Biology Commons^™

Spreading Speeds Along Shifting Resource Gradients In Reaction-Diffusion Models And Lattice Differential Equations., Jin Shang

Electronic Theses and Dissertations

A reaction-diffusion model and a lattice differential equation are introduced to describe the persistence and spread of a species along a shifting habitat gradient. The species is assumed to grow everywhere in space and its growth rate is assumed to be monotone and positive along the habitat region. We show that the persistence and spreading dynamics of a species are dependent on the speed of the shifting edge of the favorable habitat, c, as well as c^*(∞) and c^*(−∞), which are formulated in terms of the dispersal kernel and species growth rates in both directions. When …

Examination Of The Relevance Of Pi3k And Pten Pathway In Ustilago Maydis., Nathaniel Edward Dalton

Electronic Theses and Dissertations

Ustilago maydis is a fungal pathogen that is an obligate parasite on Zea mays (Corn) in order to undergo and complete its sexual life cycle. The cells grow as a haploid form until they meet a compatible partner and undergo a dimorphic switch from a budding yeast-like cell type to a filamentous dikaryon. Infection of the host plant is characterized by leaf chlorosis, anthocyanin content, and formation of large galls that develop on the stem, leaves, cobs, and flowers. Many signaling cascades such as MAPK and PKA are involved in the regulation of the infection lifecycle. The Phosphatidylinosotiol 3 Kinase/ …

Pharmacokinetics, Tissue Distribution, Synergistic Activity, And Antitumor Activity Of Two Isomeric Flavones, Crystal L. Whitted

Electronic Theses and Dissertations

Flavonoids are polyphenolic secondary metabolites found in plants that have bioactive properties including antiviral, antioxidant, and anticancer. Two isomeric flavone were extracted from Gnaphalium elegans and Achyrocline bogotensis, plants used by the people from the Andean region of South America as remedies for cancer. 5,7-dihydroxy-3,6,8-trimethoxy-2-phenyl-4H-chromen-4-one (5, 7–dihydroxy- 3, 6, 8 trimethoxy flavone/ flavone A) and 3,5-dihydroxy-6,7,8-trimethoxy-2-phenyl-4H-chromen-4-one (3, 5–dihydroxy-6, 7, 8–trimethoxy flavone/ flavone B) have shown antineoplastic activity against colon cancer cell lines dependent upon their differentiation status. Pharmacokinetic studies reported herein were used to determine dosing for antitumor assays, as well as determine target tissue concentration. These included the …

Structural And Functional Analysis Of Grapefruit Flavonol-Specific-3-O-Gt Mutant P145t, Sangam Kandel Mr

Electronic Theses and Dissertations

This research is focused on the study of the effect of mutating proline 145 to threonine on the substrate and regiospecificity of flavonol specific 3-O-glucosyltransferase (Cp3GT). While the mutant P145T enzyme did not glucosylate anthocyanidins, it did glucosylate flavanones and flavones in addition to retaining activity with flavonols. HPLC was used for product identification and showed mutant P145T glucosylated naringenin at the 7-OH position forming naringenin-7-O-glucoside and flavonols at the 3-OH position. Homology modeling and docking was done to predict the acceptor substrate recognition pattern and models were validated by experimental results. In other related work, …

Identification And Characterization Of Genes Involved In Metabolism Of N5 Monoene Precursors To N5 Anacardic Acids In The Trichomes Of Pelargonium X Hortorum., Richa A. Singhal

Electronic Theses and Dissertations

Unusual monoenoic fatty acids (UMFA’s) and specialized metabolites called anacardic acids (AnAc) are produced in glandular trichomes of Pelargonium ´ hortorum (geranium). The UMFA’s, 16:1^∆11 and 18:1^∆13 are precursors for the synthesis of unsaturated AnAc 22:1n5and 24:1n5 that contribute to pest resistance in geraniums. UMFAs and their derived AnAc metabolites not only provide a useful biological marker that differentiates the biosynthetic pathway for unusual mononenes from the common fatty acids (i.e. stearic, palmitic, oleic, linoleic and linolenic) but also have industrial, medical and agricultural applications. Fatty acid biosynthesis enzymes like acyl carrier proteins (ACPs); thioesterases (TEs) and β-ketoacyl-ACP …

