Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 16 of 16 for “"phase variation"”.
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Characterisation of Streptococcus pneumoniae opacity phase variation
… Any given strain of S. pneumoniae can undergo phase variation between two different colony phenotypes, termed opaque (O) and transparent (T), as determined by their morphology on clear, solid media. In animal models, the O form is more virulent and commonly isolated from normally sterile sites, …
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Characterization of a Strain of Salmonella Typhimurium Capable of Causing Persistent Infections in Swine
… of assays to differentiate the two phenotypic phases and the identification of more genes whose expression is controlled by phase variation. Colony color differences on Evans blue-Uranine plates allowed for differentiation of the two phenotypes. 1519 colonies appeared as light-colored while …
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Cloning and Characterization of a Gene Involved in Lipooligosaccharide Biosynthesis in Haemophilus somnus
… loci associated with lipooligosaccharide (LOS) phase variation in Haemophilus influenzae type b (Hib). In an attempt to identify H. somnus phase-variable LOS genes, the presence of CAAT repeats within the H. somnus 738 genome was confirmed using a (CAAT)7 probe. A 3.9 kb EcoRI fragment that …
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Investigation of Haemophilus somnus Virulence Factors: Lipooligosaccharide Sialylation and Inhibition of Superoxide Anion Production
… (LOS), or cell-free supernatant from mid-log phase cultures did not inhibit O2- production, indicating that O2- inhibition required contact with live H. somnus. Commensal isolates of H. somnus were less capable or incapable of inhibiting macrophage O2- production compared to isolates tested …
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Antigenic Characterization of <I>Haemophilus somnus</I> Lipooligosaccharide
… of <I>Haemophilus</I> and <I>Neisseria</I>. LOS phase variation is one mechanism by which some of these bacteria avoid the host immune response. To better understand LOS phase variation as a virulence mechanism of <I>H. somnus</I>, knowledge of the antigenic diversity of LOS epitopes must be …
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Interactions between influenza A virus and Streptococcus pneumoniae in nasal colonization and middle ear infection
… in coinfection with influenza A virus, namely phase variation and the pneumococcal neuraminidase NanA, using a novel animal model of nasal colonization and middle ear infection.
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Towards Novel Methods of Mutagenesis for Histophilus somni
… include biofilm formation, lipooligosaccharide phase variation, immunoglobulin binding proteins, survival in phagocytic cells, and many others. To identify genes responsible for virulence, an efficient mutagenesis system is needed. Mutagenesis of H. somni using allelic exchange is difficult due …
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Mutagenic Studies of RdoA, a Eukaryotic-Like SER/THR Protein Kinase in Salmonella Enterica Serovar Typhimurium
… to have a functional role in flagellin phase variation and long-term bacterial survivability. Structurally, RdoA is homologous to, choline kinase and aminoglycoside (3’) phosphotransferase IIIa (APH[3’]IIIa). These kinases all belong to a protein kinase superfamily and share highly …
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Towards High-Performance Reflectarray Antennas: Phase Sensitivity Reduction for Wide Bandwidth
… bandwidth poses a significant challenge because phase behavior varies across different frequencies. This thesis aims to address this limitation by proposing methods to widen the bandwidth while maintaining antenna performance. The research begins with an exploration of various bandwidth-enhancing …
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Single-band and Dual-band Beam Switching Systems and Offset-fed Beam Scanning Reflectarray
… The wideband antenna element with a large phase variation range and a linear phase response is one of the solutions to increase the narrow bandwidth of the reflectarray. A four beam scanning reflectarray has been developed. It is the offset-fed microstrip reflectarray that has been …
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The Molecular Characterization of Phosphorylcholine (ChoP) on Histophilus somni Lipooligosaccharide: Contribution of ChoP to Bacterial Virulence and Pathogenesis
… factors include expression and antigenic variation of lipooligosaccharide (LOS). Phosphorylcholine (ChoP) is often expressed on H. somni LOS and also undergoes antigenic variation. In this study, five genes that play a role in expression and antigenic variation of ChoP, lic1ABCD and glpQ, …
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Untersuchungen zur Genomstruktur und Biofilmbildung von pathogenen Escherichia coli Isolaten
Das Kerngenom pathogener Escherichia coli Isolate wird von zahlreichen variablen Regionen unterbrochen, die meist durch horizontalen Gentransfer erworben wurden und über das ganze Chromosom verteilt sind. Diese variablen Bereiche tragen häufig Gene für Virulenz- und Fitnessfaktoren und sind oftmals …
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Phasenvariation bei Legionella pneumophila: Vergleichende Proteomanalyse von virulenten und avirulenten Legionella pneumophila-Stämmen unter Anwendung der zweidimensionalen Gelelektrophorese
… Die Stämme unterliegen einer spontanen LPS-Phasenvariation und unterscheiden sich phänotypisch in multiplen Eigenschaften. Es zeigten sich different exprimierte Proteine der Membranoberfläche, der LPS-Biosynthese und des Bakterienstoffwechsels.
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Seismic Response of Pile Foundations in Soft Clays and Layered Soils
… and need to be accounted for. Further, the phase difference between the kinematic and inertial loads and its influence on pile accelerations, rotations and bending moments was evaluated. This research has revealed that the ratio of free-field soil natural frequency to the natural frequency …
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Epidemiologische und molekulare Untersuchungen zur Biofilmbildung in Staphylococcus epidermidis und Staphylococcus aureus
… konnte gezeigt werden, daß IS256 an der Phasenvariation der Biofilmbildung in vivo beteiligt ist. Bei einem klinischen S. epidermidis-Stamm, der von einem Patienten mit einer Katheter-assoziierten Harnwegsinfektion isoliert wurde, wurde die Insertion des Elementes im icaC-Gen …
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Studies of gravity wave and thermal tide and their interactions in the middle atmosphere
… characteristics of an inertial GW, the seasonal variation of the diurnal tide based on both the observations and models, and also the interactions between GWs and tides. One-night (October 28, 2003) temperature and horizontal wind measurements by a resonance sodium (Na) wind/temperature lidar in …