Life Sciences Commons^™

Next-Generation Sequencing Shows Increasing Temperatures Affect Stream Fungal Communities, Regan Hodgson

Electronic Theses and Dissertations

Under climate change predictions, surface air temperature is expected to continue to rise and will likely affect functioning of stream ecosystems and microbial communities. Aquatic hyphomycetes are key fungal decomposers of plant litter in headwater streams controlling carbon, energy, and nutrient flows to higher trophic levels. This project addressed the effects of temperature on stream fungal communities in two recently conducted experiments (microcosm and streamside channel studies) using Illumina sequencing. The objectives were to determine (1) if temperature affects community structure of stream fungi based on relative abundances of ITS2 rDNA sequences, (2) if the effects of temperature on aquatic …

Death Of A Bacterium: Exploring The Inhibition Of Staphylococcus Aureus By Burkholderia Cenocepacia., Tiffany Brandt

Electronic Theses and Dissertations

Antimicrobial resistance is a phenomenon of increasing concern as antimicrobial overuse and misuse eliminate current therapeutic options, ushering society into a post-antimicrobial era. Antibiotic discovery and synthesis efforts are urgently needed to counter the increasing burden of antimicrobial resistance. Staphylococcus aureus is a causative agent of a variety of clinical manifestations including bacteremia, endocarditis, soft tissue infection, osteomyelitis, and device-related infections. S. aureus infection presents additional treatment challenges due to its capacity for biofilm formation, which is a mode of growth that confers protection from antibiotics and physical elimination, and the emergence of antibiotic resistant strains, including methicillin-resistant S. aureus …

Investigating The Pi3k/Akt/Atm Pathway, Telomeric Dna Damage, T Cell Death, And Crispr/Cas9-Mediated Gene Editing During Acute And Chronic Hiv Infection, Sushant Khanal

Electronic Theses and Dissertations

Human Immunodeficiency Virus (HIV) infection initiates major metabolic and cell- survival complications. Anti-retroviral therapy (ART) is the current approach to suppress active HIV replication to a level of undetected viral load, but it is not a curative approach. Newer and sophisticated gene editing technologies could indeed be a potent antiviral therapy to achieve a clinical sterilization/cure of HIV infection. Chronic HIV patients, even under a successful ART regimen, exhibit a low-grade inflammation, immune senescence, premature aging, telomeric DNA attrition, T cell apoptosis, and cellular homeostasis. In this dissertation, we investigated CD4 T cell homeostasis, degree of T cell apoptosis, an …

Neural Stem Cells: Age-Dependent Outcomes During Viral Infections In The Central Nervous System, Manisha N. Chandwani

Electronic Theses and Dissertations

Viral infections in the central nervous system (CNS) are associated with neurodevelopmental and neurobehavioral deficits. The outcomes of viral infections can be driven by damage and death of neurons. Neural stem cells (NSCs) play key roles in neurodevelopment, repair, and physiological brain function. During a viral infection, NSC activity can disturbed by direct infection of NSCs by the virus or by anti-viral immune response. Here, we aimed to assess whether the anti-viral immune response can impact NSC activity during an immunocompetent response in the adult brain. We utilized a transgenic mouse model of Measles virus infection where only the CNS …

Novel Signal Sequences And Fusion Partners For Paratransgenesis In Asaia, Christina Grogan

Electronic Theses and Dissertations

Mosquitoes transmit many pathogens that cause human disease. One such disease, malaria, is caused by parasites in the genus Plasmodium, infecting over 200 million people and killing over 600,000 per year. Current strategies to control vector-transmitted diseases are increasingly undermined by mosquito and pathogen resistance. Research has turned to additional and novel methods of control, such as altering the microbiota of the vectors. In this method, called paratransgenesis, symbiotic bacteria are genetically modified to affect the mosquito’s phenotype by engineering them to deliver antiplasmodial molecules into the midgut to kill parasites. These molecules must be released by the …

Investigating Host Defenses Of North American Salamanders Against The Recently Emerged Chytrid Pathogen, Batrachochytrium Salamandrivorans, Kenzie Pereira

Electronic Theses and Dissertations

A recently emerged chytrid fungal pathogen, Batrachochytrium salamandrivorans (Bsal) threatens salamander biodiversity. Bsal susceptibility varies between and within salamander species, but little is known about the mechanisms underlying these differences. Susceptibility is likely influenced by numerous interacting factors, but my dissertation studied the role of host immune responses.

