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1
Damiani, Igor Alexandre Campos 1988. "Estudo do efeito terapêutico de linhagens atenuadas de Salmonella enterica Typhimurium em modelos murinos de câncer." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317027.
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Orientador: Marcelo BrocchiDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Salmonella enterica Typhimurium é uma bactéria anaeróbica facultativa que apresenta tropismo por áreas tumorais. Esta interessante propriedade abre novas perspectivas em relação à pesquisa contra o câncer, pois há muito tempo buscam-se veículos seletivos para a eliminação de neoplasias. A inibição do crescimento tumoral e até mesmo seu total retrocesso foram observados em modelos murinos de câncer tratados com linhagens atenuadas de S. enterica. Além disso, seu potencial como veículo de moléculas antitumorais exógenas (vacina de DNA, RNAi, citocinas e enzimas, por exemplo) também foi descrito. No entanto, as linhagens testadas em humanos até o presente não induziram os mesmos efeitos observados nos modelos animais. Isto indica que estudos adicionais são necessários para otimização desta terapia, incluindo o teste de novas linhagens mutantes atenuadas de S. enterica....Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: Salmonella enterica Typhimurium, a facultative anaerobic bacterium, presents tropism for tumor areas. This interesting property creates new perspectives in cancer research, in which great efforts have been done to seek a drug carrier that could selectively target and destroy malignant cells. Inhibition of tumor growth and even its total elimination were observed in murine cancer models infected by attenuated strains of S. enterica. Besides, its potential as a carrier of exogenous antitumor molecules (DNA vaccine, iRNA, cytokines and enzymes, for example) is also described. Nevertheless, when these strains were tested in humans, they did not induce the same effects observed in murine models. Thus, additional studies are needed to optimize this therapy, including the test of novel S. enterica attenuated strains...Note: The complete abstract is available with the full electronic digital thesis or dissertations
Mestrado
Microbiologia
Mestre em Genética e Biologia Molecular
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Salam, Faridah. "Development of immunosensors for Salmonella typhimurium." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/8193.
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The accidental contamination of Salmonella in raw and processed foods is a major problem for the food and feed industries worldwide. Rapid detection methods for monitoring and identification are required to solve the health and safety problems related to these pathogenic bacteria. Current detection methods require extensive sample preparation and prolonged assay procedures, thus, this research project focused on developing rapid methods which are capable of sensing these microorganisms at a high sensitivity level.
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de, Almeida Pereira Milton César. "Inflammasome signalling during Salmonella Typhimurium infection." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/283642.
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The innate immune system is the first line of defence against infection. It is comprised of physicochemical barriers and a variety of cell types including macrophages and dendritic cells. Pathogens express specific pathogen associated molecular patterns (PAMP) which are recognised by pattern recognition receptors (PRR) on macrophages to initiate an innate immune response. Gram-negative bacteria such as Salmonella enterica serovar Typhimurium express a range of bacterial PAMPs recognised by Toll-like receptors (TLRs) including lipopolysaccharides (LPS) recognised by TLR-4 and lipoproteins by TLR-2. The activation of TLRs results in activation of nuclear factor κB (NF-κB) to drive transcription of mRNA coding for pro-inflammatory proteins such as tumor necrosis factor α (TNF-α) and pro-interleukin (IL) 1β. Myeloid cells also possess intracellular PRRs including the nucleotide-binding domain and leucine-rich repeat (NLR) family. NLR family CARD domain- containing protein 4 (NLRC4) and NLR family pyrin domain-containing protein 3 (NLRP3) are the main NLRs engaged in recognising S. Typhimurium infection, leading to formation of the inflammasome. The inflammasome is a macromolecular complex assembled in the cytoplasm, and usually contains a NLR, the structural protein apoptosis-associated speck-like protein containing a CARD (ASC) and effector enzymes such as cysteine-dependent aspartate-directed protease (caspase) -1 and caspase-8. This structure is responsible for processing the cytokines pro- IL-1β and pro-IL-18 to their mature form and is involved in triggering a pro-inflammatory process of cell death termed pyroptosis. The formation of the inflammasome therefore results in cell death and secretion of proinflammatory cytokines which play important roles in controlling infections. Inflammasome activity must be tightly coordinated, as its dysregulation is associated with a variety of auto-inflammatory and auto-immune diseases. The signalling events leading to inflammasome assembly are poorly understood and the molecules involved in fine-tuning its activity are only beginning to be discovered. The aim of this thesis was to discover new molecules involved in inflammasome activation and/or in keeping its activity in check. To achieve this goal, I performed S. Typhimurium infection assays in primary bone marrow derived macrophages (BMDM) derived from C57BL/6 mice wild type (WT) and compared the resulting cellular viability, intracellular bacteria counts and IL-1β production to that of BMDMs derived from C57BL/6 mice lacking proteins involved with, or suspected to be involved with, innate immune activity. Amongst the proteins I studied, caspase recruitment domain 9 (CARD9) inhibited inflammasome-mediated IL-1β production. Multiple independent genome-wide association studies link this protein to inflammatory pathologies such as Crohn's disease, but its role in canonical inflammasomes was largely unexplored. To investigate how CARD9 inhibits inflammasome-mediated IL-1β production I have conducted assays in WT and Card9-/- BMDMs, including stimulation of specific NLRs with their purified ligands, infection with bacterial strains deficient in NLRC4 activation, and infection assays in presence of pharmacological inhibitors. By employing these approaches, I observed that CARD9 has a negative role on NLRP3-dependent IL-1β production. Specifically, in response to activation of the NLRP3 by Salmonella infection, CARD9 negatively regulates pro-IL-1β transcription, and decreases IL-1β processing by inhibiting spleen tyrosine kinase (SYK)-mediated NLRP3 activation and represses caspase-8 activity in the inflammasome. CARD9 expression is suppressed in the course of S. Typhimurium infection which may act as a mechanism to increase IL-1β production during the infection. In conclusion, I have established a connection between CARD9 and IL-1β production by the canonical NLRP3 inflammasome and elucidated some of the mechanisms involved in this process. I have also found evidence that other proteins are likely to be involved in inflammasome regulation and the elucidation of their roles will be addressed in future studies.
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Muddiman, Katie. "Functional characterisation of Salmonella Typhimurium CueP." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/functional-characterisation-of-salmonella-typhimurium-cuep(a9ded192-a63d-48f0-a34e-7d9a1ce0e011).html.
