Microbiology Commons^™

Neurosteroid-Mediated Regulation Of Brain Innate Immunity In Hiv/Aids: Dhea-S Suppresses Neurovirulence, Amber Paul, Ferdinand G. Maingat, Maria J. Polyak, Pornpun Vivithanaporn, Farshid Noorbakhsh, Samir Ahboucha, Glen B. Baker, Keir Pearson, Christopher Power

Publications

Neurosteroids are cholesterol-derived molecules synthesized within the brain, which exert trophic and protective actions. Infection by human and feline immunodeficiency viruses (HIV and FIV, respectively) causes neuroinflammation and neurodegeneration, leading to neurological deficits. Secretion of neuroinflammatory host and viral factors by glia and infiltrating leukocytes mediates the principal neuropathogenic mechanisms during, although the effect of neurosteroids on these processes is unknown. We investigated the interactions between neurosteroid mediated effects and lentivirus infection outcomes. Analyses of HIV-infected uninfected human brains disclosed a reduction in neurosteroid synthesis enzyme expression. Human neurons exposed to supernatants from HIV macrophages exhibited suppressed enzyme expression without …

The Determinants Of Helminth Infection In Baboons, Rita Monfort

Publications and Research

THE DETERMINANTS OF HELMINTH INFECTION IN BABOONS

Summary Paragraph:

Intestinal parasitic helminths are common in wild primate populations [1, 2] and can impose a significant burden on their host’s fitness. Numerous factors can affect the prevalence and diversity of intestinal parasites in natural populations including environmental factors [3, 4], the host’s behavior and genetics [5, 6]. How these different factors interact in natural populations remains unclear. This is in all probability due to the fact that previous studies have seldom looked at the prevalence and diversity of parasitic helminths in the same species but in different habitats over periods longer …

Helicobacter Pylori Hydrogenase Accessory Protein Hypa And Urease Accessory Protein Ureg Compete With Each Other For Uree Recognition, Stéphane L. Benoit, Jonathan L. Mcmurry, Stephanie A. Hill, Robert J. Maier

Faculty Articles

Background: The gastric pathogen Helicobacter pylori relies on nickel-containing urease and hydrogenase enzymes in order to colonize the host. Incorporation of Ni2+ into urease is essential for the function of the enzyme and requires the action of several accessory proteins, including the hydrogenase accessory proteins HypA and HypB and the urease accessory proteins UreE, UreF, UreG and UreH. Methods: Optical biosensing methods (biolayer interferometry and plasmon surface resonance) were used to screen for interactions between HypA, HypB, UreE and UreG. Results: Using both methods, affinity constants were found to be 5nM and 13nM for HypA–UreE and 8μM and 14μM for …

Characterization Of Xylan Utilization And Discovery Of A New Endoxylanase In Thermoanaerobacterium Saccharolyticum Through Targeted Gene Deletions, Kara K. Podkaminer, Adam M. Guss, Heather L. Trajano, David A. Hogsett, Lee R. Lynd

Dartmouth Scholarship

The economical production of fuels and commodity chemicals from lignocellulose requires the utilization of both the cellulose and hemicellulose fractions. Xylanase enzymes allow greater utilization of hemicellulose while also increasing cellulose hydrolysis. Recent metabolic engineering efforts have resulted in a strain of Thermoanaerobacterium saccharolyticum that can convert C5 and C6 sugars, as well as insoluble xylan, into ethanol at high yield. To better understand the process of xylan solubilization in this organism, a series of targeted deletions were constructed in the homoethanologenic T. saccharolyticum strain M0355 to characterize xylan hydrolysis and xylose utilization in this organism. While the deletion of …

Borrelia Burgdorferi Cp32 Bpab Modulates Expression Of The Prophage Nucp Nuclease And Ssbp Single-Stranded Dna-Binding Protein, Alicia M. Chenail, Brandon L. Jutras, Claire A. Adams, Logan H. Burns, Amy Bowman, Ashutosh Verma, Brian Stevenson

