Life Sciences Commons^™

Enhancement Of Applied Rice Breeding Programs: Exploring Factors Impacting Genomic Selection Accuracy And Discovery Of A Novel Gene For Grain Shape, Maria G. Montiel

LSU Doctoral Dissertations

Plant breeding is a crucial tool in addressing global challenges such as climate change, population growth, and the need for more resilient crops. Rice serves as a staple food for a significant portion of the global population and has served as a model crop for genetic and genomic studies. Genomic selection (GS) has become valuable tool in plant breeding, allowing breeders to predict breeding lines’ performance based on their genotypes. The training (TS) set is a central component of genomic selection and the optimization of the training set is crucial for efficient implementation of genomic selection. The first two objectives …

Spatial Mapping Of The Benthic Community And How It Is Used To Research Effects Of Dredging In Louisiana's Lake Borgne., Meghan Johnson

LSU Master's Theses

Benthic communities are vitally important for healthy aquatic ecosystems across Louisiana’s coast. Specifically in Lake Borgne, ecologically important species of fish like the Gulf Sturgeon (Acipenser oxyrinchus desotoi) rely on benthic macrofauna as their main food source. The purpose of this study was to determine the spatial landscape of biodiversity and abundance of the benthic macrofauna community in Lake Borgne. Environmental conditions played a key role in community structure during the study period (fall 2021 through summer 2023) with a major drought occurring in 2023. In 2023, the decline in the abundance of most benthic invertebrates and in …

Enhancement Of Soybean Growth And Disease Resistance Through Seed-Priming Strategy, Francisco Javier Valle

LSU Master's Theses

Disease pressure and other environmental stresses, especially increasing temperature and drought incidence, accompanied with global climatic change have presented hard challenges to Louisiana soybean producers. The objective of this study was to explore the efficacy of seed priming techniques as new alternatives to improve soybean crop protection to reduce the amount of yield losses caused by biotic and abiotic stresses. In this study, five chemicals were used as priming agents at different concentrations (0.1 mM, 1 mM, and 10 mM) to evaluate their effectiveness in enhancing disease tolerance and yield in soybeans. A seed priming procedure was developed by partially …

A Novel Goat Model To Characterize Male Fertility Following Paternal Cannabidiol Exposure, Ashlyn N. Brewer

LSU Master's Theses

Despite the increasing use of cannabidiol, both for medical and social purposes, the effect of cannabidiol on male fertility is poorly understood. Previous studies have been carried out in rodent models, but a large animal model does not exist at this time. This experiment proposes chronic cannabidiol (CBD) exposure using a goat model to understand the impact CBD has on male reproductive performance. The purpose of this project is to determine if daily exposure to CBD in male goats would impact reproductive parameters such as sperm quality and testosterone levels.

Two studies were conducted to determine the effects of CBD …

The Use Of Duddingtonia Flagrans Aged In Mineral For Gastrointestinal Parasitic Nematode Control In Small Ruminants, Elisa M. Preston

LSU Master's Theses

Gastrointestinal nematodes (GIN) are a major constraint to small ruminant health and production throughout the world. Haemonchus contortus commonly known as the “barber pole worm” is a major concern for producers and veterinarians because of the severe anemia, and other clinical symptoms these worms cause. For decades, anthelmintics have been used to control the GIN burden small ruminants face. Katahdin (n=36) and Hampshire sheep (n=12) were used in a randomized block design experiment over a 30-day period. The objective of this study was to evaluate the effectiveness of Duddingtonia flagrans spores, the active ingredient in a commercial product, Bioworma® (International …

Effects Of Treated Effluent Discharge On Tree Water Use And Growth In A Cypress Swamp., Devin Schexnayder

LSU Master's Theses

Inundated baldcypress (Taxodium distichum) trees generally respond to secondarily-treated and disinfected municipal effluent additions with increased growth rates and reduced mortality. Yet, the effects of effluent additions on the water-use and functional traits of inundated mature baldcypress are poorly understood. Because increased tree growth is associated with increased water use, effluent additions may affect the water budget in coastal swamps by increasing water uptake from the rhizosphere due to increased tree transpiration. I used sap flux density (f_d) measurements to assess water-use traits and tree-level daily transpiration (E) in seven mature inundated baldcypress trees that had …

Quantification Of Belowground Biomass And Sediment Accretion In Mangroves Of Different Coastal Environmental Settings Of The Costa Rican Pacific Coast, Denise M. Poveda

