Transcription profiling of Salmonella enterica serotype SL1344 wildtype, pSf-R27sfh and pSf-R27 at stationary and exponential growth phases, to investigate the role of the Sfh protein encoded by transmissible plasmids and involved in human typhoid
ABSTRACT: The Sfh protein is encoded by self-transmissible plasmids involved in human typhoid and is closely related to the global regulator H-NS. We have found that Sfh provides a stealth function that allows the plasmids to be transmitted to new bacterial hosts with minimal effects on their fitness. Introducing the plasmid without the sfh gene imposes a mild H-NS- phenotype and a severe loss of fitness due to titration of the cellular pool of H-NS by the A+T-rich plasmid. This stealth strategy seems to be used widely to aid horizontal DNA transmission and has important implications for bacterial evolution.
The Sfh protein is encoded by self-transmissible plasmids involved in human typhoid and is closely related to the global regulator H-NS. We have found that Sfh provides a stealth function that allows the plasmids to be transmitted to new bacterial hosts with minimal effects on their fitness. Introducing the plasmid without the sfh gene imposes a mild H-NS(-) phenotype and a severe loss of fitness due to titration of the cellular pool of H-NS by the A+T-rich plasmid. This stealth strategy seems t ...[more]
Project description:Analysis of transcriptome in a strand-specific manner to further refine previous genome annotation; RNA-seq was also combined with microarray and proteome analysis to further define the S. Typhi ompR regulon and identify novel ompR regulated transcripts.
Project description:GskA, the Dictyostelium GSK-3 orthologue, is modified and activated by the dual-specificity tyrosine kinase Zak1 and the two kinases form part of a signalling pathway that responds to extracellular cAMP. We identify potential cellular effectors for the two kinases by analysing their null mutants. There are proteins and mRNAs that are altered in abundance in only one or other of the two mutants, indicating that each kinase has some unique functions. However, proteomic and micro-array analysis respectively identified 3 proteins and 37 genes that are similarly mis-regulated in both mutant strains. The positive correlation between the array data and the proteomics data is consistent with the Zak1-GskA signalling pathway functioning by directly or indirectly regulating gene expression. The discoidin 1 genes are positively regulated by the pathway while the abundance of the H5 protein is negatively regulated. Two of the targets, H5 and discoidin 1, are well-characterised markers for early development, indicating that the Zak1-GskA pathway plays a role in development earlier than previously observed.
Project description:The representative cell line, HT29, culture in hypoxic and normoxic conditions were used to perform the miRNA microarray. The chip assay and data analysis were entrusted to KangChen Bio-tech, Inc. (Shanghai, China) and all the miRNAs with more than 2-fold variation in different samples were identified. Detailed methods were performed as previously described24 using the miRCURY Hy3 labeling kit and the microRNA array software (Exiqon, Denmark).
Project description:We describe the serendipitous discovery and first characterization of a new resistant cell type from Dictyostelium, which we propose to call the aspidocyte (aspida: Greek for shield). These cells are induced from amoebae by a range of toxins including heavy metals and antibiotics, and were first detected by their striking resistance to detergent lysis. Aspidocytes are separate, rounded or irregular shaped cells that are immotile but remain fully viable; once the toxic stress is removed, they revert to amoeboid cells within an hour. Induction takes a few hours and is completely blocked by the protein synthesis inhibitor cycloheximide. Aspidocytes lack a cell wall and their resistance to detergent lysis is active, requiring continued energy metabolism, and may be assisted by a complete cessation of endocytosis, as measured by uptake of the dye FM1-43. Microarray analysis shows that aspidocytes have a distinct pattern of gene expression with a number of genes up-regulated that are predicted to be involved in lipid metabolism. Aspidocytes were initially detected in a hypersensitive mutant, in which the AMP deaminase gene is disrupted, suggesting that the inductive pathway involves AMP levels or metabolism. Since aspidocytes can also be induced from wild-type cells and are much more resistant than amoebae to a membrane disrupting antibiotic, it is possible that they are an adaptation allowing Dictyostelium cells to survive a sudden onslaught of toxins in the wild.