Biology Commons^™

Regulation Of Yolk Microtubule Dynamics By Dachsous Cadherins, Gina Danielle Castelvecchi

Arts & Sciences Graduate Student Theses and Dissertations

The process of epiboly, or the thinning and spreading of a tissue, is a well-conserved morphogenetic process. As one of four conserved gastrulation cell movements, epiboly is important to help organize the overall body plan. Epiboly in zebrafish involves the thinning and spreading of the blastoderm originating from the animal pole to completely enclose the yolk. It is driven by a multitude of physical processes that involve the three cell types comprising the embryo: the yolk syncytial layer (YSL), enveloping layer (EVL), and deep cells. These physical aspects can be broadly described as involving cell-cell interactions through adhesion proteins, actomyosin …

Genomic Analysis Of Diverse Bacterial Pathogens, Robert Potter

Arts & Sciences Graduate Student Theses and Dissertations

Bacterial pathogens have been a historical scourge for the entirety of human existence but have been significantly thwarted since the 20th century due to the development of antibiotics. However, owing to the large selection pressure of antibiotics on bacterial populations, phenotypic antibiotic resistance from the development of vertically transmitted mutations and horizontally acquired antibiotic resistance genes (ARGs) is increasing. The sum has produced multidrug resistant organisms (MDROs) which have extremely limited treatment options. Epidemiological studies have determined that carbapenem resistant Enterobacteriaceae (CRE), Acinetobacter baumannii, and vancomycin resistant Enterococcus (VRE) are some of the most problematic MDRO infections. The advent of …

Genetic And Functional Characterization Of Novel Host Factors Regulating Virus Infection In Caenorhabditis Elegans, Luis Enrique Sandoval

Arts & Sciences Graduate Student Theses and Dissertations

Viruses infect the majority of eukaryotic life on the planet and remain a global threat to human health. These pathogens are constrained to intracellular life cycles, as they exploit and rely on host factors and machinery throughout their entire reproduction process. While many of these viral life cycle factors have been reported and studied, our knowledge in the identity and function of these factors remains incomplete and a challenge in fundamental virology and the development of antiviral therapeutics. Caenorhabditis elegans offers an innovative approach for discovering novel host factors required for virus infection in a multicellular and simple model organism. …

Pathophysiology And Proteogenomics Of Post-Infectious And Post-Hemorrhagic Hydrocephalus In Infants, Albert M. Isaacs

Arts & Sciences Graduate Student Theses and Dissertations

Post-infectious (PIH) and post-hemorrhagic (PHH) hydrocephalus occur as sequalae of neonatal sepsis or intraventricular hemorrhage (IVH) of prematurity, respectively. Together, PIH and PHH represent the most common form of infantile hydrocephalus, the most common indication for neurosurgery in children globally, and the leading cause of neurological morbidity and mortality worldwide. The lack of understanding of the pathophysiology of PIH and PHH, particularly with regards to the host central nervous system response to the antecedent infection and hemorrhage, perturbation of differentiating neural stems in the ventricular (VZ) and subventricular (SVZ) zones, and damage to periventricular white matter (PVWM) tracts carrying sensorimotor …

Mechanisms Of Cross-Presentation By Cdc1s, Derek James Theisen

Arts & Sciences Graduate Student Theses and Dissertations

Classical dendritic cells (cDCs) are specialized antigen presenting cells that can be divided into distinct subsets based on the types of pathogens they respond to and the type of immune response they generate. The cDC1 subset is specialized in priming CD8 T cell responses through the process of cross-presentation. During cross-presentation, exogenous protein antigens are taken up by cDC1 and presented on MHCI molecules, allowing for the priming of CD8 T cells during conditions when DCs themselves are not directly infected. The ability to cross-present in vivo is unique to cDC1, and is essential for anti-viral responses and rejection of …

Engineering Natural Competence Into The Fast-Growing Cyanobacterium Synechococcus Elongatus Utex 2973, Kristen Elizabeth Wendt

