Life Sciences Commons^™

Inhibiting Survival Of Salmonella During Desiccation Through The Use Of Naturally Occurring Signals, Joseph Headrick

Electronic Theses and Dissertations

A rising problem in agriculture is the increase of antibiotic-resistant Salmonella cases associated with chicken eggs, which transmit infection to humans. To counter this, new approaches to combat Salmonella in chickens and desiccated on eggshells are vital in the prevention of human foodborne illness. Disrupting signaling pathways with naturally occurring compounds provides a potential novel avenue for prevention of Salmonella infections, as this would disrupt sensing of these environments and inhibit subsequent optimal gene expression. Starting with signals identified in previous studies, salicylic acid was found to inhibit Salmonella desiccation survival on both eggshells and plastic. To expand upon this, …

Cyclic-Di-Gmp Regulates Salmonella Typhimurium Infection Of Epithelial Cells And Macrophages, Abdulafiz Musa

Electronic Theses and Dissertations

Regulation of the bacterial second messenger cyclic-di-GMP in Salmonella Typhimurium allows it to delicately alter phenotypes to optimize invasion and survive intracellularly in epithelial cells and macrophages to become virulent and cause infection. Cyclic-di-GMP concentration is regulated by the presence of external stimuli, sensory diguanylate cyclases (DGCs) and phosphodiesterases (PDEs), and cyclic-di-GMP binding effectors. Previous studies established that maintenance of low cyclic-di-GMP concentrations is required for survival in macrophages, and that deletion of 3 active PDEs reduces this survival. Here I showed that these 3 PDEs also influenced the infection of epithelial cells. Further studies re-established the decreased survival in …

Functions Of The Trna Splicing Endonuclease And Other Adventures In Rna Processing, Jennifer Hurtig, Ambro Van Hoof

Dissertations & Theses (Open Access)

The tRNA splicing endonuclease (TSEN), has been studied for over three decades for its function in tRNA splicing. However, this enzyme has other functions that are just beginning to be characterized. Mutations in TSEN cause the neuronal disease pontocerebellar hypoplasia (PCH) that is characterized by atrophy of the cerebellum and pons, overall developmental failure, and usually results in death before adolescence. How mutations in TSEN cause these neuronal defects and disease is not understood. In yeast, TSEN has another essential function that is independent of tRNA splicing and is still unknown. In this thesis I strived to understand the other …

Determining The Effects Of Maternal Adiposity On Preterm Neonatal Microbiome And Short Chain Fatty Acid Profiles, Dalton James, William A. Clark Phd, Kristy L. Thomas

Undergraduate Honors Theses

The gut microbiota and its metabolites have vast impacts on the human digestive system, immune system, and health outcomes. Short chain volatile fatty acids (SCVFAs) present in feces can be representative of the interactions of the microbiota present in the gut. Low microbiota diversity in the human gut is highly associated with obesity and adverse health outcomes. Furthermore, the maternal microbiome has a direct impact on neonatal microbiota through various pathways such as environment, skin flora, breast milk composition, and vaginal secretions. This study is aimed to further understand the associations between various factors (maternal adiposity, gestational time, length of …

Unraveling Plant-Microbe-Microbe Interactions: Host And Microbial Colonization Determinants Across Experimental Scales, Bridget O'Banion

Doctoral Dissertations

Plant microbiomes are assembled and modified through a complex milieu of biotic and abiotic factors. Despite dynamic and fluctuating contributing variables, specific host and microbial mechanisms are likely important mediators of interactions. We combine information from large-scale datasets across diverse plant hosts with experimental genetic manipulation assays in model Arabidopsis seedlings to converge on a conserved role for metabolite production and transport in mediating host-microbe interactions. Applying a diverse set of analytical tools to microbial communities at various complexity levels will advance our knowledge of the scalability of observed phenotypes and, ultimately, help to decipher the mechanisms dictating plant–microbe interactions …

Gene Expression Changes Linked To Phenylpropanoid-Based Resistance To Fusarium Head Blight Of Wheat, Shiv Singla

