Microbiology Commons^™

The Role Of Transcription In Stationary Phase Mutagenesis In Bacillus Subtilis, Holly Anne Martin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Stationary phase mutagenesis, also known as stress-induced or adaptive mutagenesis, is defined as the accumulation of mutations during conditions of no net growth or conditions of stress. This process has been implicated in acquiring antibiotic resistance and evasion of host immune responses in microbial pathogens and in the generation of mutations that lead to neoplasia in animal cells. Previous work has shown that defects in DNA synthesis and repair systems contribute to the formation of adaptive mutations; however the role of transcription in the accumulation of mutations is still being examined. It is speculated that transcriptional derepression leads to an …

Cellular Immunity In Mouse Models Of Viral Encephalitis, Christina Dawn Steel

Theses and Dissertations in Biomedical Sciences

Evidence is presented herein that intranasal application of vesicular stomatitis virus (VSV) caused acute infection of the murine central nervous system (CNS) with associated morbidity and significant mortality in mice. However, VSV encephalitis was not invariably fatal, suggesting that the CNS contained a professional antigen-presenting cell (APC) capable of inducing or propagating a protective antiviral immune response. To examine this possibility, we administered VSV via the intranasal route and then characterized the cellular elements that infiltrate the brain as well as the activation status of resident microglia, cells widely believed to represent the major APC population in the CNS. To …

Diversity Of Bacteria And Glycosyl Hydrolase Family 48 Genes In Cellulolytic Consortia Enriched From Thermophilic Biocompost, Javier A. Izquierdo, Maria V. Sizova, Lee R. Lynd

Dartmouth Scholarship

The enrichment from nature of novel microbial communities with high cellulolytic activity is useful in the identification of novel organisms and novel functions that enhance the fundamental understanding of microbial cellulose degradation. In this work we identify predominant organisms in three cellulolytic enrichment cultures with thermophilic compost as an inoculum. Community structure based on 16S rRNA gene clone libraries featured extensive representation of clostridia from cluster III, with one cluster sharing as little as 73% sequence similarity with the closest known relative. In all, 14 new GHF48 gene sequences were added to the known diversity of 35 genes from cultured …

Gene Expression Patterns In Flea Vectors Of Yersinia Pestis, Wei Zhou

Theses and Dissertations

Plague bacteria (Yersinia pestis) are transmitted to susceptible mammals by fleas. At least 25 flea species found in North America have been identified as plague vectors. The most efficient flea vector is the Oriental rat flea Xenopsylla cheopis, while the cat flea Ctenocephalides felis is a poor vector. The factors that determine vector competence of different fleas are not known. The main obstacles that the bacteria must overcome in the flea gut are also unknown. Fleas' molecular responses to Y. pestis invading could be a determining factor to control the bacterial survival and growth. Good and poor …

Maternal Consumption Of Canola Oil Suppressed Mammary Gland Tumorigenesis In C3(1) Tag Mice Offspring, Gabriela Ion, Juliana A. Akinsete, W. Elaine Hardman

Biochemistry and Microbiology

Background: Maternal consumption of a diet high in omega 6 polyunsaturated fats (n-6 PUFA) has been shown to increase risk whereas a diet high in omega 3 polyunsaturated fats (n-3 PUFA) from fish oil has been shown to decrease risk for mammary gland cancer in female offspring of rats. The aim of this study was to determine whether increasing n-3 PUFA and reducing n-6 PUFA by using canola oil instead of corn oil in the maternal diet might reduce the risk for breast cancer in female offspring.

