Life Sciences Commons^™

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 …

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, …

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 …

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 …

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 …

Heterologous Production And Characterization Of Cell Wall Degrading Enzymes Using Plants As A Bioreactor, Eridan Orlando Rodrigues Pereira

Electronic Thesis and Dissertation Repository

Plants are wonderful living organisms. They are able to store solar energy into carbohydrates by fixing CO₂ through photosynthesis which can be subsequently harvested and used for fuel production. However, one of the major limitations for transforming these carbohydrates into liquid fuels is the recalcitrance of the plant cell wall. Although microorganisms have evolved a series of cell wall degrading enzymes to harvest efficiently this energy and are considered the main source of these biocatalysts, harnessing these microorganisms for the production of enzymes is a costly process and a major factor limiting the commercialization of lignocellulosic biomass-to-ethanol processes. The …

Uncovering The Molecular Link Between Mir156.Spl15 And Carotenoid Accumulation In Arabidopsis, Davood Emami Meybodi

Electronic Thesis and Dissertation Repository

Carotenoid Cleavage Dioxygenases (CCDs) are an enzyme family that cleaves specific double bonds in carotenoids. MicroR156 in Arabidopsis regulates a network of genes by repressing 10 SPL genes, among which, SPL15 was found to regulate shoot branching and carotenoid accumulation. The expression of CCD1, CCD4, CCD7, CCD8, NCED2, NCED3, NCED5, NCED6, NCED9 and SPL15 was evaluated in siliques at 10 days post anthesis and in 10-day-old roots in Arabidopsis wild type, sk156 (miR156 overexpression mutant), RS105 (miR156 overexpression line), spl15 (SPL15 knockout mutant) and two 35S:SPL15 lines. Results showed that most of CCD/NCED genes were …

Increased Abundance Of Frost Mrna During Recovery From Cold Stress Is Not Essential For Cold Tolerance In Adult Drosophila Melanogaster., H Udaka, A Percival-Smith, B J Sinclair

Biology Publications

Frost (Fst) is a candidate gene associated with the response to cold in Drosophila melanogaster because Fst mRNA accumulation increases during recovery from low temperature exposure. We investigated the contribution of Fst expression to chill-coma recovery time, acute cold tolerance and rapid cold hardening (RCH) in adult D. melanogaster by knocking down Fst mRNA expression using GAL4/UAS-mediated RNA interference. In this experiment, four UAS-Fst and one tubulin-GAL4 lines were used. We predicted that if Fst is essential for cold tolerance phenotypes, flies with low Fst mRNA levels should be less cold tolerant than flies with normal levels of cold-induced Fst …

Cross-Tolerance And Cross-Talk In The Cold: Relating Low Temperatures To Desiccation And Immune Stress In Insects., Brent J Sinclair, Laura V Ferguson, Golnaz Salehipour-Shirazi, Heath A Macmillan

Biology Publications

Multiple stressors, both abiotic and biotic, often are experienced simultaneously by organisms in nature. Responses to these stressors may share signaling pathways ("cross-talk") or protective mechanisms ("cross-tolerance"). Temperate and polar insects that must survive the winter experience low temperatures accompanied by additional abiotic stressors, such as low availability of water. Cold and desiccation have many similar effects at a cellular level, and we present evidence that the cellular mechanisms that protect against cold stress also protect against desiccation, and that the responses to cold and dehydration likely evolved as cross-tolerance. By contrast, there are several lines of evidence suggesting that …

Trophic Level Influence On Stable Hydrogen Isotopic Composition Of Bat Fur, Leslie M. Erdman

Electronic Thesis and Dissertation Repository

The effect of trophic level on the isotopic compositions of nitrogen (δ¹⁵N), carbon (δ¹³C) and oxygen (δ¹⁸O) is well documented, but the effect that trophic level has on the stable hydrogen isotopic composition of bat fur (δ²H_fur) is not known. This can have implications when assigning the locations of origin of bats in migration studies that use δ²H_fur. I hypothesized that if there is an effect of trophic level on δ²H_fur, then δ²H_fur would correlate positively with trophic level. …