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Metals are used as cofactors for enzymes, but are toxic in excess. In order to avoid the deleterious effects posed by metals, the cell must employ strict metal homeostasis systems. One such system is the Cue copper-resistance system in Salmonella enterica serovar Typhimurium (S. Typhimurium) which includes the periplasmic copper binding protein CueP. Previous studies have shown CueP to be a major periplasmic copper-sequestering protein that has a role in supplying copper to, and thus activating, the periplasmic Cu,Zn-superoxide dismutase enzyme SodCII (Osman et al., 2013). SodCII protects the cell from reactive oxygen species (ROS), due for example to the actions of the respiratory burst oxidase in host macrophages. However, despite its ability to sequester copper and activate SodCII, the precise physiological role of CueP in S. Typhimurium has remained unresolved since cueP mutants of S. Typhimurium strain SL1344 (the wild-type stain used in this study) do not exhibit a phenotype with respect to tolerance to copper or reactive oxygen species. In addition, the copper-binding mechanism of CueP and its interactions with other copper-binding proteins, including SodCII, have not been examined. An aim of this study was to establish a phenotype for a cueP mutant of S. Typhimurium with respect to copper and/or ROS tolerance. It was hypothesised that the possession of KatG (catalase) and multiple superoxide dismutases (SodCI, SodA and SodB), in addition to SodCII, by S. Typhimurium may confer functional redundancy with respect to copper and ROS tolerance. Hence mutants lacking katG (ÎkatG) or the various superoxide dismutase encoding genes (ÎsodA/ÎsodB/ÎsodCI/ÎsodCII) with and without functional cueP were generated. The ÎkatG mutants exhibited reduced catalase activity and reduced tolerance to hydrogen peroxide, consistent with the loss of KatG, however the additional loss of cueP did not reduce tolerance to hydrogen peroxide further. Similarly, tolerance to copper and extracellular superoxide was also unaltered in the ÎkatG/ÎcueP mutant. The tolerance of the various superoxide dismutase mutants to copper and various ROS was also unaffected by the presence or absence of CueP. To examine the role of CueP in SodCII activation in vivo, SodCII was over-expressed in S. Typhimurium (in a ÎsodA/ÎsodB/ÎsodCI/ÎsodCII background) with and without functional cueP and superoxide dismutase activity measured in both whole cells and periplasmic extracts. SodCII-dependent superoxide dismutase activity was successfully identified within the periplasmic extracts. However, surprisingly, the level of activity was unaffected by the presence 16 or absence of CueP and/or the addition of copper. It is possible that SodCII is thus able to scavenge sufficient copper for activity from the reagents used in these assays. Similarly, in an alternative approach to examine the role of CueP in vitro, both SodCII and CueP (WT and potential metal-binding residue mutant forms) were successfully over-expressed in E. coli and methods for their purification optimised (without the use of affinity tags). ICP-MS analysis indicated that a CuePC104S mutant contains > 18-fold less copper than the CueP WT protein. Furthermore, superoxide dismutase activity assays using purified proteins, indicated that the CuePC104S mutant was less able to activate SodCII than the WT CueP. Taken together, these results are consistent with a role for the Cys104 residue in copper-binding by CueP. Bioinformatics results suggest the presence of CueP or homologous genes in the presence of other bacteria, including pathogens such as Klebsiella, Yersinia and Shigella spp. Further understanding of the role of CueP and the systems used by S. Typhimurium to avoid both copper and ROS stress may inform the development of novel treatment strategies for bacterial diseases.
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Wang, Liying. "Regulation of heme biosynthesis targets the key enzyme HemA by a mechanism of protein stabilization in Salmonella typhimurium." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=577.
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Thesis (Ph. D.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains xiii, 145 p. : ill. (some col.) Includes abstract. Includes bibliographical references.
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Bergman, Molly Ann. "Host responses to Salmonella typhimurium infection in vitro and in vivo /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/11503.
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Brahmbhatt, Himanshu N. "Cloning and molecular characterization of the rfb gene cluster from Salmonella typhimurium LT2 /." Title page, contents and abstract only, 1987. http://web4.library.adelaide.edu.au/theses/09PH/09phb813.pdf.
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Tai, Chia-Hui. "Kinetic and Chemical Mechanism of O-Acetylserine Sulfhydrylase-B from Salmonella Typhimurium." Thesis, University of North Texas, 1993. https://digital.library.unt.edu/ark:/67531/metadc279064/.
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Initial velocity studies of O-acetylserine sulfhydrylase-B (OASS-B) from Salmonella typhimurium using both natural and alternative substrates suggest a Bi Bi ping pong kinetic mechanism with double substrate competitive inhibition. The ping pong mechanism is corroborated by a qualitative and quantitative analysis of product and dead-end inhibition. Product inhibition by acetate is S-parabolic noncompetitive, indication of a combination of acetate with E followed by OAS. These data suggest some randomness to the OASS-B kinetic mechanism. The pH dependence of kinetic parameters was determined in order to obtain information on the acid-base chemical mechanism for the OASS-B reaction. A mechanism is proposed in which an enzyme general base accepts a proton from α-amine of O-acetylserine, while a second enzyme general base acts by polarizing the acetyl carbonyl assisting in the β-elimination of the acetyl group of O-acetylserine. The ε-amine of the active site lysine acts as a general base to abstract the α-proton in the β-elimination of acetate. At the end of the first half reaction the ε-amine of the active site lysine that formed the internal Schiff base and the general base are protonated. The resulting α-aminoacrylate intermediate undergoes a Michael addition with HS‾ and the active site lysine donates its proton to the α-carbon to give cysteine and regenerate enzyme to start the second half reaction. In addition, substrate specificity, stereochemistry of the internal Schiff base at C4', and sequence around active site lysine of O-acetylserine sulfhydrylase-A have been determined. The [4'-^3H]pyridoxamine generated by reduction of the internal Schiff base with sodium [^3H]borohydride retained most of its tritium after incubation with apoaspartate aminotransferase. These results agree with the hypothesis put forth by Dunathan (Dunathan, 1971; Dunathan and Voet, 1974) that a single surface (Re face) of the active site PLP is accessible to solvent. The sequence around the active site lysine is AsnProSerPheSerValLysCysArg.
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Hone, David. "Construction of Salmonella vaccines /." Title page, contents and abstract only, 1988. http://web4.library.adelaide.edu.au/theses/09PH/09phh7721.pdf.
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Müller, Andreas Johann. "In vivo analysis of Salmonella typhimurium infection /." [S.l.] : [s.n.], 2009. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18432.
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Osman, Deenah. "Copper Homeostasis in Salmonella Enterica Serovar Typhimurium." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509383.