LSU Master's Theses

The adaptation of intertidal ecosystems such as mangroves to anticipated accelerated relative sea level rise is dependent on net increase of sediment surface elevations and forest migration inland. Ecosystem models developed to simulate trajectories of ecosystem adaptations have determined that rates of soil formation are most sensitive to surface sediment (organic and inorganic) deposition and subsurface organic production by mangrove roots. Mangrove belowground biomass contributes to soil organic matter accumulation, while mangrove litter has minor contribution due to export and annual decay. In addition to belowground biomass production, inorganic sediment loading is also key contribution to soil formation and accretion. …

Settling Preference Of Nipponaclerda Biwakoensis (Hemiptera: Aclerdidae) On Phragmites Australis Stems, Alexia Catherine Desoto

LSU Master's Theses

Phragmites australis, a wetland grass that stabilizes the Louisiana coastline, has been undergoing a major die-off near the Mississippi River Delta (MRD) since the autumn of 2016. One suspected cause for this plant decline is the attack of an invasive scale insect, Nipponaclerda biwakoensis. We lack information on the host preference of the crawlers, the life stage that decides where to settle and when to start feeding on the plant. The objectives of this study were to identify what positions along the vertical stem N. biwakoensis prefers to settle and what host-plant traits may be influencing this choice. We recorded …

Addition And Subtraction: Coral Reproduction And Disease In A Changing Ocean, Ashley Rossin

LSU Doctoral Dissertations

Marine diseases are changing the landscapes of coral reefs particularly throughout the Western Atlantic. Stony coral tissue loss disease (SCTLD) swept through this region impacting at least 22 stony coral species. White plague (WP) is a more ephemeral disease, but still has a significant impact on coral reef health and perseverance, especially under a changing ocean. While these impacts are seen on the reef-scale, we can zoom into the tissue-level to identify disease markers for both diseases and identify their differences. This has ramifications for disease intervention, as well as mitigation strategies. Despite continuous disease outbreaks, healthy corals persist and …

Applied Depositional Geosystems Of The Coos Bay Basin, Oregon: Organic Geochemistry, Maturation, Paleoenvironmental Reconstruction And Biostratigraphy Of The Coaledo Delta During The Middle Eocene Climatic Optimum (Meco), Allison K. Barbato

LSU Doctoral Dissertations

The Coos Bay Basin on the southwestern coast of Oregon is a forearc basin that contains exceptionally preserved Eocene to Miocene, tidal to wave-dominated, shallow deltaic to deep marine sediments of the Coaledo Delta. Coastal depositional environments are known to host source, reservoir, and seal rocks. Climate, topographic relief, and geographical position all play an important role in regional vegetation development and oceanic setting. This study assesses 84 outcrop and 12 core samples from Coos Bay for their organic geochemical characteristics and microfossil assemblage to provide source rock characterization information, organofacies descriptions, environmental reconstructions, and age control.

Results indicate the …

Louisiana Agriculture Magazine, Spring 2024, Lsu Agcenter

Louisiana Agriculture

Louisiana’s warm, subtropical climate allows producers to raise an array of crops and livestock. It also provides challenges. Tropical storm winds can lay down rice and cane crops. Ample rain can turn into crop-damaging floods. Last year, a drought struck the southeastern United States, leading to more than $100 million in losses for the cattle sector.

In these cases, LSU AgCenter specialists respond to individual producers’ needs. In each parish AgCenter Extension agents help connect producers with needed resources and become a conduit for the latest knowledge gleaned from scientists at AgCenter research stations across the state.

This issue of …

Prescribed Fire Effects On Microbial Communities And Functions In Managed Ecosystems, Viet Dao

LSU Doctoral Dissertations

Microbes (both fungi and bacteria) serve important ecosystem functional roles in nutrient cycling and decomposition, which affect ecosystem response following disturbances such as prescribed fire. A multitude of abiotic and biotic factors influence microbial community compositions, which then drive microbial ecosystem functions. The factors driving microbial communities further change due to fire disturbances and progression with time. Although prescribed fire is commonly used as a technique for ecosystem management, the effects of fire on microbial communities or their functions are simply understudied. Ecosystem management decisions tend to focus on plant and ecosystem post-fire responses. Thus, incorporation of fire effects on …

Halosulfuron Plus Prosulfuron And Propanil Interactions For Weed Control In Louisiana Rice Production, John A. Williams