Department of Plant Pathology: Dissertations, Theses, and Student Research

Fusarium graminearum is a devastating pathogen of wheat that causes Fusarium head blight (FHB) and contaminates the grain with the mycotoxin deoxynivalenol (DON). Resistance to FHB is quantitative and it is important to identify additional genes conferring resistance against it. The goal of this thesis was to examine if the constitutive expression of two sorghum phenylpropanoid pathway genes, SbCCoAOMT (encoding caffeoyl-CoA O-methyltransferase) and SbC3’H (encoding p-coumarate 3-hydroxylase), in the moderately-susceptible spring wheat CB037 can provide Type-I and Type-II resistance to F. graminearum and determine the underlying mechanisms of the enhanced resistance. The constitutive expression lines (CCoAOMT413, CCoAOMT421, C3H112, …

Effect Of Temperature On The Microbiome Of A Laboratory-Reared Colony Of Haemaphysalis Longicornis Ticks, Brianna L. Mitchell

Honors Theses

Haemaphysalis longicornis ticks are invasive to the United States with potential to transmit several tick-borne pathogens that are native to the United States. Based on existing locations of H. longicornis in its native regions in Asia, as well as its invasive populations that are established in the United States, several geographic range prediction models have been produced to help understand future range expansion and distribution of this invasive tick in North America. Unfortunately, these models do not all agree and there is uncertainty associated with the potential geographic range expansion of H. longicornis ticks in North America. Climate can affect …

Diagnosis Of Urinary Tract Infections And Rapid Molecular Characterization Of Antibiotic Resistance, Mohammed Harris

All Dissertations

Urinary tract infections (UTIs) are one of the most common infectious clinical entities in both community and hospital settings. They have a broad range of clinical severity yet inflict large epidemiological burden of morbidity and mortality on patients and the healthcare system with billions of dollars in cost of treatment. Understanding what methods are optimal for diagnosing UTIs are critical to mitigate the marked impact and cost of these infections.

Chapter 1 and 2 in this work surveys the broad array of diagnostic modalities for UTIs and highlights their advantages and limitations in the context of the current standard of …

Impacts Of Bacterial Evolution On Host Lethality In Drosophila, Andrew Preston

College of Arts & Sciences Senior Honors Theses

Evolution is the process by which species change their genetic traits, such as the pathogenicity of bacteria, over time in response to changes in their environment. Although the genetic mechanisms underlying many evolutionary processes have been revealed, it is still not well understood how opportunistic pathogens, such as Pseudomonas aeruginosa, become virulent. The overall goal of this thesis is to test the Coincidental Evolution Hypothesis, which proposes that the virulence of opportunistic pathogens evolves coincidentally as a by-product of their interaction with their natural predators. I hypothesized that the virulence of ancestral Pseudomonas aeruginosa changes over time if it co-evolves …

Oncolytic Virus Immunotherapy: Development And Potential For Cancer Treatment, Olivia Guinness

Honors Scholar Theses

The American Cancer Society estimates that in 2023, 1,958,310 new cancer cases and 609,820 cancer deaths will occur in the United States [16]. A promising therapeutic option that has been supported by recent clinical trials is the use of oncolytic viruses to treat malignant tumors. The mechanism of action of existing treatments, such as chemotherapy, radiotherapy, and surgery, differs from that of oncolytic virus therapy because oncolytic viruses are able to affect cancer cells with specificity, minimizing side effects. When infecting a normal, non-cancerous cell, oncolytic viruses do not replicate, leaving healthy cells unaffected. In tumor cells, oncolytic viruses will …

Role Of Pseudomonas Aeruginosa Exoenzymes S, T, And Y In The Modulation Of Intrinsic Apoptosis In Pulmonary Microvascular Endothelial Cells, Andrea M. Vavrinek

Honors Theses

P. aeruginosa is the most common cause of ventilator-associated pneumonia in ICU patients. P. aeruginosa uses a type III secretion system to inject exoenzymes S, T, U, and Y into host cells, exhibiting unique effects. Pulmonary microvascular endothelial cells (PMVECs) are used to evaluate cellular changes caused by exoenzymes. ExoY infection of PMVECs leads to cell rounding but does not lead to cell death, unlike ExoS/T. The current study evaluated the exoenzyme-induced modulation of intrinsic apoptosis in endothelial cells. Strain PAK, producing ExoS, T, and Y, was compared to isogenic strains expressing either S, SY, T, TY, Y, or none …

Effect Of Temperature On The Microbiome Of A Laboratory Reared Colony Of Haemaphysalis Longicornis Ticks, Brianna Mitchell

Poster Presentations

Honors research poster.