Dietary Resource Utilization Patterns And Head Morphology Among Three Sympatric Watersnake Species., Micah Warren Perkins

Electronic Theses and Dissertations

The coexistence of similar species may be related to a variety of resource utilization differences. Dietary resource utilization variation may be the most important difference allowing for the coexistence of sympatric snake species. Many watersnakes (Nerodia spp.) live in sympatry and use similar aquatic habitats feeding on similar prey. While these sympatric watersnakes may have different general foraging patterns, snake diet may be affected by a variety of factors. Therefore, I initiated an investigation to understand the coexistence of sympatric plain-bellied (N. erythrogaster), diamondback (N. rhombifer) and northern (N. sipedon) watersnakes by addressing …

Venom Peptides Lasioglossin Ii And Mastoparan B As Escherichia Coli Atp Synthase Inhibitors, Rafiat Ajoke Bello

Electronic Theses and Dissertations

The inhibitory effects on Escherichia coli ATPase activity by two venom peptides, lasioglossin II and mastoparan B. Membrane bound F₁F_O ATP synthase was isolated from E. coli strain pBWU13.4/DK8 and treated with varied concentrations of lasioglossin II and mastoparan B. Lasioglossin II caused very low inhibition of ATPase activity, but the inhibition profile of mastoparan B was suggestive of an interesting biological effect. A relatively shorter total length, a smaller net positive charge, and a reduced amphipathic character of both peptides, as compared to previously tested antimicrobial peptides, may account for the limited degree of inhibition observed …

Characterization Of Sip470, A Family 1 Lipid Transfer Protein And Its Role In Plant Stress Signaling, Timothy Ndagi Audam

Electronic Theses and Dissertations

SIP470, a putative tobacco lipid transfer protein, was identified in a yeast two-hybrid screen to interact with SABP2. SABP2 is a critical role in SA-mediated signaling in tobacco and other plants. In vitro studies using purified recombinant SIP470 confirmed that it is a lipid binding protein. In an attempt to determine its role in mediating stress responses, Arabidopsis T-DNA insertion knockout lines lacking SIP470 homolog were used for the analysis. These mutant plants were defective in basal resistance against microbial pathogens. Expression of defense gene PR-1 was also delayed in these mutant plants. Interestingly, these mutant plants were not defective …

Effects Of Acclimation On Temperature Tolerance And Oxidative Damage In Daphnia Magna, Kailea J. Holbrook Ms.

Electronic Theses and Dissertations

Freshwater zooplankton crustacean Daphnia frequently face strong temperature fluctuations in its natural environment, which necessitates adaptive plastic responses. This study focuses on changes in lipid peroxidation and total oxidative capacity in Daphnia tissues in response to long-term and short-term temperature changes.

Long-term acclimation to 28ºC helped Daphnia survive longer at lethally high temperatures. This difference, however, was not accompanied by changes in lipid peroxidation, indicating that it isn’t a good measure of damage or predictor of temperature tolerance.