Arts & Sciences Graduate Student Theses and Dissertations

Synechococcus elongatus UTEX 2973 is the fastest growing cyanobacterium discovered to date. Using water, carbon dioxide, and light alone, this organism can double in 1.5 hours under optimal conditions. The accelerated doubling exhibited by Synechococcus 2973 makes it a prime candidate to serve as a model photoautotrophic system. However, Synechococcus 2973 lacks one highly desirable feature: it cannot undergo natural transformation. This thesis seeks to engineer this capacity into this fast-growing system in order to create an organism that is both fast growing and naturally competent. Synechococcus 2973 is a unique platform because it is >99% genetically identical to another …

Bumpy Road Ahead: Overcoming Dna Replication Obstacles One Barrier At A Time, Melanie Anne Sparks

Arts & Sciences Graduate Student Theses and Dissertations

DNA replication must occur efficiently and timely every cell cycle to protect the integrity of the genome. Stalled or slowed replication forks lead to replication stress that can cause replication fork collapse, and potentially genome instability. Scattered throughout the genome are tightly bound proteins, such as transcription factors, that are necessary for cell function and survival. These proteins have the potential to impede timely DNA replication. Furthermore, genomic DNA is packaged around histone octamers into structures called nucleosomes that both compact the DNA and provide an additional layer of information and regulation termed epigenetics. Thus, DNA replication is not only …

Delineating The Role Of Mir-124 For The Activation Of Neuronal Program, Ya-Lin Lu

Arts & Sciences Graduate Student Theses and Dissertations

The ectopic expression of two brain-enriched microRNAs (miRNAs), miR-9/9* and miR-124 (miR-9/9*-124), can robustly and efficiently reprogram human skin fibroblasts into neurons. The miRNAs act as repressors of non-neuronal genes in fibroblasts for the induction of the neuronal program. This process is analogous to neurogenesis in vivo when the expression of miR-9/9* and miR-124 represses anti-neurogenic genes such as REST or NRSF (neuron-restrictive silencer factor/repressor element-1 silencing transcription factor). Although we have some mechanistic insights into how miR-9/9*-124 drives fate conversion by acting as negative regulators of gene expression, little remained understood of the role of miRNAs as positive regulators …

A Test Of The Sexually Selected Egg Color Hypothesis In Eastern Bluebirds (Sialia Sialis), Annabelle Mckie-Voerste

Student Theses and Dissertations

The broad array of colors represented in avian eggshells has promoted extensive investigations into its evolutionary significance. Although many hypotheses exist that explain conspicuous egg colors, including egg recognition against brood parasitism, protection from UV rays, and thermoregulation, they fail to adequately explain the adaptive function of vivid blue eggs. The Sexually Selected Egg Color Hypothesis (SSECH) states that blue-green eggshell coloration is a post-mating, sexually selected signal that conveys female quality, and male birds that observe more pigmented eggs would increase their care accordingly, resulting in higher quality chicks. Using a population of eastern bluebirds (Sialia sialis) in northeast …

Exploring The Effects Of Geographic And Landscape Variation On Avian Communities And Species, Joseph Youtz

Student Theses and Dissertations

Ongoing and intensive anthropogenic change has modified the globe across multiple scales, yet the influence of these modifications on wildlife communities and individuals remain region and species specific. Here I explored the influence of a biogeographical pattern as it relates to climate and geography, and the effects of historic habitat loss and fragmentation on a diverse avian community. I first explored the adherence to Bergmann’s rule within a migratory songbird, the Prothonotary Warbler (Protonotaria citrea), across all life stages and time. The pattern was present from the young nestling stage through adulthood, although contemporary eggs followed a reverse relationship with …

Antioxidant Characterization Of Peanut Hairy Root Extracts Enriched With Prenylated Stilbenoids, Patrick Roberto

