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Characterizing Host-Pathogen Interactions Between Zostera Marina And Labyrinthula Zosterae, Yaamini R. Venkataraman, Amanda Shore, Sukanya Dayal, James Sanghyun Lee, Mahsa Alidoost Salimi, Grace Crandall, Malina M. Loeher, Mark Stoops, Megan Swanger, Morgan E. Eisenlord, Kathryn L. Van Alstyne, Mark D. Fast, Colleen A. Burge, Maya L. Groner

Biology

Introduction: Seagrass meadows serve as an integral component of coastal ecosystems but are declining rapidly due to numerous anthropogenic stressors including climate change. Eelgrass wasting disease, caused by opportunistic Labyrinthula spp., is an increasing concern with rising seawater temperature. To better understand the host-pathogen interaction, we paired whole organism physiological assays with dual transcriptomic analysis of the infected host and parasite.

Methods:: Eelgrass (Zostera marina) shoots were placed in one of two temperature treatments, 11° C or 18° C, acclimated for 10 days, and exposed to a waterborne inoculation containing infectious Labyrinthula zosterae (Lz) or sterile seawater. At two- and …

The Role Of Phenylacetic Acid (Paa) Catabolism In Acinetobacter Physiology, Anna Josephine Hooppaw

Arts & Sciences Graduate Student Theses and Dissertations

Microorganisms are constantly challenged by stressful environments and have evolved mechanisms to adapt to or counteract these threats. The Gram-negative pathogen Acinetobacter baumannii is thought to rely on a “persist and resist” strategy that facilitates its remarkable ability to survive in a variety of harsh conditions, giving it the capacity to cause life-threatening infections. Currently, over 60% of the global A. baumannii clinical isolates are multidrug resistant (MDR), leading the World Health Organization and the Centers for Disease Control and Prevention to categorize this pathogen as a top priority for the research and development of new antimicrobial therapies. Understanding the …

Distinct Roles For Ltα3 And Ltα1Β2 Produced By B Cells Contribute To Their Multi-Faceted Impact On Ileitis, Emma Claire Erlich

Arts & Sciences Graduate Student Theses and Dissertations

Crohn’s disease, one of the most common forms of inflammatory bowel disease, is marked by local intestinal inflammation. However, pathology in CD patients is not strictly limited to the gastrointestinal system, and almost 50% of CD patients exhibit extraintestinal manifestations of disease. Many, though not all, of these systemic pathologies are linked to intestinal inflammation and, thus, resolution of local gastrointestinal disease also ameliorates systemic disease. How the connection between local and systemic inflammation is mediated is not well understand, nor is why only some patients exhibit these extraintestinal manifestations of disease. Blocking dissemination of inflammatory signals generated in the …

The Interaction Between Predation And Sound Pollution On The Internal And External Microbiome Of The Grasshoppers Melanopus Sanguinipes, Alanna Bond

Theses and Dissertations

Anthropogenic activities such as construction and agriculture directly affect its surrounding environments. Many studies have focused on how megafauna and flora are impacted by human activities, however, relatively little is known how new occupation of land affects smaller organisms such as insects and microbes. Additionally, other stressors such as predation can impact host physiology. The grasshopper species Melanopussanguinipes was chosen to be used in a study to measure how stress caused by artificial sound and predation can alter exoskeleton and gut microbiomes once exposed to these stressors.

Nanoscale Modeling Of Membrane Systems Under Mechanical Deformation In Traumatic Brain Injury Using Molecular Dynamics, Anh Thi Ngoc Vo

Theses and Dissertations

Neuronal membrane disruption and mechanoporation are nanoscale damage mechanisms that critically affect brain cell viability during traumatic brain injury (TBI). These nanoscale cellular impairments are elusive in experiments and necessitate in silico approaches such as molecular dynamics (MD) simulations. Implementing MD, this research aims to investigate the effects of different key factors related to membrane deformation and damage, including force field resolutions, lipid compositions, and loading conditions.