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Olsen, Eric Vincent Petrenko Valery Barbaree James M. "Phage-coupled piezoelectric biodetector for Salmonella typhimurium." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Summer/doctoral/OLSEN_ERIC_17.pdf.
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Lewis, Claire. "Extracytoplasmic stress response systems in S. Typhimurium." Thesis, Thesis restricted. Connect to e-thesis to view abstract, 2008. http://theses.gla.ac.uk/362/.
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Thesis (Ph.D.) - University of Glasgow, 2007.Ph.D. thesis submitted to the Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, 2007. Includes bibliographical references. Print version also available.
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Rowley, Gary. "Characterisation of the S. Typhimurium σE regulon." Thesis, University of Glasgow, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428647.
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Okoro, Chinyere Kyna. "Invasive Salmonella typhimurium : linking phenotype to genotype." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607714.
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McGourty, Kieran D. "Interference with lysosomal biogenesis by Salmonella typhimurium." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11096.
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Salmonella enterica is an intracellular bacterial pathogen that replicates within membrane-bound vacuoles by delivering virulence (effector) proteins across the vacuolar membrane by the SPI-2 type III secretion system (T3SS). In this thesis I show that through the action of this T3SS, Salmonella selectively interferes with a subset of endosome-to-trans-Golgi network (TGN) traffic that is involved in mannose-6-phosphate receptor (MPR) recycling. Two pathways of endosome-to-TGN traffic have been described: one involves the Q-SNARE syntaxin 6; the other is defined by the Q-SNARE syntaxin 10 and involves retrograde transport of the MPRs. Salmonella specifically disrupted syntaxin 10-dependent endosome-to- TGN traffic and this was accompanied by redistribution of MPR from the TGN, misrouting of newly synthesized lysosomal enzymes and attenuation of lysosome function. The SPI-2 T3SS effector SifA is an important virulence determinant that is known to interact with the endolysosomal system. SifA was shown to be required and sufficient to mediate the effects on lysosome biogenesis during infection or following transfection of host cells. By contrast, a variant of SifA with a single amino acid substitution that prevents interaction with its host protein target, SKIP, failed to redistribute MPR or to reduce lysosomal function. SKIP was found to contribute to lysosomal biogenesis in uninfected cells. Inhibition of lysosomal enzyme function with a lysosomal protease inhibitor or by depleting cells of syntaxin 10 enhanced intracellular bacterial replication. I conclude that SifA attenuates lysosomal activity through its interaction with SKIP and that this facilitates intracellular bacterial replication.
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Toguchi, Adam James Masao. "Swarming in Salmonella typhimurium and Escherichia coli /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Rakeman, Jennifer Leigh. "Transcriptional regulation of Salmonella typhimurium invasion genes /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/11531.
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Sigmarsson, Haukur Lindberg. "PATHOGENITÄTSVERGLEICH VON SALMONELLA TYPHIMURIUM DT104 - WILDTYP UND SALMONELLA TYPHIMURIUM - DELETIONSMUTANTEN (sseD::aphT & invC::aphT) IN PERSISTENT INFIZIERTEN SCHWEINEN." Doctoral thesis, Universitätsbibliothek Leipzig, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-98570.
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ZUSAMMENFASSUNG
Haukur Lindberg Sigmarsson
PATHOGENITÄTSVERGLEICH VON SALMONELLA TYPHIMURIUM DT104 - WILDTYP UND SALMONELLA TYPHIMURIUM - DELETIONSMUTANTEN (sseD::aphT & invC::aphT) IN PERSISTENT INFIZIERTEN SCHWEINEN
Salmonella (S.) Typhimurium DT104 ist ein gram-negatives Bakterium. Es weist keine Wirtsspezifität auf und gilt als Zoonoseerreger. Jährlich erkranken daran allein in Deutschland mehrere Tausend Menschen unter dem Bild einer schwerwiegenden Diarrhö mit zum Teil tödlichem Ausgang. Das Schwein gilt als eines der Reservoire für S. Typhimurium DT104 des Menschen. S. Typhimurium DT104 gelangt über vom Schwein stammende Produkte in den menschlichen Verzehr. Die Kontrolle von S. Typhimurium DT104 einschließlich effektiver Eradikationsmassnahmen in unseren Schweinebeständen ist deshalb von entscheidender Bedeutung, um den Eintrag dieses Bakteriums in die menschliche Nahrungskette wenn möglich zu eliminieren. Dafür ist das Verständnis über S. Typhimurium DT104 einschließlich der Kenntnis seine Pathogenitätseigenschaften notwendig. Ziel dieser Arbeit waren Untersuchungen zur Pathogenität von S. Typhimurium DT104. Dabei wurden der Wildstamm mit zwei seiner Deletionsmutanten (sseD::aphT und invC::aphT) verglichen.
Die Untersuchungen erfolgten im Infektionsversuch an insgesamt 25 sechs Wochen alten männlichen Schweinen, die in einem vollklimatisierten Versuchsstall gehalten wurden. Den Tieren wurde im Anschluss an eine einwöchige Akklimatisierungsphase eines der nachfolgenden Stämme von S. Typhimurium DT104 oral in einer Konzentration von 1 x 1011 KBE verabreicht: Wildtyp (n = 8 Schweine), Deletionsmutante seeD::aphT (n = 8) und Deletionsmutante invC::aphT (n = 9). Bei den Mutanten handelt es sich um Varianten von S. Typhimurium DT104, die an den entsprechenden Abschnitten des Bakteriumgenoms (d.h. sseD-Gen bzw. invC-Gen) deletiert wurden. SseD regelt die Überlebensfähigkeit von S. Typhimurium in Makrophagen, invC dessen Invasionsvermögen. Im Mäusemodel war die Pathogenität beider Mutanten deutlich vermindert. Nach der Infektion schloss sich ein 20 tägiger Beobachtungszeitraum an, während dessen nachfolgend genannte Parameter erfasst bzw. Proben genommen wurden: klinische Symptome (Allgemeinbefinden, Erbrechen, Durchfall, Futteraufnahme, Atmung, Temperatur); Blutentnahme für Erstellung des weißen Blutbildes; Kotentnahme zum Nachweis der Ausscheidung von S. Typhimurium. Einen Tag nach Ende der Beobachtung wurden die Tiere getötet und Proben von insgesamt 15 Organen (unter anderem Tonsille; Colon und Caecum sowie dazugehörige Lymphknoten; Leber; Milz; Muskulatur) genommen. Kot sowie Gewebeproben wurden kulturell und wenn positiv auch mittels PCR untersucht.
