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Identification Of Blda As A Major Regulator Of Virulence In The Sweetpotato Soil Rot Pathogen Streptomyces Ipomoeae And Characterization Of Distinct Clostridium Sweetpotato Soft Rot Isolates, Kuei-Ting Yang

LSU Doctoral Dissertations

Streptomyces ipomoeae is the causative agent of Streptomyces soil rot on sweetpotato, a disease characterized by extensive necrosis of both adventitious and storage roots. While Streptomyces potato scab pathogens produce a phytotoxin (thaxtomin A), which is induced in the presence of cellobiose and suberin, S. ipomoeae produces a less-modified, phytotoxin (thaxtomin C), whose inducer has not been identified. To investigate transcriptional regulation of thaxtomin C production, we inserted a promoter involved in thaxtomin C synthesis upstream of the gusA reporter in an S. ipomoeae strain. Reporter gene expression was significantly upregulated in the presence of size-fractionated sweetpotato extract (SPE). The …

Differential Lead Accumulation In Brassica Juncea, Brassica Rapa, And Lactuca Sativa And Evaluation Of Ground Level Barriers To Prevent Lead Contamination Of Produce Grown In Raised Beds, Celine Vera Richard

LSU Master's Theses

High lead (Pb) contamination of soils is a threat to human health. Urban area soils are frequently contaminated with lead from settling of gasoline exhaust, brake dust, and lead paint on homes, old playground equipment, etc. Exposure to soil-lead occurs by ingestion or inhalation and poses an elevated risk for young children. Indirect ingestion can occur through the food chain through activities such as growing certain vegetables with an ability to tolerate and accumulate lead in edible tissues. Many university extension systems recommend growing vegetables in raised beds as a reasonable reduced risk option for avoiding lead accumulation in garden …

Molecular Mechanisms Of Boron Toxicity Tolerance In Plants, Guannan Wang

LSU Doctoral Dissertations

Boron toxicity is a worldwide agricultural problem that limits crop productivity and quality. However, our understanding on the genetic responses and adaption mechanisms to boron toxicity in plants is very limited. To address this gap in our knowledge, I compared boron stress-sensitive model, Arabidopsis thaliana and its stress-adapted relative Schrenkiella parvula to study how plants respond and adapt to excess boron at physiological, genomic, transcriptomic, and metabolic levels.

The overall project goal involved integration of multi-omics datasets to develop genome to phenome interpretations. To achieve this, I developed a python package, GOMCL, to facilitate the extraction of biologically meaningful information …

Sustainable Management Of Groundwater In Louisiana, Dependra Bhatta

LSU Doctoral Dissertations

The common property nature of the Mississippi River Alluvial Aquifer (MRAA) results in the formation of a cone of depression in the southern portion of the aquifer encompassing Concordia parish, Louisiana. Excessive groundwater withdrawal and the resulting cone of depression formation have caused some wells to go dry and others to be affected by saltwater intrusion. The depleting groundwater stock can be managed optimally using different groundwater management policies. The findings of this dissertation are relevant to both policymakers and researchers to understand the effects of policies to keep the aquifer sustainable.

My dissertation is written in a three-essay format. …

Sexually Dimorphic Oxytocin Receptor-Expressing Neurons In The Anteroventral Periventricular Nucleus Regulates Maternal Behavior, Kaustubh Sharma

LSU Doctoral Dissertations

The neurohypophysial hormone oxytocin is involved in the regulation of social behaviors, including social recognition, pair bonding, and sex-specific parental behaviors in a variety of species. Oxytocin triggers these social behaviors by binding to oxytocin receptors (OXTR) in various parts of the brain. Oxytocin-induced sex-typical behavior, therefore, suggests a sexual dimorphic distribution of OXTR in the brain. In recent years, the oxytocin system in the brain received tremendous attention as a potential pharmacological target for treatment of many psychiatric disorders, such as anxiety, autism spectrum disorders, and even sex-specific psychiatric disorder like postpartum depression (PPD). An important problem and a …

Quantifying Structure And Variation In Complex Phylogenetic Data, Genevieve Geraldine Mount

LSU Doctoral Dissertations

Identifying the source and structure of variation in nature is crucial to understanding fundamental aspects of evolution. Despite a recent plethora of genetic and morphological data, many interesting questions about the relationships between different groups remain unresolved. My dissertation evaluates three approaches for identifying and quantifying the variation within phylogenetic datasets. Characterizing variation within datasets and across analytical methods gives insight into biologically interesting characters, unusual evolutionary processes, and areas for model improvement.