LSU Master's Theses

A greenhouse study was conducted on November 18, and December 2, 2020 at Louisiana State University in Baton Rouge, Louisiana to evaluate the interaction between a pre-packaged mixture of halosulfuron plus prosulfuron mixed with propanil for alligatorweed control. Antagonism occurred when halosulfuron plus prosulfuron at 55 g ha-1 was mixed with propanil at 2,242 g ha-1 at all evaluation dates and antagonism was also observed with halosulfuron plus prosulfuron at 83 g ha-1 mixed with propanil at 2,242 g ha-1 at all evaluation dates except 14 DAT with observed controls of 69 to 77% compared with expected controls of 94 …

Parental Environnement Influences Offspring Gene Expression In The Olympia Oyster, Ostrea Lurida., Mark S. Yeats

LSU Master's Theses

The Olympia Oyster is the only native oyster species on the Pacific coast of North America. Seasonality in water temperatures across this threatened species’ broad and fragmented range has been linked to its development, reproductive timing, reproductive activity, growth, and survival rates. Recent evidence suggests parental environments can have carry-over effects on larval growth and respiration rates in response to temperature. In this study, we utilized transcriptomic methods to identify the underlying mechanisms of this cross-generation plasticity. Sequence libraries of adult ctenidia tissue and pooled larval replicates were extracted and spawned from hatchery raised oysters of the same parentage immediately …

The Ecological Responses To Hydroperiod Of Wetland Plant Species Determined By Manipulated Soil Surface Elevation (Marsh Organs), Brandon Wolff

LSU Master's Theses

As sea level rise, subsidence, and abandonment of natural deltaic processes due to a highly engineered Mississippi River continue to threaten Louisiana’s coastal wetlands, the need for a system-wide understanding of natural wetland land-building and preservation processes has never been greater. A key component of any wetland is the ever-changing water environment that periodically floods and dries the marsh platforms. The flooding depth, duration, and frequency, known as the hydroperiod, along with salinity and soil fertility are key determining factors of vegetation and marsh types at a particular location. Different types of vegetation will have different growth characteristics such as …

Machine Learning-Based Soybean Yield Prediction And Optimizing Lidar-Mounted Uav Efficiency, Leticia Santos

LSU Master's Theses

The first chapter of this thesis explores the predictive capabilities of random forests algorithm on datasets obtained from field plot experiments on crop management systems in soybean. Furthermore, the chapter presents a complementary analysis of model performance according to dataset sizes and two techniques on how to impute and deal with missing data. Random forests are being compared with standard statistical techniques such as linear regression on a well-structured, information-rich agronomic experiment. The key findings of this chapter includes the best hyperparameters adjustment and the identification of the dataset threshold for optimal algorithms performance. The second chapter has a research …

Diving At High Altitude: O2 Transport And Utilization In The Ruddy Duck And Torrent Duck In The Andes, Kevin G. Mccracken, Graham R. Scott, Luis Alza, Andrea Astie, Ciska Bakkeren, Emil Bautista, Mariana Bulgarella, Rebecca Cheek G. Cheek, Beverly A. Chua, Neal J. Dawson, Alexis Diaz, Catherine M. Ivy, Peter B. Frappell, Cecilia Kopuchian, Sabine L. Laguë, John N. Maina, Violeta Muñoz-Fuentes, Elizabeth R. Schell, Matthew M. Smith, Ryan J. Sprenger, Pablo L. Tubaro, Elizabeth R. Schell, Matthew M. Smith, Ryan J. Sprenger, Pablo L. Tubaro, Thomas Valqui, Roy E. Weber, Daniela Wilner, Robert E. Wilson, Julia M. York, William K. Milsom

Occasional Papers of the Museum of Natural Science, Louisiana State University

Hypoxia and cold temperatures create unique physiological challenges for high-altitude organisms that can vary depending on lifestyle. While nearly all studies of air-breathing animals at high altitude are from terrestrial species, species that breath-hold dive underwater at high altitude encounter a very different set of selective pressures influencing their phenotype. The goal of this publication is to highlight the changes in O2 transport and utilization in high-altitude diving birds relative to divers at sea level, and the extent to which these changes are qualitatively distinct from phenotypic changes in non-diving species at high altitude. For example, while high capacities for …

Louisiana Agriculture Magazine, Winter 2024, Lsu Agcenter

Louisiana Agriculture

Research at the LSU AgCenter extends well beyond the farm gate. Across 150 acres at the Hammond Research Station, experts in landscape horticulture test the best ways to grow ornamental plants and trees. In Baton Rouge, researchers study how to protect homes in the path of a hurricane. Across the state the AgCenter Healthy Communities team works to empower food pantries and improve sidewalks and other pedestrian infrastructure in rural areas.