To examine the impact of force field resolution, MD deformation simulations were conducted on 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) lipid bilayer membranes, using all-atom (AA), united-atom (UA), and coarse-grained Martini (CG-M) force fields. The mechanical responses …

Roles Of Type I Interferon Signaling In Drug Resistant Mycobacterium Tuberculosis Infection, Suhas Bobba

Arts & Sciences Graduate Student Theses and Dissertations

Tuberculosis (TB) is a global health threat, with 10 million people developing active TB disease and a million deaths attributed to TB annually. Emergence of drug resistance in Mycobacterium tuberculosis (Mtb), the causative agent of TB, has led to half a million cases of drug resistant (DR) TB annually. Further, clinical reports suggest dysregulation and suppression of immune responses in DR TB patients as compared with DS TB patients. However, we do not understand how acquisition of drug resistance-conferring mutations can drive broad and systemic differences in immune responses of DR TB patients. We found that rpoB-H445Y a specific DR …

Analyzing Pseudomonas Aeruginosa With Bacteriophage Tags Using Photoacoustic Flow Cytometry, Jennifer C. Schinke

Electronic Theses and Dissertations

The number of daily bacterial infections is climbing and the CDC explains that this is due to the antibiotic-resistant threat in the United States. Finding a faster way of bacterial identification is necessary as it currently takes 1-4 days for a medical lab to culture and identify bacteria. Photoacoustic flow cytometry (PAFC) can be used as an alternative method resulting in swift identification within an hour (Edgar, 2019). Pseudomonas aeruginosa, cell line PA01, will be coated in up to a few hundred red dyed phages making it detectible by the photoacoustic flow cytometry system. Bacteriophages (phages) are viruses that …

Molecular Detection And Characterization Of Rickettsia Sp. In Hard Ticks Collected In Nacogdoches, Texas, Haley Nicole Standifird

Electronic Theses and Dissertations

The number of cases of tick-borne diseases is increasing in the United States. Many efforts to control ticks have been made and are continuously being developed. These methods include surveillance of ticks and detection of the tick-borne pathogens.This study examined hard ticks in Nacogdoches, Texas, to test for the presence of Rickettsia sp. 47 ticks were collected from vegetation by flagging and their species, sex, and developmental stage were determined using available keys. Individual ticks were processed for nucleic acid extraction and molecular detection of Rickettsia sp. using PCR-based methods. The citrate cynthease gene, 17kDa gene, and outer membrane protein …

Glycerophosphocholine Is Used For Lipid And Phosphate Metabolism By Candida Albicans, Will King

Electronic Theses and Dissertations

The metabolism of phosphatidylcholine (PC), a major eukaryotic membrane lipid, has been shown to be an important aspect of pathogenesis in Candida albicans. Of note, PC turnover product, glycerophosphocholine (GPC), is abundant renal metabolite available within the host. GPC is readily imported by C. albicans, and deletion of the major GPC transporter, Git3, leads to decreased virulence in a bloodstream infection model. Here I have characterized two potential metabolic fates of internalized GPC. The first metabolic fate explored is internalized GPC can be hydrolyzed to release P_i. To determine if GPC import and subsequent metabolism impact phosphate …

Mechanisms Of Immunopathology And Protection In Genital Herpes Simplex Virus 2 Infection, Ying Shiang Lim

Arts & Sciences Graduate Student Theses and Dissertations

Genital Herpes Simplex Virus-2 (HSV-2) infections is a highly prevalent and incurable sexually transmitted disease. Upon infection at the primary genital mucosa, HSV-2 localizes to the sensory ganglia to establish chronic latency. Symptomatic and asymptomatic recurrences can then occur episodically to promote viral transmissions. Painful genital and peri-genital lesions can be formed, increasing the risk for secondary HIV-1 acquisition by three times. Despite being a serious public health risk with severe physiological and psycho-sociological impacts, there are currently no cures or FDA-approved vaccines for this chronic infection. Thus, it is imperative to understand how the immune system interacts with HSV-2 …

Two Structurally Defined Aβ Polymorphs Promote Different Pathological Changes In Susceptible Mice, Ruben Gomez-Gutierrez, Ujjayini Ghosh, Wai-Ming Yau, Nazaret Gamez, Katherine Do, Carlos Kramm, Hamid Shirani, Laura Vegas-Gomez, Jonathan Schulz, Ines Moreno-Gonzalez, Antonia Gutierrez, K Peter R Nilsson, Robert Tycko, Claudio Soto, Rodrigo Morales

Faculty, Staff and Student Publications

Misfolded Aβ is involved in the progression of Alzheimer's disease (AD). However, the role of its polymorphic variants or conformational strains in AD pathogenesis is not fully understood. Here, we study the seeding properties of two structurally defined synthetic misfolded Aβ strains (termed 2F and 3F) using in vitro and in vivo assays. We show that 2F and 3F strains differ in their biochemical properties, including resistance to proteolysis, binding to strain-specific dyes, and in vitro seeding. Injection of these strains into a transgenic mouse model produces different pathological features, namely different rates of aggregation, formation of different plaque types, …

Insects Are Attracted To White Wind Turbine Bases: Evidence From Turbine Mimics, Madison S. Crawford, Delina E. Dority, Michael E. Dillon, Lusha M. Tronstad