Network-based community detection approaches offer a powerful tool to describe variation in phylogenetic signal across the genome (i.e., gene tree variation). In Chapter 2, I investigate the …

Function, History, And Ecology In The Exceptional Radiation Of Murine Rodents, Jonathan Allen Nations

LSU Doctoral Dissertations

Life’s diversity is not spread evenly across all lineages, and this unevenness is thought to be due, in part, to a few interwoven factors: biogeographic history, the evolution of successful functional traits, and the ecological opportunity these traits afford. My dissertation focuses on the evolution of a species-rich and morphologically diverse clade of mammals, the murine rodents (Murinae; Muridae; Rodentia) to address 1) morphological adaptations associated with niche transition to arboreality 2) the effect of repeated ecological transitions on murine diversification, and 3) the role of atypical ecological niches in the assembly of hyperdiverse communities. My dissertation has revealed that …

Evolution Of Green Blood In New Guinea Lizards: Phylogenomics, Biogeography, And Comparative Genomics, Zachary Rodriguez

LSU Doctoral Dissertations

Non-model organisms with evolutionary novelties and complex distributions can provide valuable insight into the mechanisms underlying biological diversity. Green blood is one of the most unusual vertebrate physiologies and has repeatedly evolved in lizards from the megadiverse island of New Guinea. An unusually high concentration of the toxic green bile pigment biliverdin causes the green coloration of these lizards' blood, muscles, and bones. This dissertation uncovered the complex history of this novel trait (Chapter 2), identified protein-coding sequences that underlie green blood in lizards (Chapter 3), and explored evolutionary processes that drive genetic diversity in high-elevation lizards. To accurately trace …

Identification Of Novel Host Genes Required For Antiviral Immunity And Viral Genome Replication In C. Elegans, Fei Meng

LSU Doctoral Dissertations

RNA interference (RNAi) is a wide-spread gene silencing mechanism that control diverse biological functions and triggered by small interfering RNAs (siRNAs) processed from the viral genome or its replication intermediates. Mechanistic studies of antiviral RNAi in Caenorhabditis elegans has led to the identification of several critical factors involved in the process. As a result, whether antiviral RNAi requires additional novel genes remains to be an open question.

Viruses are intracellular parasites that rely on host products for reproduction. Disrupting their interaction with host factors can significantly compromise their replication and keep them under control. Thus, identification of host genes …

Evaluation Of Louisiana Farm To School Programming: Harvest Of The Month And Local Food Procurement, Arin M. Shaffer

LSU Master's Theses

Farm to school is a growing movement that is beginning to draw serious interest in different parts of the United States due to its ability to connect communities with their local producers while providing many benefits. Farm to school entails three main components: school gardening, education and curriculum, and local food procurement. The farm to school movement is relatively new to the state of Louisiana and very little research has been conducted to evaluate the impact of the farm to school programs on local food procurement and the effect on school food environments. Case studies of three Louisiana parish school …

Within-Field Yield Prediction For Sugarcane And Rice Focused On Precision Agriculture Applications, Felippe Hoffmann Silva Karp

LSU Master's Theses

Food and energy security are two main topics when it comes to the on-growing world population. Rice and sugarcane play an important role in this scenario since sugarcane can be used for energy production and rice is one of major staple cereals. In this scenario, Precision Agriculture (PA) management strategies aims to improve productivity, efficiency, profitability, and sustainability, and can help agriculture to fulfill the needs of the growing population in a sustainable way. However, yield maps are essential for PA, but its adoption is still very low. Thus, the main objective of this study was to evaluate the potential …

Insecticide Resistance Management Approaches And Naturally Derived Toxicants For The Control Of Fall Armyworm, Spodoptera Frugiperda, Sarah Mccomic

LSU Master's Theses

Spodoptera frugiperda, the fall armyworm (FAW), is a major agricultural pest causing billions of dollars in damage annually to staple crops. Agricultural losses stemming from this pest continues to increase as resistance to commercialized insecticide classes evolves and spreads. Considering this, novel chemistries with new modes of action as well as novel resistance management strategies need to be developed to achieve continued control of FAW populations. This project consisted of two main goals. First, we aimed to develop a neurophysiological assay to enable a more precise understanding of pyrethroid and organophosphate resistance at the level of the nerve. We …

Florpyrauxifen-Benzyl Activity And Use In Louisiana Rice Production, Samer Youssef Rustom Jr.