Microbiology, Immunology, and Molecular Genetics Faculty Publications

The Borrelia burgdorferi BpaB proteins of the spirochete's ubiquitous cp32 prophages are DNA-binding proteins, required both for maintenance of the bacteriophage episomes and for transcriptional regulation of the cp32 erp operons. Through use of DNase I footprinting, we demonstrate that BpaB binds the erp operator initially at the sequence 5′-TTATA-3′. Electrophoretic mobility shift assays indicated that BpaB also binds with high affinity to sites located in the 5′ noncoding regions of two additional cp32 genes. Characterization of the proteins encoded by those genes indicated that they are a single-stranded DNA-binding protein and a nuclease, which we named SsbP and NucP, …

Genomic Characteristics Of An Environmental Microbial Community Harboring A Novel Human Uncultured Tm7 Bacterium Associated With Oral Diseases, Michael Abrams, David Barton, Eamon Vandaei, Diana Romero, Adam Caldwell, Cleber C. Ouverney

Faculty Publications, Biological Sciences

The diversity of prokaryotes associated with humans has been dominated by uncultured species (not isolated in pure culture). For instance, nearly 80% of the human gut and 68% of the human oral microbes are thought to be uncultured; some of which have been associated with human oral, digestive, vaginal, and cardiovascular diseases. The revalence of uncultured pathogens is expected to continue to increase within the near future. In fact, public databases such as GenBank have nearly quadrupled the number of candidate phyla (those made entirely of uncultured organisms) since the 1980s and currently lists many new lineages of unclassified Bacteria …

Differential Virus Host-Ranges Of The Fuselloviridae Of Hyperthermophilic Archaea: Implications For Evolution In Extreme Environments, Ruben M. Ceballos, Caleb D. Marceau, Joshua O. Marceau, Steven Morris, Adam J. Clore, Kenneth M. Stedman

Biology Faculty Publications and Presentations

An emerging model for investigating virus-host interactions in hyperthermophilic Archaea is the Fusellovirus-Sulfolobus system. The host, Sulfolobus, is a hyperthermophilic acidophile endemic to sulfuric hot springs worldwide. The Fuselloviruses, also known as Sulfolobus Spindle-shaped Viruses (SSVs), are "lemon" or "spindle"-shaped double-stranded DNA viruses, which are also found worldwide. Although a few studies have addressed the host-range for the type virus, Sulfolobus Spindle-shaped Virus 1 (SSV1), using common Sulfolobus strains, a comprehensive host-range study for SSV-Sulfolobus systems has not been performed. Herein, we examine six bona fide SSV strains (SSV1, SSV2, SSV3, SSVL1, SSVK1, SSVRH) and their respective infection characteristics on …

Loss Of The Lipopolysaccharide Core Biosynthesis Rfad Gene Increases Antimicrobial Chemokine Binding And Bacterial Susceptibility To Ccl28 And Polymyxin: A Model For Understanding The Interface Of Antimicrobial Chemokines And Bacterial Host Defense Avoidance Mechanisms, Cynthia S. Lew

Theses and Dissertations

In order to better understand the mechanism of antimicrobial chemokine activity, including binding to and killing of bacteria, random transposon mutagenesis was performed in Yersinia pseudotuberculosis. Resulting mutants were screened for increased binding to chemokine and high binding clones were selected for further study. One mutant, designated mutant 27, was found to have a single insertion mutation in the rfaD gene. The rfaD gene product is involved in heptose biosynthesis, one of the sugars of the inner core oligosaccharide of Gram- negative lipopolysaccharide (LPS). Mutant 27 was found to bind both CCL25 and CCL28, two antimicrobial chemokines, more efficiently than …

Formation And Characterization Of Non-Growth States In Clostridium Thermocellum: Spores And L-Forms, Elizabeth B. Mearls, Javier A. Izquierdo, Lee R. Lynd

Dartmouth Scholarship

Clostridium thermocellum is an anaerobic thermophilic bacterium that exhibits high levels of cellulose solublization and produces ethanol as an end product of its metabolism. Using cellulosic biomass as a feedstock for fuel production is an attractive prospect, however, growth arrest can negatively impact ethanol production by fermentative microorganisms such as C. thermocellum. Understanding conditions that lead to non-growth states in C. thermocellum can positively influence process design and culturing conditions in order to optimize ethanol production in an industrial setting.