On the other hand, total oxidation capacity was lower 28ºC- than in 18ºC-acclimated Daphnia, suggesting that acclimation resulted in higher amounts …

Insights Into The Introduction Histories And Population Genetic Dynamics Of The Nile Monitor (Varanus Niloticus) And Argentine Black And White Tegu (Salvator Merianae) In Florida., Jared Price Wood

Electronic Theses and Dissertations

This dissertation examines the population genetic dynamics of two Florida invasives: the Nile monitor (Varanus niloticus) and Argentine black and white tegu (Salvator merianae). I also provide insights into the introduction histories of both species. This study was developed as part of a collaborative effort with the Florida Wildlife Commission to expand our knowledge of these highly detrimental, invasive lizards. All research activities involving animals and animal tissues were approved by the University of Louisville’s Institutional Animal Care and Use Committee (IACUC Proposal #: 12024). I start with a brief introduction into what makes invasive species …

Neuroprotection Comparison Of Different Nutraceutical Compounds Against Mechanistically Distinct Cell Death Inducing Agents, Faten I. Taram

Electronic Theses and Dissertations

Neurodegenerative diseases like Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), include the progressive loss of structure and function of neurons leading to neuronal death. All of these diseases are fatal, as there is no cure for them. The causes of these diseases are unknown; however, there are many proposed mechanisms that lead to neurodegenerative diseases. Oxidative stress is the leading cause of cell death in neurodegenerative diseases, in addition to other mechanisms including endoplasmic reticulum stress, proteasome inhibition, nitrosative stress, inflammation and excitotoxicity. More understanding of the death mechanisms at work in neurodegeneration is necessary to …

Ex-Vivo Slaughterhouse Porcine Crystalloid-Perfused Beating Heart Via Langendorff Method, Rahiemin Talukder

Electronic Theses and Dissertations

The objective of this study was to resuscitate isolated beating porcine hearts obtained from slaughterhouse swine for a minimum of 1 hour with a crystalloid buffer reperfusion instead of blood via an extracorporeal Langendorff apparatus. The isolated beating heart functions outside of the body under simulated physiologic conditions. Live functional anatomy was controlled under benchtop experimental settings. Porcine hearts (26 total) were topically cooled with saline. 300mL of 25°C cardioplegia with 20KU Streptokinase was preflushed via aortic root. WIT was less than 5 minutes. 1L 4°C cardioplegia was flushed antegrade with aortic cannula (Group 1) or coronary catheterization (Group 2). …

The Role Of P38 Mapk In Protein Homeostasis And Aging, Sarah Mae Ryan

Electronic Theses and Dissertations

Aging is characterized by a failure to maintain proper protein homeostasis, potentially leading to tissue dysfunction. Though a variety of genes have been found to regulate lifespan and age-related behaviors how these genetic factors contribute to protein homeostasis has not been fully explored. Here, we report that the evolutionarily conserved aging gene p38 MAPK (p38Kb) regulates age-dependent protein homeostasis. Over-expression of p38Kb results in reduced protein aggregation, while knockout of p38Kb leads to increased protein aggregation. Furthermore, we find that p38Kb regulates protein homeostasis, lifespan, and age-dependent locomotor functions through an interaction with the Chaperone Assisted Selective Autophagy complex; a …

Proteomics Study Of Pre-Harvest Sprouting In Wheat, Pramod Khadka

Electronic Theses and Dissertations

Pre-harvest sprouting (PHS) of wheat (Triticum aestivum L.) is a condition characterized by the early germination of spikes during moist environmental conditions. PHS lowers yield, degrades the quality of grain and thus limits the profits of wheat producers groups. During this investigation, proteomics studies of PHS-resistant and PHS-susceptible wheat embryos were conducted at different imbibition time periods via a cutting-edge technology called iTRAQ. Proteomic analysis revealed that 190 differentially expressed proteins might be involved in various cellular functions, such as carbohydrate metabolism, nitrogen metabolism, stress response, redox regulation, ATP synthesis, and protein translation, during this untimely germination of the wheat …

The Endophytes Of Pediomelum Esculentum: A Unique Case In Legume Evolution, Tyrel Ryan Deutscher

Electronic Theses and Dissertations

Pediomelum esculentum (commonly prairie turnip) is a perennial legume of the Great Plains, consisting of a deep taproot and large edible tuber, and has served as a nutritious staple in Native American diets. The tuber is capable of storing up to 20 percent protein by weight. P. esculentum is a legume, but not a prominent nodule former; instead, it grows in nitrogen-limited soils and produces large amounts of protein. This suggests the involvement of biological nitrogen fixation. We have investigated the presence of diazotrophic endophytes in P. esculentum. Bacteria were isolated from wild plants on nitrogen free media, identified …

