Digital Commons Network^™

Genetic Components To Worker Sterility In The Honey Bee, Apis Mellifera, Alanna Gabrielle Backx

Digitized Theses

The primary characteristic that defines eusocial species is reproductive division of labour. Honey bee (Apis mellifera) colonies typically have a single reproductive queen and thousands of sterile workers. Here, I review the factors affecting worker reproduction and then contrast the brain gene expression of workers considered either reproductively altruistic (sterile) or selfish (fecund) over a series of time points. I confirmed that although, theoretically, the genes that allow workers to reproduce must be expressed in order for them to do so, it is the environmental cues, such as nutrition and pheromones, that ultimately control worker reproductive status. I then identify …

Functional Role Of Aldehyde Dehydrogenase-1a1 (Aldh1a1) In Breast Cancer Metastatic Behaviour, Irene Ngai Ki Ma

Digitized Theses

Previous work in our lab indicates “stem-like” breast cancer cells can be identified by an ALDHhlCD44+phenotype and that these cells are significantly more metastatic than ALDHlowCD44‘cells. The purpose of this project was to investigate the functional role of overexpressed human ALDH1A1 in breast cancer behaviour. ALDH1A1 was stably overexpressed in MCF-7 human breast cancer cells and these cells were assessed using functional in vitro assays of metastasis (proliferation, adhesion, migration, colony formation). Despite overexpression of ALDH1A1, no significant differences were observed in malignant cell behaviour between empty vector control and MCF- 7/ALDH1A1 cells. However, it was observed that MCF-7/ALDH1A1 cells …

Increased Bmp Signaling Decreases Epithelial Ovarian Cancer Tumour Growth On The Chick Cam By Inhibiting Angiogenesis, Jason Matthew Reed

Digitized Theses

Current limitations regarding the treatment of metastatic epithelial ovarian cancer (EOC) are attributed to our poor overall understanding of its progression due to the limited number of appropriate model systems. To this end, I have characterized EOC tumour growth and angiogenesis using the innovative chick chorioallantoic membrane (CAM) model system. Bone morphogenetic protein (BMP) signaling has been implicated in multiple processes of EOC metastasis, although its role in tumour angiogenesis has never been assessed. I found an inverse correlation between the level of BMP signaling in mouse EOC cells and their abilities to induce angiogenesis both in vitro using HUVEC …

Interspecific Competition Among Juvenile Salmonids: Social Behaviour And Hormone Levels Of Atlantic Salmon And Two Non-Native Trout Species, Jessica Arden Van Zwol

Digitized Theses

Competition with ecologically similar non-native salmonids may hinder efforts to restore Atlantic salmon (Salmo salar) in Lake Ontario. I examined the competitive effects of juvenile brown trout (S. truttci) and rainbow trout (Oncorhynchus mykiss), two non-native competitors, on aggression, dominance, growth, and hormone concentrations of three candidate strains of juvenile Atlantic salmon selected for réintroduction into Lake Ontario. Interspecific competition in semi-natural streams reduced aggression, dominance, and growth of Atlantic salmon, coincident with increasing concentrations of cortisol, a hormone that functions in part in the stress response. An aggression-associated hormone, 11-ketotestosterone, was largely unaffected. Interestingly, the most ecologically similar competitor, …

Predicting The Language Abilities Of Children, Sarah Elyse Cloutier

Digitized Theses

The ability to learn language is influenced both by children's biological abilities and the environment in which they find themselves. Rather than low test scores alone, it may be that children who exhibit disproportionately low language abilities relative to what would be predicted from their biological abilities and expectations based on their environmental situations may be considered to exhibit a specific language impairment. The present study explores this hypothesis by taking measures aimed at estimating 45 children’s biological potential through direct measures o f parental abilities and environmental situations and examining the ability of these measures to predict children’s language …

Profiling Arabidopsisarogenate Dehydratases: Dimerization And Subcellular Localization Patterns, Danielle Marie Styranko