Alle mit dem Wildtyp infizierten Schweine wurden mehr oder weniger stark krank. Häufig zeigten erkrankte Schweine zeitgleich mehrere Krankheitssymptome (z. B. Erbrechen und Durchfall). Die Erkrankung hielt über mehrere Tage an. Im Vergleich dazu waren die Krankheitssymptome der Tiere, die mit Mutanten infiziert wurden, mild. Nur wenige Tiere erkrankten und dann auch nur kurzzeitig. Gewöhnlich war nur einer der erfassten Parameter verändert. Typische Veränderungen im weißen Blutbild waren nur bei Wildtyp-infizierten Tieren zu beobachten, während Tiere beider Mutanten kaum auf die Infektion reagierten. Alle 25 infizierten Tiere schieden S. Typhimurium mit dem Kot während der ersten Woche post inocculationem aus. Danach wurden in allen drei Gruppen etwa gleichviel intermittierende Ausscheider beobachtet. Zwischen 65 und 67 % der Gewebeproben der mit dem Wildtyp und mit der sseD::aphT-Mutante infizierten Tiere waren sowohl in der Kultur als auch mittels PCR S. Typhimurium positiv, während dieser Anteil nach Infektion mit invC::aphT nur 49 % betrug. Alle Tiere waren in Mandibularlymphknoten und im Colon positiv, während S. Typhimurium nur selten in Muskulatur und Leber nachzuweisen war.
Die Ergebnisse dieser Arbeit bestätigen, dass Infektionen mit dem Wildtyp von S. Typhimurium zu einer schweren Erkrankung führen können. Gleichzeitig konnte gezeigt werden, dass beide in dieser Arbeit verwendeten Mutanten weniger krankmachend sind. Es muss davon ausgegangen werden, dass die Deletionen in den sseD bzw. invC-Bereichen tatsächlich zu Veränderungen bestimmter Eigenschaften geführt haben, die Teil der Pathogenitätsmechanismen für das Schwein sind. Im Unterschied zur Maus war sseD beim Schwein allerdings invasiv. Es kann vermutet werden, dass die durch sseD kodierten Pathogenitätseigenschaften von S. Typhimurium bei der Maus anders als beim Schwein wirken und somit unterschiedliche Bedeutung haben. Da die invC::aphT-Mutante jedoch und wie erwartet wesentlich schwächer als Wildtyp und sseD::aphT invadierte ist davon auszugehen, dass die Deletion im invC Bereich das Invasionsvermögen der Mutante beim Schwein ähnlich wie bei der Maus verringerte.
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McClure, G. David (George David). "A Study of the Intrinsic Fluorescence of O-Acetyl-L-Serine Sulfhydrylase-A from Salmonella typhimurium." Thesis, University of North Texas, 1993. https://digital.library.unt.edu/ark:/67531/metadc278975/.
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O-Acetyl-L-serine sulfhydrylase-A (OASS-A) forms acetate and L-cysteine from O-acetyl-L-serine (OAS) and sulfide. One molecule of the cofactor pyridoxal 5'- phosphate (PLP) is bound in each holoenzyme protomer.
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Ohlson, Maikke B. "Characterization of the intracellular activities of SseJ and SifA, two Salmonella enterica serovar typhimurium type III secretion effector proteins /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/11485.
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Cunning, Christofer Lee. "Regulation of the synthesis and protein stability of the alternative sigma factor RpoS in Salmonella typhimurium." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=533.
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Bronstein, Philip Alan. "Identification and characterization of a type III chaperone, InvB /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/11524.
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Rappl, Catherine. "Charakterisierung eines Typ III-Sekretionssystems für Virulenzproteine aus Salmonella typhimurium." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964612909.
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Passerat, Julien. "Exploration du potentiel de virulence de Salmonella typhimurium active mais non cultivable." Montpellier 2, 2005. http://www.theses.fr/2005MON20174.
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Fung, Mei-yuk Ami. "Isolation and characterization of a Salmonella enterica serotype typhi variant." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23373106.
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Igue, Patience. "Survival of Salmonella typhimurium in simulated intestinal fluids." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31242.
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Salmonella species are among the major foodborne intestinal pathogens that are of public concern with respect to food safety. The ability of intestinal pathogens to resist gastric acidity corresponds to their oral infective dose (ID). The survival and lipopolysaccharide (LPS) profiles of Salmonella typhimurium grown at different pH values and to different phases of growth were examined in simulated gastric fluid (pH 1.5), ileal fluid (pH 7.0), colon fluid (pH 8.0). The survival and growth of S. typhimurium were also examined during sequential passage through all three fluids. Viable cells were rapidly reduced from 106 CFU.ml-1 to <10 CFU.ml-1 within 4 min in gastric fluid. Cells inoculated directly into ilea] and colon fluids survived and multiplied extensively. When low numbers of viable cells of Salmonella in contact with gastric fluid (0.5 min of contact) were transferred sequentially to ileal and colon fluids, only the early and late stationary phase cells were capable of recovery and growth to high numbers. The harsh environment of the gastric fluid did not change the LPS profiles of the inoculated Salmonella cells. Entrapment of S. typhimurium in calcium alginate beads and chocolate increased its survival in gastric fluid. This implies that Salmonella cells are protected from killing when ingested with food. These results may explain why Salmonella species have a very low ID when consumed as part of some contaminated food sources.
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Salcedo, Suzana Pinto. "Analysis of salmonella typhimurium interaction with host cells." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406437.
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Gunel, Ozcan Aysen. "Cloning and characterization of Salmonella typhimurium dehydroquinate synthase." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267843.
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Lai, Jyhmirn. "Epidemiological studies on Salmonella typhimurium DT104 in Scotland." Thesis, University of Glasgow, 2007. http://theses.gla.ac.uk/5439/.
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Salmonella Typhimurium definitive type 104 (ST DT104) isolates resistant to antibiotics have been an issue since the multi-resistant clone was identified in 1985. In order to advance understanding of ST DT104 infections in Scotland, 2,796 human and 2,439 animal isolates with their corresponding antibiotic resistance patterns submitted from 1988 to 2004 were used to conduct descriptive, hierarchical, and geographical cluster studies and to construct a time series model. The analyses showed that using the 13 antibiotics used by the Scottish Salmonella Reference Laboratory, isolates could be allocated into two distinct groups. The first group containing the ApC1SpStSuTe R-type with its associated resistance patterns, mainly the ApCISpStSuTeTm and the ApCISpStSuTeNa R-types, dominated the trend throughout the study period. The second group, mainly composed of fully sensitive isolates, formed a low proportion except during the period from 1988 to 1990. Temporal analyses showed that there was an epidemic from 1993 to 1998 in human ST DT104 and from 1992 to 1999 in animals. Spatial analysis identified the southern part of Scotland as the higher relative risk area for both human and animal infections caused by multi-resistant ST DT104 strains In contrast, the central belt of Scotland was mainly the relative risk lower spatial cluster for the multi-resistant ST DT104 R-types. Of note in the spatio-temporal analysis was the stability and persistence of the chromosomally mediated multiple resistance compared to the more sporadic plasmid mediated resistance types of the second group. Although there were many similarities between the infections in humans and animals, there was no consistent temporal association between the emergence of clones in humans compared with animals suggesting that the ecological and epidemiological direction of the relationships is complex.
