Life Sciences Commons^™

Phenotypic And Transcriptomic Characterization Of Colonial Phase Variation In The Cholera Pathogen Reveals A Novel Smooth Biofilm-Defective Form, Bliss Nicole Lambert

LSU Doctoral Dissertations

Biofilm formation, through the production of Vibrio polysaccharide (VPS), greatly enhances the environmental fitness and pathogenic success of Vibrio cholerae. As a result of phase variation, V. cholerae can switch from a smooth form to rugose, whose cells produce excess VPS, resulting in highly structured biofilms and greater resistance to stress. To further characterize the reversible process of phase variation, we isolated three colonial lineages. Each lineage began with a smooth parent, N16961, and contained a rugose variant derived from the parent, N16961R, as well as a smooth revertant of the rugose, N16961SD. We found clear phenotypic and transcriptomic …

Harnessing The Anopheles Microbiome To Conditionally Express Anti-Plasmodial Effectors During The Blood Meal, Jackie Shane

Electronic Theses and Dissertations

The control of vector-borne diseases such as malaria has been an extremely important research subject for hundreds of years. Because of the complex lifecycles of the pathogens that cause these diseases, finding a comprehensive treatment or preventative strategy has proven extremely difficult. Malaria alone is responsible for almost half a million deaths annually, most of them children under 5 years old. This disease is caused by parasitic protists in the genus Plasmodium that are transmitted to humans from Anopheles sp. mosquitoes. Most preventative strategies that are in use today revolve around controlling the vectors, including bed nets, insecticides, and larval …

Efficacy Of A T Cell-Biased Adenovirus Vector As A Zika Virus Vaccine, Brianna L. Bullard, Brigette N. Corder, Matthew J. Gorman, Michael S. Diamond, Eric A. Weaver

Nebraska Center for Virology: Faculty Publications

Zika virus (ZIKV) is a major public health concern due to the risk of congenital Zika syndrome in developing fetuses and Guillain-Barre syndrome in adults. Currently, there are no approved vaccines available to protect against infection. Adenoviruses are safe and highly immunogenic vaccine vectors capable of inducing lasting humoral and cellular immune responses. Here, we developed two Adenovirus (Ad) vectored Zika virus vaccines by inserting a ZIKV prM-E gene expression cassette into human Ad types 4 (Ad4-prM-E) and 5 (Ad5-prM-E). Immune correlates indicate that Ad5-prM-E vaccination induces both an anti-ZIKV antibody and T-cell responses whereas Ad4-prM-E vaccination only induces a …

Effects Of Urbanization On The Foraging Ecology And Microbiota Of The Generalist Seabird Larus Argentatus, Matthew Fuirst, Richard R. Veit, Megan Hahn, Nolwenn Dheilly, Lesley H. Thorne

Publications and Research

Larus gull species have proven adaptable to urbanization and due to their generalist feeding behaviors, they provide useful opportunities to study how urban environments impact foraging behavior and host-associated microbiota. We evaluated how urbanization influenced the foraging behavior and microbiome characteristics of breeding herring gulls (Larus argentatus) at three different colonies on the east coast of the United States. Study colonies represented high, medium and low degrees of urbanization, respectively. At all colonies, gulls frequently foraged at landfills and in other urban environments, but both the use of urban environments and gull foraging metrics differed with the degree of urbanization. …

Mechanistic Characterization Of Resistome And Microbiome Dynamics Across Diverse Microbial Habitats, Andrew John Gasparrini

Arts & Sciences Electronic Theses and Dissertations

Increasing antibiotic resistance in pathogens is a serious public health challenge, with over two million antibiotic resistant infections in the United States leading to at least 23,000 deaths and an estimated $55 billion in excess healthcare and societal costs. Antibiotic resistance has risen steadily in both pathogenic and benign bacteria since antibiotics’ introduction to agriculture and medicine 70 years ago. A dramatic reduction in the number of antibiotics approved for human use has accompanied this rise in antibiotic resistance, leading to the alarming prospect of a post-antibiotic era. Understanding the evolutionary origins, genetic contexts, and molecular mechanisms of antibiotic resistance …

