Life Sciences Commons^™

Utilization Of Ferrioxamine Microarrays For The Rapid Detection Of Pathogenic Bacteria, Nigam Bir Arora

Open Access Dissertations

Siderophores are low-molecular weight species utilized by bacteria for the sequestration of iron, an essential nutrient. Siderophores and their cognate receptors are considered to be virulence factors, due to their prominent role in pathogenicity. The work presented here focuses on ferrioxamine (FOx) as an “immutable” ligand for pathogen detection. A number of bacterial strains expressing high-affinity FOx receptors were identified by a proteomic BLAST search, and screened against microarrays patterned with FOx conjugates for detection using label-free optical imaging. Aspects such as inkjet printing and surface chemistry, iron-limiting conditions and bacterial selection protocols, and linker conjugate design were addressed and …

Investigating The Effects Of Ph On Alphaviral E3-E2 Glycoprotein Association, Organization, And Cellular Tropism, Jason Michael Sequra

Open Access Dissertations

In alphaviruses the role of E3 is required in protecting the fusion peptide region of E1 during intracellular transport. Throughout viral processing, the association of E2 and E3 is required for the successful trafficking and incorporation of E1 into the mature virion. This E3-E2 association has been observed to extend to mature virions in the solved structure for the envelope of Semliki Forest virus (SFV) and supported by the solved structure for the entire Venezuelan equine encephalitis virion (VEEV) with exclusive contacts being made between E3-E2. Immunization with monoclonal antibodies against VEEV E3 provided protection for mice challenged by lethal …

Complex Glycan Utilization Preferences Of Human Gut Bacteria, Yunus Emre Tuncil

Open Access Dissertations

Complex glycans, making up dietary fiber, have gained significance in recent years as they are the main energy source for the colonic microbiota which are physiologically important for the host health. Understanding glycan utilization strategies of the members of this community is essential to maximize beneficial health outcomes obtained from them. In order to investigate how the members of our gut microbiota utilize glycans and activate their respective polysaccharide utilization loci (PULs), we performed a series of time-course assays in which two model organisms, Bacteroides thetaiotamicron (Bt) and B. ovatus (Bo), were individually grown in a medium containing carbohydrates utilized …

Genomic And Transcriptomic Analysis Of Biofilm Formation In Persistent And Transient L. Monocytogenes, Clara Assisi

Open Access Theses

The Next Generation Sequencing (NGS) has been popularized and aid in the advancement of many fields of science. The other field of science that is being revolutionized is food science and technology, especially food safety. NGS application in food safety, especially the whole genome sequencing analysis (WGS), has been widely used for tracing back the source of outbreaks. The other application of NGS that is also being developed is the analysis of global transcriptomic or RNA-sequencing (RNA-Seq). In this research, we utilize NGS (Ilumina MiSeq Sequencing platform) to perform sequence comparison and identify single nucleotide polymorphisms (SNPs) and observe the …

Repurposing Non-Antimicrobial Drugs To Treat Multi-Drug Resistant Bacterial And Fungal Infections, Shankar Thangamani

Open Access Dissertations

Bacterial and fungal resistance to conventional antimicrobials is a burgeoning global health epidemic that necessitates urgent action. Even more alarming, the development of new antimicrobials to treat these multidrug-resistant pathogens has not kept pace with the rapid emergence of resistance to current antimicrobials. Antimicrobial drug development through the traditional de novo process is a risky venture given the significant financial and time investment required by researchers and limited success rate of translating these compounds to the clinical setting. This has led researchers to mine existing libraries of clinical molecules in order to repurpose old drugs for new applications (as antimicrobials). …

Antibacterial Activity Of Essential Oil Encapsulated Sodium Iota-Carrageenan Fibers, Carlos D. Carter