LSU Doctoral Dissertations

Abstract

Field studies were conducted in 2018 at two locations at the H. Rouse Caffey Rice Research Station (RRS) to evaluate the activity of titrated rates of florpyrauxifen-benzyl on aquatic weeds. Florpyrauxifen-benzyl was applied at 0, 3.6, 7.3, 11, 14.6, 18.3, 22, 25.6, and 29.5 g ai ha^-1into 91-cm diameter galvanized rings containing ducksalad, alligatorweed, cattail, creeping water primrose, grassy arrowhead, and pickerelweed. Ducksalad control was 89 to 99% when treated with all rates of florpyrauxifen at 11 to 29.5 g ha^-1; however, control was reduced to 51 to 79% when treated with rates lower than …

Regulation Of Mpcs And Kat8 During Adipogenesis And Nutritional Regulation, Jasmine Burrell

LSU Doctoral Dissertations

Obesity is a global epidemic characterized by an expansion of adipose tissue. Adipose tissue, composed of adipocytes and a stromal vascular fraction, is an endocrine organ that regulates whole body homeostasis. Obesity leads to the dysregulation of adipocytes and is often associated with increased susceptibility to metabolic diseases such as Type II diabetes mellitus (T2DM). Understanding the mechanisms by which adipocyte function and development are regulated is crucial. Mitochondrial pyruvate carriers (MPCs) are transmembrane proteins that transport pyruvate from the cytosol into the mitochondrial matrix to generate acetyl CoA. Although MPCs have been studied extensively, their roles in adipocytes are …

Boxwood Dieback: Molecular Detection, In-Vitro Fungicide Efficacy, And Host Susceptibility For Managing A New Emerging Disease Caused By Colletotrichum Theobromicola, Harleen Kaur

LSU Master's Theses

Boxwood (Buxus spp. L) is one of the most common and widely planted perennial ornamentals in both home gardens and commercial landscapes. Grown for its evergreen, dark green foliage, boxwood cultivation dates back to 4000 BC in Egypt. Although considered hardy, boxwood is susceptible to several plant pathogens. Recently reported boxwood dieback, a fungal disease caused by Colletotrichum theobromicola, has been spreading at an alarming rate within the United States. Boxwood dieback consists of symptoms that resemble to those caused by Phytophthora root rot, Volutella blight, and some abiotic disorders and can be easily misdiagnosed in nurseries and …

Salt Dependence Of Thermodynamic Stability Of A Cold-Active Dna Polymerase I Fragment, Xinji Zhu

LSU Doctoral Dissertations

P. ingrahamii is a halo-psychrophilic bacterium isolated from Arctic sea ice. We have cloned and purified the large fragment of the cold-active DNA polymerase I from P. ingrahamii, named Klenpin. The objective of this project is to directly compare the thermodynamic stability of Klenpin, and the salt dependence of that stability, with Klenow and Klentaq; two homologous polymerases from a mesophile (E. coli) and a thermophile (Thermus aquaticus).

We first examined the effects of salts on the thermal stability (Tm) of Klenpin and Klenow across the Hofmeister series. Significantly different trends were observed on …

Exploring The Role Of Ccp1 And Ccp2 In The Chlamydomonas Reinhardtii Carbon Dioxide Concentrating Mechanism, Lillian Laplace

Honors Theses

No abstract provided.

Characterizing Drosophila Melanogaster Sleep Models Using An Optogenetic Engineered Caspase And Channelrhodopsins, Corey Cooper

Honors Theses

No abstract provided.

Ribosomal Rna Synthesis After Induced Nucleolar Stress In Drosophila Melanogaster, Kyle Maher

Honors Theses

No abstract provided.