A Recombinant Virus And Reporter Mouse System To Study Chronic Chikungunya Virus Pathogenesis, Alissa Roxanne Young

Arts & Sciences Electronic Theses and Dissertations

Chikungunya virus (CHIKV) is an arthritogenic alphavirus that during acute disease causes fever as well as severe joint and muscle pain. Chronic joint and muscle pain persists in a significant subset of patients, yet we still have a poor understanding of what drives this chronic disease. While replicating virus has not been detected in the joints of patients with chronic arthritis or in various animal models at chronic time points, persistent viral RNA can be detected for months after acute infection.

To identify the cells that could be contributing to chronic CHIKV pathogenesis, we developed recombinant viruses that express Cre …

Prokaryotic Diversity And Aqueous Geochemistry Of Subsurface Environments Of The Death Valley Regional Flow System, Joshua David Sackett

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation summarizes over four years of effort towards the completion of a Ph.D. in Biological Sciences. The work presented in this document covers a broad range of topics, but a central unifying theme is prokaryotic life in the continental subsurface. The work presented in each chapter relied heavily on cultivation-independent methods for assessing prokaryotic communities, including prokaryotic community structure reconstruction from high-throughput sequencing of 16S rRNA gene libraries and single-cell genome analysis of novel uncultivated bacteria.

Chapter 2 examines the aqueous geochemistry and prokaryotic diversity of Devils Hole, a cavernous limnocrene and sole natural habitat for the critically endangered …

The Effects Of Inulin And Galactooligosaccharides On The Production Of Reuterin By Lactobacillus Reuteri, Micah Dwight Forshee

ELAIA

The microbiome is a dynamic community that can positively and negatively influence host health. Lactobacillus reuteri is a probiotic that has received much attention for its ability to inhibit pathogens such as Salmonella typhimurium, Escherichia coli, and Clostridium difficile. It does so by its unique ability to metabolize glycerol into the antimicrobial compound 3-HPA, which is commonly referred to as reuterin. The ability to secrete reuterin is dependent not only on glycerol availability but also the concentration of glucose. In fact, there appears to be a “goldilocks” ratio between glucose and glycerol as either too much or too little …

Adaptation Mechanism And Tolerance Of Rhodopseudomonas Palustris Psb-S Under Pyrazosulfuron-Ethyl Stress, Xiang-Wen Luo, De-Yang Zhang, Teng-Hui Zhu, Xuguo Zhou, Jing Peng, Song-Bai Zhang, Yong Liu

Entomology Faculty Publications

Background: Pyrazosulfuron-ethyl is a long lasting herbicide in the agro-ecosystem and its residue is toxic to crops and other non-target organisms. A better understanding of molecular basis in pyrazosulfuron-ethyl tolerant organisms will shed light on the adaptive mechanisms to this herbicide.

Results: Pyrazosulfuron-ethyl inhibited biomass production in Rhodopseudomonas palustris PSB-S, altered cell morphology, suppressed flagella formation, and reduced pigment biosynthesis through significant suppression of carotenoids biosynthesis. A total of 1127 protein spots were detected in the two-dimensional gel electrophoresis. Among them, 72 spots representing 56 different proteins were found to be differently expressed using MALDI-TOF/TOF-MS, including 26 up- and 30 …

Floxed-Cassette Allelic Exchange Mutagenesis Enables Markerless Gene Deletion In Chlamydia Trachomatis And Can Reverse Cassette-Induced Polar Effects, Gabrielle Keb, Robert Hayman, Kenneth A. Fields