Open Access Theses

Spoilage microorganisms cause food waste and loss of quality. While the foodborne pathogen outbreaks lead to thousands of hospitalizations and deaths. Essential oils (EOs), plant extracts, possess the required antimicrobial activities and thus their usage stands out as a feasible approach for controlling the undesirable bacterial growth in food systems. However, EOs are highly volatile and lose their activity upon exposure to environmental conditions. In this regard, their encapsulation in Generally Recognized As Safe (GRAS) matrices such as food grade polysaccharides especially iota-carrageenan could be one of the viable alternatives. Iota-carrageenan, sulfated polysaccharide from marine algae, is being used in …

Recombinant Listeria Adhesion Protein Expressing Probiotics Protect Against Listeria Monocytogenes Infection In Animal Models, Valerie E. Ryan

Open Access Theses

Listeria monocytogenes (Lm) is a foodborne pathogen, found ubiquitously in nature, and has a high morbidity rate among immunocompromised individuals, the elderly, and especially pregnant women and their fetuses resulting in abortion, stillbirth, and neonatal infection. There are currently no preventative medical interventions against Lm infection. The Listeria adhesion protein (LAP) is present in both pathogenic and non-pathogenic Listeria (i.e., L. innocua) and has shown to interact with host epithelial proteins causing tight junction dysregulation aiding in pathogen attachment and paracellular translocation across the host intestinal epithelium. Our lab has demonstrated that recombinant probiotics, Lactobacillus casei (LbcWT) expressing LAP …

Effects Of Acute Heat And Oxidative Stress On The Hepatic Expression Of Orexin And Its Related Receptors, Stephanie Khaldi

Graduate Theses and Dissertations

It is widely known that orexin A and B peptides as well as their receptors are expressed in the hypothalamus and distributed throughout the central nervous system, but there have been few studies regarding its presences in other parts of the body. There is now evidence that orexin (ORX) and its receptors (ORXR1/2) are present in the avian liver; however, their regulation under different environmental conditions is still unknown. In the current study, we sought to determine the effects of heat and oxidative stress using hydrogen peroxide (H2O2) and 4-hydroxynonenal (4-HNE) on the hepatic expression of ORX and ORXR1/2 in …

A Portable And Automatic Biosensing Instrument For Detection Of Foodborne Pathogenic Bacteria In Food Samples, Zhuo Zhao

Graduate Theses and Dissertations

Foodborne diseases are a growing public health problem. In recent years, many rapid detection methods have been reported, but most of them are still in lab research and not practical for use in the field. In this study, a portable and automatic biosensing instrument was designed and constructed for separation and detection of target pathogens in food samples using nanobead-based magnetic separation and quantum dots (QDs)-labeled fluorescence measurement. The instrument consisted of a laptop with LabVIEW software, a data acquisition card (DAQ), a fluorescent detector, micro-pumps, stepper motors, and 3D printed tube holders. First, a sample in a syringe was …

Genetic Determinants Of Salmonella And Campylobacter Required For In Vitro Fitness, Rabindra Kumar Mandal

Graduate Theses and Dissertations

Non-typhoidal Salmonella (NTS) and Campylobacter play a major role in foodborne illness caused by the consumption of food contaminated by pathogens worldwide. A comprehensive understanding of the genetic factors that increase the survival fitness of these foodborne pathogens will effectively help us formulate mitigation strategies without affecting the nutrition ecology. The objective of this study was to identify the genetic determinants of Salmonella and Campylobacter that are required for fitness under various in vitro conditions. For the purpose, we used a high throughput Transposon sequencing (Tn-seq) that utilizes next generation sequencing (NGS) to screen hundreds of thousands of mutants simultaneously. …

Shifts In Myxomycete Community Structure In Selected Microhabitats Across Nutrient Treatments In A Lowland Tropical Forest Of Panama, Laura M. Walker

Graduate Theses and Dissertations

Myxomycetes (plasmodial slime molds) are abundant amoeboid predators of bacteria and other microorganisms. They are found worldwide, largely in association with decaying plant material in terrestrial habitats. Their consumption of bacterial prey puts microbial predators such as myxomycetes in a key position in various ecosystem processes wherein they help regulate the flow of nutrients (e.g., N and C) through the ecosystem. The importance of microbial predators in nutrient cycling and plant productivity is well established. Given the extent to which tropical ecosystems influence global nutrient fluxes, along with the ecologically significant role that myxomycetes play in these processes, there is …