This issue of Louisiana Agriculture focuses on these topics along with new research on soil health and high-tech delivery systems for sugarcane ripening agents. Other articles focus on the …

Iron–Sulfur Cluster Assembly Scaffold Protein Iscu Is Required For Activation Of Ferric Uptake Regulator (Fur) In Escherichia Coli, Huangen Ding

Faculty Publications

No abstract provided.

An Intersection Of Science & Art: Vitrification Approaches And Open-Fabricated Tools For The Biomedical Model Sea Hare, Aplysia Californica, Allyssa M. Oune

LSU Master's Theses

The California sea hare (Aplysia californica) is an important biomedical model for molecular neurobiology, electrophysiology, learning, and memory due to their well-mapped and large neurons and well-characterized learning capabilities. The National Resource for Aplysia (NRA, University of Miami) maintains large stocks of live animals and relies on regular shipments of wild-caught individuals to maintain genetic diversity. This is labor and cost-intensive, and environmental changes could alter the availability of wild animals increasing the need to preserve this genetic resource. One solution is vitrification, ultra-fast cooling which produces an amorphous glass that minimizes damage to cells. Aplysia californica presents …

Prey Selection By Common Nighthawks (Chordeiles Minor) Across Seasons And Fire Management Regimes, Eliza D. Stein

LSU Master's Theses

Common Nighthawks (Chordeiles minor, hereafter nighthawks) belong to the aerial insectivore guild, which is rapidly declining in part because of changes in insect prey bases. To understand the ability of nighthawks to accommodate fluctuating prey communities, it is necessary to understand their degree of diet specialization, how specialization changes throughout the annual cycle, and the effects of land management practices on prey availability and nighthawk habitat use. We examined prey selection by breeding and non-breeding nighthawks by collecting fecal samples during two breeding seasons in Florida, USA, and two non-breeding seasons in Corrientes Province, Argentina. We used DNA …

Applying Optimization Theory To Predict Stomatal Behavior In Waterlogged Trees Based On Photosynthetic And Hydraulic Traits, Marisa J. Brennan

LSU Master's Theses

Climate change has increased the occurrence of flood events in many regions. Predicting the impacts on ecosystems is a major challenge. Dynamic global vegetation models that project ecosystem dynamics in response to disturbances rely on predictions of stomatal conductance (g_sw). Stomatal Conductance can be modeled based on optimality theory, which finds that plant stomata have evolved to optimize g_sw by maximizing the difference between the gain of carbon uptake (A) and the cost of water loss (Θ). However, the interplay between hydraulic and photosynthetic physiological mechanisms driving changes in g_sw, particularly in flood …

Optimizing Virulence And Understanding The Endophytic Colonization Of Metarhizium Spp. In Sweetpotato For The Control Of Cylas Formicarius Elegantulus (Summers), Santosh Bhandari

LSU Master's Theses

In the United States, control of the sweetpotato weevil [SPW, Cylas formicarius elegantulus (Summers)] occurs through quarantine and regular use of chemical insecticides. However, an overreliance on chemical control may lead to resistance. Entomopathogenic fungi have potential to act as an alternative to chemical control. In this study, we assessed four different strains of Metarhizium isolated from soil collected in Louisiana (Mp-K048, Ma-K056, Mr-K082, and Mr-K101) and compared them to a well-known licensed strain (Mb-ARSEF 1095) for virulence against C. formicarius elegantulus. Results suggested that Mp-K048, Ma-K056, and Mr-K082 …

A Study Of Tissue-Specific Rho Signaling Activation During Tubular Organ Formation In Drosophila, Charlotte Jean-Louise Adams

LSU Master's Theses

Several organs within the human body are tubular in structure. In the event of a malfunction in the development of these tubular structures, maladies like spina bifida, anencephaly, and several other defects can arise. To understand the mechanisms of tubular organ formation, we use the Drosophila embryonic salivary gland (SG) as a model. During embryogenesis, SG cells undergo a series of cell shape changes, like apical constriction, to accommodate the developing gland. Apical constriction is regulated in part by the signal of the secreted ligand Folded gastrulation (Fog) and its G protein-coupled receptor (GPCR) at the cell membrane, which leads …