Haemaphysalis longicornis is a species of tick native to eastern Asia, including eastern China, Japan, eastern Russia, and Korea. To date, it has invaded and has now established its existence in Australia, New Zealand, and several of the Pacific Islands. This species of tick has recently been introduced to the United States, having a confirmed sighting in November 2017 on a sheep farm in New Jersey and since establishing populations in 18 states along the east coast and Appalachia. Based on the existing locations of H. longicornis in its native regions, as well as in the United …

The Stringent Response In Pseudomonas Aeruginosa Influences The Phenotypes Controlled By The Gac/Rsm System, Michael Shawn Hooker

Electronic Theses and Dissertations

Pseudomonas aeruginosa is a ubiquitous, opportunistic pathogen that causes acute and chronic infections. Infection is typically initiated via motile and virulent strains. After exposure to stressors, acute infections make both genotypic and phenotypic switches to a chronic, sessile strain. This is due to intricate regulatory networks directing gene expression in response to stressors. One network, GacA/GacS, has been established to control virulence factors. The stringent response of bacteria is mediated by alarmones produced primarily by RelA which responds to starvation.

To study the effect of the stringent response on the virulence switch. A series of experiments were run in both …

Isolating And Characterizing Lipid Degrading Microbes From Human Decomposition Soils, Brooke Amara Talley, Allison R. Mason, Jennifer Debruyn

Chancellor’s Honors Program Projects

No abstract provided.

The Alphaviral Capsid Protein Inhibits Irak1-Dependent Tlr Signaling To Promote Pathogenesis., V. "Trey" Landers

Electronic Theses and Dissertations

Alphaviruses are positive-sense RNA viruses spread by mosquitos. They can cause a severe multi-joint febrile arthritis or encephalitis resulting in death or life-long cognitive impairments. To date there are no approved antiviral therapeutics or vaccine strategies for the treatment of alphaviruses creating a critical need to better understand the host pathogen interactions of alphaviruses that enable pathogenesis. It is known that alphaviruses evade innate immune responses by shutting down host transcription and translation, but these methods are dependent on viral gene expression and leave a critical time frame during early infection before viral gene expression has begun that the virus …

Desert Spring Prokaryotes And Benthic Macroinvertebrates: Geological And Ecological Controls, Ariel D. Friel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Desert springs are aquatic oases, being considered among the most diverse and imperiled ecosystems on Earth. Despite the ecological significance and threatened status of desert springs, few studies have surveyed the microorganisms in these systems or their interactions with other community members. The primary goal of this dissertation was to describe the major controls influencing the community ecology of prokaryotic and BMI communities in cold- and moderate-temperature desert springs of the southern hydrographic Great Basin. Chapter 1 provides a broad overview of spring ecosystems and of each chapter included in this dissertation. Chapter 2 documents the first-ever, regional-scale survey of …

Biochemical Characterization Of Fsa1572 From Fervidibacter Sacchari, The First Hyperthermophilic Gh50 With Β-1, 4-Glucanase Activity, Jonathan Covington

UNLV Theses, Dissertations, Professional Papers, and Capstones

The bacterium Fervidibacter sacchari is an aerobic hyperthermophile that catabolizes various polysaccharides and is the only cultivated member of the class Fervidibacteria within the phylum Armatimonadota. Among its glycoside hydrolase (GH) cache is an enzyme from GH family 50 (GH50), an understudied family with only 25 characterized representatives and two known activities from 1,518 predicted members in the Carbohydrate-Active EnZyme (CAZy) Database. Here, we expressed, purified, and functionally characterized an extracellular GH50 from F. sacchari called Fsa1572. Using colorimetric assays, we show it has novel β-1,4-glucanase activity and only weak agarose activity that is typical for GH50 enzymes. The purified …

Effects Of Cations And Dipicolinic Acid On B. Anthracis Spore Physiology And Cytotoxicity, Chandler P. Hassan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Inhalation of Bacillus anthracis spores leads to the most severe form of anthrax. Following phagocytosis by alveolar macrophages, spores germinate inside the phagolysosome. The mechanism used by the newly germinated B. anthracis cells to survive within macrophages is not completely understood.B. anthracis spores contain large concentrations of calcium in complex with dipicolinic acid (Ca-DPA). Upon germination, the cell excretes the large depot of Ca-DPA. DPA is an amphipathic molecule that could act as a buffer and modulate phagolysosome acidification. Intracellular calcium overload can disrupt signaling pathways required for normal macrophage function and trigger cell death. We hypothesized the release of …