The Effects Of Extrinsic And Intrinsic Factors On The Reproductive Biology Of Male Western Bean Cutworm Moths, Striacosta Albicosta (Smith), Jasmine Farhan

Electronic Thesis and Dissertation Repository

Pheromones are important in the mating systems of nocturnal moths as they are relied on to find and/or assess mates. Extrinsic and intrinsic factors have been shown to influence female emission of and male response to pheromones. My thesis focuses on the reproductive biology of males of the western bean cutworm, Striacosta albicosta, a pest of beans and corn that has recently began expanding its range eastwardly. I conducted a field-based experiment to determine the effects of extrinsic factors on pheromone trap catches. I also conducted laboratory based mating experiments to determine the effect of male age on acceptance …

Characterization Of Staphylococcus Aureus Lipase, Vithooshan Vijayakumaran

Electronic Thesis and Dissertation Repository

USA300, a strain of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA), has become prevalent in the community. Colonization of human skin requires mechanisms that allow this bacterium to overcome the innate immune defenses on the skin, including secretion of antimicrobial lipids. Antimicrobial lipids inhibit S. aureus growth and induce the staphylococcal proteolytic cascade, producing aureolysin (Aur) which processes the lipase glycerol ester hydrolase (Geh). Nearly all S. aureus strains secrete Geh, yet little information exists concerning its function. Using purified Aur and Geh we confirm that aureolysin processes proGeh to Geh. We then confirmed that geh was required for lipase activity …

Role Of Branched-Chain Amino Acid Transporters In Staphylococcus Aureus Virulence, Sameha Omer

Electronic Thesis and Dissertation Repository

Branched-chain amino acids (BCAAs) act as effector molecules that signal a global transcriptional regulator, CodY, to regulate virulence factors in nutrient depleted environments. Staphylococcus aureus contains three putative BCAA transporters (BrnQ1, BrnQ2, BrnQ3) whose role in BCAA uptake is unknown. We hypothesize that BrnQ transporters are involved in BCAA uptake and contribute to virulence in S. aureus by modulating CodY activity. Results from radioactive uptake assays indicate that BrnQ1 is the predominant BrnQ transporter of isoleucine, valine and leucine. Meanwhile, BrnQ2 is more specific for isoleucine. Furthermore, only the lack of BrnQ1 hinders growth of S. aureus in chemically-defined media …

Modeling Leafhopper Populations And Their Role In Transmitting Plant Diseases., Ji Ruan

Electronic Thesis and Dissertation Repository

This M.Sc. thesis focuses on the interactions between crops and leafhoppers.

Firstly, a general delay differential equations system is proposed, based on the infection age structure, to investigate disease dynamics when disease latencies are considered. To further the understanding on the subject, a specific model is then introduced. The basic reproduction numbers $\cR_0$ and $\cR_1$ are identified and their threshold properties are discussed. When $\cR_0 < 1$, the insect-free equilibrium is globally asymptotically stable. When $\cR_0 > 1$ and $\cR_1 < 1$, the disease-free equilibrium exists and is locally asymptotically stable. When $\cR_1>1$, the disease will persist.

Secondly, we derive another general delay differential equations system to examine how different life stages of leafhoppers affect crops. The basic reproduction numbers $\cR_0$ is determined: when …

Effect Of Plant Hormones On The Production Of Biomass And Lipid In Microalgae, Malihe Mehdizadeh Allaf

Electronic Thesis and Dissertation Repository

Limited fossil fuel reserves, increasing demand for energy in all parts of the world are some driving forces to look for new sources of transportation fuels. Among different options available, microalgae are currently attracting wide interests as an alternative and renewable fuel source.

Microalgae are single cell photosynthetic organisms that are known for rapid growth and high energy content and as a part of photosynthesis; they produce oil that can be used as a feedstock for biodiesel production. Some algae strains could contain lipid up to 80% of the dry biomass. The amount of lipid production is in direct relation …

Applying The Reference Condition Approach To Bioassessment Of Cape Breton Island Streams, Kari A. Moreland

Electronic Thesis and Dissertation Repository

The reference condition approach (RCA) to bioassessment assesses the effect of human activity on ecosystems relative to sites that are relatively unexposed to such activity. This study uses the RCA to characterize the nature of relatively pristine streams on Cape Breton Island, Nova Scotia as a comparison to assess sites that have various degrees and types of exposure to human activities, including sites that have been remediated from acid mine drainage related to coal mining.