Microbiology, Immunology, and Molecular Genetics Faculty Publications

As obligate intracellular bacteria, Chlamydia spp. have evolved numerous, likely intricate, mechanisms to create and maintain a privileged intracellular niche. Recent progress in elucidating and characterizing these processes has been bolstered by the development of techniques enabling basic genetic tractability. Florescence-reported allelic exchange mutagenesis (FRAEM) couples chromosomal gene deletion with the insertion of a selection cassette encoding antibiotic resistance and green fluorescent protein (GFP). Similar to other bacteria, many chlamydial genes exist within polycistronic operons, raising the possibility of polar effects mediated by insertion cassettes. Indeed, FRAEM-mediated deletion of Chlamydia trachomatis tmeA negatively impacts the expression of tmeB. We …

Dna Methylation By Restriction Modification Systems Affects The Global Transcriptome Profile In Borrelia Burgdorferi, Timothey Casselli, Yvonne Tourand, Adam Scheidegger, William K. Arnold, Anna Proulx, Brian Stevenson, Catherine A. Brissette

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Prokaryote restriction modification (RM) systems serve to protect bacteria from potentially detrimental foreign DNA. Recent evidence suggests that DNA methylation by the methyltransferase (MTase) components of RM systems can also have effects on transcriptome profiles. The type strain of the causative agent of Lyme disease, Borrelia burgdorferi B31, possesses two RM systems with N6-methyladenosine (m6A) MTase activity, which are encoded by the bbe02 gene located on linear plasmid lp25 and bbq67 on lp56. The specific recognition and/or methylation sequences had not been identified for either of these B. burgdorferi MTases, and it was not previously known whether these RM …

Sensitivity Of Salmonella Serovars And Natural Microflora To High-Pressure Pasteurization: Open Access Data For Risk Assessment And Practitioners, Abimbola Allison, Aliyar Fouladkhah

Agricultural and Environmental Sciences Faculty Research

Industrial adoption of high-pressure processing is gaining importance and momentum as an alternative method to traditional utilization of antimicrobials and heat-based pasteurization. This indicates the need for extensive validation studies and available data for feasible and efficacious adoption of the technology by practitioners and the private industry. Current dataset is obtained utilizing elevated hydrostatic pressure of 35 to 380 MPa for time intervals of 0 (untreated controls) to 10 min, for decontamination of mesophilic background microflora and inoculated Salmonella in orange juice [1]. This open accessed data could be incorporated as part of risk assessment analyses for mitigating the risk …

Herbivorous Turtle Ants Obtain Essential Nutrients From A Conserved Nitrogen-Recycling Gut Microbiome, Yi Hu, Jon G. Sanders, Piotr Łukasik, Catherine L. D'Amelio, Mark P. Schotanus

University Faculty Publications and Creative Works

Nitrogen acquisition is a major challenge for herbivorous animals, and the repeated origins of herbivory across the ants have raised expectations that nutritional symbionts have shaped their diversification. Direct evidence for N provisioning by internally housed symbionts is rare in animals; among the ants, it has been documented for just one lineage. In this study we dissect functional contributions by bacteria from a conserved, multi-partite gut symbiosis in herbivorous Cephalotes ants through in vivo experiments, metagenomics, and in vitro assays. Gut bacteria recycle urea, and likely uric acid, using recycled N to synthesize essential amino acids that are acquired by …

Insights Into The Reactivation, Regulation And Essentiality Of Oxidative Protein Folding Pathways In Actinobacteria, Belkys Sanchez

Dissertations & Theses (Open Access)

Accurate disulfide bond formation is important for proper folding, stability and function of exported proteins. The process of disulfide bond formation, termed oxidative protein folding, is catalyzed by thiol-disulfide oxidoreductase enzymes. Oxidative protein folding pathways influence processes essential for bacterial physiology and pathogenicity. In the Gram-positive actinobacterial pathogens Actinomyces oris and Corynebacterium diphtheriae oxidative protein folding is catalyzed by the primary thiol-disulfide oxidoreductase MdbA. MdbA is required for assembly of adhesive pilus, which mediate receptor-dependent bacterial interactions, or coaggregation, in A. oris. In the first part of this dissertation, I identify components of the electron transport chain (ETC) required for …