Western North American Naturalist

Wind power is one of the fastest growing forms of renewable energy, but the interactions between wind turbines and insects are largely unknown beyond the observation that the accumulation of dead insects on turbine blades drastically reduces the power produced. Insects may be attracted to wind energy facilities because of topography, the heat that turbines produce, the lighting, or the visual cue of the turbine itself. Turbines can present a striking visual contrast relative to the surrounding landscape, particularly when they are painted bright white and reflect ultraviolet wavelengths. To test the hypothesis that wind turbine color attracts insects, we …

The Impact Of Soil Disturbance On Soil Bacterial Community Composition, Marie A. Rodriguez, Mark Peach, Timothy D. Trott

Research in Biology

Soil bacterial communities are an important part of terrestrial ecosystems due to their roles in biogeochemical cycling processes. Consequently, understanding how soil disturbance affects the soil bacterial diversity is vital to understanding the entire ecosystem. In this study we examined the effects of soil disturbance (by mining) on the soil bacterial community composition from three sites on Bauxite Ridge in Southeast Tennessee compared to three undisturbed sites in a nearby location. The soil bacterial community was analyzed by 16S rDNA amplicon sequencing of total DNA extracted from the soil samples collected from each of the six sites. Characterization of the …

Examining The Different Soil Horizons Of White Oak Mountain, Tn And Their Effect On The Soil Microbial Community, Ji Won Moon, Timothy D. Trott

Research in Biology

Soil microorganisms participate in the diverse interaction within virtually all ecosystems, consequently affecting the associated human and animal population. Identifying how edaphic variables alter the functional and taxonomic diversity of the soil microbial community requires an examination of total microbial soil diversity and abundance. This research study examined the effect of soil depth and horizon on the soil microbial community composition of White Oak Mountain. The soil microbial community was characterized by 16S/18S/ITS rDNA amplicon sequencing of the DNA extract of six samples from the three major soil types identified: HcE, MoE, and uMvC. OTU clustering analysis and both alpha …

Microglial Response To Glucocorticoids During Chronic Sleep Fragmentation, Christian Chelson

Masters Theses & Specialist Projects

Sleep is one of the body’s greatest and most basic needs. Chronic sleep loss (<6 hours a day) is linked to many cardiovascular issues, diabetes, and inflammatory conditions and has been shown to lower life expectancy. Obstructive sleep apnea (OSA) is a complication that causes sleep fragmentation in >8% of adults from developed countries, and many with OSA may be unaware of their condition. Having long-term OSA is linked to neuroinflammation caused by activated microglia in the brain, but the mechanics of this inflammation are not well understood. It is known that glucocorticoids, steroid hormones produced and released from the adrenal glands, have a suppressive effect on microglia. The purpose of this study is to explore the role that glucocorticoids have upon microglia activation induced by chronic sleep fragmentation (SF). C57BL/6J mice were …

Behavioral Response To Conspecific Sounds In Loricariid Catfishes (Pterygoplichtys Pardalis And Otocinclus Vittatus), Hephzibah Obafunmiso

Masters Theses & Specialist Projects

Sound production is a means of communication among many fish species. In fishes, sound is produced through various mechanisms, but in the family Loricariidae, known as armored suckermouth catfishes, sound is produced primarily through pectoral fin spine stridulation. Previous experiments have described the sounds produced and shown the mechanism of sound production in two species of loricariid catfishes, Pterygoplichthys gibbiceps and Otocinclus affinis, but the functional significance of loricariid sounds is still unknown. To address this question, I examined the behavioral responses of Pterygoplichthys pardalis and Otocinclus vittatus to conspecific calls. Individual fish (N=10 for P. pardalis) or groups …

Assessing The Effect Of Reservoirs On Gene Flow In The Southern Two-Lined Salamander (Eurycea Cirrigera), Anna Favalon

Masters Theses & Specialist Projects

Biodiversity is an essential component of natural environmental dynamics. Unfortunately, diversity is threatened by human activities and relies on conservation efforts. An important aspect of biodiversity conservation lies in protecting population connectivity and gene flow. In the mid-1900s, many Kentucky rivers were dammed, creating deep, lentic reservoirs in the valleys once occupied by dynamic, lotic rivers. For species inhabiting the rivers and associated tributaries, the central reservoirs may reduce connectivity among populations and impose a barrier to gene flow. The connectivity of populations on landscapes altered by the creation of reservoirs can be assessed by merging the principles of landscape …

Mammalian & Avian Community Response To African Elephant (Loxodonta Africana) Habitat Modification In Southeastern Kenya, Dakota Vaccaro