Methods: Female SV 129 mice were divided into two groups and placed on …

Electrically Mediated Delivery Of Plasmid Dna To The Skin, Using A Multielectrode Array, Richard Heller, Yolmari Criz, Loree C. Heller, Richard A. Gilbert, Mark J. Jaroszeski

Bioelectrics Publications

The easy accessibility of skin makes it an excellent target for gene transfer protocols. To take full advantage of skin as a target for gene transfer, it is important to establish an efficient and reproducible delivery system. Electroporation is a strong candidate to meet this delivery criterion. Electroporation of the skin is a simple, direct, in vivo method to deliver genes for therapy. Previously, delivery to the skin was performed by means of applicators with relatively large distances between electrodes, resulting in significant muscle stimulation and pain. These applicators also had limitations in controlling the directionality of the applied field. …

Structural Dynamics And Signaling Roles Of The Aer Pas And F1 Regions, Asharie J. Campbell

Loma Linda University Electronic Theses, Dissertations & Projects

The Aer aerotaxis receptor in Escherichia coli mounts such a rapid response to redox that E. coli changes its swimming behavior within 100 ms after an oxygen pulse. This receptor is a membrane-bound homodimer, and it monitors internal energy (redox) via an FAD cofactor bound to a cytoplasmic N-terminal PAS domain. Understanding PAS sensing is important, as PAS domains comprise a superfamily of more than 25,000 members from all kingdoms. This study focused on the Aer N-terminal PAS sensor, as well as the region tethering it to the membrane anchor, known as the F1. Previous genetic studies on these regions …

Dual-Action Hygienic Coatings: Benefits Of Hydrophobicity And Silver Ion Release And Surface Analysis, Niall Stobie, Brendan Duffy, John Colreavy, Patrick Mchale, Steven Hinder, Declan Mccormack

Articles

Coatings that demonstrate reduced attachment of crystalline precipitates and the medical device colonising Staphylococcus epidermidis were prepared by the immobilisation of silver doped perfluoropolyether–urethane siloxane thin films on glass substrates. The presence of stratified hydrophobic perfluoropolyether groups protects the coating surface from the attachment of crystalline hydrophilic species such as chlorides and phosphates, whilst silver ion release inhibited attachment of S. epidermidis and subsequent biofilm formation in vitro. The release of silver ions protects the perfluoro groups from the hydrophobic interactions of S. epidermidis cells, which can reduce the hydrophobicity of the protective coating. These coatings also exhibited significant antibacterial …

Crystal Structure Of The Cystic Fibrosis Transmembrane Conductance Regulator Inhibitory Factor Cif Reveals Novel Active-Site Features Of An Epoxide Hydrolase Virulence Factor, Christopher D. Bahl, Christophe Morisseau, Jennifer M. Bomberger, Bruce A. Stanton, Bruce D. Hammock, George A. O'Toole, Dean R. Madden

Dartmouth Scholarship

Cystic fibrosis transmembrane conductance regulator (CFTR) inhibitory factor (Cif) is a virulence factor secreted by Pseudomonas aeruginosa that reduces the quantity of CFTR in the apical membrane of human airway epithelial cells. Initial sequence analysis suggested that Cif is an epoxide hydrolase (EH), but its sequence violates two strictly conserved EH motifs and also is compatible with other alpha/beta hydrolase family members with diverse substrate specificities. To investigate the mechanistic basis of Cif activity, we have determined its structure at 1.8-A resolution by X-ray crystallography. The catalytic triad consists of residues Asp129, His297, and Glu153, which are conserved across the …

Farnesol Induces Hydrogen Peroxide Resistance In Candida Albicans Yeast By Inhibiting The Ras-Cyclic Amp Signaling Pathway, Aurélie Deveau, Amy E. Piispanen, Angelyca A. Jackson, Deborah A. Hogan

Dartmouth Scholarship

Farnesol, a Candida albicans cell-cell signaling molecule that participates in the control of morphology, has an additional role in protection of the fungus against oxidative stress. In this report, we show that although farnesol induces the accumulation of intracellular reactive oxygen species (ROS), ROS generation is not necessary for the induction of catalase (Cat1)-mediated oxidative-stress resistance. Two antioxidants, α-tocopherol and, to a lesser extent, ascorbic acid effectively reduced intracellular ROS generation by farnesol but did not alter farnesol-induced oxidative-stress resistance. Farnesol inhibits the Ras1-adenylate cyclase (Cyr1) signaling pathway to achieve its effects on morphology under hypha-inducing conditions, and we demonstrate …

Il-28 Supplants Requirement For Treg Cells In Protein Σ1-Mediated Protection Against Murine Experimental Autoimmune Encephalomyelitis (Eae), Agnieszka Rynda, Massimo Maddaloni, Javier Ochoa-Repáraz, Gayle Callis, David W. Pascual

