provide a rigorous test of the Developmental Stress Hypothesis in song sparrows (Melospiza melodia). My three objectives were to determine the long-term effects of early-life stress on: 1) physiological traits (Chapters 2, 3, and 4); 2) male song production (Chapter 5); and 3) the response of females to song (Chapter 6). Nestlings were hand-reared in captivity under one of three treatment conditions: control, food …

Effects Of Biodiesel Concentration On Microbial Deterioration Of Polyethylene In A Simulated Fuel Storage Tank, Juan Manuel Restrepo-Florez

Electronic Thesis and Dissertation Repository

In this study a simulated fuel storage tank was used to investigate the effect of biodiesel concentration on biodegradation of polyethylene. This research is relevant in the field of fuel storage. The simulated storage system consisted of a number of identical conical flasks. Each flask was comprised of two layers, an upper one consisting of a fuel blend of diesel with biodiesel in concentrations ranging from 0 to 100% of biodiesel and the bottom layer containing an aqueous mineral media inoculated with a community obtained from a real fuel storage facility. Polyethylene slabs cut to a specific size were immersed …

Understanding Honey Bee Worker Sterility: A Conceptual-Empirical Framework, Emma K. Mullen

Electronic Thesis and Dissertation Repository

Kin selection explains how complex social behaviour can evolve at the gene level, but this theory does not identify which genes are necessary for the expression of altruism. In my first chapter I overview seven criteria for genes for altruism using the honey bee as a model species. In the second chapter I explore one criterion in detail – that altruism genes are differentially expressed between reproductive and sterile workers. I used results from previous microarray studies to reconstruct nine knowledge-based gene networks that describe reproductive altruism by means of ovary activation and de-activation. All networks were enriched for Gene …

Developmental Plasticity Of Muscle Cellularity And Swim Performance Of Juvenile Chinook Salmon In Response To Temperature, Dan Dohyung Lim

Electronic Thesis and Dissertation Repository

I investigated the influence of incubation temperature on muscle development and swim performance in juvenile Chinook salmon (Oncorhynchus tshawytscha). In 2011 and 2012, embryos were incubated at different combinations of temperature (7, 9, 15 °C), before and after the onset of free swimming. High-intensity fixed velocity swim tests were performed to assess anaerobic capacity of juveniles. In 2012, these tests were done at a standardized body size (~40 mm). The mean (least-squares) logged times to fatigue of the 15 °C-incubated fish was higher (0.623 ± 0.049 SE) than the 7 °C-incubated fish (0.435 ± 0.048 SE) even after …

Reproductive Biology And Speciation In Drosophila Pseudoobscura, Josh H.M. Alpern

Electronic Thesis and Dissertation Repository

Sexual selection is an important force driving the evolution of reproductive traits, including sperm morphology and mating behaviour. Divergent sexual selection among populations can eventually lead to errors in spermatogenesis in inter-population hybrids, and subsequently speciation. In Chapter 2, I identify a novel sperm class and how its proportion in the ejaculate is adjusted when Drosophila pseudoobscura males are exposed to competition. In Chapter 3, I assess how competition causes both males and females to adjust their mating behaviour. In Chapter 4, I characterize interspecific hybrid spermatogenic breakdown from two closely-related sub-species. While the genetics of hybrid sterility has been …

Iron-Regulated Cyanobacterial Predominance And Siderophore Production In Oligotrophic Freshwater Lakes, Ryan J. Sorichetti

Electronic Thesis and Dissertation Repository

The frequency and intensity of cyanobacterial blooms (cyanoblooms) is increasing globally. Contrary to existing phosphorus (P) and nitrogen (N) paradigms describing cyanobloom proliferation in eutrophic (nutrient-rich) freshwater lakes, many of the recent cyanobloom reports pertain to oligotrophic (nutrient-poor) freshwater lakes with no prior history of cyanobloom occurrence. There exists a critical research need to re-visit existing conceptual models, identify regulating factors currently unaccounted for and improve our ability to effectively detect and measure cyanobacterial toxins (cyanotoxins) in lakes. Iron (Fe) is required in nearly all pathways of cyanobacterial macronutrient use, though its direct role in regulating cyanobacterial biomass is not …

A Hybrid Visual Control Scheme To Assist The Visually Impaired With Guided Reaching Tasks, Duane Jacques