Digitized Theses

In Arabidopsis, a family of six arogenate dehydratases (ADTs) has been identified which catalyze the terminal step of phenylalanine biosynthesis. ADTs share considerable sequence similarity to bacterial prephenate dehydratases, which form homodimers. The protein-protein interaction profiles of Arabidopsis ADTs were characterized using Yeast-2-Hybrid and Bi-molecular Fluorescence Complementation approaches. Results show that ADT1, but not ADT2, is able to form homo- and heterodimers with all other ADTs in yeast. In contrast, all six ADTs form all possible homo- and heterodimer combinations in ptanta, where they display two different subcellular localization patterns. Most ADT dimers localize to the chloroplast in a stromule-like …

Relative Abundance And Habitat Associations Of Least Bitterns (Ixobrychus Exilis) At Long Point, Lake Erie, Ontario, Nickolas D. Bartok

Digitized Theses

The Least Bittern is a threatened species in Canada, with an estimated 1500 breeding pairs. I estimated relative abundance and determined habitat associations of Least Bitterns at Long Point, Lake Erie, Ontario. I conducted call-broadcast point counts during 2008 and 2009 with 96 and 197 individual Least Bitterns detected, respectively. I estimated 195 pairs of Least Bitterns at Long Point and 1434 pairs in coastal wetlands of the Canadian lower Great Lakes. Habitat assessments identified percent cover of Cattail and Bulrush, and number of dead Cattail stems as the best predictors of Least Bittern presence. Interspersion and percent cover of …

Song Complexity And Stereotypy In The Song Sparrow {Melospiza Melodia) As Indicators Of Constitutive Immune Function, Shawn Phillip Kubli

Digitized Theses

Indicator models of sexual selection predict that ornaments may reliably advertise male quality and in particular, viability. Songbird song is a well-studied ornament used by females to evaluate potential mates. In this thesis I examine the reliability of two different aspects of song, thought to develop over different timescales, in indicating immune function of breeding male song sparrows [Melospiza melodia). Immunity was assessed through multiple measures of constitutive innate immune function. Overall, I observed a pattern of constitutive immunity that suggests within- system trade-offs. Moreover, this pattern was associated with measures of song complexity. Male song sparrows with more complex …

The Distribution And Potential Benefits Of Rhizosphere- Associated Bacteria In Corn (Zea Mays L.), Laura Catherine Quigley

Digitized Theses

Plant growth-promoting rhizobacteria (PGPR) are known for their potential use as biofertilizers, which can help to reduce the need and cost for synthetic fertilizers. The distribution and quantification of three PGPR in association with corn (Zea mays L.) was determined by the detection of chaperoninQO genes through real-time quantitative PCR. Sphingobacterium canadense, Azospirillum zeae, and Gluconacetobacter azotocaptans were detected at concentrations approaching 106 CFU/g in root tissues and rhizosphere soils in corn-growing regions of Ontario and Québec. Three additional bacterial isolates were recovered from corn rhizosphere soil and roots then identified via colony PCR. Greenhouse trials of all six bacteria …

Sublethal Freezing Effects On Nitrogen Uptake And Growth In Poa Pratensis, Andrey Malyshev

Digitized Theses

In northern temperate regions, climate warming is predicted to increase the

frequency of soil freeze-thaw cycles (FTC) and reduce plant cold acclimation in late fall and early spring. To test if FTC inhibit plant nitrogen (N) uptake, I exposed Poa

pratensis tillers to FTC in late fall, mid winter, and early spring, then used a 15N tracer to assess N uptake from a hydroponic solution. To assess the direct effects of FTC on plant growth, I exposed P. pratensis tillers to FTC on the same dates, then measured plant biomass the following summer. Freezing of short duration at -10 °C …

Surface Functionalization Of Polymer Vesicles With Dendritic Groups: Effects On Physical And Biological Properties, Ryan C. Amos