Student Theses and Dissertations

Peanut (Arachis hypogaea) is a prolific producer of prenylated stilbenoids that may confer health benefits in humans by their antioxidant activity. Therefore, the objective of this study was to use peanut hairy roots as a bioproduction system of extracts enriched with prenylated stilbenoids and evaluate their antioxidant activity in vitro. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay suggested that the whole extract and pure prenylated stilbenoids exhibit antioxidant activity. High-performance liquid chromatography combined with DPPH identified arachidin-1, arachidin-3, and arachidin-5 as the principle antioxidants in the extract. The DPPH assay revealed that the arachidin portion of the extract contains greater antioxidant capacity than …

Drosophila Model To Study Muscle Atrophy, Aaron Aghai

Master of Science in Integrative Biology Theses

Muscle atrophy (MA) is a phenomenon of muscle mass loss due to accelerated protein degradation in muscle fibers. Some pathological conditions, such as chronic inflammation or cancer, induce accelerated MA, which complicates medical treatment, hampers recovery of fragile patients, and ultimately can be the cause of a patient’s death. To gain better control over MA, more information is required about the whole spectrum of genetic factors that can influence MA.

Drosophila provides an excellent platform for genetic screening, although it has somewhat limited utility for MA research since insect muscles lack the level of plasticity found in mammalian muscles. We …

Cerulean Warbler Habitat Selection, Breeding Biology, Survival, And Space Use In The Ozark Region, Jacob Louis Wessels

Student Theses and Dissertations

For many declining migratory birds, gaps in information on their ecology can impede conservation efforts. Cerulean Warblers (Setophaga cerulea; hereinafter ceruleans) are one such rapidly declining species and have regional ecological variation, so more comprehensive information may benefit their effective conservation. We studied ceruleans in the Ozark region of Arkansas to increase the scientific knowledge of this species in an understudied region that likely supports a ‘natural population’ of ceruleans. We assessed habitat selection, breeding biology, survival, and space use of ceruleans. Consistent with other regions, ceruleans at our study sites selected areas with large trees across spatial scales. Males …

Testing The Combined Module Swapping And Repair By Modification Strategies: A Step Toward Universal Toolbox, Catherine A. Martini

Biology Theses

The crux of synthetic biology is the engineering of biological components to modulate the activity of specific DNA-based promoter(s) to drive gene expression; thus, providing a means to modulate pathways between signal detection and cellular response. However, the longstanding frustration of synthetic biologists has been the inability to transfer those engineered components between cellular systems — this lack of “modular universality” or “universal toolbox” impedes research by forcing a metaphorical reinvention of the wheel in new systems. The modular swapping strategy expanded the available “toolbox” with customizable hybrid repressors formed from “swapping” the DNA-recognition modules (DRMs) and environmental-sensing modules (ESMs) …

Comparative Genomic Study Of Lactobacillus Jensenii And The Newly Defined Lactobacillus Mulieris Species Identifies Species-Specific Functionality, Catherine Putonti, Jason W. Shapiro, Adriana Ene, Oleksandra Tsibere, Alan J. Wolfe

Bioinformatics Faculty Publications

Lactobacilli are dominant members of the “healthy” female urogenital microbiota. One of these species, Lactobacillus jensenii, is routinely identified in the urinary microbiota of women both with and without urinary tract symptoms. In March 2020, the new bacterial species Lactobacillus mulieris was introduced, and phylogenetic and average nucleotide identity analysis identified eight L. jensenii strains that should be classified as members of the L. mulieris species. This prompted our phylogenomic study of all publicly available L. jensenii and L. mulieris genome sequences. While there is little variation in the 16S rRNA gene sequences, the core genome shows a clear distinction …

Battle Of The Buttercups: Investigating Hybrid Zone Dynamics In A Ranunculus Species Complex, Jessica Persinger