Characterization Of Histone Mutants Associated With Mitotic Defects In Saccharomyces Cerevisiae, Md Riajul Hossain

Graduate Theses and Dissertations

Nucleosomes, the basic unit and the building blocks of chromatin have an essential role in the tight packaging of DNA into higher order chromatin. Work from our lab and others have provided information on the contributions of different histone proteins and specific domains within the nucleosome made to create the centromeric chromatin structure required for normal chromosome segregation during mitosis. The DNA entry/exit site is a particular region of the nucleosome where histone H2A, H3 and H4 form critical interactions that appear to be essential for the association of Sgo1, a tension sensing protein that monitors kinetochore-microtubule attachment. In our …

Listeria Monocytogenes Strain Variation: Starvation, Metabolism, And Macrophage Survival, Nathan A. Jarvis

Graduate Theses and Dissertations

Listeria spp. are often isolated from raw and processed food products. Listeria monocytogenes is responsible for death rates of 10 to 30% in immune compromised people; it can also infect a vast range of animals. There are numerous reports of poultry harboring or becoming infected with L. monocytogenes. First, this research assessed the ability of L. monocytogenes to replicate within chicken macrophages. Using the gentamicin-killing assay, a cell culture of chicken macrophage-like cells (HD11) were infected with two strains of L. monocytogenes individually (EGD-e and Scott A). Results show that unlike data on mouse macrophages, intracellular L. monocytogenes do not …

Genome Engineering In Mammalian Cells By Flp And Cre Dna Recombinase Variants, Riddhi Shah

Doctoral Dissertations

Genome engineering relies on DNA modifying enzymes that are able to locate a DNA sequence of interest and initiate a desired genome rearrangement. Currently, the field predominantly utilizes site-specific DNA nucleases that depend on the host DNA repair machinery to complete a genome modification task. We show here that genome engineering approaches that employ self-sufficient, versatile site-specific DNA recombinase Flp and Cre can be developed into promising alternatives. We demonstrate that a Flp variant evolved to recombine an FRT-like sequence FL-IL10A, which is located upstream of the human interleukin-10 gene, can target this sequence in the model setting and native …

Oxidative Stress Response In Archaea: Elucidation Of Oxidant Sensing And Tolerance Mechanisms In Methanosarcina Acetivorans, Matthew Edward Jennings

Graduate Theses and Dissertations

Methanogens are archaea possessing a conserved metabolic pathway which produces methane. Many of the enzymes in the methanogenesis pathway are Fe-S proteins, meaning methanogens are sensitive to conditions which disrupt Fe-S clusters. Molecular oxygen is capable of disrupting Fe-S clusters through oxidation of the iron atoms. Furthermore, reduced iron can facilitate the production of reactive oxygen species (ROS), meaning methanogens must possess antioxidant mechanisms. Detection and eradication of ROS is important for all cells, due to the potentially fatal consequences of unchecked oxidation. This dissertation presents two separate projects investigating mechanisms the model methanogen Methanosarcina acetivorans possess for dealing with …

The Ccaat-Binding Factor Dependent Regulation Of The Oxidative Stress Response In Candida Albicans, Ananya Chakravarti

Graduate Theses and Dissertations

The success of Candida albicans as an opportunistic human pathogen has been attributed to several factors, including the ability to survive in limiting iron environments and the ability to evade the respiratory burst of human macrophages and neutrophils. The goal of this research is to elucidate the role of the CCAAT-binding factor in the oxidative stress response of Candida albicans. Prior whole genome microarray studies performed in our lab compared the gene expression of a wild type Candida albicans strain versus a hap5Δ strain under iron-limiting growth conditions. Among the differentially regulated genes, CTA1, encoding catalase, had a four-fold higher …