Poop! There It Is! Anti-Germinants And Biological Variables As Modulators Of Clostridioides Difficile Infection (Cdi), Jacqueline Renee Phan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Clostridioides difficile infection (CDI) is a major cause of antibiotic-associated diarrhea. Due to its insidious nature, the Centers for Disease Control and Prevention (CDC) has declared CDI an urgent threat. A key characteristic of C. difficile is its ability to form dormant spores that act as the infectious vehicles for disease. In the gut, spores recognize bile salts to germinate into toxin-producing cells.Dysbiosis of the gut microbiome is a key factor in allowing the C. difficile spores to germinate. Normal gut microbiota naturally protects from CDI. However, biological variables such as diet and sex have been found to modulate to …

Oral Prevalence Of Akkermancia Muciniphila Among Pediatric And Adult Orthodontic And Non-Orthodontic Patients, Ching Shen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Akkermansia muciniphila (AM) is one of many highly abundant intestinal microbes that influences homeostasis and metabolic disorders and may also play a role in oral disorders. However, there is little evidence regarding the oral prevalence of this organism. Based upon this lack of evidence, the primary goal of this project is to survey an existing saliva repository to determine the overall prevalence of this organism and any associations with demographic or patient characteristics (age, sex, body mass index, race/ethnicity, orthodontic therapy). Using an approved protocol, a total n = 141 pediatric samples from an existing saliva repository were screened using …

The Effect Of Different Types Of Plastic And Rubbers Often Found In Healthcare Facilities On The Survival Of Potentially Pathogenic Bacteria, Ashely George

Honors Theses

This study focused on the survival of different species of bacteria on different types of plastics and rubbers found in healthcare facilities. The gram-positive coccus Staphylococcus aureus and the gram negative bacillus Escherichia coli, known to have importance as potential pathogens in healthcare facilities, were tested on two types of plastic (polyurethane and Polyvinyl Chloride (PVC)) and two types of rubbers (latex and nitrile) typically found on reusable healthcare surfaces. Known quantities of bacteria were aseptically placed on disinfected plastic surfaces in triplicate, air-dried, and then incubated at room temperature for 30 minutes, 20 hours, and 40 hours. After incubation, …

Analysis Of Microbial Abundance On Marine Snow In The Deep Ocean, Matthew Qilan Thompson

Undergraduate University Honors Capstones

The ocean plays a critical role in the carbon cycle, with phytoplankton serving as a source of energy and nutrients (such as nitrogen and phosphorus) to larger organisms in upper trophic levels. Additionally, marine snow, a cluster of components including dead zooplankton, organic carbon debris, and polymers as carbohydrates, proteins, and DNA, transport these nutrients and associated microorganisms to the deeper parts of the ocean. However, the relationship between microbial abundance and particle sizes of marine snow across the water column is not well understood. Previous studies suggest that microbial abundance is lower in the bathypelagic zone (1,000m - 4,000m) …

A Forensic Assessment Of Current Water Quality Using Idexx Techniques In The Himmarshee Canal And New River In Fort Lauderdale, Florida, Catherine Margaret Bilodeau

All HCAS Student Capstones, Theses, and Dissertations

Fecal contamination has continued to plague local communities around the United States and the world, especially in highly populated areas like Southern Florida. Newer techniques are beginning to be used to track microbes properly as they are found in waterways. Some more recent techniques in Microbial Source Tracking (MST) use IDEXX kits to detect fecal indicator bacteria (FIB). Two IDEXX kits Colilert-18^® which detects total coliforms and Escherichia coli in water or fecal coliforms in wastewater, and Enterolert^®, which targets enterococci, were used in the waterways of the Himmarshee Canal and South Fork of the New River …

Testing Of Indazole Inhibitors Of Kasa, A Vital Enzyme Of M. Tuberculosis, Karissa Highlander

Student Research Submissions

Tuberculosis is a disease that affects the lungs caused by Mycobacterium tuberculosis (M. tuberculosis). Although drug treatment options exist, increased rates of antibiotic resistant strains have become more prevalent in recent years, driving a need for new treatment approaches. KasA, a β-ketoacyl synthase, has been found to synthesize parts of the cell wall and been identified as an attractive drug target. Previous medicinal chemistry research has been completed to synthesize six effective competitive inhibitors of KasA that would potentially block the enzyme from binding the substrate, preventing elongation of the backbone and creation of the mycolic fatty acids that …