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Morgan, Eirwen. "Direct search for Salmonella serotype typhimurium gut invasins." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364990.
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Reed, Katharine Anne. "Interactions between Salmonella typhimurium and polarised epithelial cells." Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242364.
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Komitopoulou, Evangelia. "Environmental sensing and stress resistance in Salmonella typhimurium." Thesis, University of Surrey, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252342.
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Crago, Aimee Marie. "Virulence-related outer membrane proteins of Salmonella typhimurium." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624399.
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Kalupahana, Ruwani Sagarika. "Interaction of Salmonella typhimurium with antigen presenting cells." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620666.
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Avendano, Perez Gaspar. "Interactions between Salmonella typhimurium and human gut bacteria." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/54306/.
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Salmonella enterica subsp. enterica serovar Typhimurium is an important enteropathogen that causes human morbidity and mortality worldwide. It is essential to study the interaction between Salmonella and the gut bacteria to elucidate the elements that influence the ability of the pathogen to overcome the colonisation barrier mediated by the gut microbiota and why Salmonella can persist in ‘healthy’ individuals in a carrier state after infection. In this study the effect of faecal bacteria on the growth and survival of S. Typhimurium was investigated. Initially, experiments involved co-cultures of the pathogen and single strains of intestinal bacteria obtained from culture collections; results showed that when E. coli reached its maximum concentration density, the growth of S. Typhimurium was halted. S. Typhimurium was then inoculated with multi-strain gut bacteria from culture collections and also with faecal samples in batch cultures mimicking the conditions of the human colon. A significant reduction of S.Typhimurium concentration was observed in mixed cultures with faecal samples from different human donors; however, bacteria obtained from culture collection had no effect on S. Typhimurium. Close proximity with faecal bacteria was required as the pathogen was not affected when it was separated from the faecal bacteria by a 0.45 µm pore size membrane. S. Typhimurium was also affected in a continuous culture system. Transcriptomic analysis indicated that some of the functions associated with the genes expressed by S. Typhimurium during Salmonella inactivation were related to stress responses. Molecular profiling of faecal bacteria measured by denaturing gradient gel electrophoresis did not show any change specifically associated to S. Typhimurium inactivation. It was not possible to identify the bacterial strains responsible for the inactivation of S. Typhimurium; however, this effect caused by cell-cell contact with human faecal bacteria is reported for the first time in this study.
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Reyner, Jacqueline Louise. "Characterisation of the CspA paralogues of Salmonella Typhimurium." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4651.
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In cold temperatures, the survival of Salmonella enterica serovar Typhimurium (S. Typhimurium) requires the action of cold shock protein A (CspA) paralogues. These are thought to melt misfolded ribonucleic acids, facilitating their translation at low temperatures. However, through phenotypic analysis of our SL1344 csp null mutant (lacking all CspA paralogues), it has been shown that CspA paralogues function during other environmental stresses, outwith temperature reduction, and play an essential role in colony formation of an SL1344 rpoS mutant at 37°C. The general stress σ subunit, RpoS, plays an important role in adapting cells to a number of stresses including oxidative stress, temperature changes, low pH and stationary phase. Under such conditions, RpoS acts as an ‘emergency co-ordinator’, subsequently inducing the transcription of necessary stress response genes. In Escherichia coli, RpoS is regulated posttranscriptionally by at least three small RNAs (sRNAs): OxyS, DsrA and RprA; that require interactions with the Sm-like RNA chaperone, Hfq. In S. Typhimurium, the stability of the RpoS protein itself is regulated by ClpXP, an ATP-dependent protease responsible for RpoS degradation, and a specific recognition factor that targets RpoS to this protease, MviA. The present study has shown that the CspA paralogues of S. Typhimurium are involved in the expression of RpoS and aims to elucidate the role of these proteins in RpoS production. Comparative phenotypic tests were carried out in strains carrying mutations in rpoS, hfq and the csp genes to gain insight into the interactions of Hfq and CspA paralogues, with respect to RpoS expression. Both significant phenotypic overlaps, such as peroxide sensitivity, and phenotypes unique to certain mutant strains, such as cold acclimation in the csp null strain, were observed. CspA paralogues and Hfq are functionally distinct, not only in their involvement in RpoS expression, but also in RpoS-independent processes, such as cold acclimation, motility and to some extent, growth at 37°C. The roles of Hfq and the CspA paralogues, in RpoS expression, were also assessed at the molecular level. A combination of qRT-PCR analysis, transcriptional fusions and immunoblotting (with anti-σ antibodies) has shown that DsrA and RprA are not essential for RpoS expression in S. Typhimurium, during stationary phase or exponential cold shock, and do not require Hfq under these conditions. Contrary to reports in E. coli, DsrA is not induced upon cold shock in SL1344. Northern blots have shown that neither Hfq nor the CspA paralogues are involved in regulating rpoS transcription during either stationary phase at 37°C or cold shock in exponential phase. Immunoblotting and translational fusions have identified different pathways for the regulation of RpoS during stationary phase at 37°C and cold shock in exponential phase. Hfq is involved during the former condition only, whilst CspA paralogues are involved in both. Protein stability experiments have shown that the CspA paralogues do not play a major role in stabilising RpoS protein against degradation. Together, these results have pointed to a role for both the CspA paralogues and Hfq in facilitating the efficient translation of rpoS mRNA. An SL1344 csp null rpoS mutant is unable to form colonies on LB agar at 37°C, a phenomenon found when introducing combinations of mutations to SL1344 for phenotypic assessment. A conditional rpoS mutant revealed that the SL1344 csp null rpoS strain is viable but non-culturable. From the csp gene family, only cspA and cspB were able to restore colony forming ability to the rpoS mutant. Further complementation experiments pointed to faulty cell division, due to abnormal RNase E activity, as the cause.
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Hebrard, Magali. "Etude des systèmes antioxydants dans le métabolisme et la virulence de Salmonella typhimurium." Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX22022/document.