RCA models consisted of general linear models with environmental characteristics of reference sites as the predictor variables and biotic indices as the response variables. Findings …

Cyanobacteria Predominance In Alberta's Eutrophic Lakes Linked To Iron Scavenging Strategy That Uses Siderophores And Toxins, Xue L. Du

Electronic Thesis and Dissertation Repository

The role of the micronutrient iron in the regulation of cyanobacteria dominance and cyanotoxicity is poorly understood. Iron is required for important metabolic pathways, including both phosphorus (P) and nitrogen (N) assimilation, and low levels of this element may influence the assimilation of the macronutrients. The hypothesis tested was that cyanobacteria produce and utilize siderophores and toxins in low iron conditions to scavenge iron, when P and N are not limiting algal growth, providing some cyanobacteria with a competitive advantage over other algal species. Among the naturally eutrophic lakes studied, cyanobacteria were dominant at low iron (>pFe19) concentrations (Spearman …

Cold Tolerance Of The Eastern Subterranean Termite, Reticulitermes Flavipes (Isoptera: Rhinotermitidae), In Ontario., Matthew W. Clarke, Graham J. Thompson, Brent J Sinclair

Biology Publications

We characterized the cold tolerance of natural populations of the Eastern subterranean termite (Reticulitermes flavipes (Kollar) [Isoptera, Rhinotermitidae]) in southwestern Ontario, Canada. We measured cold tolerance in workers from six colonies of termites established from Pelee Island in Lake Erie, and Point Pelee National Park. The mean critical thermal minimum, at which termites entered chill coma, ranged from 8.1 to 5.7°C. Mean supercooling points (SCP, the temperature at which individuals freeze) ranged from -4 to -4.6°C, and did not differ significantly between colonies, nor was SCP dependent on body size. Individuals survived brief exposure to low temperatures, as long as …

Characterization Of A Putative Activation Domain In The Hulk Gene Family, Christopher Doan

Electronic Thesis and Dissertation Repository

The HULK gene family participates in regulation of both flowering time and development in the plant Arabidopsis thaliana. The proteins encoded by these genes share conserved domain structures including a proline-rich region (PRR) in the carboxyl-terminus. Based on sequence analysis and the presence of a proline-rich domain, it has been suggested that the HULKs are putative transcription factors in which HUA2 is known to regulate several late-flowering genes: FLC, FLM and MAF2.

To investigate the putative transcriptional activation domain in the carboxyl-terminus of the HULKs, full-length HULKs and deletion constructs were 3-AT titrated in yeast-one hybrids. It …

The Role Of Metallothionein In Zinc Homeostasis, Kelly L. Summers

Electronic Thesis and Dissertation Repository

The structure of the unique metal-binding protein, metallothionein (MT), consists of two metal-thiolate-clustered binding domains; the β-domain binds up to three divalent metals and the α-domain binds four. The mechanisms through which the metals are bound and arranged into domains, as well as the function of MT in metal ion homeostasis, remains largely unknown. By utilizing electrospray ionization mass spectrometry (ESI MS) to identify each species, and by comparing the data with simulations, MT 1a was found to bind Zn²⁺ non-cooperatively. Through a competition experiment between MT and its individual domain peptides, MT was proposed to bind Zn^{2+ …}

Array-Based Genomic Diversity Measures Portray Mus Musculus Phylogenetic And Genealogical Relationships, And Detect Genetic Variation Among C57bl/6j Mice And Between Tissues Of The Same Mouse, Susan T. Eitutis

Electronic Thesis and Dissertation Repository

Mouse models lack affordable genomic technologies slowing the identification of candidate variants contributing to complex phenotypes. The Mouse Diversity Genotyping Array (MDGA) is a low cost, high-resolution platform permitting genomic diversity assessment. Using a validated list of >500,000 single nucleotide polymorphisms (SNPs), we applied the first comprehensive analysis of SNP differences to detect genetic distance across 362 Mus musculus samples. Genetic distance measured between distantly and closely related mice correlates with known phylogeny and genealogy. Variation detected between C57BL/6J mice is consistent with previous reports of variants within this strain. Putative genetic variation detected between and within tissues indicates somatic …