Development And Characterization Of A Recombinant Orf Virus Vector Expressing The Spike Protein Of Porcine Epidemic Diarrhea Virus, Kyle Hain

Electronic Theses and Dissertations

Orf virus (ORFV), the type member of the genus Parapoxvirus of the family Poxviridae, causes orf or cutaneous pustular dermatitis in sheep and goats. ORFV is a ubiquitous virus capable of re-infecting its hosts multiple times over time. ORFV causes a non-systemic, self-limiting disease which is usually restricted to the skin surrounding the virus entry sites. ORFV has evolved several immunomodulatory proteins (IMPs) that evade and/or modulate host immune responses to infection and contribute to virus virulence and disease pathogenesis. Given biological properties and unique immunomodula tor y properties, ORFV has gained significant attention in recent years for its …

Analysis Of Starch Branching Enzyme 1 (Sbe1) Gene In Maize, Abiskar Gyawali

Electronic Theses and Dissertations

A previous study revealed a quantitative trait locus (QTL) in maize on the short arm of chromosome 5 (5S) for endosperm amylose content. In that original study, both low and high amylose parental lines, H99ae and GEMS-0067 respectively, were homozygous recessive for amylose extender 1 (ae1) and the polymorphism responsible for this QTL was additive (semi-dominant). Located within the QTL interval is starch branching enzyme 1 (sbe1), which makes it a candidate gene. In order to test whether a polymorphism in sbe1 is the source of this QTL, we crossed a plant homozygous for ae1 and sbe1-Mu onto a …

The Search For Modifiers Of The Maze Gametophyte Factor Ga1-S And Quantitative Trait Polymorphisms Emerging From Doubled-Haploid Maize Lines, Vivek Shrestha

Electronic Theses and Dissertations

The project was designed to conduct two independent projects. The first project was to identify the genomic localization of the modifiers of the maize gametophyte factor (Ga1-s) and the second project was to establish and identify heritable polymorphic lines that have descended from a single doubled-haploid B73 plant. The objectives were (1) to search for modifier genes and loci on the maize chromosomes for the trait and determine genetic effects of them using QTL mapping; (2) to demonstrate the heritable polymorphism of the quantitative traits emerged from the descendants of a single doubled-haploid maize plant. Regarding the QTL …

An Evaluation Of Feeding A Blend Of Essential Oils And Cobalt Lactate To Lactating Dairy Cows, Olivia Jayne Kuester

Electronic Theses and Dissertations

The objective of this study was to determine if the inclusion of a blend of essential oils and cobalt lactate (EOC) in the diet of lactating dairy cows could result in improved nutrient utilization and lactational performance in addition to assessing the application of EOC to control feed mycotoxins and spoilage. The trial was conducted in two experimental periods (Phase 1 (P1) and Phase 2 (P2)) on a commercial dairy in southwest Minnesota equipped with two robotic milking units. Phases 1 and 2 were cross over design trials with two pens. Cows were housed in two freestall pens (57 ± …

Enhancing The Industrial Potential Of Filamentous Cyanobacteria, Tylor J. Johnson

Electronic Theses and Dissertations

The objectives of this project were to improve the industrial potential of filamentous N2-fixing cyanobacteria by increasing its biofuel tolerance, and to evaluate the economic feasibility and environmental impacts of a theoretical, cyanobacteria-based biofuel production facility. To develop a method to quantify filamentous cyanobacteria in dilute culture media, a dual-stained fluorescence assay was evaluated. While the viable cell stain (SYTO® 9) was accurate, the non-viable cell stain (propidium iodide) also bound to viable cells. Additional non-viable cell stains were evaluated, but none were accurate at quantifying viability. Thus we concluded that the viable cell stain SYTO® 9 is a reliable …