Mastering Mycological Mysteries With Explorations Of Harpellales Associated With Culicidae And Other Dipterans In Idaho, Michael Mccormick

Boise State University Theses and Dissertations

Presented is the first field survey and laboratory-based study focused on Harpellales gut fungi found in Culicidae (mosquito) larvae collected from various parts of Idaho. Overall, 34 sites were sampled ranging from urban storm drains and irrigation puddles to pristine stream-side puddles. These sites yielded 17 different species of mosquitoes and three previously described species of gut fungi. Three species of mosquitoes were the first recorded observations as hosts of the following gut fungi: Culiseta alaskaensis was infested with Zancudomyces culisetae (from Renwyck Creek), Culex tarsalis with Smittium culicis (from Cottonwood Creek), and Ochleratus sp. with Smittium minutisporum (from Bear …

The Antimicrobial Properties Of Honey And Their Effect On Pathogenic Bacteria, Shreena Himanshu Mody

Theses and Dissertations

Honey has been used to heal wounds since ancient times. There are many references in ancient literature that cite honey for its medicinal uses. It is used as an alternative agent to cure infections of wounds, burns, ulcers etc. Researchers have shown some of the antimicrobial properties of honey when used as an ointment. When applied to an affected area, it helps to promote the growth of healthy tissue. One of the factors on which the quality of the honey depends, is its geographical origin. Based on the location, honey types can vary as much as 100-fold from each other …

Galleria Mellonella As An Alternate Infection Model For Burkholderia Species And A Comparison Of Suspension And Surface Test Methods For Evaluating Sporicidal Efficacy, Joseph D. Thiriot

Theses and Dissertations

Melioidosis is a neglected tropical disease that continues unabated in many countries, particularly in Southeast Asia. There is no vaccine and antimicrobial treatment is expensive and complicated. Virulence models are important tools used to investigate genes involved in pathogenesis. Galleria mellonella is the larvae of the wax worm moth that has been used to model various infections. Based on previous studies, we attempted to establish an infection model using Burkholderia pseudomallei and Burkholderia thailandensis, a related species which is avirulent in humans. Injections of various forms of these species (fresh and frozen) were used to develop Kaplan-Meier plots. We …

The Effects Of Seasonal Variations In Chemistry And Hydrology On The Microbial Community And Its Sulfide Oxidation Potential In A Naturally Acidic Maine Stream, Raymond C. Kahler Iii

Electronic Theses and Dissertations

Sulfide minerals oxidize through interaction with water and oxygen, releasing hydrogen ions. The process often occurs naturally near metal sulfide deposits, and can be accelerated through mining. Microorganisms accelerate the rate of sulfide oxidation. Acidified streams typically contain high metal concentrations (e.g. aluminum) and microbes in these systems may develop resistances to metal toxicity. Stream flow can affect sulfide oxidation and microbial community structure. Baseflow can influence stream chemistry from interactions with the surrounding bedrock, while stormflow affects stream chemistry and the local microbial community through dilution and addition of microbes transported by runoff. Microbial community composition is affected by …

Host Mediated Mechanisms Of Fungal Cell Spread In A Transparent Zebrafish Infection Model, Allison Scherer

Electronic Theses and Dissertations

Innate immunity has developed elegant processes for the detection and clearance of invasive fungal pathogens. Disseminated candidiasis is of significant concern for those with suppressed immune systems or indwelling medical equipment, and mortality in these groups approaches 70%. Poor patient outcomes have spurred the need to understand how this non-motile pathogen spreads in the host. Technical limitations have previously hindered our ability to visualize the role of innate immunity and host tissue barriers in the spread of C. albicans in vivo. Using the zebrafish model to overcome these limitations, we have examined three potential host-mediated mechanisms of dissemination: movement …

Aqueous Ozone Inactivation Of Viruses And Bacteria On Biotic And Abiotic Surfaces, Cailin Dawley

