Digital Commons Network^™

Intraguild Predation: Interactions Between Predators, Pathogens, And Their Shared Resources In Crop Pest Communities, Andrew Jason Flick

LSU Doctoral Dissertations

Crop pest management requires an understanding of the complex interactions among pest species that potentially damage crop yield and species that may be crucial for controlling pest species outbreaks. For example, predators, parasitoids, and pathogens are constantly interacting via their shared prey or hosts. Predators may prefer infected prey, which can be easier to catch; however, infected prey may be less nutritious or even lethal for predators. These interactions then dictate the short-term dynamics of host and pathogen as well as between prey and predator. "How these dynamics change as the species in the system change either empirically or theoretically?" …

Phenotypic And Transcriptomic Characterization Of Colonial Phase Variation In The Cholera Pathogen Reveals A Novel Smooth Biofilm-Defective Form, Bliss Nicole Lambert

LSU Doctoral Dissertations

Biofilm formation, through the production of Vibrio polysaccharide (VPS), greatly enhances the environmental fitness and pathogenic success of Vibrio cholerae. As a result of phase variation, V. cholerae can switch from a smooth form to rugose, whose cells produce excess VPS, resulting in highly structured biofilms and greater resistance to stress. To further characterize the reversible process of phase variation, we isolated three colonial lineages. Each lineage began with a smooth parent, N16961, and contained a rugose variant derived from the parent, N16961R, as well as a smooth revertant of the rugose, N16961SD. We found clear phenotypic and transcriptomic …

Changing Land-Use From Pinus Elliottii To Eucalyptus Bentamii In Southwest Louisiana Affects Understory Vegetation Richness, Diversity, And Functional Diversity Patterns, Andrea De Stefano

LSU Doctoral Dissertations

In the Western Gulf region of the United States cold-tolerant eucalyptus have been explored as pulpwood feedstock. However, non-native plantations may alter understory species diversity, modifying environmental conditions and soil characteristics. Few studies have compared eucalyptus plantations with other ecosystems to understand the impacts of converting these land uses on understory vegetation in the United States. Three plantations were selected: (1) slash pine (Pinus elliottii) established in 2008, (2) slash pine established in 2013, and (3) and Camden white gum (Eucalyptus benthamii) established in 2013. The objectives of this study were to: (1) investigate potential changes …

Men’S Jeans Fit Based On Body Shape Categorization, Elahe Saeidi

LSU Doctoral Dissertations

The purpose of this study was to categorize lower body shape in men and to investigate the interplay between body shape and fitting issues appearing in men’s jeans. More specifically, the goal of the study was to improve apparel fit based on body shape. The detailed objectives of the study were to: (1) Categorize male body shapes using statistical analysis; (2) use 3D virtual fitting technology to assess fit and develop a shape-driven pants block pattern for each body shape.

This quantitative study was conducted in three stages: (1) categorizing the body shape of 1420 male scans, aged 18-35, from …

Rats Fed Dietary Bioactive Components (Resistant Starch, Whole Grains, And Fat) Undergo Altered Biometrics And Gene Expression As A Result Of Gut Fermentation, Justin Lamont Guice

LSU Doctoral Dissertations

The whole grain and fat content of the diet have been previously shown to affect intestinal fermentation and phenotype conferred by high–amylose maize resistant starch (HAMRS), a form of fermentable dietary fiber. The current studies were designed to compare rodent gut health following consumption of whole grain and non–whole grain prebiotics on moderate fat (MF) and high fat (HF) diets, and to optimize health effect based on dosage of whole grain resistant starch prebiotics.

Study 1: Diets were prepared to contain the following factors RS (Present/Absent), WG (Present/Absent), and Fat (HF/MF). A three–way ANOVA was performed with statistical slice …

Speciation And Hybridization In Jamaican-Endemic Streamertail Hummingbirds (Trochilus Polytmus And T. Scitulus), Caroline D. Judy

LSU Doctoral Dissertations

Streamertails hummingbirds (Trochilus polytmus and T. scitulus) are recently diverged sister taxa that appear to have speciated in situ on the island of Jamaica. They are distinguished by male bill color, a secondary sexual trait that is coral red in T. polytmus and jet black in T. scitulus. They hybridize in a narrow zone where their ranges meet in eastern Jamaica. In Chapter 2, I performed a formal population survey of T. scitulus to determine the size of the population, which was unknown. I determined that the total population contains well over 100,000 individuals despite its limited …

Transforming Lives In Coastal Communities Through Economic Development: Breeding Crassostrea Virginica For Alternative Oyster Culture, Brian Randall Callam