My first aim investigated between species differences by studying the bioactive properties of salamander skin peptides against Bsal and the related pathogen, B. dendrobatidis (Bd). Skin peptides were collected from five salamander species, used for in vitro assays, and analyzed by RP-HPLC. While skin peptides from one …

Identification And Characterization Of Genetic Elements That Regulate A C-Di-Gmp Mediated Multicellular Trait In Pseudomonas Fluorescens, Collin Kessler

Electronic Theses and Dissertations

Microbial communities contain densely packed cells where competition for space and resources are fierce. These communities are generally referred to as biofilms and provide advantages to individual cells against immunological and antimicrobial intervention, dehydration, and predation. High intracellular pools of cyclic diguanylate monophosphate (c-di-GMP) cause cells to aggregate during biofilm formation through the production of diverse extracellular polymers. Genes that encode c-di-GMP catalytic enzymes are commonly mutated during chronic infections where opportunists display enhanced resistance to phagocytosis and antibiotics. Our lab uses an emergent multicellular trait in the model organism Pseudomonas fluorescens Pf0-1 to study the emergence of c-di-GMP mutations …

Weaving An Interdisciplinary Microbiome Career Using Threads From Different Ecosystems, Sarah Hosler

Electronic Theses and Dissertations

Animals have trillions of microorganisms living in or on many body sites, these communities of microorganisms are called microbiomes. Microbiomes are typically host-specific, and a lot of information about the host can be determined from investigating them. Microbiome research has many real-world applications, and this thesis utilizes the One Health perspective, which acknowledges the connection of humans, animals, and environments, and emphasizes the need for collaborative, interdisciplinary research. The first interdisciplinary project is an investigation into the bacteria in wild and cultured Atlantic deep-sea scallop, Placopecten magellanicus larvae. Adults in hatcheries can be induced to spawn, but the last two …

Cyclic Di-Gmp Regulates Motility, Biofilm Formation, And Desiccation Tolerance In Acinetobacter Baumannii, Garrett Reynolds

Electronic Theses and Dissertations

Acinetobacter baumannii is an increasingly multidrug-resistant pathogen contributing to hospital-acquired infections necessitating the discovery of novel treatments. A bacterial second messenger, cyclic diguanosine monophosphate (cyclic di-GMP), can regulate various persistence factors that are potentially advantageous for survival in hospital environments. Cyclic di-GMP–modulating enzymes and cyclic di-GMP–binding effectors predictively are encoded in the Acinetobacter baumannii genome. I hypothesized that cyclic di-GMP controls motility, biofilm formation, and desiccation tolerance in Acinetobacter baumannii. Disrupting cyclic di-GMP–modulating enzymes or cyclic di-GMP–binding effectors should alter the regulatory effectiveness of these phenotypes. I tested the multidrug-resistant isolate Acinetobacter baumannii strain AB5075 and identified several transposon …

Defining The Importance Of The Hnrnp I Interaction To The Sindbis Virus Subgenomic Viral Rna Using An Innovative Tethering Approach., Claire Westcott

Electronic Theses and Dissertations

Old World alphaviruses cause significant outbreaks of illness and debilitating multi-joint arthritis for prolonged periods. Currently, there are no FDA approved vaccines or antiviral therapies; and thus, there is a critical need to identify and characterize the molecular biology of alphaviruses. Alphaviruses rely on the host cell machinery to complete the viral lifecycle and are dependent on interactions with host RNA binding proteins. Accordingly, several host heterogenous nuclear ribonucleoprotein proteins (hnRNPs) have been found to bind to the Sindbis virus (SINV) RNAs. Disrupting the interaction sites in the viral RNAs of these RNA:Protein interactions results in decreased viral titers in …

Effect Of Mycorrhizae Inoculation On The Growth And Success Of Three Taxodium Distichum Hybrids In Saline - Impacted Coastal Soils, Elif Ilhan

Electronic Theses and Dissertations

In 2008, Galveston Island was severely impacted by Hurricane Ike, resulting in high salt deposition in the soil and groundwater. This caused a loss of many native plant species. A study was initiated to determine effective ways to promote the growth conditions of three bald cypress genotypes (Taxodium distichum var distichum and Taxodium distichum var mexicanum crosses) in salt-affected soils. The treatments applied were mycorrhizae inoculation, fertilizer application, and a combination of mycorrhizae inoculation and fertilizer application. A total of sixty (60) trees planted in plots of three rows and divided into five randomized replication blocks of four treatments …