Graduate Theses and Dissertations

Produce is susceptible to contamination by foodborne pathogens. Food service establishments utilize sanitizing agents to reduce microbes on produce surfaces. The research objectives were to evaluate the efficacy of aqueous ozone 1) on the inactivation of viruses and bacteria on produce; 2) on the inactivation of viruses on stainless steel; and 3) against viruses in association with bacteria on produce surfaces. For objective 1, Boston bibb lettuce and cherry tomatoes were spot inoculated with a cocktail of viruses (murine norovirus (MNV) and MS2 bacteriophage) or bacteria (Enterobacter cloacae and Bacillus cereus) and washed for 40 min with samples taken every …

Genetic And Genomic Analyses Of Bacterial Responses To Different Stress Environments, Sakshi Rampal

Graduate Theses and Dissertations

Bacteria encounter a plethora of environmental stresses and have evolved different mechanisms to recognize and respond to various harmful conditions. Understanding and elucidating common themes as well as unique aspects of the molecular mechanisms underlying stress adaptation is important and can provide valuable strategies for applications. This study focuses on stress responses in three different bacteria, namely, Acidothermus cellulolyticus, Mycobacterium smegmatis and Escherichia coli. The thermophilic and acidophilic organism A. cellulolyticus was used as a model system to understand the effects of lignin phenolic acids on cellulolytic bacteria. Lignin phenolic acids pose a significant challenge to microbial deconstruction of lignocellulosic …

Virulence Regulation In Pseudomonas Aeruginosa Via The Alginate Regulators, Algu And Algr, The Posttranscriptional Regulator, Rsma, And The Two-Component System, Algz/R, Sean Stacey

Electronic Theses and Dissertations

Pseudomonas aeruginosa is a Gram-negative bacillus able to colonize a wide variety of environments. In the human host, P. aeruginosa can establish an acute infection or persist and create a chronic infection. P. aeruginosa is able to establish a niche and persist in human hosts by using a wide array of virulence factors used for: movement, killing host cells, and evading immune cells and antibiotics. Understanding virulence factors and their regulation has proved to be an important means of combating the morbidity and mortality of P. aeruginosa as well as the ever-increasing threat of drug resistance. By targeting virulence factors …

Investigation Of Novel Virulence Mechanisms In Candida Albicans, Elisa Marie Tafoya Vesely

Dissertations & Theses (Open Access)

Candida albicans is the most important fungal species associated with humans. Normally present in the human microbiome as a commensal colonizer, C. albicans is also the fourth most prevalent organism isolated from bloodstream infections in hospitals. Disseminated infections have an associated mortality rate of around 40%. The results of the work described in this dissertation cover the broad subject of C. albicans adaptation to the host and the mechanisms by which this organism is able to survive and cause infection through a variety of means. A key determinant in disease progression is interaction with innate immune cells, specifically macrophages and …

Assessment Of Salmonella Enterica Biofilms And Expression Differences Among Serovars, Zhaohao Shi

Graduate Theses and Dissertations

Biofilms are communities of microorganisms associated by a matrix of extracellular polymers. In this state, microorganisms occupy an ecological niche distinct from their free-floating, planktonic counterparts. Also, biofilm bacteria become biologically unique as they form communities and lose motility. The acquisition of these physiological attributes enables the biofilm to persist through harsh environmental conditions, including antimicrobial induced stress and to resist sanitization efforts. Because of these features, biofilms can rapidly disseminate across numerous surfaces and as they establish, become challenging to remove. This is a particular issue for the food industry as processing plants offer favorable conditions for biofilm formation …

Distribution Of Dengue And Zika Virus Igg Immunoglobulin, Madison Smith, Awadalkareem Adam, Anuja Mathew

Senior Honors Projects

Introduction. Dengue Virus (DENV) and Zika Virus (ZIKV) are viruses that belong to the Flavivirus family. They are transmitted by the Aedes aegypti species of mosquitoes. Infection with DENV can result in no symptoms, mild symptoms which include fever, rash, and headache (dengue fever) or more severe symptoms which include hemorrhage, dengue hemorrhagic fever (DHF) and shock, dengue shock syndrome (DSS). ZIKV, until recently caused mild disease but an outbreak in Brazil was associated with fetal complications such as microcephaly or Guillain-Barré syndrome in adults. Due to the similarity between ZIKV and DENV, antibodies (Abs) generated in humans to these …