Digitized Theses

Polymer vesicles (polymersomes) are spherical assemblies with aqueous cores, formed

by the self-assembly of amphiphilic polymers in an aqueous environment. They resemble

phospholipid vesicles, but typically exhibit much greater stabilities. The chemical versatility of

the polymer synthesis makes it possible to tune the vesicle characteristics such as vesicle size

and: circulation time in vivo. As such, they are highly promising materials for various

applications including drug delivery. Our research group recently developed a versatile approach

for the conjugation of dendritic groups to the surfaces of polymer vesicles which allows the

surface properties to be readily tuned for specific biological properties …

Study Of Alfalfa Somatic Embryos For Recombinant Protein Production, Guohua Fu

Digitized Theses

Transgenic plants have been explored as a potentially inexpensive expression system for recombinant protein production. However, improvement in protein yield is still the most challenging problem limiting the commercial utilization of plant expression systems. In this study, alfalfa (Medicago sativa L.) somatic embryo was evaluated as a tissue for increased recombinant protein expression. Three heterologous genes: fi- glucuronidase (GUS), cholera toxin B subunit (CTB), and human interleukin 13 (hIL-13) were independently introduced into alfalfa via Agrobacterium-mediated transformation. Induced alfalfa somatic embryos store approximately two-fold more ectopically expressed proteins (as a percentage of total soluble protein) than vegetative organs such as …

The Green Phenotype Of Arabidopsis Thaliana Cell Cultures Is Insensitive To Sucrose Concentrations, Michelle Chung

Digitized Theses

Plant cell cultures are typically grown in media supplemented with 3% (w/v) sucrose and exhibit a non-green phenotype. I show that Arabidopsis thaliana cell cultures remain green even at 15% (w/v) sucrose when grown in the light and exhibit the major constituents of a normal photosynthetic apparatus. However, growth in the light was inhibited when no exogenous carbon source was provided. Gas exchange measurements indicated that rates of photosynthesis never exceeded rates of respiration. Thus, these green cells grow below their light compensation points. However, increasing sucrose concentration from 3% to 15% (w/v) decreased both photosynthetic efficiency and capacity. Furthermore, …

The Evolution Of Pre-Zygotic Reproductive Isolation, Vanda T.K. Mcniven

Digitized Theses

Pre-zygotic barriers to interbreeding have received an increasing amount o f attention during the past several decades. Emergent areas of interest include how novel sexual communication systems evolve, and intersexual conflict between sperm and the female reproductive tract. Here, I show for the first time that natural genetic variation between Drosophila simulans and D. mauritiana at a single genomic region can induce both

species-specific female choosiness and the male trait they are discriminating against. Additionally, there were two separate regions of the genome that were individually capable o f inducing this trait/preference combination, suggesting that trait/preference linkage may be widespread. …

The Effects Of Environmental Cues On Reproductive Physiology Of American Goldfinches (Carduelis Tristis), Thomas William Luloff

Digitized Theses

Many songbirds use information from the environment to coordinate seasonal reproduction. American goldfinches (Carduelis tristis) demonstrate seasonal reproduction but differ from other songbird species by delaying reproduction until late- summer. Using correlational evidence collected from nesting cards across North America, I determined that timing of breeding for goldfinches was significantly related to ambient temperature and thistle blooming phenology. In a captive experiment, my results demonstrate that temperature and blooming thistle phenology significantly affect gonad recrudescence and testosterone levels. In summer temperature conditions, goldfinches exposed to blooming thistle plants had significantly higher levels of testosterone compared with birds shown a non-blooming …

The Effect Of Connexin43 On The Development Of Skeletal Muscle Using Cell And Animal Models Of Oculodentodigital Dysplasia, Pasquale Vecchio