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Les Formes Actives de l’Oxygène (FAO), molécules dérivées de l’oxygène, sont capables d’oxyder et d’endommager les macromolécules biologiques. Au cours de son cycle de vie, Salmonella typhimurium est exposée à des FAO provenant de deux sources : soit de son métabolisme aérobie, soit du macrophage, sa cellule hôte au cours de l’infection. Parmi les FAO existantes, l’H2O2 est l’une des plus néfastes. Au cours de ma thèse, j’ai étudié la contribution des catalases et des peroxyrédoxines dans le métabolisme et la virulence de S.typhimurium. Cinq enzymes ont ainsi été identifiées pour leur capacité à éliminer l’H2O2 : les catalases KatG, KatE, KatN et les peroxyrédoxines AhpCF et TsaA. Des tests de virulence ont également permis de montrer que ces enzymes participaient à l’établissement de la virulence.A l’aide d’une sonde moléculaire capable de détecter et de signaler l’H2O2, nous avons montré que S. typhimurium percevait cette FAO au cours de l’infection dans des macrophages murins. Ces résultats ont souligné l’importance des catalases et des peroxyrédoxines au cours de la vie intracellulaire de S. typhimurium. L’analyse du mutant DahpCF DtsaA Dtpx a également révélé que les peroxyrédoxines AhpCF, TsaA et Tpx contribuaient à la capacité de prolifération de la bactérie dans le macrophage. Enfin, l’étude des méthionine sulfoxyderéductases a montré que les caractéristiques d’un mutant DmsrA DmsrB étaient proches de celles de la souche sauvage. Les gènes msrA et msrB ont également été inactivés dans une souche dépourvue de katG, katE et ahpCF. Dans cette souche accumulant de l’H2O2endogène, la contribution de MsrA et MsrB devient évidente pour lutter contre les effets liés au stress oxydant. L’ensemble de ces travaux a permis d’identifier et de caractériser l’implication de systèmes antioxydants dans la virulence et le métabolisme de S. typhimuriumReactive Oxygen Species (ROS), produced from molecular oxygen, can oxidize and damagebiological macromolecules. During its lifestyle, Salmonella typhimurium is submitted to ROScoming from two sources: its aerobic metabolism and its host cell upon infection, themacrophage. Among the ROS, H2O2 is one of the most toxic. In this work, the contribution ofcatalases and peroxiredoxins in the metabolism and the virulence of S. typhimurium wasstudied. Five enzymes are implied in H2O2 degradation, the catalases KatG, KatE, KatN andthe peroxiredoxins, AhpCF and TsaA. Virulence tests showed that these enzymes wereinvolved in virulence. Using a molecular probe able to detect and quantify H2O2, we showedthat S. typhimurium sensed H2O2 during infection in murine macrophages. These resultsunderlined the importance of catalases and peroxoxyredoxines for the intracellular life of S.typhimurium. Analysis of the mutant DahpCF DtsaA Dtpx revealed that the peroxiredoxinsAhpCF, TsaA and Tpx contributed to the bacterial proliferation inside macrophage. Finally,the study of the methionine sulfoxyde reductases showed that the phenotype of the mutantDmsrA DmsrB was related to the wild type strain. Then, msrA and msrB were inactivated in astrain deleted of katG, katE and ahpCF. In this strain impaired in H2O2 degradation, thecontribution of MsrA and MsrB to fight against oxidative stress effect is stronger. Altogether,these results allowed the identification and the contribution of antioxidant systems in S.typhimurium virulence and metabolism
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Simmons, James Walter. "O-Acetylserine Sulhydralase-A from Salmonella typhimurium LT-2: Thermodynamic Properties and SPectral Identification of Intermediates." Thesis, University of North Texas, 1993. https://digital.library.unt.edu/ark:/67531/metadc278042/.
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O-Acetylserine Sulfhydrylase (OASS) is a pyridoxal phosphate enzyme that catalyzes the reaction of O-acetyl-Lserine with sulfide to give L-cysteine. OASS is present as two isoforms, designated -A and -B. The kinetic mechanism of OASS-A is well known and there is also much known concerning the acid-base chemistry of the enzyme. However, little is known concerning the location of the rate determining steps, the sequencing of chemical steps that occur at the active site, or the nature of the rate determining transition states. The studies performed to help elucidate these aspects of the OASS-A mechanism included determination of the thermodynamics of both half reactions, along with studies utilizing substrate analogs of OAS halting the reaction at specific points along the reaction pathway allowing the identification of reaction intermediates. The free energy change of the first half reaction was shown to be -5.7 Kcal/mole while the second half reaction was shown to be, for all intents and purposes, irreversible. Intermediates along the reaction pathway that have been previously identified include the internal Schiff base and the a-aminoacrylate. The external Schiff base was identified using the analogs cysteine, alanine, and glycine while the geminal diamine was identified using the analog serine. Formation of the external aldimine was shown to be pH dependent with a pK of 8.1 ± 0.3 most likely representing a general base that accepts a proton from the a-amine of cysteine to facilitate a nucleophilic attack on C4r of the PLP imine. Formation of the geminal diamine was also shown to be pH dependent with two pK values having an average value of 8.1. One of the groups most likely represents the general base which accepts a proton from the a-amine of cysteine while the second group likely interacts with the amino acid side chain to orientate the amino acid into the correct configuration.
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Main-Hester, Kara L. "Counter-silencing of laterally acquired genes, including Salmonella Pathogenicity Island 4, by three DNA binding proteins, HilA, HilD, and SlyA /." Thesis, Connect to this title online; UW restricted, 2008. http://hdl.handle.net/1773/11498.
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Neves, Meiriele da Silva das 1990. "Caracterização fenotípica e molecular de linhagens atenuadas de Salmonella enterica Typhimurium = Phenotipic and molecular characterization of attenuated strains of Salmonella enterica Typhimurium." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316402.