Methanogens, Plausible Extraterrestrial Life Forms On Mars, And Their Tolerance To Increasing Concentrations Of Illite Clay, Chandler Kern

Biological Sciences Undergraduate Honors Theses

Methanogens, some of Earth’s most primitive prokaryotic organisms, are candidates for possible life forms capable of inhabiting Mars. Specifically, four different species (Methanobacterium formicicum, Methanococcus maripaludis, Methanosarcina barkeri, Methanothermobacter wolfeii) were analyzed for their tolerance to the presence of illite clay. Illite is a crystalline mineral that has been identified from regions of Mars’s surface. Results indicated that all four species grew with some success in the illite at different concentrations. This experimentation with methanogens’ abilities to survive and reproduce in the presence of illite allows for a more accurate understanding of the potential capability of microbial …

Assembly And Display Of Surface Proteins In Actinomyces Oris, Sara Siegel

Dissertations & Theses (Open Access)

Bacteria are an integral part of human health and disease. In the human host, dental plaques form as a result of up to 700 individual bacterial species colonizing oral surfaces and forming a multispecies biofilm. These biofilms are the cause of prevalent human diseases such as dental caries, gingivitis, and periodontitis. The microbes present in the oral biofilm are highly spatially and temporally structured and require a primary colonizing species to adhere to host tissue. As an important primary colonizer of the oral biofilm, the actinobacterium Actinomyces oris utilizes cell wall anchored proteins and glycoconjugates to initiate adherence to host …

Investigating The Single Cell Heterogeneity And Physiological Impact Of Mistranslation, Christopher Evans

Dissertations & Theses (Open Access)

Bacterial populations grow clonal populations; however, individual cells have a variety of phenotypes. The physiological heterogeneity observed in populations has been attributed to variations in the processes of gene expression. For example, promoter expression has been shown to be heterogeneous within a population and contribute to increased stress tolerance in a subpopulation of cells. In comparison to transcription, the influence of translation on single cells is unclear. In this study, my collaborators and I have developed a dual-fluorescence reporter that allows us to measure the mistranslation rate in single cells in vivo. Using this reporter, we found that mistranslation …

The Role Of Non-Neuronal Acetylcholine In Urogenital Chlamydial Infection, Jessica R. Lockhart

Electronic Theses and Dissertations

Chlamydia trachomatiscauses a bacterial sexually transmitted infection, Chlamydia, that is often chronic and casues reproductive complications in women. We hypothesized that Chlamydia infection increases local acetylcholine (ACh) production, which regulates the host’s inflammatory response to the infection. Female mice infected with C. muridarumwere sacrificed at days 3, 9, 15, and 21 post-infection, genital tract tissues harvested, and immunohistochemistry performed to enumerate ACh-producing cells. Infection increased the number of ACh-producing cells in cervical tissue at days 3,15, and 21 post-infection (pi), uterine tissue at day 3 and 9 pi, and ovarian tissue day 3, 15, and 21 pi. These …

Stress Response Mechanisms Of Listeria Monocytogenes, Oindrila Paul

Dissertations

Listeria monocytogenes is a Gram-positive, facultative intracellular food-borne pathogen that causes the disease listeriosis. In order to establish an infection, L. monocytogenes must survive multiple stressors encountered within the gastrointestinal tract, including alterations in pH, bile, salt, and oxygen availability. This dissertation focused on understanding the stress response of L. monocytogenes to bile. Bile acts as a bactericidal agent by disrupting the membrane integrity and causing instability to macromolecules like DNA. Thus, a bacterium must be able to maintain its membrane architecture, composition and integrity.

Often times, bacteria will modulate their fatty acid composition in the membrane to cope with …