Dartmouth Scholarship

Conventional methods to induce tolerance in humans have met with limited success. Hence, efforts to redirect tolerogen uptake using reovirus adhesin, protein sigma 1 (pσ1), may circumvent these shortcomings based upon the recent finding that when reovirus pσ1 is engineered to deliver chicken ovalbumin (OVA) mucosally, tolerance is obtained, even with a single dose. To test whether single-dose tolerance can be induced to treat EAE, proteolipid protein (PLP_130–151) was genetically fused to OVA to pσ1 (PLP:OVA-pσ1) and shown to significantly ameliorate EAE, suppressing proinflammatory cytokines by IL-10⁺ forkhead box P3 (FoxP3)⁺ CD25⁺CD4⁺ T …

Genome Sequence Of The Pea Aphid Acyrthosiphon Pisum, The International Aphid Genomics Consortium

Biology Articles and Papers

Aphids are important agricultural pests and also biological models for studies of insect-plant interactions, symbiosis, virus vectoring, and the developmental causes of extreme phenotypic plasticity. Here we present the 464 Mb draft genome assembly of the pea aphid Acyrthosiphon pisum. This first published whole genome sequence of a basal hemimetabolous insect provides an outgroup to the multiple published genomes of holometabolous insects. Pea aphids are host-plant specialists, they can reproduce both sexually and asexually, and they have coevolved with an obligate bacterial symbiont. Here we highlight findings from whole genome analysis that may be related to these unusual biological features. …

Regulation Of Polar Peptidoglycan Biosynthesis By Wag31 Phosphorylation In Mycobacteria, Charul Jani, Hyungjin Eoh, Jae Lee, Khozima Hamasha, Moodakare Sahana, Jeong-Sun Han, Seeta Nyayapathy, Jung-Yeon Lee, Joo-Won Suh, Sang Lee, Steve J. Rehse, Dean C. Crick, Choong-Min Kang

Wayne State University Associated BioMed Central Scholarship

Abstract

Background

Sensing and responding to environmental changes is a central aspect of cell division regulation. Mycobacterium tuberculosis contains eleven Ser/Thr kinases, two of which, PknA and PknB, are key signaling molecules that regulate cell division/morphology. One substrate of these kinases is Wag31, and we previously showed that partial depletion of Wag31 caused morphological changes indicative of cell wall defects, and that the phosphorylation state of Wag31 affected cell growth in mycobacteria. In the present study, we further characterized the role of the Wag31 phosphorylation in polar peptidoglycan biosynthesis.

Results

We demonstrate that the differential growth among cells expressing different …

Real-Time Pcr Method For The Quantification Of Burkholderia Cepacia Complex Attached To Lung Epithelial Cells And Inhibitionn Of That Attachment, Ciara Wight, Gillian Herbert, Ruth Pilkington, Máire Callaghan, Siobhan Mcclean

Articles

To develop a rapid method to quantify the attachment of the cystic fibrosis pathogen, Burkholderia multivorans, to lung epithelial cells (16HBE14o(-)) using real-time PCR with a view to monitoring potential inhibition of lung cell attachment. Mammalian and bacterial DNA were purified from bacteria attached to lung epithelial cells. The relative amount of bacteria attached was determined by amplification of the recA gene relative to the human GAPDH gene, in the presence of SYBR Green. The method was thoroughly validated and shown to correlate well with traditional plating techniques. Inhibition of bacterial attachment with simple sugars was then evaluated by real-time …

Primary Gamma-Herpesviral Infection In Zambian Children, Veenu Minhas, Brad P, Brayfield, Kay L. Crabtree, Chipepo Kankasa, Charles D. Mitchell, Charles Wood

Nebraska Center for Virology: Faculty Publications

Background: HHV-8 is closely related to Epstein-Barr virus (EBV), but the clinical presentations of these two infections in early childhood are not well understood. Also, it is not known whether infection by one virus correlates with another. Here, we compare the natural history of infection by these two viruses along with the clinical manifestations and risk factors that are associated with early childhood infection in Zambia, which is an endemic area for HHV-8.