Antony Van Leeuwenhoek: Creation “Magnified” Through His Magnificent Microscopes, Alan L. Gillen, Douglas Oliver

Faculty Publications and Presentations

Although van Leeuwenhoek was not the inventor of the microscope, he advanced it more than anyone else for seeing living things.

Antony van Leeuwenhoek1 (Fig. 1) found great joy in God’s smallest creatures. He first discovered protozoans in his youth. The Dutch haberdasher retained a child-like joy of discovery from his youth until his death at age 90. He lived to see tiny microbes though his homemade microscopes. He loved to grind and focus a new lens in order to see the unseen world. Leeuwenhoek spent countless hours grinding tiny lenses and looking through them. This Christian lay biologist …

Farnesol And Cyclic Amp Signaling Effects On The Hypha-To-Yeast Transition In Candida Albicans, Allia K. Lindsay, Aurélie Deveau, Amy E. Piispanen, Deborah A. Hogan

Dartmouth Scholarship

Candida albicans, a fungal pathogen of humans, regulates its morphology in response to many environmental cues and this morphological plasticity contributes to virulence. Farnesol, an autoregulatory molecule produced by C. albicans, inhibits the induction of hyphal growth by inhibiting adenylate cyclase (Cyr1). The role of farnesol and Cyr1 in controlling the maintenance of hyphal growth has been less clear. Here, we demonstrate that preformed hyphae transition to growth as yeast in response to farnesol and that strains with increased cyclic AMP (cAMP) signaling exhibit more resistance to farnesol. Exogenous farnesol did not induce the hypha-to-yeast transition in mutants …

The Crispr/Cas Adaptive Immune System Of Pseudomonas Aeruginosa Mediates Resistance To Naturally Occurring And Engineered Phages, Kyle C. Cady, Joe Bondy-Denomy, Gary E. Heussler, Alan R. Davidson, George A. O'Toole

Dartmouth Scholarship

Here we report the isolation of 6 temperate bacteriophages (phages) that are prevented from replicating within the laboratory strain Pseudomonas aeruginosa PA14 by the endogenous CRISPR/Cas system of this microbe. These phages are only the second identified group of naturally occurring phages demonstrated to be blocked for replication by a nonengineered CRISPR/Cas system, and our results provide the first evidence that the P. aeruginosa type I-F CRISPR/Cas system can function in phage resistance. Previous studies have highlighted the importance of the protospacer adjacent motif (PAM) and a proximal 8-nucleotide seed sequence in mediating CRISPR/Cas-based immunity. Through engineering of a protospacer …

Analysis Of Microbial Diversity By Amplicon Pyrosequencing, Ryan Legge

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Microorganisms numerically dominate terrestrial biodiversity, and play important biochemical and geochemical roles in the environments they inhabit. To understand structure and function of complex ecosystems, it is essential to identify primary drivers of microbial diversity and community structure. Historically, the study of microbial ecology was reductive, limited to microbes able to be cultured and enumerated. Microbes meeting this criterion were thought to comprise the dominating members of the environments they were isolated from, however, estimates suggesting up to 99% of the endogenous species are uncultivable with existing methodologies; a concept that reflects experimental failure, rather than a verifiable conclusion. Therefore …

Characterizing The Role Of Hspb2 In Cardiac Metabolism And Muscle Structure Using Yeast And Mammalian Systems, Jonathan Paul Neubert

Theses and Dissertations

HspB2 is a small heat shock protein encoded on human chromosome 11. Less than 1000 base pairs away from HSPB2 and situated in a head-to-head orientation lies the gene encoding another small heat shock protein, CRYAB. Because they are uncommonly close to one another they share regulatory elements. In addition, they share protein homology as sHSPs, suggesting that they perhaps perform aimilar functions. SHSPs such as HspB2 and CryAB are traditionally thought to provide protective effects to cells in response to a variety of stress inducers. In response to stress they form complexes around misfolded proteins or proteins in danger …