Dissertations and Theses

Plants pose a well-known challenge to the biological species concept because hybridization is a common occurrence. Range dynamics have a crucial role in determining whether species are given the opportunity to interbreed or not. Successful hybridization can be of particular concern when considering range-limited species and their persistence. In my thesis research, I examine the apparent hybrid zone between the southern Oregon endemic Ranunculus austro-oreganus, a candidate threatened species due to its limited range, and its widespread congener, Ranunculus occidentalis, whose range spans from California to Alaska. The discovered contact zone was recognized in populations which contained apparent …

Enhanced Hyaluronan Signaling And Autophagy Dysfunction By Vps35 D620n, Abir A. Rahman, Alejandro Soto-Avellaneda, Iva Stojkovska, Nathan K. Lai, Joshua E. Albright, Abby R. Webb, Emily Oe, Jacob P. Valarde, Alexandra E. Oxford, Paige E. Urquhart, Brandon Wager, Connor Brown, Isabella Amado, Peyton Vasquez, Nicholas Lehning, Xinzhu Pu, Brad E. Morrison

Biology Faculty Publications and Presentations

The motor features of Parkinson’s disease (PD) result from the loss of dopaminergic (DA) neurons in the substantia nigra with autophagy dysfunction being closely linked to this disease. A PD-causing familial mutation in VPS35 (D620N) has been reported to inhibit autophagy. In order to identify signaling pathways responsible for this autophagy defect, we performed an unbiased screen using RNA sequencing (RNA-Seq) of wild-type or VPS35 D620N-expressing retinoic acid-differentiated SH-SY5Y cells. We report that VPS35 D620N-expressing cells exhibit transcriptome changes indicative of alterations in extracellular matrix (ECM)-receptor interaction as well as PI3K-AKT signaling, a pathway known to regulate autophagy. Hyaluronan (HA) …

Metabolomics Analysis Of Annual Killifish (Austrofundulus Limnaeus) Embryos During Aerial Dehydration Stress, Daniel Zajic, Jason Podrabsky

Biology Faculty Publications and Presentations

The annual killifish, Austrofundulus limnaeus, survives in ephemeral ponds in the coastal deserts of Venezuela. Persistence through the dry season is dependent on drought-resistant eggs embedded in the pond sediments during the rainy season. The ability of these embryos to enter drastic metabolic dormancy (diapause) during normal development enables A. limnaeus to survive conditions lethal to most other aquatic vertebrates; critical to the survival of the species is the ability of embryos to survive months and perhaps years without access to liquid water. Little is known about the molecular mechanisms that aid in survival of the dry season. This study …

No Water, No Problem: Stage-Specific Metabolic Responses To Dehydration Stress In Annual Killifish Embryos, Daniel E. Zajic, Jonathon P. Nicholson, Jason Podrabsky

Biology Faculty Publications and Presentations

Annual killifish survive in temporary ponds by producing drought-tolerant embryos that can enter metabolic dormancy (diapause). Survival of dehydration stress is achieved through severe reduction of evaporative water loss. We assessed dehydration stress tolerance in diapausing and developing embryos. We measured oxygen consumption rates under aquatic and aerial conditions to test the hypothesis that there is a trade-off between water retention and oxygen permeability. Diapausing embryos survive dehydrating conditions for over 1.5 years, and post-diapause stages can survive over 100 days. Diapausing embryos respond to dehydration stress by increasing oxygen consumption rates while post-diapause embryos exhibit the same or reduced …

Preliminary Evidence Of The Role Of Medial Prefrontal Cortex In Self-Enhancement: A Transcranial Magnetic Stimulation Study, Birgitta Taylor-Lillquist, Vivek Kanpa, Maya Crawford, Mehdi El Filali, Julia Oakes, Alex Jonasz, Amanda Disney, Julian Keenan