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Orientador: Marcelo BrocchiDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: O gênero Salmonella pertence à família Enterobacteriaceae que agrupa bacilos Gram-negativos, anaeróbios facultativos, fermentadores e geralmente flagelados. S. enterica é um dos patógenos de origem alimentar mais prevalente, sendo que infecções causadas por essa bactéria podem estar relacionadas a praticamente todos os tipos de alimentos. O trabalho foi proposto com o intuito de realizar a caracterização fenotípica e molecular de linhagens atenuadas de Salmonella enterica Typhimurium para genes codificadores de proteínas associadas ao nucleóide (NAPs Nucleoid associated Proteins). As características fenótipicas dos mutantes nulos de Salmonella enterica para os genes ihfA ou ihfB, codificadores das subunidades A e B de IHF, foram avaliadas através de crescimento in vitro, motilidade, sobrevivência frente ao estresse nutricional (sobrevivência em fase estacionária), sob condições ácidas, na presença de sais biliares e quanto à capacidade de invasão e sobrevivência em macrófagos (linhagem J774A.1). Testes de confirmação da atenuação e avaliação da capacidade de induzir proteção em caso de infecção por S. enterica foram realizados utilizando o modelo murino. Os mutantes não apresentaram diferença no crescimento in vitro e na capacidade de sobreviver na presença de sais biliares em comparação com a linhagem selvagem. As linhagens mutantes para os genes ihfA ou ihf ihf ihfB) apresentaram uma menor capacidade de sobrevivência sob condições ácidas quando comparadas com a linhagem selvagem. A motilidade dos mutantes simples também foi reduzida. Os mutantes simples e duplo apresentaram maior capacidade de sobreviver sob estresse nutricional quando comparados com a linhagem selvagem. O mutante para o gene ihfA e o duplo mutante apresentaram um aumento na capacidade de invadir macrófagos. ihf ihfB mostraram uma capacidade aumentada em sobreviver no interior de macrófagos quando comparadas com a linhagem selvagem. Os mutantes nulos viii de Salmonella enterica para os genes ihfA ou ihfB apresentam atenuação, em diferentes graus, quanto à virulência e apresentaram capacidade de induzir proteção no modelo murino de infecção por S. enterica. Esses resultados demonstram que essa proteína apresenta função relacionada com a virulência bacteriana, sendo um importante alvo de estudo na busca de linhagens atenuadas
Abstract: The genus Salmonella belongs to the Enterobacteriaceae family that comprises Gram-negative bacillus, facultative anaerobe, fermenting and generally flagellate. S. enterica is one of the most prevalent food-borne pathogen, and infections caused by this bacterium can be associated to almost all types of food. The work was proposed with the purpose of performing phenotypic and molecular characterization of attenuated strains of Salmonella enterica Typhimurium for genes encoding proteins associated with the nucleoid (NAPs - Nucleoid associated Proteins). The phenotypic characteristics of the null mutants of Salmonella enterica for genes ihfA or ihfB, encoding the A and B subunits of IHF, were evaluated by in vitro growth, motility, survival under nutritional stress (survival in the stationary phase), under acidic conditions, in the presence of bile salts and for the ability of invasion and survival in macrophages (J774A.1 strain). Attenuation tests and evaluation of the capacity to induce protection in case of infection by S. enterica were performed using the murine model. The mutants showed no difference in the in vitro growth and the ability to survive in the presence of bile salts in comparison with the wild type strain. The single mutant for ihfA or ihf ihf ihfB) showed decreased survival under acidic conditions when compared to the wild type strain. Motility of single mutants was also reduced. Single and double mutants showed higher ability to survive under nutritional stress when compared with the wild type strain. The mutant gene for ihfA and the double mutant showed an increased ability to invade ihf ihfB mutants showed an increased ability to survive within macrophages when compared with the wild type strain. Null mutants of Salmonella enterica for ihfA or ihfB genes exhibited attenuation, to varying degrees, for virulence and showed ability to induce protection in a murine model of infection by S. enterica. x These results demonstrate that this protein has function associated to bacterial virulence and is an important subject of study in search for attenuated strains
Mestrado
Genetica de Microorganismos
Mestra em Genética e Biologia Molecular
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馮美玉 and Mei-yuk Ami Fung. "Isolation and characterization of a Salmonella enterica serotype typhivariant." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31970230.
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Pattni, Krupa. "Subcellular localisation of rat inositol 1,4,5 trisphosphate 3 kinase B and phosphatidylinositol (3) phosphate in living cells." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274843.
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Rosche, Kristin. "Infection with Salmonella typhimurium defaces the splenic tissue architecture and alters the proportion and distribution of cells." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1686.
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Salmonella enterica serovar Typhimurium (S. typhimurium) is a gram-negative bacteria capable of infecting a variety of warm-blooded vertebrate hosts. In humans, consumption of S. typhimurium through contaminated food or water typically leads to an acute but self-limiting gastroenteritis and oftentimes an enlargement of the spleen (splenomegaly). Splenomegaly has been attributed to the expansion of phagocytes, B and T lymphocytes, and immature CD71+Ter119+ red blood cells (RBCs). The spleen is an important organ with distinct roles in RBC recycling, the capture of blood-borne pathogens, and as a site of initiation of the adaptive immune response. The spleen has a characteristic tissue architecture composed of three compartments. The white pulp (WP), largely populated by B and T lymphocytes is surrounded by the red pulp (RP), which primarily contains F4/80+ macrophages. The border between the WP and RP, the marginal zone (MZ), is populated by MOMA+ and MARCO+ macrophages which are important for the capture of blood-borne pathogens. This precise organization of the spleen allows for efficient antigen capture and activation of adaptive immunity, due to the close proximity of antigen presenting cells and lymphocytes. It is known that Salmonella spp. infections delay the adaptive immune response in comparison to other bacteria, such as Listeria monocytogenes. Therefore, we investigated the effect of an attenuated S. typhimurium strain (÷9088) on in situ splenic organization. We utilized four-color immunofluorescence microscopy (IFM) in combination with flow cytometry to characterize the in situ changes of spleen architecture and cell population profiles during S. typhimurium infection in mice. Within the first week of infection, splenomegaly is evident and after three weeks of infection, the spleen comprises over 5% of the mouse's total body weight. During this time S. typhimurium has not been cleared from the spleen and mice are anemic with decreased pack cell volume. We confirmed previous studies that reported extramedullary erythropoiesis was a major cause of splenomegaly. However, we also show that RP F4/80+ macrophages significantly expand and take over the WP regions of the spleen, increasingly co-localizing with immature (CD71+Ter119+) and mature (CD71-Ter119+) RBC subsets. As a result of these dramatic changes in cell proportions and their in situ distribution, the splenic architecture becomes unrecognizable. The boundary between WP and RP is lost as proportions of MOMA+ macrophages of the MZ are reduced following infection. Likewise, B and T cell zones of the WP are also drastically reduced, most likely due to their increased co-localization with F4/80+ macrophages. As a result of infection, the increased cellularity of splenomegaly results in changing proportions of cell populations, potentially disrupting the link between infection and immune response. Together, these data provide further insight into the disease process of S. typhimurium infection in mice. Understanding how the changes in splenic architecture affect the adaptive immune response has implications for the design of more effective Salmonella-based vaccines and therapies.