From Regulation Of Secondary Metabolites To Increased Virulence Under Sublethal Dosage Of Antibiotics: An Unprecedented Role Of Global Regulator, Mftr, In Burkholderia Thailandensis, Sudarshan Singh Thapa

LSU Doctoral Dissertations

The rise of multi-drug resistant bacteria combined with a decreasing pool of effective antibiotics has placed an increasing need for the development of novel antibiotics. Bacterial natural products or secondary metabolites have been the greatest source for development of novel antibiotics. The genus Burkholderia has recently emerged as a source of promising compounds with antibacterial, antifungal, and anti-cancer activities. Bacterial secondary metabolites provide added advantage to bacteria under stressful environments such as during host infection, evading predators or nutrient deficient conditions. However, genes involved in synthesis of these novel compounds remain silent under normal laboratory growth, creating a hurdle in …

Novel Information About The Kinetic Effects Of Equine Shoe Modifications And Kinematic Effects Of Human Digital Devices For Improved Performance In Both Species, Pengju Wang

LSU Master's Theses

Equine shoes are frequently modified to enhance traction for horses that travel on paved surfaces for work, pleasure, or entertainment. Little is known about other common shoe modifications used to enhance traction like calks, tungsten carbide granules, or plastic composition. This information is vital to shoe design to protect the safety and welfare of all service, working, and leisure horses. The objective of the first part of this thesis was to quantify the effect of shoes with and without traction adaptions on kinetic measures in non-lame, light breed horses at a trot. Kinetic data was collected with a force platform …

The Life History And Population Dynamics Of Southern Flounder, Kenneth A. Erickson

LSU Master's Theses

Southern Flounder, Paralichthys lethostigma, are a coastal, estuarine-dependent flatfish species that inhabits the Southeastern US Atlantic Ocean and Gulf of Mexico. Throughout their range, Southern Flounder are exploited by both commercial and recreational fisheries. Recently, numerous sources have expressed concerns about Southern Flounder populations, with stock assessments indicating declines in spawning stock biomass and recruitment. To estimate life history traits needed for informed management, such as age, growth, and maturity, I collected 327 Southern Flounder from Louisiana and obtained 14,184 historical records from the Louisiana Department of Wildlife and Fisheries. Using a von Bertalanffy growth equation in a Bayesian …

Louisiana Southern Flounder: Commercial And Recreational Trends, David Russell Smith

LSU Master's Theses

Southern Flounder (Paralichthys lethostigma) is a coastal flatfish species that supports recreational and commercial fisheries throughout Louisiana. The recreational and commercial sectors of the Southern Flounder fishery in Louisiana both lack current information that profiles the fishery’s ability to meet stakeholder interest. This project characterized the Louisiana Southern Flounder fishery through an evaluation of fishery-dependent data and a survey of coastal Louisiana anglers.

Fishery-dependent data was gathered to characterize the recreational and commercial Southern Flounder fisheries in Louisiana. This study had three objectives for this evaluation: 1) modeling landings data to evaluate any trends, 2) examine the seasonality of landings, …

The Effects Of Radical Containing Combustion Derived Particulate Matter In Adult Mouse Respiratory System, Jeffrey Harding

LSU Doctoral Dissertations

Epidemiological data associates high levels of combustion-derived particulate matter (PM) with deleterious respiratory outcomes, but the mechanism underlying those outcomes remains elusive. It has been acknowledged by the World Health Organization that PM exposure contributes to more than 4.2 million all-cause mortalities worldwide each year. Current literature demonstrates that PM exacerbates respiratory diseases, impairs lung function, results in chronic respiratory illnesses, and is associated with increased mortality. The proposed mechanisms revolve around oxidative stress and inflammation promoting pulmonary physiological remodeling. Our data demonstrate that environmentally persistent free radicals (EPFRs) stabilized on the surface of PM are capable of inducing oxidative …

The Roles Of Host Species, Geographic Scale And Environmental Stressors In Shaping The Composition Of Coral Microbiomes, Alicia Marie Riegel Parker

LSU Doctoral Dissertations

Reef-building corals are long-lived and may take many centuries to adapt, making them especially susceptible to climate change. However, corals host microbial symbionts that can change quickly, potentially speeding acclimation. My dissertation aimed to determine the degree of coevolution and flexibility between corals and their microbiomes among hosts, across space, and in response to stress.