Masters Theses & Specialist Projects

African elephants (Loxodonta africana) play a significant role in the modification of their habitat, foremost by decreasing woody vegetation cover and density and in some parts of Africa high elephant densities damage small sanctuaries and preserves. For wildlife that depend on forested patches, this increased modification could lead to displacement and/or decreases in abundance. If suitable habitat is not available elsewhere, elephants and other wildlife may move closer to humans in search of resources, which can result in increased human-wildlife conflict. Evaluating this impact was one of the goals of the Elephants and Sustainable Agriculture in Kenya (ESAK) …

Polar Body Membrane Breakdown Occurs Independent Of Macroautophagy In C. Elegans, Shruti Kolli

Electronic Theses and Dissertations

Failure to digest cell corpses can lead to lupus-like autoimmune disorders in mammals. To better understand if LC3-associated phagocytosis (LAP) drives cell corpse breakdown in phagolysosomes, we studied the clearance of the C. elegans polar body during embryonic development. ATG16L1 has separable roles in regulating LC3 recruitment during macroautophagy and LAP. We demonstrated that the ATG16L1 C. elegans orthologs, ATG-16.1 and ATG-16.2, function redundantly to promote polar body membrane breakdown. We also discovered that truncating the LAP-specific WD40 domain of ATG-16.2 unexpectedly disrupts autophagy. Furthermore, we confirmed that polar body membrane breakdown occurs independent of macroautophagy. We also showed that …

Molecular Mechanisms That Regulate The Stress Response In A. Baumannii, Feroz Ahmed

Biology Dissertations - Archive

Acinetobacter baumannii is particularly problematic in hospital settings, where infections can occur in a range of tissues. This bacterium can endure extreme stress from various antimicrobial agents, biocides, host immune response etc. Not much is known about how these bacteria react to such high stress. A. baumannii also possesses a unique ability to inactivate lipooligosaccharide (LOS) biosynthesis, which is an essential molecule in most Gram-negative bacteria. LOS is enriched in the outer membrane and is the targeted by the last-resort antibiotic, colistin. LOS-deficient A. baumannii is highly resistant to the list-line antimicrobial. Previously, our lab discovered that a two-component system, …

Biodiversity In The Anthropocene, Understanding The Impacts Of Land-Use Change, And Species Interactions., Alexander H. Murray

Biology Dissertations - Archive

The extent of human influences on the environment and biodiversity has led to naming our current time period the Anthropocene. A primary way in which humans impact biodiversity is through habitat modification. Despite the knowledge that habitat modification is negative for many species, we still don’t understand why some species are able to persist despite habitat modification while others do not. In my first chapter I used a trait-based approach to understand what determines species’ sensitivity to habitat modification. Trait-based approaches from different regions often disagree on the importance of the same traits, and I thought climate and land use …

Determining How Anthropogenic Change Filters Biological Communities And How Species Modify Their Traits In Response To Urbanization, Kristopher Warren Row

Biology Dissertations - Archive

Humans are significantly altering the environment at an alarming pace, leading to a reduction in species diversity. This transformation has created modified habitats where some species struggle to survive, while a few others not only manage to survive but thrive. One of the most drastic forms of habitat modification is urbanization, which is spreading worldwide and contributing to the decline of biodiversity. Urbanization has given rise to urban-tolerant species that differ ecologically from species that avoid urban areas across various niche dimensions. These urban-tolerant species must adapt to changes in food sources, microhabitat conditions, and alterations in physical habitat structures. …

An Investigation Of Freshwater Turtle Ecology Using Stable Isotopes, Jonathan Duran

Biology ETDs

In 2022 I investigated niche partitioning among native and invasive freshwater turtles across three sites in the Middle Rio Grande using bulk stable isotope analysis. I found high degrees of niche partitioning at sites in which Red-eared sliders (Trachemys scripta) have yet to establish. However, at sites in which red-eared sliders are now the most abundant species they overlapped greatly in isotopic niche with all native turtles, in particular the painted turtle (Chrysemys picta). Using these same techniques, I then examined the trophic interactions between red-eared sliders and their acanthocephalan parasites. My results suggest that acanthocephalans …

Thermoregulation In Nocturnal Volant Endotherms Occupying Hot Deserts, William A. Talbot

Biology ETDs

The study of thermoregulation is of growing concern in this era of rapid climate change. Earlier studies such as those pioneered by Scholander and Bartholomew directed focus toward the study of endotherm survival in conditions of cold weather adversity. As techniques evolved in the measurement of parameters quantifying thermoregulation, metabolism and energy allocation, the standardization procedures has increased the comparability of data from diverse taxa. We can now search historical records and current research for explanations to the changes in the distribution, migration, extirpation or survival of animal and plant populations through time. It is increasingly common to observe dramatic …