Methods: This study was conducted in a cohort of 12 month old Zambian children (N = 677). Data on socio-economic status and a wide range …

Localization Of Phosphatidylinositol (3,4,5)-Trisphosphate To Phagosomes In Entamoeba Histolytica Achieved Using Glutathione S-Transferase- And Green Fluorescent Protein-Tagged Lipid Biosensors, Yevgeniya A. Byekova, Rhonda R. Powell, Brenda H. Welter, Lesly A. Temesvari

Publications

Entamoeba histolytica is an intestinal protozoan parasite that causes amoebic dysentery and liver abscess. Phagocytosis by the parasite is a critical virulence process, since it is a prerequisite for tissue invasion and establishment of chronic infection. While the roles of many of the proteins that regulate phagocytosis-related signaling events in E. histolytica have been characterized, the functions of lipids in this cellular process remain largely unknown in this parasite. In other systems, phosphatidylinositol (3,4,5)-trisphosphate (PIP₃), a major product of phosphoinositide 3 kinase (PI3-kinase) activity, is essential for phagocytosis. Pleckstrin homology (PH) domains are protein domains that specifically bind …

Identification And Molecular Characterisation Of Mycobacteriophages And Their Lysis Proteins, Marine Henry

Theses

Given their potential as specific and natural biocontrol agents, bacteriophages and their associated proteins have become the focus of renewed interest over the last decade. This study reviews the current state of mycobacterial diseases control worldwide and presents how phage therapy and the production of recombinant bacteriophage lysis proteins can be applied as novel biocontrol strategies for mycobacteria.

Chapter 11 presents an overview of the predicted LysA and LysB proteins in all the mycobacteriophages sequenced to date and proposes an in silico 3D predictive model of the lysin B of a recently isolated and characterised mycobacteriophage. Our data also confirms …

The Rapid Identification Of Novel Anti-Mycobacterial Drugs And The Transporters Involved In Their Resistance, James Carroll

Theses

Despite the success of anti-mycobacterial drugs over the past 70 years, mycobacterial disease, particularly tuberculosis is still responsible for millions of deaths worldwide. Additionally, the emergence of Multidrug Resistant (MDR-TB) and Extensively Drug Resistant (XDR-TB) Tuberculosis throughout the world has motivated calls by the World Health Organization for novel mycobacterial drugs, vaccines and diagnostic tests. Consequently, this study sought to identify and evaluate the efficacy of a range of anti-mycobacterial compounds against a representative cohort of pathogenic mycobacterial species. The development and employment of the rapid, robust and inexpensive microtitre alamarBlue assay (MABA) facilitated the assessment of a vast array …

Isolation And Molecular Characterization Of Mycobacterium Avium Subsp. Paratuberculosis In Ireland, Pierre Emmanuel Douarre

Theses

MAP is a proven animal pathogen causing Johne's disease, one of the most widespread and economically important diseases of ruminants. Since 1992 and the opening of the European market, the prevalence of MAP in Ireland has increased considerably. Improvements in diagnostic strategies for Ireland and elsewhere are urgently required. MAP infects a wide host range and has emerged as a potential threat to human health and has been associated with Crohn's disease. The control of paratuberculosis infection requires a better understanding of the genetic diversity of the pathogen. The objective of this study was to isolate and characterize this enteric …

Characterization Of Biofilms Formed By Mycobacterium Aviumn Subspecies Paratuberculosis In Psychologically Relevant Conditions, Richard Brunner

All Graduate Theses, Dissertations, and Other Capstone Projects

Mycobacterium avium subspecies paratuberculosis (Mpt) is the cause of Johne's disease, a gastrointestinal disease that mainly affects ruminants. Despite being an obligate intracellular pathogen, Mpt can survive in the environment for months. How Mpt survives in the environment has yet to be determined, but one tactic Mpt may use is the formation of biofilms. Biofilms may provide sufficient protection and allow Mpt endure in the environment until a new host is encountered. The conditions affecting Mpt biofilm formation have not been investigated. Both in the host and in the environment, Mpt experiences physiological stresses that may induce biofilm formation including …