Characterization Of The Cellular And Organellar Dynamics That Occur With A Partial Depletion Of Mitochondrial Dna When Arabidopsis Organellar Dna Polymerase Ib Is Mutated, John D. Cupp

Theses and Dissertations

Plant mitochondrial genomes are large and complex, and the mechanisms for maintaining mitochondrial DNA (mtDNA) remain unclear. Arabidopsis thaliana has two DNA polymerase genes, polIA and polIB, that have been shown to be dual localized to mitochondria and chloroplasts but are unequally expressed within primary plant tissues involved in cell division or cell expansion. PolIB expression is observed at higher levels in both shoot and root apexes, suggesting a possible role in organelle DNA replication in rapidly dividing or expanding cells. It is proposed that both polIA and polIB are required for mtDNA replication under wild type conditions. An Arabidopsis …

Minor Pilins Of The Type Iv Pilus System Participate In The Negative Regulation Of Swarming Motility, S L. Kuchma, E. F. Griffin, G. A. O'Toole

Dartmouth Scholarship

Pseudomonas aeruginosa exhibits distinct surface-associated behaviors, including biofilm formation, flagellum-mediated swarming motility, and type IV pilus-driven twitching. Here, we report a role for the minor pilins, PilW and PilX, components of the type IV pilus assembly machinery, in the repression of swarming motility. Mutating either the pilW or pilX gene alleviates the inhibition of swarming motility observed for strains with elevated levels of the intracellular signaling molecule cyclic di-GMP (c-di-GMP) due to loss of BifA, a c-di-GMP-degrading phosphodiesterase. Blocking PilD peptidase-mediated processing of PilW and PilX renders the unprocessed proteins defective for pilus assembly but still functional in c-di-GMP-mediated swarming …

Analyzing Environmental Microbes For Genomic Regions Promoting Ionic Liquid Tolerance In E. Coli, Ann Nguyen, Alison Richins, Thomas Rüegg, Steven Singer, Michael Thelen

STAR Program Research Presentations

Ionic liquids (ILs) are promising as solvents to increase the efficiency of biofuel production; however, ILs are toxic to microbes used in the fermentation of liquid fuels. To engineer IL resistant biofuel hosts, environmental bacteria were screened for tolerance, and these were used to create gene libraries to test in E. coli. Future characterization of these libraries using molecular techniques will be used to identify genes that contribute IL-tolerance to transformed microbes.

Study Of Cellular Responses Under Chemically Induced Hypoxia, George Coricor

Theses

No abstract provided.

Survival Of B. Horneckiae Spores Under Ground-Simulated, Sneha Tharayil, Parag Vaishampayan

STAR Program Research Presentations

Increasing efforts to find and study habitable conditions and the possibility of life on extraterrestrial cosmic bodies have also deepened the need for planetary protection advancements to prevent possibilities of forward and backward contamination. Despite stringent precautions to ensure spacecraft cleanliness, a number of spore-forming bacteria, including the biofilm forming strain, Bacillus horneckiae have been isolated from spacecraft associated surfaces. B. horneckiae spores have demonstrated unusually high resistance to rigorous sterilization procedures, and extreme conditions, including intense UV radiation. This exceptionally high tolerance of extreme conditions demonstrated by spore-forming bacteria highlighted the need to assess the viability of these microbes …

A Genome-Wide Over-Expression Screen Identifies Genes Involved In Phagocytosis In The Human Protozoan Parasite, Entamoeba Histolytica, Ada V. King, Brenda H. Welter, Amrita B. Koushik, Lindsay N. Gordon, Lesly A. Temesvari

Publications

Functional genomics and forward genetics seek to assign function to all known genes in a genome. Entamoeba histolytica is a protozoan parasite for which forward genetics approaches have not been extensively applied. It is the causative agent of amoebic dysentery and liver abscess, and infection is prevalent in developing countries that cannot prevent its fecal-oral spread. It is responsible for considerable global morbidity and mortality. Given that the E. histolytica genome has been sequenced, it should be possible to apply genomic approaches to discover gene function. We used a genome-wide over-expression screen to uncover genes regulating an important virulence function …