Measuring Vocal Performance In Song Sparrows (Melospiza Melodia), And Its Relationship To Age, Morphology And Song Complexity., Steven D. Moore

Electronic Thesis and Dissertation Repository

Vocal performance in birds, measured as the ability to rapidly produce broadband trills, has been proposed to reflect male quality. However, little is known about whether performance is consistent across a male’s song repertoire, or whether better performers also have larger repertoires. I quantified vocal performance in 21 male song sparrows (Melospiza melodia). Performance varied among and within males, but was significantly repeatable when considering multiple exemplars of the same trill type within an individual’s repertoire. This suggests that within-individual variation in performance reflects trill types varying in complexity and performance difficulty. Performance was positively and significantly correlated …

Are Long Chain Acyl Coas Responsible For Suppression Of Mitochondrial Metabolism In Hibernating 13-Lined Ground Squirrels?, Alex Cooper

Electronic Thesis and Dissertation Repository

I found 44% suppression of succinate-fuelled liver mitochondrial respiration in torpid 13-lined ground squirrels compared to interbout euthermia (IBE). Palmitoyl CoA, predicted to suppress respiration by inhibiting succinate transport at the dicarboxylate transporter (DCT), reduced respiration by ~70%, while butylmalonate, a known inhibitor of the DCT, only inhibited respiration by ~40%. In both cases inhibition of respiration proportionally affected both torpid and IBE mitochondria, suggesting that the DCT is likely not already inhibited in torpid mitochondria. The addition of carnitine, predicted to reverse suppression by facilitating transport of palmitoyl CoA into the mitochondrial matrix, had no rescuing effect on the …

Examining Population Genetic Structure Of The Pitcher Plant Mosquito (Wyeomyia Smithii) Across Multiple Spatial Scales Using Aflp Markers, Kristina M. Zilic

Electronic Thesis and Dissertation Repository

The population genetic structure of the pitcher plant mosquito (Wyeomyia smithii Coquillett 1901) provides insight into its dispersal patterns and behaviour. I developed a suite of 117 amplified fragment length polymorphism (AFLP) markers for W. smithii and, using larvae collected from purple pitcher plants in Algonquin Provincial Park (Ontario, Canada), I studied the population genetic structure of the mosquito across multiple spatial scales. At the finest scale I examined genetic differentiation among samples from different leaves within a single plant, and at the largest scale I examined differentiation among samples from groups of peatlands ~ 26 km apart. Samples …

Identification Of Cyclophilin Gene Family In Soybean And Characterization Of Gmcyp1, Hemanta Raj Mainali

Electronic Thesis and Dissertation Repository

I identified members of the Cyclophilin (CYP) gene family in soybean (Glycine max) and characterized the GmCYP1, one of the members of soybean CYP. CYPs belong to the immunophilin superfamily with peptidyl-prolyl cis-trans isomerase (PPIase) activity. PPIase catalyzes the interconversion of the cis- and trans-rotamers of the peptidyl-prolyl amide bond of peptides. After extensive data mining, I identified 62 different CYP genes in soybean (GmCYP1 to GmCYP62), of which 8 are multi-domain proteins and 54 are single domain proteins. At least 25% of the GmCYP genes are expressed in soybean. GmCYP1 …

Structure Of An Ensemble Of Insectivorous Bats, Matthew A. Emrich

Electronic Thesis and Dissertation Repository

Ensembles of species show distinct characteristics that may permit resource partitioning but few studies focus on more than one or two traits. Using seven sympatric Jamaican bats, I examined features which could allow for spatial, temporal, behavioural and dietary partitioning including wing morphology, echolocation characteristics, flight behaviour, habitat use, and diet. Using acoustic arrays I compared activity patterns at different sites to determine temporal and spatial partitioning and generated flight paths to determine flight speeds. From captured bats I measured wing morphology to examine morphological differences and did genetic analysis of guano to determine dietary partitioning. Morphology, call structure and …