Digitized Theses

Skeletal muscle development involves the differentiation of myoblasts into myotubes; likely involving connexins (Cx) and the gap junctional exchange of secondary messengers and metabolites. Many patients with oculodentodigital dysplasia (ODDD), a rare primarily autosomal dominant disease caused by mutations in the gene encoding Cx43, become less ambulatory with aging and exhibit symptoms that may reflect defects in skeletal muscle development, maintenance, and repair. In this study, the role of Cx43 in skeletal muscle development was examined in differentiation-competent L6 myoblasts and two ODDD- linked Cx43-mutant mouse lines. Undifferentiated L6 myoblasts exhibited high levels of Cx43-based gap junctions which were inhibited …

The Hos2p Histone De-Acetylase Promotes The Successful Completion Of Cytokinesis In Schizosaccharomyces Pombe., Charnpal Grewal

Digitized Theses

A cell cycle checkpoint at the G2/M boundary of fission yeast cells ensures that the G2/M transition of daughter cells only occurs after successful cytokinesis in the mother cell. The Lst complex is necessary for proper functioning of this checkpoint and is orthologous to a human histone de-aceylase complex (HDAC3/NCOR2-SMRT), with a known role in cytokinesis. However, the fission yeast orthologue of the human HDAC3 histone de-acetylase, Hos2p, was never previously characterized with respect to the Lst complex. Through a combination of phenotypic analyses on hos2 mutants, live-cell imaging of Hos2p localization, live-cell imaging of cytokinesis dynamics as they relate …

The Genetic Basis Of Interspecific Female Preference In Drosophila Simulans, Meghan Elizabeth Laturney

Digitized Theses

Behavioral differences between species have a genetic basis and contribute to species isolation. Genomic regions have been identified that influence female rejection of heterospecific males on the right arm of the third chromosome in Drosophila, however, no individual loci have been identified. Here, I used deficiency mapping to locate regions that influence the rejection of D. melanogaster males by D. simulans females. First, I tested two genes that have been previously shown to affect female within-species mate choice: neither of these genes was found to contribute to between-species female preference. Next, 1identified five small significant regions that contain candidate genes …

The Detection Of Hepatitis C Viral Ns3-4a Protease And Prostate Specific Antigen Using Electrochemical Techniques, Modupeola A. Sowole

Digitized Theses

This work attempts to detect hepatitis C viral (Hep CV) NS3-4A protease and prostate specific antigen (PSA) proteins using electrochemical methods. The sensing probes used in detecting these biological markers are their inhibitory peptides. The inhibitory peptide for the hepatitis C viral NS3-4A protease is Asp-Glu-Ile-Val-Pro-Nva with an IC50of 7.5 pM and the inhibitory peptide for prostate specific antigen is the peptide Ser-Lys-Ser- Lys-Ser-Lys-Ser-Cys-Val-Phe-Ala-His-Asn-Tyr-Asp-Tyr-Leu-Val-Cys with a K, of 0.8 pM.

The steps involved in the fabrication of the sensor surface include the formation of a self assembled monolayer (SAM) using a thioctic acid modified ferrocene compound. The use of a …

The Influence Of North American Ginseng On The Initiation And Progression Of Atherosclerosis, Colin Patrick Carruthers

Digitized Theses

Atherosclerosis is a major cause of cardiovascular morbidity and can lead to complications such as stroke and myocardial infarction. Ginseng, a natural health supplement, has been shown to have anti-atherogenic properties, including attenuating inflammation, oxidation and hyperlipidemia. I examined the effects of North American ginseng on inflammation-associated VCAM-1 and ICAM-1 expression in cultured porcine endothelial cells and monocyte adhesion to the activated endothelium in hypercholesterolemic and hyperhomocysteinemic rats. No definitive downregulation of inflammatory VCAM-1 and ICAM-1 expression was observed in vitro and only an aqueous ginseng extract was effective in reducing homocysteine-induced monocyte adhesion to the aortic endothelium. I also …

The Neuroplastic Response Of The Song-Control System To Testosterone Metabolites In The Adult European Starling (Sturnus Vulgaris), Zachary Jonas Hall