LSU Doctoral Dissertations

This dissertation helped address the commercialization of triploid Crassostrea virginica production and develop tetraploid C. virginica broodstock in Louisiana by addressing triploid commercialization and tetraploid broodstock development. This was done by: 1) developing regional breeding plans for diploid and tetraploid C. virginica targeted at the Gulf Coastal Region, 2) assessing the effect of chromosome set manipulation on gonadal development in diploid, triploid, and tetraploid C. virginica, 3) quantifying the variation of commercially important hatchery traits in triploid C. virginica larvae from different tetraploid parents, 4) developing an up-to-date remote setting manual for the Gulf Coastal Region for industry use, …

Analysis Of The Soil Health Of Pastures Over-Seeded With Winter Annuals, Kathleen M. Bridges

LSU Doctoral Dissertations

Utilizing winter annuals in livestock pastures reduces feed costs of hay, and provides additional vegetative cover that is beneficial to the soil. However, how this practice affects the soil microbial communities has not been well studied. Two sites were included in this study. Both were commercial cattle grazing operations that over-seeded a mixture of grasses, legumes, and brassicas into pastures dominated by bahiagrass (Paspalum notatum). Soil health was assessed using a suite of physical, chemical, and biological properties. Soil physical assessments included bulk density and aggregate stability. Soil chemical assessments included macronutrients, pH, soil organic matter (SOM), total …

Genome Wide Association Studies For Identification Of Markers Linked To Sucrose Traits In Sugarcane, Nathanael Darrell Fickett

LSU Doctoral Dissertations

Sugarcane, being a complex aneu-polyploid, poses unique challenges to fine mapping of quantitative trait loci (QTL) controlling agronomic traits of interest. Genome-wide association studies (GWAS) could be a better alternative to identify molecular markers associated with specific traits due to high linkage disequilibrium in sugarcane. In the first study, marker-trait associations (MTAs) were evaluated for three sucrose traits, Brix, total recoverable sugar (TRS), and percent sucrose on 48 elite and historic Louisiana breeding clones using 1,062 alleles. These sucrose traits were highly correlated (P-value < 0.0001) at >0.96. TASSEL 5.1 and JMP Genomics 8.0 were compared with eight models run in each program. …

Induced Resistance In Rice, Oryza Sativa, To Herbivores In The Southern United States, Emily Clare Kraus

LSU Doctoral Dissertations

The effects of herbivory and chemical applications as potential inducers of resistance to herbivores in rice, Oryza sativa L., were explored through a series of field, greenhouse, and laboratory experiments. Studies were conducted to investigate the preference and performance of several herbivore pests of rice with a focus on, Lissorhoptrus oryzophilus Kuschel, the rice water weevil (RWW), under conditions where rice plants had been stressed by previous herbivory or chemical applications. The effects of defoliation by Spodoptera frugiperda (J.E. Smith), the fall armyworm, on resistance and tolerance of rice to RWW under field conditions were examined. Herbivory by fall …

Soybean Response To Dicamba: Associated Injury Criteria And Development Of A Model To Predict Yield Loss, Matthew Ryan Foster

LSU Doctoral Dissertations

In research conducted using indeterminate soybean [Glycine max (L.) Merr.], fourteen injury criteria observed following dicamba at 0.6 to 280 g ae ha^-1 (1/1000 to ½ of 560 g ha^-1 use rate) were rated using a scale of 0= no injury, 1= slight, 2= slight to moderate, 3= moderate, 4= moderate to severe, and 5= severe. Greatest crop injury 15 d after treatment (DAT) was observed following dicamba applied at 0.6 to 4.4 g ha^-1 at V3/V4 for upper canopy pale leaf margins (3.8 to 4.2) and at R1/R2 for terminal leaf cupping (4.1 to 5.0) …

Genome-Wide Screening Identifies Genes And Biological Processes Implicated In Chemoresistance And Oncogene-Induced Apoptosis, Tengyu Ko

LSU Doctoral Dissertations

Anti-proliferative responses such as senescence and apoptosis are often used by normal cells to combat oncogenic insults and to prevent tumorigenesis. However, oncogenic mutations are frequently found in cancers, suggesting that additional mutations may occur to facilitate the bypass of these anti-proliferative responses. It is believed that some of these additional mutations may also contribute to the chemoresistance of cancers. This dissertation focused on identifying novel genes and biological processes implicated in chemoresistance and tumorigenesis.