Investigations Of Emerging Zoonotic And Vector-Borne Viruses At The Juncture Of Environmental, Human, And Animal Health, Erik A. Turner

LSU Doctoral Dissertations

Reemerging and emerging zoonotic viruses are some of the most important public and One Health threats facing the world. Understanding the transmission dynamics of these viruses is vital to reducing the disease burden, and one of the key aspects to these transmission systems is the environmental vertex of the One Health triangle. SARS-CoV-2 has only recently emerged as a global public health threat, and within 4 years, over 700 million cases have been reported. As a novel pathogen, many aspects of transmission, including environmental fomite transmission and disinfection, were initially a glaring gap in knowledge. Additionally, while chikungunya virus (CHIKV) …

Mirna As Systemic Mediators For Environmentally Persistent Free Radical-Induced Cardiovascular Dysfunction, Ankit Aryal

LSU Doctoral Dissertations

Air pollution is consistently linked with elevations in cardiovascular disease (CVD) and its mortality. Particulate matter (PM) is a pivotal factor in air pollution-associated CVD. PM containing environmentally persistent free radicals (EPFR) forms from the incomplete combustion of organic wastes. These products adhere to particulate matter carrying redox-active transition metals on its surface. To enable systematic research of the health impacts of EPFR, our colleagues developed a combustion method to produce EPFR-containing PM that closely resemble urban PM and validated their use for typical laboratory settings. We exposed mice to laboratory generated EPFR through whole-body inhalation and investigated their dose-dependent …

Regulatory Mechanisms Of Epithelial Tube Formation During Drosophila Embryogenesis, Vishakha Vishwakarma

LSU Doctoral Dissertations

The formation of three-dimensional tubes by invagination from flat epithelial sheets is a fundamental process in forming organs, such as lungs and kidneys. Defects in tube formation can lead to many diseases, such as spina bifida and pulmonary agenesis. Therefore, determining the mechanisms underlying tube formation is essential to understanding many developmental processes and common human diseases. To investigate the regulatory mechanisms behind the formation of epithelial tubes, the Chung lab uses Drosophila melanogaster as a model system with simple and complex epithelial tubular organs such as the salivary gland (SG) and trachea. My work broadly aims to identify and …

Using Machine Learning To Measure Changes In Immunity Due To Climate Change In The Fall Armyworm, Spodoptera Frugiperda, Nathaniel T. Haulk

LSU Master's Theses

Object detection is a recent development that allows for the detection of multiple objects in photographs. Numerous machine learning algorithms have been developed for object detection. Here we sought to determine which algorithm performed best when relating to an organism's health and immunological response. The fall armyworm (Spodoptera frugiperda) is a major agricultural pest causing millions of dollars in damage to farmlands across the globe. With their recent spread into Africa and Asia, the need for understanding how best to control population outbreaks via biocontrol has increased. While viruses are a major biocontrol agent for controlling insect pests, we …

Containerized Satsuma Mandarin Production Under Protective Screens As A Management Strategy, Anna Timmerman

LSU Master's Theses

Many of the world’s citrus growing regions are experiencing challenges related to citrus greening, also known as Huanglongbing (HLB) caused by the presumed bacterial agent Candidatus Liberibacter spp. HLB is vectored by the Asian citrus psyllid (Diaphorina citri) and through propagation of infected citrus material. HLB impacts tree health as well as fruit development, ripening, and quality of the resulting citrus fruit, often leading to an unmarketable product. Producers are growing citrus in high density orchards underneath protective screening material that excludes the Asian citrus psyllid, preventing new HLB infections. Four ultra-high containerized tree spacings of 2 feet …

Impact Of Area-Wide And Localized Mosquito Adulticide On Insecticide Susceptibility In Populations Of Culex Quinquefasciatus (Diptera: Culicidae) In New Orleans, Louisiana., Erin Rita Cloherty

LSU Doctoral Dissertations

Abstract

Mosquitoes are a public nuisance and can vector pathogen causing diseases that affect both animal and human health. West Nile virus, vectored by Culex quinquefasciatus, the Southern House mosquito, made its entry into Louisiana early in the 21^st century, causing serious morbidity and mortality. Effective use of insecticides can be useful to combat these mosquitoes and reduce transmission of disease, however use of insecticides can lead to insecticide resistance.

The objectives of this study were to: (1) to screen adult Cx. quinquefasciatus throughout Orleans Parish, Louisiana for insecticide resistance and explore target-site and metabolic mechanisms of resistance, (2) …