Antibacterial Properties Of Devil’S Walking Stick And Winged Sumac Extracts, Raven L. Turner, Kayla L. Medina

ATU Research Symposium

Many native plants are used for the treatment of various diseases. Mainly those species in high chemical compound plant families can have antimicrobial properties. We selected two native plants in Arkansas, Devil’s walking stick (Aralia spinosa), and Winged sumac (Rhus copallinum), and tested them for antibacterial properties. We used three gram-positive bacteria (Bacillus cereus, Bacillus subtilis, and Staphylococcus epidermidis) and three gram-negative bacteria (Alcaligenes faecalis, Escherichia coli, and Serratia marcescens). The disc diffusion method is employed to identify any potential antibacterial properties for the two plant species. For this experiment, 6.50 g of dehydrated plant material (leaves of each plant …

Distribution Of Micropredators In The Longleaf Pine Soil Microbiome, Faith Arends, Eithar Mirghani

Symposium of Student Scholars

Bacterial micropredators of the soil, like their larger-scale counterparts, play a key role in shaping their ecosystem and are thus of particular interest from an ecological standpoint. An important micropredator to study are Myxobacteria. Myxobacteria are gram-negative rod-shaped social bacteria that hunt in wolf packs to lyse their prey and facilitate their growth. Myxobacteria are a potential source of novel antibiotics, therefore, the isolation of new strains is of great interest. We investigated longleaf pine soil as a source of novel isolates. The Longleaf Pine Ecosystem is an endangered ecosystem that is of crucial importance due to its ability to …

Antibacterial Activity Of Native Plants In Arkansas, Kayla L. Medina, Raven L. Turner, Katie Huffman

ATU Research Symposium

American beautyberry (Callicarpa Americana), Sugarberry (Celtis laevigata) and Red buckeye (Aesculus pavia) are native plants of Arkansas. Plant families with species having high chemical compounds can have antimicrobial properties. In this study, the antibacterial properties of the plants are investigated against three gram positive (Bacillus cereus, Bacillus subtilis, and Staphylococcus epidermidis) and three negative bacteria (Alcaligenes faecalis, Escherichia coli, and Serratia marcescens). The disc diffusion assay method is employed to identify any potential antibacterial properties of the plants. For this experiment, 6.41 g of dehydrated plant material (leaves for both species) was combined with 50 mL of 75% ethanol creating …

Fema: A Gene Necessary For High Levels Of Methicillin Resistance In All Staphylococcus Aureus, Faith Moua

Research and Scholarship Symposium Posters

Staphylococcus aureus is one of the largest leading causes of skin and tissue infections that leads to boils, cellulitis, etc. On a more serious note, it can cause bacteremia, pneumonia, and many other serious conditions that could lead to death. S. aureus can be spread through skin-to-skin contact which makes it more susceptible to high levels of infection and variability. What causes more variability in S. aureus infections are due to virulence factors that S. aureus carry.

Fema And Its Effects On Staphylococcus Aureus And Staphylococcus Epidermidis., Txiajmeng Lee

Research and Scholarship Symposium Posters

Staphylococcus aureus is a bacteria that may lead to sickness and in some extreme cases death. It is a cocci shaped gram positive bacteria that is found in many places including nose, ground, water, and eben in the air. Staphylococcus is encoded with many different types of genes. This list includes Selx, alpha, nuc, SEA, SEB, SEA, and FemA. Staphylococcus is known for it’s infection rate. It is known to cause the most amount infections and diseases in humans.

Staphylococcus Aureus Strains Exhibit Exclusivity In Regards To It’S Toxin Prevalence, Especially With Toxins Responsible For Food Poisoning And Necrotizing Pneumonia, Malia Braiedy, Taylor Mach, Amanda Brosnahan

Research and Scholarship Symposium Posters

Staphylococcus aureus is a bacteria that can exist asymptomatically, but can be dangerous due to it’s individual toxin profile. These various toxins, however, seem to be mutually exclusive from another in some cases. Samples of S. aureus often have superantigen SELX and some samples have Staphylococcal Enterotoxin (SE) A, B, or C. Through the use of Airtable and various methods of data organization and comparison on the strains we’ve collected on campus, we found that SELX exhibits an inverse relationship with SE- A/B/C, and that SE- A/B/C also exhibits exclusivity between the three toxins. Through thorough research on S. aureus, …