Department of Biology Faculty Scholarship and Creative Works

Humans employ a number of strategies to improve their position in their given social hierarchy. Overclaiming involves presenting oneself as having more knowledge than one actually possesses, and it is typically invoked to increase one’s social standing. If increased expectations to possess knowledge is a perceived social pressure, such expectations should increase bouts of overclaiming. As the medial prefrontal cortex (MPFC) is sensitive to social pressure and disruption of the MPFC leads to decreases in overclaiming, we predicted that transcranial magnetic stimulation (TMS) applied to the MPFC would reduce overclaiming and the effects would be enhanced in the presence of …

Evaluating The Biological Effects And Safety Of Exposure To Low, Putatively Safe Concentrations Of The Common Pesticide Chlorpyrifos Using An Anuran Model, Sara Mcclelland

Electronic Theses and Dissertations

In the US, over 1.1 billion pounds of pesticides are applied annually. Unfortunately, pesticides contaminate natural habitats affecting animal health. Chlorpyrifos (CPF) is an organophosphorous insecticide that contaminates surface waters. Few studies have assessed the impacts of CPF at low, ecologically realistic doses. I aimed to test the effects of low dose CPF exposures on biological parameters including body morphology, hormone levels, and brain development in Northern Leopard Frogs (Lithobates pipiens), a common vertebrate model. To determine if CPF exposure has direct impacts or indirectly impacts animals through the disruption of the food web, I examined CPF exposure …

Complex Tissue Regeneration In Mammals Is Associated With Reduced Inflammatory Cytokines And An Influx Of T Cells, Thomas R. Gawriluk, Jennifer Simkin, Corin K. Hacker, John M. Kimani, Stephen G. Kiama, Vanessa O. Ezenwa, Ashley W. Seifert

Biology Faculty Publications

While mammals tend to repair injuries, other adult vertebrates like salamanders and fish regenerate damaged tissue. One prominent hypothesis offered to explain an inability to regenerate complex tissue in mammals is a bias during healing toward strong adaptive immunity and inflammatory responses. Here we directly test this hypothesis by characterizing part of the immune response during regeneration in spiny mice (Acomys cahirinus and Acomys percivali) vs. fibrotic repair in Mus musculus. By directly quantifying cytokines during tissue healing, we found that fibrotic repair was associated with a greater release of pro-inflammatory cytokines (i.e., IL-6, CCL2, and CXCL1) …

Use Of Multibeam And Split-Beam Sonar To Observe Changes In Fish School Biomass In Relation To Dolphin Abundance, Reece Eleanor Aponte

Electronic Theses and Dissertations

No abstract provided.

Structure And Evolution Of Lizard Immunity Genes, Trent Santonastaso

LSU New Orleans Theses and Dissertations

One of the most important gene families to play a role in adaptive immunity is the major histocompatibility complex (MHC). MHC class II loci are considered to be the most variable loci in the vertebrate genome, and studies have shown that this variability can be maintained through complex co-evolutionary dynamics between host and parasite. Despite the rich body of research into the MHC, there is comparatively little understanding of its genomic architecture in reptiles. Similarly, loci associated with innate immunity have received little attention in reptiles compared to other vertebrates. In the first chapter, we investigated the structure and organization …

Assessing Seasonal Changes In Body Condition For Spotted (Phoca Largha), Ringed (Pusa Hispida), And Bearded (Erignathus Barbatus) Seals, Michelle Hartwick

Master's Theses

Anthropogenic global warming is causing unprecedented changes to occur within Arctic ecosystems. As sea ice continues to decline in both thickness and extent, ice-adapted species will be particularly affected. Specifically, Arctic seals are reliant on sea ice during critical life-history stages and many of their preferred prey depend on reliable patterns in annual sea ice cover. Thus, ongoing changes will likely affect the ability of Arctic seals to carry out key life-history tasks and maintain positive energy balance. One way to assess energy reserves is through examination of body condition. For seals, this is often done by measuring overall blubber …

Hind Wing Eyespots Of Brassolini Butterflies (Lepidoptera, Nymphalidae): Evolutionary Diversification And Functions In Anti-Predator Defense And Mating Behavior, Logan Crees