Lysosomal Evasion Of Legionella Pneumophilia The Effector., Bethany Vaughn

Electronic Theses and Dissertations

Legionella pneumophila is a Gram-negative facultative intracellular bacterium found in freshwater environments that has co-evolved to survive and proliferate in various amoeba and protozoan species, which serve as the natural host for the bacterium. Humans are an accidental host of L. pneumophila, where infection occurs upon inhalation of aerosolized water droplets that contain the bacteria. Intracellular proliferation of L. pneumophila in alveolar macrophages is essential for manifestation of pneumonia, designated as Legionnaires’ Disease. Biogenesis of the legionella containing vacuole (LCV) occurs via interception of ER-Golgi vesicle trafficking and avoids the default endosomal/lysosomal degradation pathway. Intracellular proliferation of L. pneumophila …

Aggregatibacter Actinomycetemcomitans Exploits And Modulates The Immune Response By Human Neutrophils For Survival In The Anaerobic Environment., Hazel Ozuna

Electronic Theses and Dissertations

Aggregatibacter actinomycetemcomitans (Aa) is a Gram-negative facultative anaerobe and an opportunistic oral pathogen, strongly associated with localized periodontitis and other inflammatory diseases. Periodontitis is a chronic inflammation of the periodontium resulting from the inflammatory response of the host towards the dysbiotic microbial community present at the gingival crevice. The host immune response creates a hostile environment for microorganisms; therefore, it is important for Aa to be able to regulate the necessary genes to survive and thrive in such an environment. Aaexpresses several virulence factors such as a cytolethal distending toxin (Cdt), lipopolysaccharide (LPS) and leukotoxin A (LtxA), …

Characterizing The Interaction Between Candida Albicans And Two Enterobacter Species, Abigail Cornett

Electronic Theses and Dissertations

Candida albicans is the most common human fungal pathogen. The relationship between C. albicans and Enterobacter bacteria have yet to be explored. The hypothesis of this study is that C. albicans and both E. aerogenes and E. cloacae have a positive relationship and work together to infect the host. In this study, the physical cell-to-cell interaction, molecular components of said interaction, and the impact of the interaction on a live organism were explored. Results indicate that Enterobacter adheres to C. albicans and inhibits growth with unidentified secreted molecules. Als1p has potential involvement in the attachment of E. cloacae to C. …

Decoding The Mystery Of Antibiotic Persistence, Tahmina Hossain

Electronic Theses and Dissertations

This work combines microbiology, molecular biology, Next-Generation Sequencing and system biology approaches to explore the mechanism of antibiotic persistence: a multi-drug tolerant, non-dividing, and metabolically altered state present in a subpopulation of cells due to phenotypic diversity rather than genetic variation (i.e. mutations). Persister can survive lethal antibiotic state and resuscitate after the treatment period is over. They are considered as the major contributing factor behind recurring infections. They also have a high mutation rate, which increases the chances of bacteria gaining antibiotic resistance. The formation of this phenotypic variant (persister) threatens the therapeutic effectiveness of antibiotics and understanding how …

Characterization Of Porcine Respiratory Epithelial Cells And Their Innate Immune Responses To Bacterial And Viral Ligands, Yam Prasad Gautam

Electronic Theses and Dissertations

In response to a pathogenic attack, the host produces a series of defense mechanisms through various intracellular signaling pathways. The byproduct of these signaling pathways helps tackle the invading pathogen and protects the body from getting into a diseased state. This system is called the immune system. The immune system can be divided into two branches namely the innate immune system and adaptive immune system. The groups of immune cells that provide protection regardless of the pathogen specificity constitute the innate immune system. The system that acts according to the pathogen specificity is called the adaptive immune response. The production …

Genistein-Enriched Pig Gut Microbiota Library As A Potential Probiotic Consortium, Theresah Amponsah

Electronic Theses and Dissertations

Plant-based diets contain numerous flavonoid compounds that produce antibacterial effects and gut health improvement. Genistein is among the most abundant isoflavones present in a plant-based diet and can be found in high amounts in soy products (up to 1g Kg-1). We describe here a robust method to identify genistein tolerant and metabolizing bacteria in swine gut microbiota and to screen the strains that have antibacterial and immunestimulatory properties. Such strains could be developed as non-antibiotic alternatives to prevent enteric infections in pigs and improve gut immunity. To this end, a mini bioreactorbased system was used to enrich genistein metabolizing bacteria …