Cisplatin-based chemotherapeutic regimens are frequently used for treatments of solid tumors. However, tumor cells may have inherent or acquired resistance to cisplatin, and the underlying …

Development, Validation, And Testing Of A Self-Determination Theory Instrument Called The Motivation To Prepare Healthy Foods Questionnaire, Ariana Delong Bailey

LSU Doctoral Dissertations

The objectives of these studies were to validate and confirm the structure of a previously developed questionnaire that measures the psychosocial constructs defined by the Self-Determination Theory (SDT) and then test this questionnaire in a nutrition education setting. The instrument, titled the Motivation to Prepare Healthy Foods Questionnaire (MPHFQ), included items that measured intrinsic motivation, perceived competence, relatedness, autonomy, and autonomy support. These studies evaluated the questionnaire’s validity and ability to measure changes in the SDT construct scores.

The MPHFQ is a previously developed and reliable instrument intended to measure adults’ intrinsic motivation and perceived competence to prepare healthy foods, …

The Distinctive Regulatory Mechanisms Of Bacterial Acetyl-Coa Carboxylase, Alexandra Leigh Evans

LSU Doctoral Dissertations

Metabolic Regulation is a complex system used to control cellular metabolism in response to conditions in the cell’s environment. For most enzymes, the cell can rely upon a minimal amount of regulation; however, critical enzymes, such as acetyl-CoA carboxylase, must be regulated at multiple levels. Acetyl-CoA carboxylase catalyzes the first committed step in fatty acid synthesis. In bacteria, acetyl-CoA carboxylase forms a complex of three subunits–biotin carboxylase, biotin carboxyl carrier protein, and carboxyltransferase–which catalyze the carboxylation of acetyl-CoA to form malonyl-CoA via two half-reactions. In the first half-reaction, biotin covalently linked to biotin carboxyl carrier protein is carboxylated by biotin …

Bio-Based Polyurethane Foams Made From Microwave Liquefaction Of Biomass, Xingyan Huang

LSU Doctoral Dissertations

Polyurethane (PU) foam is one of the most versatile construction insulations due to its low density, low thermal conductivity, and high mechanical performance. However, it is still highly dependent on petro-based chemicals, i.e. polyol and isocyanate. In this work, biomass, such as rape straw, switchgrass, and yaupon holly (Ilex vomitoria) were liquefied using microwave energy to produce bio-based polyol in order to substitute petro-based polyol in the production of PU foam. Cellulose nanocrystals (CNCs) were also extracted from liquefaction solid residue. They were then applied to reinforce high bio-content PU foam. Moreover, lignin was fractionated from bio-polyol by …

Direct Quantification Of Deubiquitinating Enzyme Activity In Single Intact Cells, Nora Safabakhsh

LSU Doctoral Dissertations

Challenges in drug efficacy occur during the treatment of most types of cancer due to the heterogeneity of the tumor microenvironment. This has led to the development of personalized medicine. Due to the clinical success of the proteasome inhibitors Bortezomib and Carfilzomib in treatment of multiple myeloma, interest has shifted towards molecularly-targeted chemotherapeutics for ubiquitin-proteasome system (UPS). Deubiquitinating enzymes (DUBs) are an essential part of this pathway which have been found to promote Bortezomib resistance in multiple myeloma patients. Unfortunately, there is a lack of specific, high throughput biochemical assays to characterize DUB activity in patient samples before and after …

Louisiana Urban And Suburban Homeowners’ Fertilizer Management Behavioral Beliefs, Intentions, And Past Behaviors, Natalie Levy

LSU Doctoral Dissertations

Nutrient runoff of nitrogen and phosphorus from improper lawn and landscape fertilization practices contributes to water quality issues within the Mississippi River drainage basin and the Northern Gulf of Mexico (NRC, 2009a; Robbins & Birkenholtz, 2003). The implementation of fertilizer best management practices has become a critical strategy for reducing nutrient runoff (Carey et al., 2012a; Carey et al., 2013; U.S. EPA, 2005). The purpose of this study was to determine if relationships exist among selected perceptual measures regarding home lawn and landscape fertilizer management practices among Louisiana urban and suburban homeowners. Ajzen’s (1991) Theory of Planned Behavior (TPB) was …

The Effects Of Biochar And Nitrogen Stabilizers Application On Forage Crop Growth, Greenhouse Gas Emission And Soil Quality, Joseph Elias Rodrigues Mikhael

LSU Doctoral Dissertations

ABSTRACT

Forage systems are important for animal production. Nitrogen fertilization and herbicides use has led to a significant increase in forage production. Therefore, this study aimed to investigate the effects of biochar and N-(n-butyl) thiophosphoric triamide + dicyandiamide (NBPT+DCD) application on manure and urea fertilized soil by focusing on nitrogen fertilizer efficiency use, greenhouse gases emissions, microbial community, soil aggregate stability, and organic carbon functional groups. In addition, herbicides effect on greenhouse gases emission was assessed. Biochar and NBPT+DCD increased nitrogen use efficiency of both fertilizers managements and reduced the N₂O emissions following manure fertilization. However, NBPT+DCD was …