Digitized Theses

The song-control system is a network of discrete nuclei in the songbird brain that controls the production and learning of birdsong, and exhibits some of the greatest neuroplasticity found in the adult brain. This plasticity is driven by the gonadal steroid testosterone. When acting on neural tissue, however, testosterone can be metabolized into 5a-dihydrotestosterone (DHT) or 17|3-estradiol (E2), which activate different hormonal signalling pathways. By treating adult starlings with both testosterone metabolites and metabolite antagonists, I isolated the effects of DHT and E2 treatment on neuroplasticity in the song-control system. E2 treatment induced some, but not all neuroplastic effects

reported …

The Relationship Between Hpa Regulation And Fitness In A Free-Living Population Of Song Sparrows (Melospiza Melodia), Ainsley Anne Furlonger

Digitized Theses

In a changing environment, individuals must have the ability to physiologically cope with unpredictable stressors. The endocrine response to stressors is one mechanism vertebrates can use. The corticosterone (CORT)-fitness hypothesis predicts a negative relationship between acute stress induced levels of CORT and fitness. I examined the effectiveness of hypothalamo-pituitary-adrenal (HPA) axis regulation through exogenous hormone stimulation and plasma CORT levels as a predictor for various fitness measures in free-living song sparrows (Melospiza melodia). CORT levels at 30 minutes and in response to dexamethasone injection were predictive of lay date in this population. However, no relationships were observed between HPA regulation …

The Role Of Ccl21/Ccr7 Chemokine Axis In Vegf-C Mediated Breast Cancer Induced Lymphangiogenesis, Elena Tutunea-Fatan

Digitized Theses

Although the molecular mechanisms underlying lymphangiogenesis associated with breast cancer continue to remain insufficiently understood, a growing body of evidence suggests that many of the currently unknown answers revolve around the crosstalk between the lymphangiogenic factor VEGF-C and chemokines. The present study proposed the CCL21/CCR7 chemokine axis as a regulatory mechanism of VEGF-C mediated breast cancer-induced lymphangiogenesis. In order to address the hypothesis, the positive correlations between CCR7 signalling and VEGF-C expression/secretion by MDA-MB-231 cells were sought, along with the molecular mechanism underlying their correlation. Furthermore, the direct effect of CCL21/CCR7 interaction on lymphatic endothelial cells (LECs) was tested through …

The Role Of Insulin-Like Growth Factor Binding Protein-6 In The Differentiation Of Placental Mesenchymal Stem Cells Into Skeletal Muscle, Doaa Abdulkalig Aboalola

Digitized Theses

Insulin-like growth factor binding protein-6 (IGFBP-6), a component of the stem cell niche involved in the differentiation of skeletal muscle myogenesis, is expressed in developing muscle cells and is the main regulator of IGF-II. In this study, I investigated the role of IGFBP-6 in the commitment of skeletal muscle derivation from placenta mesenchymal stem cells (PMSCs). I hypothesized that IGFBP-6 inhibits the temporal maintenance of PMSCs and promotes the differentiation of PMSCs into muscle via both extracellular and intracellular mechanisms. PMSCs can differentiate into muscle cells expressing the muscle markers Pax3/7, MyoD, and Myogenin with the formation of multi-nucleated fibers. …

The Porcine Radial Artery Smooth Muscle Cell As A Valve Interstitial Cell Surrogate For Heart Valve Tissue Engineering, Jennifer Nicole Redwood

Digitized Theses

Heart valve tissue engineering (HVTE) has the capacity to overcome limitations in current valve design, enabling the creation of an autologous valve replacement. We propose that treating radial artery cells (RACs) with a combination of growth factors (GFs) may produce cells more similar to valve interstitial cells (VICs) for HVTE. RACs were treated with combinations of epidermal GF (E), basic fibroblast GF (F), platelet-derived GF (P), and transforming GF-beta 1 (T). Alpha smooth muscle actin (aSMA) expression was examined using real time polymerase chain reaction and confocal microscopy. A reduction in aSMA expression indicated cell transdifferentiation. A combination of E, …

Transgenic Plants As A Novel Bioreactor To Produce Antidiabetic Proteins For The Treatment Of Type 2 Diabetes, Jeehye Choi

Digitized Theses

Glucagon-like peptide-1 (GLP-1) and exendin-4 (Ex-4) are small peptides with potent insulin secretory effect which makes them attractive drug candidates for the treatment of Type 2 diabetes mellitus (T2DM). However, the synthesis of these small peptides is difficult due to recombinant protein degradation and instability.