Dissemination And Persistence Of Plasmid Located, Integron Associated Antibiotic Resistant Genes In Wastewater Treatment Plant Effluent And Stream Water Bacteria, _ Suhartono

Graduate Theses and Dissertations

Transmissible plasmid-mediated integrons play important role in the persistence and dissemination of antibiotic resistance throughout the environment. Plasmids from 139 multi-antibiotic resistant Escherichia coli recovered from wastewater treatment plant effluent and upstream and downstream receiving stream water in Northwest Arkansas were extracted and profiled. Genes of class 1 and class 2 integrase (intI), mobilization (mob), sulfamethoxazole resistance (sul), and trimethoprim resistance (dfr) were detected using PCR and confirmed through DNA sequencing. Plasmids from almost half of the isolates (47%) were transmissible with mobF12 gene as the most frequently detected mobilization gene. Plasmid-borne class 1 with and without class 2 integrons …

Magnesium Regulates Transcription Of The Mgta (Magnesium Transporter) Gene In Salmonella Enterica Serovar Typhimurium Via Prolyl-Bond Formation During Translation Of The Mgtl Leader Orf, Aaron R. Gall

Open Access Dissertations

In Enterobacteriaceae, the mgtA gene encodes a P-type ATPase that mediates Mg2+ uptake and is up-regulated by the PhoQP two-component system during invasion of host epithelial cells and macrophages. The regulation of mgtA has recently gained special interest given that it exists at several stages, including transcription, post-transcription and post-translation, in response to Mg2+availability. The mgtA mRNA has a 264-nucleotide 5’ leader that contains a 17 codon, proline-rich ORF, termed mgtL, whose translation has been proposed to affect the folding of the 5’ leader mRNA, which in turn regulates whether transcription is terminated before the mgtA structural gene at high …

Microbial Ecology Of Waterborne Pathogens In Sus Scofra And Odocoileus Virginianus In The Jackson Bienville Wildlife Management Area, Jaymes Hunter Collins

Doctoral Dissertations

Previous studies have demonstrated that feral swine (Sus scofra ) are significant reservoirs for a number of pathogens that present a potential threat to wildlife and humans. Despite this, few studies have gone beyond quantifying the incidence of these pathogens to further probe their ecology within a specific habitat or ecosystem.

Overall, the objective of this study was to characterize three potential reservoirs in a feral swine infested habitat; two ungulates, and one aquatic reservoir. Our study area was the Jackson-Bienville Wildlife Management Area (J-B WMA). We chose four waterborne bacteria: Brucella spp., Leptospira interrogans, Salmonella enterica, and Helicobacter …

Investigating Physiological Collaborations Between A Lower Termite And Its Symbionts, Brittany F. Peterson

Open Access Dissertations

This project was completed in an effort to better understand the contributions of symbiotic microbes to the biology of Reticulitermes flavipes, the eastern subterranean termite. Lower-termites, like R. flavipes, house symbionts from all three domains of life within their hindgut paunch. This intimate association is reflected in nearly every aspect of termite biology. Here, I investigate these physiological collaborations as they relate to digestion and immunity. My efforts focused on 1) quantifying the role of bacteria in wood digestion within the termite gut, 2) evaluating the role of symbionts in protection against pathogens, and 3) identifying gene products that bacterial …

Factors Affecting Transduction Efficiency Of Pseudotyped Viral Vectors Incorporating Alphaviral Glycoproteins, Aditi Kesari

Open Access Dissertations

The genome of an organism has the complete set of biochemical instructions required for sustenance of life. Mutations or abnormalities in this genome lead to genetic disorders. Currently available therapeutic options mostly focus on treating the symptoms, but not curing them. Gene therapy promises to be a curative form of medicine. In gene therapy cells carrying a defective gene are targeted and replaced with a healthy copy of that gene. The vehicles used for delivering this gene are known as vectors. Retroviruses are popularly used gene therapy/transfer vectors. However, retroviruses are limited in the range of cells they can enter …