Regulation Of Epithelial Sodium Channels In Vasopressin Neurons In The Hypothalamus, Natalie Jean Mills

LSU Doctoral Dissertations

Salt-sensitive individuals have blood pressure that is unusually sensitive to salt intake. Because salt-sensitivity is a common disorder and may cause high blood pressure, it is a significant public health concern. All three epithelial Na⁺ channel (ENaC) subunits (a, b, and g) and the mineralocorticoid receptor (MR), a known regulator of ENaC, are expressed by vasopressin (VP) synthesizing magnocellular neurons in the hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei. A growing body of evidence indicates that epithelial Na⁺ channels (ENaCs) in the hypothalamus play a significant role in the development of salt-sensitivity. My dissertation research tests the hypothesis …

Conservation Of Freshwater Live-Bearing Fishes: Development Of Germplasm Repositories For Goodeids, Yue Liu

LSU Doctoral Dissertations

Fishes of the family Goodeidae are considered to be among the most imperiled taxa in the world. The goal of this project was to provide a foundation for development of sperm repositories for goodeids and to use them as a model to assist conservation programs for imperiled freshwater live-bearing fishes. Development of such repositories is challenging because of unusual reproductive characteristics of live-bearing fishes, such as sperm bundles, internal fertilization, and the bearing of live young. Standardized methods were established to evaluate quality-related attributes of sperm bundles. The different features between activation of free and bundled sperm were investigated and …

Chemosensory Communication And Neural Substrates Of Social Behavior In The African Cichlid Fish, Astatotilapia Burtoni, Karen Elizabeth Field

LSU Doctoral Dissertations

Social animals must constantly assess their environment to make appropriate decisions. In several fish species, chemosensory signaling is crucial for social communication, conveying information on sex, reproductive state, and social status. Despite its importance in fishes, relatively little is known about how they employ chemical signaling, with only a few of the over 30,000 extant species investigated thus far. Further, there is a scarcity of information about where and how socially-relevant chemosensory signals are processed in the brain of fishes, or how chemosensory signals are integrated with other senses to elicit appropriate behaviors. For my doctoral research, I examined the …

Characterizing Cytoplasmic Maturation And Improving Competence Of Bovine In Vitro Matured Oocytes, Brittany Alanna Foster

LSU Doctoral Dissertations

As the necessity to improve in vitro embryo production efficiency is ever increasing, so too is the prerequisite obligation to improve oocyte competence. The ability of an oocyte to successfully produce a viable embryo requires that it both completes meiotic maturation and synchronously achieves cytoplasmic competence; an encompassing term that refers to the oocytes correct accumulation and storage of mRNAs, proteins and factors as well as the development and reorganization of organelles and the cytoskeleton. The current research was designed to analyze those methods that go into oocyte collection and pre-maturation handling to determine if there are ways to ensure …

Evaluation Of Oncolytic And Immunomodulatory Potential Of The Hsv-1 Live-Attenuated Vaccine Strain Vc2 In An Immunocompetent Murine Melanoma Model, Natalie Wall Fowlkes

LSU Doctoral Dissertations

Melanoma accounts for 90% of skin cancer-related deaths in humans. Treatment options for metastatic melanoma in people is very limited. Melanoma is considered to be an immunogenic tumor, spurring interest in development of immunotherapies for the treatment of metastatic melanoma. Oncolytic virotherapy has been widely investigated. The first ever oncolytic virotherapy to receive FDA-approval is an HSV-1-based virus (Talimogene Laherperavec (T-Vec) or Imlygic) containing a transgene for human GM-CSF to enhance anti-tumor immune responses after injection. Durable response rate in human patients was only 16% despite impressive efficacy in anti-tumor effects in vitro and in murine tumor models. Novel viruses …

Endocannabinoid Metabolome Of Human Breast Milk, Adriana V. Gaitan Espinoza

LSU Doctoral Dissertations

Human breast milk (HBM) is an extremely complex yet fascinating biofluid tailored to meet an infant’s nutritional requirements for development. Amongst the nutrients present in HBM, the long-chain polyunsaturated fatty acids (LCPUFAs) are of high importance due to the pivotal role they play in infant cognitive and visual development, and growth. In addition, the LCPUFAs are precursors to endocannabinoids (EC) which are endogenous lipid mediators. EC exert metabolic responses including appetite and food intake regulation, and they have been identified to play a role in establishing the suckling response of the newborn that is needed to nurse. Thus, we aimed …