Human serum transferrin (hTf) is an iron-transport protein that has great potential as an efficient carrier system for protein-based drugs. The use of hTf as a fusion partner will provide a new strategy to enhance the therapeutic potential of GLP-1 and Ex-4. This project investigates the development of transgenic tobacco plants as bioreactors for generating …

Xenopus Laevis Peroxiredoxins Are Expressed In Distinct Tissues During Early Embryogenesis, Maxwell Eric Robert Shafer

Digitized Theses

Development in the frog, Xenopus laevis, requires the utilization of yolk glyco- lipo-proteins in a temporally- and spatially-dependent manner. The metabolism of the yolk produces H20 2, a potent Reactive Oxygen Species (ROS). Peroxiredoxins (Prdxs) are a family of 6 anti-oxidant enzymes that, amongst other roles, reduce H20 2. Prdxs reduce H20 2through a thiol-redox reaction at conserved cysteine residues, which results in the creation of disulfide bonds. Recently the thiol-redox reaction of Prdxs has also been implicated in several cell signaling systems. Herein is a report of the cloning and expression patterns during development of 6 peroxiredoxin homologs from …

Octopamine Receptor Gene Expression In Lepidopteran Insects, Felix Lam

Digitized Theses

The invertebrate octopaminergic system affects many diverse processes and represents the counterpart to the vertebrate adrenergic/noradrenergic system with the classes of octopamine receptor (OAR) being homologous to those of vertebrate adrenergic receptors. However, there is still little information on the OARs present in different species, and the levels and distribution of these receptors throughout the body. cDNAs sharing high similarity with known insect OARs were cloned in three lepidopteran species: the cabbage looper, Trichoplusia nr, the true armyworm, Pseudaletia unipuncta; and the cabbage white, Pieris rapae. Seven major larval tissues and one adult tissue were examined in T. ni using …

Investigating Staphyloferrin B Biosynthesis In Staphylococcus Aureus, Johnson Cheung

Digitized Theses

In S. aureus, the iron-scavenging siderophores staphyloferrin A and staphyloferrin B are synthesized by enzymes encoded within the sfa and sbn gene clusters, respectively. This work details the in vitro functional characterization of the Sbn enzymes responsible for synthesizing staphyloferrin B. As demonstrated through UV-vis spectrophotometric enzymatic assays and LC-ESI-MS experiments, staphyloferrin B can be synthesized in vitro by incubating purified Sbn enzymes (SbnCEFH) with fundamental components of the siderophore such as L-2,3-diaminopropionic acid, citric acid, and alpha-ketoglutaric acid. Furthermore, a novel iron-regulated citrate synthase has been characterized and is named SbnG, which condenses acetyl-CoA with oxaloacetate to form the …

Core-Shell Nanofibres For Heart Valve Leaflet Tissue Engineering, Erica E.M. Lee

Digitized Theses

The aortic heart valve regulates blood flow as it exits the heart and enters the body; when this valve malfunctions it creates serious health problems. While current valve replacement options are satisfactory, the ultimate goal is to create a living valve replacement that can self repair, regenerate and remodel as the patient grows. An approach is via tissue engineering, which uses principles from engineering and cell biology to create functional tissue substitutes for in vivo replacement. This study aims at fabricating nanofibrillar scaffolds by coaxial electrospinning for the treatment of valvular disease. Many electrospun biopolymers promote cell adhesion, but lack …