Transgene Delivery Via Microelectromechanical Systems, Aubrey Marie Mueller Wilson

Theses and Dissertations

The invention of pronuclear microinjection initiated the field of transgenic research. Over 30 years later microinjection remains the most straight-forward and most commonly used transgene delivery option. In this work we address the current progress of microelectromechanical systems (MEMS) used as transgenic delivery mechanisms. The nanoinjector is a specially designed MEMS device which uses electrostatic charge to manipulate transgene molecules. The process of nanoinjection was designed as an alternative to microinjection which causes less damage to developing embryos, improves embryo survival, birth rates, and overall efficiency of injections. In vivo testing of nanoinjection demonstrates it is both safe and effective. …

Production And Degradation Of 4-Ethylphenol In Lactobacillus Sp. Pep8 Cultures And In Blended Swine Lagoon Enrichments, Clinton W. Copp

Masters Theses & Specialist Projects

4-Ethylphenol (4-EP) is a malodorant of swine waste and is derived from a component of lignin called p-coumaric acid (p-CA). The production of 4-EP from lignin in swine waste is untested. Additionally, the effect of Fe (III) on 4-EP levels is unknown. Four experiments were performed to determine if Lactobacillus sp. pep8 cultures, as well as enriched swine lagoon slurries, could liberate p-CA from lignin and convert p-CA to 4-EP. Furthermore, it was tested if the addition of Fe (III) influences the conversion of p- CA to 4-EP.

Experiment 1 tested Lactobacillus sp. pep8 cultures to determine if the addition …

In Vivo Quantification Reveals Extensive Natural Variation In Mitochondrial Form And Function In Caenorhabditis Briggsae, Kiley Ann Hicks, Dana K. Howe, Aubrey Leung, Dee R. Denver, Suzanne Estes

Biology Faculty Publications and Presentations

We have analyzed natural variation in mitochondrial form and function among a set of Caenorhabditis briggsae isolates known to harbor mitochondrial DNA structural variation in the form of a heteroplasmic nad5 gene deletion (nad5Δ) that correlates negatively with organismal fitness. We performed in vivo quantification of 24 mitochondrial phenotypes including reactive oxygen species level, membrane potential, and aspects of organelle morphology, and observed significant among- isolate variation in 18 traits. Although several mitochondrial phenotypes were non-linearly associated with nad5Δ levels, most of the among-isolate phenotypic variation could be accounted for by phylogeographic clade membership. In particular, isolate-specific mitochondrial membrane potential …

Inhibition Of Burkholderia Multivorans Adhesion To Lung Epithelial Cells By Bivalent Lactosides, Ciara Wight, Rosaria Leyden, Paul V. Murphy, Máire Callaghan, Trinidad Velasco-Torrijos, Siobhan Mcclean

Articles

Burkholderia cepacia complex (Bcc) is an opportunistic pathogen in cystic fibrosis patients which is inherently resistant to antimicrobial agents. The mechanisms of attachment and pathogenesis of Bcc, a group of 17 species, are poorly understood. The most commonly identified Bcc species in newly colonised patients, Burkholderia multivorans, continues to be acquired from the environment. Development of therapies which can prevent or reduce the risk of colonization on exposure to Bcc in the environment would be a better alternative to antimicrobial agents. Previously, it has been shown that Bcc strains bound to many glycolipid receptors on lung epithelia. Using a …

Host-Microbe-Diet Interplay: Dietary Modulation Of The Gut Microbiota In Relation To Health, Inés Martínez

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Vertebrates are associated with trillions of bacteria, with the densest populations residing in the large intestine. The symbiosis between vertebrates and their gut microbiota has resulted in important implications of the gut microbiome on host health. Diet is an important factor that shapes gut microbiota composition, and because of the interplay between host-microbiome-diet, dietary strategies that modulate gut microbiome structure are deemed a relevant tool to improve host health. However, gaps in knowledge exist with respect to these interactions, and it is essential to obtain a mechanistic understanding of how these relations take place to develop successful therapeutic strategies that …