Exploring The Role Of Rna Polymerase Iii Complex Assembly On Ribosomal Dna Silencing In Saccharomyces Cerevisiae, Kyle Thomas Kern

LSU Doctoral Dissertations

The yeast rDNA region is host to a number of transcriptional regulatory elements, which work in conjunction to generate essential RNA subunits of ribosomes, as well as protecting the region from DNA damage. The role of RNA polymerase III complex binding at the 5S gene on rDNA silencing in the NTS2 region was investigated, both by use of a TY1:MET15 reporter insert and a MET15 gene integration at an endogenous SphI site. It was discovered that Pol III complexes do have an effect on reporter expression in the NTS2 region, though the specific effect was different based on the method …

Determining The Drivers Of Anti-Tropical Distributions Across The Fish Tree Of Life, William Benton Ludt

LSU Doctoral Dissertations

Anti-tropical distributions are those where populations of a single species, or multiple closely related taxa, are distributed outside of, and on opposing sides of, the tropics. These latitudinally disjunct distributions have been noted for over a century. Despite this long history of interest, little has been concluded regarding the actual mechanisms that drive this pattern, with several prominent hypotheses competing with one another in the literature. Here I review the proposed drivers of anti-tropicality, and subsequently test them using fishes with a variety of life history and taxonomic differences. This includes (1) a temperately restricted family with anti-tropical distributions – …

Risk Assessment Of Fall Armyworm Resistance To Transgenic Corn Containing Single Or Pyramided Bacillus Thuringiensis Genes, Ying Niu

LSU Doctoral Dissertations

The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a target pest of Bacillus thuringiensis (Bt) crops in North and South America. However, after more than two decades of the intense use of Bt crop technology, S. frugiperda has developed resistance to Bt corn in several countries. The objectives of this study were: 1) to characterize the inheritance and fitness costs of Cry1A.105 resistance in S. frugiperda; 2) to evaluate larval survival and plant injury of Cry1A.105-susceptibile, -resistant, and -heterozygous S. frugiperda populations on transgenic corn plants containing single or pyramided Bt genes; 3) to estimate the frequency of Cry2Ab2 …

Impact Of Temperature, Plant Species, And Sorghum Cultivar On The Population Dynamics Of Melanaphis Sacchari, Monique Ferreira De Souza

LSU Doctoral Dissertations

Sugarcane aphid, Melanaphis sacchari Zehner, is now widely established in sorghum, Sorghum bicolor L., production areas of the United States and is an important economic pest. However, detailed studies of temperature, host range and plant resistance effects on the biology and population parameters of the M. sacchari biotype responsible for the sorghum outbreak in the United States have not been performed previously. Therefore, the present study aimed to investigate: 1) How temperatures affect M. sacchari 2) M. sacchari interaction with host plants 3) M. sacchari interaction with sorghum genotypes. The response of M. sacchari to six different constant temperatures (15, …

Evaluation Of Dopaminergic And Antidopaminergic Agents For Use In Equine Metabolic Physiology, Nicole Arana Valencia

LSU Doctoral Dissertations

A series of experiments studied the effects and practical applications of dopaminergic and antidopaminergic compounds in equine metabolic physiology. The first experiment was performed to assess the long-term effects of repeated cabergoline injections (every 10 days for a total of seven injections) on prolactin and α-melanocyte stimulating hormone concentrations in insulin insensitive mares. Additionally, the experiment also evaluated the use of cabergoline for improving insulin sensitivity. Plasma prolactin and α-melanocyte stimulating hormone concentrations were suppressed throughout the duration of the experiment even when the mares were challenged with a low-dose dopamine antagonist, sulpiride, the day previous to their subsequent cabergoline …

Endocytosis And The Nitric Oxide-Dependent Release Of Chloride, Vernon K. Dunn Jr

LSU Doctoral Dissertations

Understanding the regulation of retinal synapses is a key step in elucidating the processing of information in the retina. Our lab has previously shown that nitric oxide (NO) can alter the synaptic response properties of amacrine cells by releasing Cl- from internal acidic compartments. This alteration in the Cl- gradient brings about a positive shift in the reversal potential of the GABA-gated current, which can convert inhibitory synapses into excitatory synapses. Recently, we have shown that the cystic fibrosis transmembrane regulator (CFTR) Cl- channel is involved in the Cl- release. Here, we test the hypothesis that (acidic) synaptic vesicles are …