Role Of Silencing Rna Fgsir34 In Fusarium Graminearum's Pathogenicity To Wheat, Subha Dahal

Electronic Theses and Dissertations

Fusarium graminearum is an ascomycetous fungal pathogen that causes Fusarium head blight (FHB) disease in wheat and other cereal grains. Mycotoxin produced by the fungus, predominantly deoxynivalenol (DON), is considered as an important virulence factor for the spread of disease. Our previous study of a Dicer-like 2 knockdown mutant has led to our hypothesis that a silencing RNA, fgsiR34, might play a key role in regulating DON biosynthesis and some other virulent factors. To test this hypothesis, we generated an fgsiR34 over-expressing mutant (ΔfgsiR34+) using Inverse Repeat Transgene method and studied the pathogenicity of the mutant in …

Loblolly Pine Genetics Structure Its Mycorrhizal Community, Bridget Joan Piculell

Electronic Theses and Dissertations

Plant populations are constantly exposed to a multitude of biotic and abiotic environmental selection pressures. The ability of a population to persist in or adapt to its environment is heavily influenced by the genetic underpinnings of the traits involved. Thus, in order to understand patterns in current plant populations, and to predict future populations dynamics, an understanding of the genetic basis of adaptive traits is necessary. For example, genetic correlations between traits (driven by pleiotropy or linkage disequilibrium) could influence how species evolve under multiple, conflicting selection pressures, potentially either constraining or enhancing the adaptation of species to each other. …

Influence Of Plant Species, Location, And Seasonality On Rhizosphere Bacterial Communities In Freshwater Wetlands, Hakchul Lee

Electronic Theses and Dissertations

Plant-associated microbes influence plant functions, including development and growth and abiotic stress tolerance. Rhizosphere microbial communities have been shown to vary according to differences in wetland vegetation. Owing to the complexity of factors influencing soil microbial community structure, a greater knowledge of the relationship between rhizosphere microbial communities and different types of plant species will lead to a deeper understanding of plant-microbe interactions in wetlands. Thus, the purpose of my research was to determine the influence of plant species on rhizosphere microbial communities from different freshwater wetlands. The spatial variability, associated with different wetland sites, of rhizosphere microbial communities was …

Biochemical Composition Of Caribbean Gorgonian Corals And Their Symbiosis Under Ambeint And Stressful Conditions, Kartick Prakash Shirur

Electronic Theses and Dissertations

Gorgonian corals are the dominant benthic fauna on Caribbean reefs. Unlike scleractinian corals, gorgonian abundance on these reefs has remained stable or has increased. Therefore, to predict how climate change will affect the reef community, it is essential to understand gorgonian physiology under ambient and stressful situations. Under ambient conditions, eight gorgonian species hosted different clade B Symbiodinium, and in two gorgonian species in which the bacterial microbiomes were investigated, two distinct communities were found. In the eight gorgonian species, skeletal content varied from 75-96%, with those having more tissue also having more Symbiodinium density within their branches. The composition …

The Biotic Effects Of Tertiary Geoclimatic Change In The Southern Hemisphere, Stuart Val Nielsen

Electronic Theses and Dissertations

I explore how pre-Quaternary geoclimatic phenomena and geographical heterogeneity influenced sub-continental speciation processes and contemporary biogeographic patterns across the Southern Hemisphere, with particular focus on two regions that have experienced elevated levels of ongoing aridification – sub-Saharan (particularly Southern) Africa and Australia. I used standard methods from the molecular phylogeneticists’ toolbox (e.g. tree building using maximum likelihood and Bayesian approaches, haplotype networks, uncorrected p-distances) combined with environmental niche modeling, morphometric principal components and fossil calibrated molecular dating analyses in order to ascertain the role that Miocene geo-climatic events played in promoting lineage accumulation and diversification through time. I found a …