LSU New Orleans Theses and Dissertations

Ventral hind wing eyespots are prominent pattern elements in Brassolini butterflies, likely functioning in predator-prey interactions and reproductive activities. Caligo and Opsiphanes differ in male mate-seeking behaviors and it has been suggested that Caligo females use the male cua1 eyespot as a mate-locating cue, but Opsiphanes females do not seem to do so. We predict Caligo males should have larger eyespots than congeneric females, but the sexes would not differ in eyespot size in Opsiphanes. Our analyses supported both these predictions. Displacing the eyespot to the center of the wing makes eyespots more conspicuous, we asked if eyespot position …

Functional Morphology Of Gliding Flight I. Modeling Reveals Distinct Performance Landscapes Based On Soaring Strategies, Lindsay D. Waldrop, Yanyan He, Tyson L. Hedrick, Jonathan Rader

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The physics of flight influences the morphology of bird wings through natural selection on flight performance. The connection between wing morphology and performance is unclear due to the complex relationships between various parameters of flight. In order to better understand this connection, we present a holistic analysis of gliding flight that preserves complex relationships between parameters. We use a computational model of gliding flight, along with analysis by uncertainty quantification, to 1) create performance landscapes of gliding based on output metrics (maximum lift-to-drag ratio, minimum gliding angle, minimum sinking speed, lift coefficient at minimum sinking speed); and 2) predict what …

The Effect Of Bacterial Endotoxin Lps On Serotonergic Modulation Of Glutamatergic Synaptic Transmission, Jate Bernard, Abigail Greenhalgh, Oscar Istas, Nicole T. Marguerite, Robin L. Cooper

Biology Faculty Publications

The release of the endotoxin lipopolysaccharides (LPS) from gram-negative bacteria is key in the induction of the downstream cytokine release from cells targeting cells throughout the body. However, LPS itself has direct effects on cellular activity and can alter synaptic transmission. Animals experiencing septicemia are generally in a critical state and are often treated with various pharmacological agents. Since antidepressants related to the serotonergic system have been shown to have a positive outcome for septicemic conditions impacting the central nervous system, the actions of serotonin (5-HT) on neurons also exposed to LPS were investigated. At the model glutamatergic synapse of …

Plasticity Ensures Robust Cell Wall Metabolism In Escherichia Coli, Elizabeth A. Mueller

Arts & Sciences Graduate Student Theses and Dissertations

Single-celled organisms must adapt their physiology to persist and propagate across a wide range of environmental conditions. The growth and division of bacterial cells depends on continuous synthesis of an essential extracellular barrier: the peptidoglycan cell wall, a polysaccharide matrix that counteracts turgor pressure and confers cell shape. This dissertation identifies mechanisms that ensure robust peptidoglycan integrity and metabolism in Escherichia coli across growth environments and examines how these adaptations impact cell growth, division, morphogenesis, and antimicrobial resistance. The majority of enzymes involved in synthetizing and remodeling the peptidoglycan cell wall appear functionally redundant. In this dissertation (Chapters 2 and …

Heterotrophic Carbon Fixation In A Salamander-Alga Symbiosis, John A. Burns, Ryan Kerney, Solange Duhamel

Biology Faculty Publications

The unique symbiosis between a vertebrate salamander, Ambystoma maculatum, and unicellular green alga, Oophila amblystomatis, involves multiple modes of interaction. These include an ectosymbiotic interaction where the alga colonizes the egg capsule, and an intracellular interaction where the alga enters tissues and cells of the salamander. One common interaction in mutualist photosymbioses is the transfer of photosynthate from the algal symbiont to the host animal. In the A. maculatum–O. amblystomatis interaction, there is conflicting evidence regarding whether the algae in the egg capsule transfer chemical energy captured during photosynthesis to the developing salamander embryo. In experiments …