Amyloid-Beta42 Toxicity Reduction In Human Neuroblastoma Cells Using Cholera Toxin B Subunit-Myelin Basic Protein Expressed In Chloroplasts, Alexandra Ayache

HIM 1990-2015

Alzheimer's disease (AD) is an age progressive neurodegenerative brain disorder, affecting 37 million people worldwide. Cleavage of amyloid precursor protein by ?- and ?-secretase produces the amyloid-beta (A?) protein, which significantly contributes to AD pathogenesis. The A? aggregates, formed at the surface of neurons and intracellularly, cause neurotoxicity and decrease synaptic function. Inhibiting or degrading A? accumulation is a key goal for development of new AD treatments. Evidence shows that human Myelin Basic Protein (MBP) binds to and degrades A? thereby, preventing cytotoxicity. A potential method for oral drug delivery that will allow plant-derived bioencapsulated MBP to pass through intestinal …

Multiple Aspects Of Natural Killer Cell Expansion In Relevance To Immunotherapy For Hematologic Malignancies, Dominic Colosimo

HIM 1990-2015

Natural Killer (NK) cells are a subset of lymphocytes that regulate adaptive immune responses and utilize "missing self" recognition to activate anti-tumor and anti-viral cytotoxicity. Clinical research, as well as murine and ex vivo models, have shown that a variety of NK cell applications have proven useful as immunotherapeutic treatments for patients with hematologic malignancies. However, the selective expansion of NK cells to yield relevant amounts of these lymphocytes has been a major hurdle in the development of methods for clinical therapeutic use. Here, we demonstrate a novel ex vivo expansion method utilizing k562 leukemic cell lines and soluble cytokines …

Effects Of Moisture Augmentation Of Municipal Solid Waste Through Addition Of Food Waste Or Wastewater Treatment Biosolids On Bio-Gas Formation For Power Generation, Jared Michael Gore

UNLV Theses, Dissertations, Professional Papers, and Capstones

An investigation into the effect of moisture augmentation by manipulation of food waste proportion or wastewater treatment plant biosolids proportion was undertaken to determine the effects on production of methane and other biogases from municipal solid waste (MSW). Laboratory microcosm experiments were performed to determine the effect of various proportions of influent waste streams on the production of biogas. Results indicated that moisture augmentation through the addition of food waste to MSW increases the overall bio-gas and hydrogen gas formed during fermentation. Moisture augmentation through addition of wastewater treatment bio-solids lead to inconclusive results. Addition of food waste to MSW …

Cell Bioenergetics In Leghorn Male Hepatoma Cells And Immortalized Chicken Liver Cells In Response To 4-Hydroxynonenal Induced Oxidative Stress, Alissa Laura Piekarski

Graduate Theses and Dissertations

Bioenergetic mechanisms responsible for ATP production are essential in carrying out maintenance and cell-specific functions. In this study, hepatocytes (liver cells) were used to test both endogenous and exogenous stress on cellular respiration. The secondary lipid peroxide, 4-hydroxynonenal (HNE), was used because it alters bioenergetics by increasing mitochondrial proton leak that attenuates mitochondrial radical production and, therefore, endogenous oxidative stress. The major objective of this study was to demonstrate effects of HNE-induced oxidative stress on avian hepatocyte bioenergetics. Various chemical which help enable the determination of oxygen (O2) consumption linked to ATP synthesis (oligomycin), maximal O2 consumption (FCCP), and proton …

Systems Biology Approaches To Probe Gene Regulation In Bacteria, Diogo F. Troggian Veiga

Dissertations and Theses (Open Access)

Mechanisms that allow pathogens to colonize the host are not the product of isolated genes, but instead emerge from the concerted operation of regulatory networks. Therefore, identifying components and the systemic behavior of networks is necessary to a better understanding of gene regulation and pathogenesis. To this end, I have developed systems biology approaches to study transcriptional and post-transcriptional gene regulation in bacteria, with an emphasis in the human pathogen Mycobacterium tuberculosis (Mtb).

First, I developed a network response method to identify parts of the Mtb global transcriptional regulatory network utilized by the pathogen to counteract phagosomal stresses …