Resolving The Paradox Of Polyploidy: Underexplored Facets Of Polyploid Plants, Benjamin P. Gerstner

Biology ETDs

Polyploidy, or whole genome duplication, is a common phenomenon in plants, but the establishment and persistence of mixed-ploidy populations remains a paradox. This dissertation explores factors that contribute to the persistence and establishment of mixed-ploidy populations in nature. The first chapter investigates the role of unreduced gametes in neopolyploid establishment and finds that variability in their formation rate can have a significant impact on polyploid establishment and persistence. The second chapter searches for evidence of soil microbes exhibiting ploidy-specificity, a pre-condition for microbe-mediated niche differentiation, a possible stabilizing mechanism contributing to ploidy coexistence. Finally, the third chapter tests for microbe-mediated …

Modeling The Egyptian Goose (Alopochen Aegyptiaca) Invasion; And Future Concerns, Percival Matzinger Marshall

Graduate Theses and Dissertations

In an increasingly interconnected world, the ecological and financial cost of invasive species is expected to continue to climb through the movement of exotic biota. Understanding the driving forces behind how a species invades, what environments promote their establishment, and what impacts they are likely to have on the invaded environment are all critical for management. Waterfowl, order Anseriformes, are one such category of invasive species of concern due to their popularity of accidental introduction, ease of movement, and propensity to affect both terrestrial and aquatic ecosystems. The Egyptian Goose (Alopochen aegyptiaca) is a native to the African continent that …

Cullin 3–Mediated Regulation Of Intracellular Iron Homeostasis Promotes Thymic Invariant Nkt Cell Maturation, Emily L. Yarosz, Ajay Kumar, Jeffrey Singer, Cheong-Hee Chang

Biology Faculty Publications and Presentations

The E3 ubiquitin ligase cullin 3 (Cul3) is critical for invariant NKT (iNKT) cell development, as iNKT cells lacking Cul3 accumulate in the immature developmental stages. However, the mechanisms by which Cul3 mediates iNKT cell development remain unknown. In this study, we investigated the role of Cul3 in both immature and mature thymic iNKT cells using a mouse model with a T cell–specific deletion of Cul3. We found that mature iNKT cells lacking Cul3 proliferated and died more than wild-type cells did. These cells also displayed increased glucose metabolism and autophagy. Interestingly, we found that tight regulation of iron homeostasis …

Cellular Heat Responses Of Desert Mammals Promote Survival In Extreme Conditions, Janessa Montenegro

UNLV Theses, Dissertations, Professional Papers, and Capstones

Increasing temperatures with the potential for heat stress is among the future threats facing many mammals. Cellular mechanisms to maintain homeostasis in the face of heat stress likely differ across species based on naturally tolerated intracellular variability. In some mammals, the homeostatic set point in cells has a narrow range. Other species tolerate more varied intracellular conditions, including in temperature. Heat stress responses of cultured dermal fibroblasts from several mammals were compared to detect cell proliferation and cellular death (chapter 2). Cells from heat- tolerant species (13-lined ground squirrel, dromedary camel, round-tailed ground squirrel, and white-tailed antelope squirrel) were compared …

Visual Circuitry In Adaptive Behavior: Extraction Of Complex Visual Image Information By Arrays Of Non-Image Forming Eyes, Thomas Kipp Halladay Groves

Dissertations

A complete understanding of how neural circuitry underlies the detection and integration of visual cues continues to elude researchers in the 21st century. Since the dawn of life on earth, light has exerted enormous selective pressure on all living organisms. Visual systems represent one of the most common sensory systems in existence, with significant homologies among elements of these systems, such as photopigments and developmental genes. Offering nearly unmatched single cell access at all levels of its nervous system, the European medicinal leech (Hirudo spp.) is an excellent system in which to identify behaviorally relevant neuronal circuits. Hirudo evolved discrete …

Mate Choice And Sexual Conflict In A Livebearing Fish, Julia C. Kasper

Master's Theses

Eavesdropping occurs when a receiver extracts information from an interaction without directly engaging with the signaler. Eavesdropping has been shown to be an effective way of evaluating the quality of potential mates and their abilities in male-male competition, without having to directly interact with them, thereby reducing energy costs and mating harassment. Girardinus metallicus is a livebearing poeciliid fish endemic to Cuba whose mating system is dominated by mating harassment in the form of sneak copulations, persistent displaying, and male-male aggression. G. metallicus has a male specific polymorphism in both melanin coloration and behavior. Males with melanin coloration are known …