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Teixidó, Devesa Laura. "Estudio del regulón Fur en Salmonella enterica serovar Typhimurium." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/117269.
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El hierro es un oligoelemento esencial para la supervivencia celular ya que es un cofactor de muchas enzimas y forma parte de la estructura de muchas proteínas. Es por este motivo que los microorganismos necesitan mecanismos eficientes para la captación de hierro cuándo carecen del mismo. Está ampliamente descrito que la captación de hierro es uno de los pasos clave en el desarrollo de un patógeno dentro de su huésped 1. Pero, aunque el Fe es indispensable, su exceso en el citoplasma es tóxico para la célula ya que cataliza la reacción de Fenton con la consiguiente formación de radicales hidroxilo 2, 3.
Por todo ello la homeóstasis del Fe2+ se encuentra estrictamente controlada. La proteína Fur (ferric uptake regulator) es el principal regulador transcripcional implicado en la respuesta celular a la concentración de hierro, controlando tanto la inducción de sistemas de captación de Fe2+ de alta afinidad, como la expresión de proteínas para el almacenamiento y enzimas que utilizan hierro 4. Normalmente Fur, asociado al ión Fe2+, se une a una secuencia concreta denominada caja Fur presente en la región promotora de los genes que regula, bloqueando de esta manera su transcripción 5. Aunque también puede activar la expresión de diferentes genes de forma directa o indirecta 1.
En el presente trabajo se estudia, mediante microarrays de DNA, el papel de la proteína Fur en el patógeno intracelular S. enterica serovar Typhimurium y la relación de este regulador con los mecanismos de virulencia de dicho microorganismo.Iron is an essential trace element for the cell since it is a cofactor for many enzymes and is a part of the structure of many proteins. It is for this reason that the microorganisms need efficient mechanisms for iron uptake when lacking it. It is widely reported that iron uptake is one of the key steps in the development of a pathogen within its host 1. Although Fe2+ is indispensable, its excess in the cytoplasm is toxic to the cell since it catalyzes the Fenton reaction leading to the formation of hydroxyl radicals 2, 3. Therefore Fe2+ homeostasis is strictly controlled. Protein Fur (ferric uptake regulator) is the major transcriptional regulator involved in the cellular response to iron concentration, by controlling the induction of Fe2+ high affinity uptake systrems and the protein expression of iron storing and utilizing enzymes 4. Normally, Fur, associated to the Fe2+ ion, binds to a specific sequence called Fur box present in the promoter region of genes the regulated genes, thus blocking its transcription 5. Fur also can activate the expression of different genes directly or indirectly 1. The role of the Fur protein in the intracellular pathogen S. enterica serovar Typhimurium and its relationship with the virulence mechanisms of this microorganism is studied in this work by DNA microarrays.
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Selke, Martin. "Development of a DIVA vaccine against Salmonella Typhimurium infection." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=983732760.
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Thiel, Susanne Andrea. "Aktuelle Ergebnisse zur Feintypisierung von Salmonella Typhimurium aus Hackfleisch." Diss., lmu, 2005. http://nbn-resolving.de/urn:nbn:de:bvb:19-43437.
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Holden, Nicola Jean. "The cold shock response of Salmonella enterica serovar Typhimurium." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/28240.
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The alternative sigma factor, ss, did not appear to play a significant role in cspB expression at low temperature. In contrast, Fis appeared to act as a positive regulator of cspB in stationary phase cultures. Cell survival assays (measured by ability to form colony forming units on nutrient agar plates) showed that 4% of cells that were in early exponential phase survived a rapid cold shock to 4°C, although survival was almost complete when cells were in lag phase or in late exponential phase. The alternative sigma factor, ss, did not appear to play a significant role in cell survival in response to a rapid temperature reduction to 4°C. The addition of an osmoprotectant, 0.3 M sucrose, protected against loss of plating viability to some degree for early exponential phase cells, when diluted to 4°C. 2-D PAGE analysis showed that the response of exponential phase S. typhimurium cells incubated at 10°C consisted of an adaptive phase followed by an acclimation phase, in agreement with previous reports for E. coli. Identification of CspA was verified by N-terminal sequencing. The response was delayed at 4°C and recovery of protein synthesis in the acclimation phase was not as extensive, as observed at 10°C. CspA was synthesised throughout the period of incubation at 4°C. Growth phase was found to severely affect de novo protein synthesis at low temperature. Incubation of stationary phase cells at 10°C or 4°C resulted in repression of the synthesis of the majority of proteins, although a small set of proteins was induced. CspA was not detected at 37°C, but was highly induced at 10°C. However, prolonged incubation at 4°C led to complete repression of protein synthesis, except for CspA. This study has shown that S. typhimurium adapts to low temperature in a dynamic fashion and expression of CspA is a major feature of the response. Furthermore, it appears that exponential phase S. typhimurium cells are metabolically active even after 4 days at refrigeration temperatures.
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Zhang, Rui. "Exogenous dihydroorotate as a pyrimidine source for Salmonella typhimurium." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq30578.pdf.
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Boutt, Elizabeth Ann. "Evolutionary and Functional Analysis of SlyA in Salmonella typhimurium." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-08132002-094341/.
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Salmonella species cause a variety of infections in humans and domestic animals, ranging from mild food poisoning-gastroenteritis Salmonella typhimurium to severe systemic disease Salmonella typhi. Salmonella is used as a paradigm to understand how intracellular pathogens withstand the onslaught of the host innate immune system, namely the professional macrophage. SlyA is a global transcriptional regulator that is necessary for the virulence of Salmonella typhimurium. In a mouse model system, a slyA mutant is profoundly attenuated for virulence and is unable to survive in macrophages. To understand the evolutionary history of SlyA in Eubacteria, a phylogenetic analysis was performed. Several alignments of amino acid sequences were constructed with MarR and also with known SlyA homologues. Searches for other SlyA homologues were undertaken using databases of unfinished and finished microbial genomes and more than 50 putative homologues were found. SlyA has been classified as a MarR-like transcriptional regulator by homology. This classification may not be appropriate given the differences in function. Therefore it is suggested that a new class of SlyA-like regulators be formed incorporating all of the homologues found in this study. In order to determine the extent of the SlyA regulon, studies were conducted to analyze the DNA-binding properties of SlyA. The target promoters from this study included genes that were shown to be either activated or repressed by SlyA by utilizing a Salmonella genomic DNA microarray. SlyA was shown to bind specifically to the promoters of clyA, pagC, pagK and mig-14. The approximate Kd values appear to be similar between each of the promoters indicating a similar propensity for SlyA to bind.