Characterizing The Lir Domain Of Abin1 And Identifying Its Role As A Regulator Of Mitophagy, Andrew Rhiner

Electronic Theses and Dissertations

A20 Inhibitor of NF-κB (ABIN1/TNIP1) is a known regulator of TNFα signaling induced cell death and inflammation. The regulatory activity has been attributed to ABIN1’s recruitment of the ubiquitin editing enzyme TNF-α-induced protein 3 (TNFAIP3/A20) to Receptor-interacting serine/threonine-protein kinase 1 (RIPK1). The regulation of RIPK1 by ABIN1 and A20 relies on a third player, linear ubiquitin chain assembly complex (LUBAC), which is involved in the recruitment of ABIN1 to RIPK1. Loss of LUBAC or ABIN1 is embryonic lethal, but loss of A20 is not embryonic lethal. The embryonic lethality due to loss of ABIN1, paired with the lack of lethality …

E. Coli Persister Cell Survival And Rhizobia Attachment To Soybean Roots, Tanim Islam

Electronic Theses and Dissertations

The theme of this thesis revolves around how bacteria respond and thrive during stress. Chapters 1-3 are about how bacteria deal with life-threatening antibiotics. Chapter 4 covers new research on how bacteria can move from a stressful individual lifestyle (free-living bacteria) to initiating a symbiotic relationship with a plant (a less stressful lifestyle). In Chapter 1, I briefly summarize the current state of knowledge in the field of antibiotic resistance and persistence. In Chapter 2, I add to this knowledge by providing new insights into several antibiotics' potency and exploring the antibiotic Eagle effect. In Chapter 3, I use pyruvate …

Leveraging Queueing Theory To Develop Advanced Synthetic Biological Circuits, Prajakta K. Jadhav

Electronic Theses and Dissertations

The complexity and redundancy in the network topology of the cell hinder our understanding of the natural system, making it challenging to engineer living organisms with the desired functionality. The long-term goal of synthetic biology and bioengineering is to engineer cells to perform specific functions with increased robustness. The robust engineered systems can be easily applied to different species with the same outcome. An effective approach is a bottom-up approach where we tease apart the biological pathways and study them independently. Understanding the underlying mechanisms of biological pathways can be further applied to construct complex biological circuits that function similarly …

Microbial Communities And Nitrogen Dynamics In Prairie And Cropland Soils, Bikram Kumar Das

Electronic Theses and Dissertations

Soil microbial communities are affected by many factors, such as soil nitrogen (N) and the quantity of grass-root exudates, changing seasons, fertilization method, plant diversity, and their origin. This holds for both natural and fertilized soils. This research was intended to expand the current understanding of soil microbial interactions associated with ecological functions. The objectives of the research were (I) to characterize prokaryotic soil communities, estimate functional potential, and quantify nitrogen cycle-associated prokaryotic gene expressions across three phases of the growing season, (II) to explore the diazotrophic community composition in a natural system using nifH sequencing as well as 16S …

Role Of Host Restriction Factors On Porcine Reproductive And Respiratory Syndrome Virus (Prrsv) Replication, Pratik Katwal

Electronic Theses and Dissertations

In this study, the role of IFITM3 on PRRSV replication was studied in vitro by expressing exogenous IFITM3 in MARC-145 cells. An average of 31% reduction in PRRSV N protein expression and an average of 5.4 fold decrease in virus titer in the supernatant were observed in IFITM3 overexpressing cells as compared to vector control cells at 24 hours post infection (hpi). Moreover, there was a positive correlation between interferon- induced IFITM3 up-regulation and reduced PRRSV replication. To determine the role of endogenous IFITM3 in PRRSV replication, siRNA induced knockdown of IFITM3 was employed. RT-PCR validated the successful silencing of …

Exploring Bioprocessing Technologies For Diverse Industrial Application Of Canola, Ahmad Fawzi N Alhomodi