Electronic Thesis and Dissertation Repository

In recent years, numerous researchers have been working towards adapting technology developed for robotic control to use in the creation of high-technology assistive devices for the visually impaired. These types of devices have been proven to help visually impaired people live with a greater degree of confidence and independence. However, most prior work has focused primarily on a single problem from mobile robotics, namely navigation in an unknown environment. In this work we address the issue of the design and performance of an assistive device application to aid the visually-impaired with a guided reaching task. The device follows an eye-in-hand, …

Soil Freezing Effects On A Grass-Dominated Old Field Ecosystem Under Current And Future Rates Of Atmospheric Nitrogen Deposition, Mat Vankoughnett

Electronic Thesis and Dissertation Repository

Climate change is expected to alter the intensity and dynamics of soil freezing as a result of increased air temperatures and reduced snow cover. Soil freezing can influence ecosystem nitrogen (N) cycling by damaging plants and soil microorganisms, but little is known about how soil freezing effects on ecosystem N cycling may combine or interact with increased atmospheric N deposition, which is also expected to exert a strong influence on terrestrial ecosystems in the coming decades. The objective of my thesis was to examine the combined and possibly the interactive effects of climate induced changes in soil freezing and N …

Transforming Growth Factor-Beta Receptor Signalling Is Modulated By Integrin-Linked Kinase, Stellar H. Boo

Electronic Thesis and Dissertation Repository

Transforming growth factor-beta 1 (TGF-β1) modulates regeneration after injury through induction of fibroblast proliferation, migration, and differentiation into myofibroblasts. Induction of myofibroblast differentiation by TGF-β1 requires expression of integrin-linked kinase (ILK). I now show that ILK interacts with TGF-β receptor type II (TβRII) in primary dermal fibroblasts. Further, colocalization of ILK and TβRII can be observed at the cell membrane and in intracellular vesicles. The association of TβRII and ILK does not require TGF-β1 stimulation, kinase activity of TGF-β1 receptor type I or TβRII, and it does not involve interactions between ILK and focal adhesion-associated proteins. When this interaction is …

Characterization Of The Interaction Between Bone Sialoprotein And Type I Collagen, Rose Yee

Electronic Thesis and Dissertation Repository

The mechanism of biomineralization is unknown. In bone, it has been proposed that an acidic phosphoprotein of the extracellular matrix (ECM) is important in the nucleation of hydroxyapatite (HA). The mineralized tissue protein, bone sialoprotein (BSP), has been shown to be a potent nucleator of HA and this activity is increased upon binding to type I collagen. The collagen-binding domain of BSP has been determined to be a highly conserved region (spanning residues 18-45); however, the area of collagen involved in this interaction is unknown.

In this study, a chemical cross-linking method was initially utilized to map the BSP-binding region …

The Role Of Morphology In Diet And Flower Visitation By Five Species Of Cuban Flower-Visiting Bats, Lindsey Clairmont

Electronic Thesis and Dissertation Repository

Pollinator and flower morphology are important factors in structuring the plant-pollinator relationship. A pollinator’s morphology may influence aspects of its diet. Flower-visiting bats are an important pollinator group but very little is known about what influences their interactions with food plants. I examined the role of morphology in the partitioning of food resources for five species of flower-visiting Cuban bats. I analyzed cranial traits and body size to examine differences among species and to determine the degree of morphological specialization for flower-feeding for each species. I also collected dietary data from guano and used acoustic monitoring to assess bat activity …

Dna Barcoding Expands Dietary Identification And Reveals Dietary Similarity In Jamaican Frugivorous Bats, Colin E. Hayward

Electronic Thesis and Dissertation Repository

Detailed identification of diet is imperative for investigations of community structure, pollination and seed dispersal. Using DNA barcoding, I studied the diets of Jamaican fruitbats and how they compared. I identified dietary constituents of three morphologically distinct bat species, Artibeus jamaicensis, Ariteus flavescens and Glossophaga soricina from 135 fecal samples collected in Cockpit Country, Jamaica. DNA barcoding identified 11 fruit taxa in the fruitbats' diets, seven more taxa than detected by traditional methods. Dietary overlap among fruitbat species was significantly high (O = 0.66, p<0.05) despite distinct morphologies but A. jamaicensis and G. soricina consumed some fruit taxa exclusively. A. jamaicensis (largest) had …