Project description:NADPH dependent phagocytic oxidase, by producing hydroxyradicals such as hydrogen peroxide, is essential for host defense against Salmonella infection. We used gene array analysis to identify Salmonella enterica serovar Typhimurium genes regulated by NADPH dependent phagocytic oxidase intracellularly in comparison to those expressed in vitro by hydrogen peroxide.
Project description:DNA microarrays were used to provide a global transcriptional profile of S. typhimurium during the intracellular growth phase of infection pathogenesis following infection of macrophages.
Project description:The integration host factor, IHF, is a DNA-binding and -bending protein with roles in local DNA structural organization and transcriptional regulation in Gram-negative bacteria. This heterodimeric protein is composed of the two highly homologous subunits IHF alpha and IHF beta. DNA microarray analysis was used to define the regulon of genes subject to IHF control in Salmonella enterica serovar Typhimurium. The transcription profile of the wild type was compared with those of mutants deficient in IHF alpha, IHF beta, or both IHF alpha and IHF beta. Our data reveal a new connection between IHF and the expression of genes required by the bacterium to undergo the physiological changes associated with the transition from exponential growth to stationary phase. When a mutant lacking IHF entered stationary phase, it displayed downregulated expression of classic stationary-phase genes in the absence of any concomitant change in expression of the RpoS sigma factor. Purified IHF was found to bind to the regulatory regions of stationary-phase genes indicating an auxiliary and direct role for IHF in RpoS-dependent gene activation. Loss of IHF also had a profound influence on expression of the major virulence genes and epithelial cell invasion, indicating a role in co-ordinating regulation of the pathogenic traits with adaptation to stationary phase. Although the three mutants showed considerable overlaps in the genes affected by the ihf lesions, the observed patterns were not identical, showing that S. Typhimurium has not one but three overlapping IHF regulons.
Project description:Epithelial cells are the first cell type Salmonella Typhimurium will encounter when infecting a host. Using DNA array techology we identified the Salmonella enterica Typhimurium genes regulated inside human epithelial cells and their variation through time.
Project description:Streptococcus mutans was grown for 48 h in a biofilm in the absence (single species) and in the presence (dual species) of Veillonella parvula. In addition V. parvula single species 48 h biofilms were grown, to be used as a control. RNA was harvested from all types of biofilms and the transcript levels of the two types of biofilms containing S. mutans were compared with the use of S. mutans microarrays. V. parvula RNA was hybridized to S. mutans microarrays as a control for possible cross-hybridisation.