Microbial communities are usually surveyed by sequencing the 16S rRNA gene, however the PCR primers used also amplify coral DNA, thereby limiting prokaryotic read coverage. To mitigate this contamination, I designed a peptide nucleic acid clamp that increased the recovery of bacterial reads by 2-11x …

Do Ground Layer Microhabitats In Old-Growth Pine Savanna Influence Recruitment Of Longleaf Pine?, Matthew Blanchard

LSU Master's Theses

Savanna tree populations typically share two demographic characteristics, high mortality of juvenile stages and low mortality of established trees. Juvenile savanna tree species escape demographic bottlenecks when they reach a safe size and annual mortality becomes low. Longleaf pine (Pinus palustris Mill.) is the dominant tree species in pine savannas of the southeastern United States. The seeds and juvenile seedlings experience bottlenecks to recruitment to a safe size, the grass stage. Low intensity, frequent savanna fires facilitate establishment of seedlings, but also kill juvenile seedlings that have not grown sufficient above ground biomass. We hypothesized that juvenile seedlings escape the …

Isolation And Characterization Of Bacteria In A Toluene-Producing Enrichment Culture Derived From Contaminated Groundwater At A Louisiana Superfund Site, Madison Mikes

LSU Master's Theses

In an effort to better understand the role that various microbes may play in toluene production, bacteria from a toluene-producing enrichment culture derived from contaminated groundwater at a Superfund site were cultivated and isolated on low nutrient solid media. A total of 14 solid medium formulations containing varying pH ranges, carbon sources, solidifying agents, and incubation gas headspaces were used to obtain 278 isolates in pure culture. Isolated bacteria, identified using partial 16S rRNA gene sequences, were most closely related with the genera Anoxybacillus, Azospira, Bacillus, Bradyrhizobium, Cellulosimicrobium, Micrococcus, and Propionicimonas.

Further attempts …

The Collection Of Baseline Data On Insect And Plant Communities Across Multiple Salinity Zones Within Louisiana's Tidal Marshes, Benjamin G. Aker

LSU Master's Theses

Tidally influenced coastal marshes provide numerous important ecosystem services, but these habitats are experiencing extreme habitat loss. Louisiana’s coastal marshes in particular are vulnerable to land loss resulting from both anthropogenic and natural causes, but especially to subsidence and relative sea-level rise. In response, the Louisiana Coastal Restoration and Protection Authority has outlined and is currently implementing the largest ever attempt at habitat restoration. A major component of this habitat restoration attempt is the use of freshwater and sediment diversions to increase the input of low salinity water, sediment, and nutrients needed to slow marsh loss and build land. Coastal …

Habitat Fragmentation And Range Margin Effects On Dispersal And Interactions Between Competitors, Rachel Roxann Harman

LSU Doctoral Dissertations

Dispersal is a fundamental process that affects local and regional dynamics, including population persistence, range expansion, and interspecific interactions, particularly as disturbance through habitat fragmentation and climate change. Here, my main objective was to ascertain how fragmentation affects dispersal and the interactions of competitors within the local patch and regional landscape. In my second chapter, I assessed dispersal through a literature review and population persistence model to examine the breadth and frequency of different density-emigration forms that occur in nature, including forms that are not prevalent in the literature. I conclude that these rare forms have important population dynamic consequences …

Ecology Of The Roseau Cane Scale (Nipponaclerda Biwakoensis, Hemiptera: Aclerdidae) In Coastal Louisiana, Leslie Alejandra Aviles Lopez

LSU Master's Theses

Common reed, Phragmites australis, is the dominant plant in the Mississippi River Delta (MRD), Louisiana. Phragmites australis stands reduce soil erosion from wave action, protect the oil infrastructure, and freshwater habitats. In the fall of 2016, widespread reed die-backs in the MRD were associated with outbreaks of an invasive scale Nipponaclerda biwakoensis (Hemiptera: Aclerdidae). Due to the recent detection of the scale, there was limited knowledge of its ecology in the adventive range, and its impacts on P. australis lineages. Therefore, the objectives of my thesis were to determine (1) the host specificity of the N. biwakoensis in important economic …