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 181 for “"Bacteroides"”.
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DNA repair in bacteroides fragilis
Bacteroides fragilis is a gut commensal in both humans and animals where it benefits the host through metabolizing indigestible compounds, stimulating the immune system and protecting against pathogen colonization. However, it is also an opportunistic pathogen, responsible for approximately half of …
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Glutamine synthetase in Bacteroides fragilis
Bactereroides fragilis is a gram-negative, non spore-forming, obligate anaerobe of the human intestinal microbiota. It is, however, an opportunistic pathogen and has been ranked as the most prevalent isolate in cases of anaerobic septicaemia. Similar to most bacteria, ammonium is assimilated in B. …
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Bacteroides Conjugative Transposons: Ecology and Mechanisms
CTnDOT is a 65 kb Bacteroides CTn that carries genes encoding for tetracycline resistance and erythromycin resistance. Previous studies had shown that the attDOT recombination site and integrase of CTnDOT (IntDOT) are sufficient and essential for integration in vivo. Even though the integrase of …
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Molecular genetic studies of bacteroides fragilis
Some genetic systems operative in Bacteroides fragilis have been successfully investigated. Firstly the bacteriocin produced by the B.fragilis BF-1 strain was purified and partially characterized. This bacteriocin was found to be cell bound and constitutively produced by the bacteria. The purified …
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The microaerophilic nature of <i>Wolinella recta, Wolinella curva, Bacteroides ureolyticus</i>, and <i>Bacteroides gracilis</i>
… pylori), Wolinella recta, Wolinella curva, Bacteroides ureolyticus</i>, and <i>Bacteroides gracilis</i> revealed that sheathed flagella occur only in species of rRNA group II (except <i>W.succinogenes</i>). This is helpful in differentiating this group. Campylobacters are microaerophilic: …
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Excision of the Bacteroides Conjugative Transposon CTnDOT
In this study, we showed that expression of the exc operon is regulated by tetracycline and mediated by the regulatory proteins, RteA, RteB, and RteC. Tetracycline induces the expression of rteA and rteB, genes in the tetQ operon. Then, RteB induces the expression of rteC. RteC, subsequently, …
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Regulation of Bacteroides chondroitin sulfate utilization genes
… chondroitin sulfate utilization (csu) system in Bacteroides thetaiotaomicron as the model system to study regulation.
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DNA repair in Bacteroides fragilis Bf-2
Repair deficient mutants of Bacteroides fragilis have been isolated in order to study the responses of this organism to various DNA damaging agents at the physiological and molecular levels. Two types of mutants were isolated by ethyl methane sulphonate mutagenesis of B.fragilis followed by …
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Activities of Bacteroides Conjugative Transposons: CTnGERM1 and CTnDOT
… transposon (CTn) that is found in many Bacteroides strains. Transfer of CTnDOT is stimulated 100--1000 fold if the cells are exposed to tetracycline (Tc). An operon that contains a Tc resistance gene, tetQ, and two regulatory genes, rteA and rteB, is essential for control of excision and …
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Regulatory Genes of the Bacteroides Conjugative Transposon, CTnDOT
In order to examine which genes are responsible for excision, I first demonstrated that the excision genes orf2c, orf2d, orf3, and exc are part of an operon (the orf2c operon) and that this operon is regulated at the transcriptional level. I found that RteC is an DNA-binding activator of the orf2c …
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Integration and Excision Mechanism of Bacteroides Conjugative Transposons
… be global regulators that regulate many genes on Bacteroides host. Whether RteB regulates CTnDOT and NBU1 excision directly or not is investigated in this study. Both RteB and the mutant are over-expressed in E. coli and partially purified. RteB is a soluble protein and gel shift result shows that …
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Characterization and Regulation of Bacteroides Mobilizable Transposons, NBUs
Bacteroides MTns forms a heterogeneous group of elements with conserved functional regions. But the conserved region on different elements is different. This raises a possibility that Bacteroides MTns are modularly assembled. This speculation is supported by partial sequencing of NBU3. The sequence …
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Persistence of Bacteroides ovatus under simulated sunlight irradiation
The persistence of Bacteroides ovatus, a human-associated anaerobic fecal contamination indicator bacteria species, was evaluated under simulated sunlight exposure and conditions similar to surface water and seawater. By combining propidium monoazide (PMA) treatment and quantitative polymerase …
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Positive regulators of Bacteroides CTnDOT excision and transfer
… stimulates both excision and transfer of a Bacteroides Conjugative transposon CTnDOT. It was shown previously that a gene, rteC, is necessary for tetracycline-stimulated transcriptional regulation of the xis2c operon, which contains the excision genes. The protein encoded by this gene, RteC, …
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Identification of Bacteroides genes involved in Metronidazole resistance
Bacteroides species are Gram-negative obligate anacrobes that live in the gastrointestinal tract of mammals and are thought to account for approximately 30% of the colonic microbiota. Certain Bacteroides species, such as B. fragilis and to a lesser extent B. thetaiotaomicron, can become …
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In vivo metal substitution in bacteroides superoxide dismutase
The effect of various growth conditions on the type of superoxide dismutase (SGD) formed anaerobically in three Bacteriodes species was studied. B. fragilis, B. distasonis, and B. thetaiotaomicron were grown in ironâ restricted media with or without manganese supplementation. Iron availability was …
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Bacteriostatic and bactericidal effects of antibiotics on Bacteroides
… and penicillin were determined against sixteen Bacteroides fragilis strains and six B. thetaiotaomicron strains. Drugs were considered bactericidal when minimal bactericidal concentration (MBC) to minimal inhibitory concentration (MIC) ratios were less than or equal to four. As expected, …
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Enzymes involved in utilization of pullulan by Bacteroides thetaiotaomicron
A pullulanase I gene from Bacteroides thetaiotaomicron has been cloned. To determine whether the cloned pullulanase gene was essential for pullulan utilization, I used directed insertional mutagenesis to inactivate the B. thetaiotaomicron pullulanase gene.
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Tetracycline resistance and its dissemination in the Bacteroides group
… resistance (Tc$\sp{\rm r})$ in the human colonic Bacteroides and in the related genus Prevotella appears to be conferred by a single resistance determinant. This determinant represents a new class of ribosome protection Tc$\sp{\rm r}$ genes which was designated TetQ, because it has a deduced amino …
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