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 20 of 23 for “"AI-2"”.
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ALTERING THE AI-2 MEDIATED QUORUM SENSING CIRCUITRY TO QUENCH BACTERIAL COMMUNICATION NETWORKS
… interspecies signaling molecule autoinducer-2 (AI-2), which is produced or recognized by over 70 species of bacteria. Our first approach is to bring the native intracellular AI-2 signal processing mechanisms to the extracellular surroundings to quench the QS response of bacteria. Specifically we …
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Autoinducer-2-based quorum sensing of foodborne pathogenic bacteria under food related conditions
… evaluate potential involvement of autoinducer (AI)-2-based quorum sensing (quorum sensing: cell density dependent cell-to-cell signaling) of foodborne pathogenic bacteria in food environments. Under the conditions of these studies, AI-2 activity of Salmonella and Escherichia coli O157:H7 was not …
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Intercellular communication in uropathogenic Escherichia coli and the probiotic Lactobacillus reuter
… to characterize the role of autoinducer 2 (AI-2) in the regulation of virulence factors of uropathogenic Escherichia coli J96, determine if the probiotic Lactobacillus reuteri RC-14 produced AI-2, and evaluate if secreted products from the probiotic could affect pathogen recognition by the …
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Novel Virulence Factors in the Pathogenesis of Yersinia pestis Infection, the Causative Agent of Plague
… CO92. From this screen, 118 clones showing impairment in disseminating to spleen were obtained. In a subsequent screen, 20/118 mutants exhibited attenuation when tested individually in a mouse model of bubonic plague, with 10/20 aforementioned mutants providing 40% or higher survival rates at …
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HAEMOPHILUS INFLUENZAE AND MORAXELLA CATARRHALIS INTRA- AND INTERSPECIES QUORUM SIGNALING
… via quorum signaling. Autoinducer-2 (AI-2) is termed an interspecies signal as the genetic determinant for AI-2 production (<italic>luxS</italic>) is highly conserved and many species possess the machinery to respond to AI-2. <italic>H. influenzae</italic> has a <italic>luxS</italic> …
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Mutant analysis of luminescence and autoinduction in a marine bacterium
… One of the autoinducers (autoinducer-2, or AI-2) was chemically purified and shown to be Noctanoyi- L-homoserine lactone. The genetic locus encoding the AI-2 synthase was cloned and designated ain (autoinducer). Manipulation of ain and AI-2 in V. jischeri demonstrated that the function of …
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Development of an Improved Synthesis of S-D-Ribosyl-L-Homocysteine (SRH) and Progress Toward SRH Analogs Modified at the C3 Position
… quorum sensing molecule used in this system is AI-2. AI-2 is biosynthesized by the enzyme LuxS from the precursor SRH. This thesis describes an improved synthesis of SRH through the exploration of different protecting group strategies. The knowledge gained from the improved synthesis of SRH is …
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Shewanella oneidensis MR-1 cell-to-cell signaling and its influences on biogeochemical processes
… either an acyl-homoserine lactone (AHL) or AI-2 quorum sensing signal, despite previous work that indicated that it produced an AHL that would enhance it ability to growth in certain anaerobic environments. Using a variety of quorum sensing signal sensors, no evidence could be found that S. …
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Synthesis of S-Ribosyl-L-homocysteine and Analogs Modified at the Homocysteine-C3 Position
… of QS pathways may lead to treatment options against many bacterial diseases. The LuxS enzyme converts <em>S</em>-ribosyl-L-homocysteine (SRH) into homocysteine (HCys) and 4(<em>S</em>),5-dihydroxypentane-2,3-dione (DPD), which is the precursor of autoinducer-2 (AI-2). Thus, inhibitors of LuxS …
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Biochemical Assay Optimization and Computational Screening Efforts to Identify Potential LuxS Inhibitors
… by the small signaling molecule autoinducer-2 (AI-2) and is implicated in the infectious behaviors of various bacterial species. AI-2 is biosynthesized from <em>S-</em>ribosylhomocysteine (SRH) by the enzyme LuxS and induces interspecies cell-to-cell communication. Inhibition of LuxS would …
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The Functional Characterization of the LysR-Type Transcriptional Regulator QseD and the SorC-Type Transcriptional Regulator LsrR in Enterohemorrhagic Escherichia coli
… of bacterially produced autoinducers (AI) AI-2, and 3 by LsrR, and QseBC respectively [1, 3]. Through the interpretation and integration of these multiple regulatory signaling networks that often involve intracellular regulatory proteins, such as the lysine regulator (LysR) type …
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Regulation and production of extracellular signaling molecules in Bacillus subtilis
… a putative interspecies signaling activity, AI-2, that depends on the conserved protein LuxS. To determine the effect of luxS on regulation of transcription in B. subtilis, I performed experiments to compare the transcriptional profiles of B. subtilis when luxS was deleted or overexpressed. I …
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Biochemical Evaluation of SRH Analogs as Potential LuxS Inhibitors
… quorum sensing is facilitated by the autoinducer AI-2. The enzyme LuxS catalyzes the formation of AI-2 from <em>S</em>-ribosyl homocysteine (SRH) in a wide variety of bacterial species. Inhibition of LuxS would therefore inhibit interspecies quorum sensing. The goal of this project is to establish …
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PATTERNED BIOFILM FORMATION TO INVESTIGATE BACTERIA-SURFACE INTERACTIONS
… and effective control of biofilm formation remains challenging. Biofilm formation is a dynamic process that involves numerous changes in bacterial gene and protein expression. These changes are highly sensitive to environmental factors such as surface chemistry, topography, charge, and …
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Comparative and Functional Genomic Studies of Histophilus somni (Haemophilus somnus)
… of H. somni, the genomes of pneumonia strain 2336 and preputial strain 129Pt have been sequenced. Using the genome sequence data and comparative analyses with other members of the Pasteurellaceae, putative genes that encode proteases, restriction-modification enzymes, hemagglutinins, …
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New Sensing Modalities for Bacterial and Environmental Phenomena
… is a ubiquitous phenomenon across all domains of life, ranging from archaea to bacteria to eukarya. In bacteria, this is often achieved using small molecules that allow bacteria to sense and respond to environmental cues about the presence, identity, and number of neighboring bacteria. …
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Knowledge-enhanced Document Representation Learning for Legal Judgment Support
The application of Artificial Intelligence (AI) to the legal domain, or LegalAI, has long been recognized as a potent tool for enhancing the efficiency of legal professionals. Despite this potential, prior research applied general AI models and neglected the knowledge in law. Such oversights have …
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Investigating galactose metabolism in Streptococcus pneumoniae
… the different carbon sources that are available. While the pneumococcus typically prefers to metabolise glucose, this carbon source is actively eliminated from the human nasopharynx in an attempt to maintain airway sterility. In the absence of glucose, galactose is the predominant sugar …
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The microbiology of diabetic foot infections: a Ghanaian perspective
… Klebsiella pneumoniae and Proteus mirabilis in maintaining the chronicity of diabetic foot ulcers. Using 3 in vitro biofilm models; the conventional microtitre plate and Minimum Biofilm Eradication Concentration (MBEC™) High-Throughput assays and the Quasi–Vivo® continuous flow system, K. …
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Synthesis and evaluation of novel quorum sensing inhibitors
This thesis details the synthesis of a range of furanones and the subsequent evaluation of their quorum sensing inhibitory effects. Chapter One focuses on the role of quorum sensing in bacteria and fungi. It explores the potential use of quorum sensing inhibitors as an alternative to, or in …
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