Electronic Theses and Dissertations

Globally, canola is the second largest oilseed crop after soybean, which is processed for the commercial production of high value oil. The industrial processing steps for canola oil extraction include preprocessing (cleaning, pressing, flaking, and cooking), mechanical pressing, and/or organic solvents. This process results in large quantities of protein-rich (~ 40% dry basis) meal as a co-product. The meal is used partially in animal diet (<30% inclusion) due to high levels of antinutritional factors (ANFs) such as high fibers, phytic acid, and glucosinolates, and low metabolizable energy. Thus, this research was designed to examine various bioprocessing technologies (i.e., traditional sprouting, solid state fermentation, submerged state fermentation, co-culture fermentation, mild pretreatments, and their combinations) for possible advancement in canola use. Canola seed sprouting for 6-day period led to an increase in protein content and a reduction in ANFs and oil content of sprouts compared to ungerminated seed. Subsequent submerged state fermentation of 6- day old sprouts using three different strains (Aureobasidium pullulans, Trichoderma reesei and Neurospora crassa) further increased protein content and lowered ANFs. Solid-state fermentation of 144 h old sprouts using A. pullulans, N. crassa and T. reesei enhanced the protein content and reduced ANFs of sprouts. Sprouting canola seed for three days helped in hull removal, leading to high protein meal accompanied by low fiber and phytic acid level. Three-day seed sprouting had no effect on oil yield, but free fatty acid content was higher compared to seed oil. Co-culture fermentation of HECM under solid state process showed maximum reduction in fiber content with co-culture of A. pullulans and N. crassa while a combination of A. pullulans and T. reesei promoted the highest GLS and phytic acid reductions compared to other combinations, which indicated the advantage of coculture inoculation over monoculture in terms of ANFs reduction. Mild pretreatment of HECM using deionized water resulted in washed HECM (WHECM) with lower soluble sugars and GLS compared to untreated HECM, whereas protein and amino acid were concentrated due to the removal of soluble components. WHECM compared to HECM showed higher protein digestibility when fed to rainbow trout. Subsequent mono- and coculture fermentation of HECM and WHECM under submerged process resulted in higher protein and amino acid content and lower ANFs levels compared to uninoculated controls. The results of cellulase, endoglucanase and β-glucosidase activity indicated the crucial role of used substrates, fungi, fermentation modes (solid state/submerged stated) and inoculation methods (mono-/co-culture) on enzyme activities.

Beneficial Plant-Microbe Interactions To Improve Nutrient Uptake And Biotic Stress Response In Crops, Jaya Krishna Yakha

Electronic Theses and Dissertations

Mutualism is a very common phenomenon among living organisms on earth. Legumes because of their high protein content, serve as a great nutrient resource for animals. This group of plants can form a mutualistic symbiosis with beneficial microbes. For example, Alfalfa (Medicago) and soybean (Glycine max) can get colonized with arbuscular mycorrhizal fungi (AMF) and rhizobia bacteria simultaneously forming a complex tripartite interaction for nutrient benefits. Most of the previous research evaluated individual symbionts, either rhizobia bacteria or AMF, but not both. There are only a few reports which discuss the nutrient exchange mechanisms in a tripartite interaction. Thus, there …

Endogenous And Exogenous Factors Driving Bacterial Community Composition In Aquatic Ecosystems, Javad Sadeghi

Electronic Theses and Dissertations

The bacterial community (BC) composition in various habitats, ranging from ecosystems to host anatomy, plays an important role in determining the nature and role of BC function in the ecosystem or host. However, the relative importance of host endogenous and environmental exogenous factors in determining the composition of the BC in aquatic habitats (e.g., freshwater lakes, fish hosts) remains poorly understood. To address this knowledge gap, this thesis makes several contributions to the estimation of the relative effects of endo-exogenous factors in driving the BC composition in aquatic ecosystem. To test the impact of biotic and abiotic factors on aquatic …

Understanding Freshwater Ecosystems And Human Health Implications In Recreational Water Through Microbial Characterization, Source Tracking, And Sediment-Microbe Dynamics, Danielle Gleason

Electronic Theses and Dissertations

Contamination of natural aquatic ecosystems is a serious global concern as populations increase and the environment is impacted by climate change. Nonpoint source (NPS) contamination of allochthonous materials, such as sediments, nutrients, and microorganisms, is commonly introduced to a body of water through runoff and wash-off which cumulates over a large area, and is subsequently transported to surface waters (e.g., rivers, streams, lakes) and shorelines. The principal form of microbial contamination of water resources is often from fecal pollution derived from humans, domesticated animals, or wildlife, and contains a variety of human pathogens. There are also numerous factors (with limited …