Seasonal Changes In Biomass Of Two Comfreshwater Wetland Plants: Storage Of Nutrients, Emily Kathryn Mccann

Electronic Theses and Dissertations

In this study, I quantified differences in above- and belowground biomass and storage of nutrients. I hypothesized that storage of phosphorous would be greater in belowground biomass in the non-growing season compared to the growing. I also hypothesized that the storage of phosphorous would be greater in aboveground biomass in the growing season compared to the non-growing season. Furthermore, I hypothesized that the total amount of nutrients in plant tissue would be greater in the growing season, than the non-growing season. Typha latifolia and Carex lurida were placed in mesocosms at the University of Mississippi Field Station (UMFS) and dosed …

Assessment Of Staphylococcus Aureus Genetics: Clinical Versus Community Epidemiology, Matthew Lawrance

Electronic Theses and Dissertations

Staphylococcus aureus has an historical relationship with anthropogenic environments, particularly hospitals, where infection characteristics differ from community-acquired disease. This has promoted a designation of strains as healthcare or community associated. Despite this affiliation, genetic approaches have failed to support these groupings. In order to establish the genetic relationship between S. aureus from differing anthropogenic environments, I have analyzed the relatedness between three cohorts of S. aureus: nasal carriage isolates from community participants, infectious isolates from hospitals, and a cohort from an uninvestigated environment, an ambulatory clinic. Multilocus Sequence Typing (MLST) and Staphylococcus aureus protein a (spa) repeat regions were analyzed …

Effects Of Harmful Algal Blooms Caused By Aureoumbra Lagunensis (Brown Tide) On Larval And Juvenile Life Stages Of The Eastern Oyster (Crassostrea Virginica), Panagiota Makris

Electronic Theses and Dissertations

Harmful algal blooms caused by the marine microalga Aureoumbra lagunensis have been associated with negative impacts on marine fauna, both vertebrate and invertebrate. Within the Indian River Lagoon (IRL) estuary system along Florida's east coast, blooms of A. lagunensis in excess of 1×106 cells mL-1 have occurred along with higher than average salinities (> 35 PSU) during times of peak reproduction and growth for the eastern oyster Crassostrea virginica. Field and laboratory studies were used to investigate the effects of A. lagunensis and high salinities on early life stages of eastern oysters, late pediveliger to early juvenile. Natural recruitment of …

Involvement Of Mirnas In The Development Of Androgen Independent Prostate Cancer, Richard Ottman

Electronic Theses and Dissertations

Development of resistance to androgen deprivation therapy (ADT) is a major obstacle for the management of advanced prostate cancer. Therapies with androgen receptor (AR) antagonists and androgen withdrawal initially result in tumor regression but development of compensatory mechanisms including AR bypass signaling leads to tumor re-growth, independent of circulating androgens. The result is the emergence of castration resistant prostate cancer (CRPC), a highly morbid disease exhibiting aberrant expression of many protein-coding and non-coding genes. Under the umbrella of non-coding RNAs is a class of small regulatory RNAs referred to as microRNAs (miRNAs). MicroRNAs are believed to function in the maintenance …

Akap150 Dynamics In Anterior Pituitary Cells, Kristen E. Dew

Electronic Theses and Dissertations

Cellular communication occurs as a result of changes in signaling pathways. A well-studied signaling pathway is through G protein coupled receptors (GPCRs). In gonadotropes, GPCR stimulation by GnRH leads to the activation of protein kinase A (PKA). Activated PKA can phosphorylate ion channels, potentially causing an influx of calcium, depolarization and secretion of hormones. A scaffolding protein known as AKAP150 anchors PKA near L-type calcium channels. In addition, AKAP150 anchors phosphatases, which provides temporal control during signaling events. It was recently shown that AKAP150 is mobile in neuronal dendrites, providing regulation to where the signaling cascade occurs in the cell. …