Project description:The gene expression of Salmonella enterica Typhimurium MB282 residing in the food vacuole (phagosome) of Tetrahymena was analyzed by microarray.
Project description:The gene expression of Salmonella enterica Typhimurium MB282 residing in the food vacuole (phagosome) of Tetrahymena was analyzed by microarray. A minimum of three biological replicates were used. Each biological rep was comprised of at least two technical replicate arrays. MB282 incubated in H2O and MB282 grown to mid - log in LB were used as controls.
Project description:Salmonella enterica serovar Typhimurium (S. Typhimurium) is a zoonotic pathogen that causes diarrheal disease in humans and animals. During salmonellosis, S. Typhimurium colonizes epithelial cells lining the gastrointestinal tract. S. Typhimurium has an unusual lifestyle in epithelial cells that begins within an endocytic-derived Salmonella-containing vacuole (SCV), followed by escape into the cytosol, epithelial cell lysis and bacterial release. The cytosol is a more permissive environment than the SCV and supports rapid bacterial growth. The physicochemical conditions encountered by S. Typhimurium within the cytosol, and the bacterial genes required for cytosolic colonization, remain unknown. Here we have exploited the parallel colonization strategies of S. Typhimurium in epithelial cells to decipher the two niche-specific bacterial virulence programs. By combining a population-based RNA-seq approach with single-cell microscopic analysis, we identified bacterial genes/sRNAs with cytosol-specific or vacuole-specific expression signatures. Using these genes/sRNAs as environmental biosensors, we defined that Salmonella is exposed to iron and manganese deprivation and oxidative stress in the cytosol and zinc and magnesium deprivation in the SCV. Furthermore, iron availability was critical for optimal S. Typhimurium replication in the cytosol, as well as entC, fepB, soxS and sitA-mntH. Virulence genes that are typically associated with extracellular bacteria, namely Salmonella pathogenicity island 1 (SPI1) and SPI4, had a cytosolic-specific expression profile. Our study reveals that the cytosolic and vacuolar S. Typhimurium virulence gene programs are unique to, and tailored for, residence within distinct intracellular compartments. Therefore, this archetypical vacuole-adapted pathogen requires extensive transcriptional reprogramming to successfully colonize the mammalian cytosol.
Project description:Many non-typhoidal serovars of Salmonella such as Salmonella enterica serovar Typhimurium (S. Typhimurium) are the leading cause of food-borne gastroenteritis, resulting in millions of infections each year and sometimes death. Salmonella enterica serovar Typhimurium is the most common non-typhoidal Salmonella strain isolated from patients around the world and is used as a mouse model to study bacterial pathogenesis and host-microbe interactions. Furthermore, S. Typhimurium is an important pathogen in livestock animals including chickens and cattle. S. Typhimurium utilises a multitude of virulence factors to reach and invade host cells and for its intracellular survival. However, little is known about the mechanism of protein synthesis of these virulence factors at the codon level. Here, we performed RNA-seq and ribosome profiling. Ribosome profiling allows the global mapping of translating ribosomes on the transcriptome and therefore provides direct measure of protein synthesis.
Project description:This experiment set includes 64 arrays representing 26 serovars and strains of Salmonella spp. including many representatives of subspecies I, Arizona from subsp. IIIa, and S. bongori from subsp. V. The genomic DNA from all strains were labeled with Cy5 and hybridized against an equal amount (1.5 ug) of S. typhimurium SL1344 reference genomic DNA that was labeled with Cy3, all on an S. typhimurium SL1344 spotted DNA microarray. Most of the arrays are present in triplicate to account for variability in probe generation, hybridization, and slide quality. Several are represented in duplicate, and a few without any replicates. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Keywords: Logical Set
Project description:FabR ChIP-chip on Salmonella enterica subsp. enterica serovar Typhimurium SL1344 using anti-Myc antibody against strain with chromosomally 9Myc-tagged FabR (IP samples) and wildtype strain (mock IP samples)
Project description:Cell to cell communication in bacteria to regulate various cellular processes with respect to their population density is termed quorum sensing and is achieved using signaling molecules called autoinducers. LuxS, which is involved in the synthesis of the autoinducer molecule-2 (AI-2), is conserved in several Gram-positive and Gram-negative bacteria including the enteric pathogen Salmonella Typhimurium. Genes that are regulated by luxS in S. Typhimurium were identified using microarrays and RNA samples from wild type S. Typhimurium and its isogenic luxS mutant, in two growth conditions (presence and absence of glucose), and at two different time points (mid-log and early-stationary phases). Minimal differential gene expression was observed in the presence of glucose. In the absence of both luxS and glucose, a total of 1560 genes were differentially expressed and 1361 genes were identified as luxS/AI-2-regulated at the mid-log phase and 199 genes at the early-stationary phase. Quantitative real-time PCR was performed on selected genes to validate the microarray results. These results suggest that although the expression of the luxS gene in S. Typhimurium is independent of the growth condition, its role in the production of AI-2 depends on the growth condition. It was found that luxS/AI-2 plays a vital role in a variety of processes such as metabolism, virulence gene expression, motility, transcription and translation. Keywords: Salmonella Typhimurium, quorum sensing, luxS mutant, autoinducer-2
Project description:Transcriptional profiling of Salmonella Typhimurium SL1344 wild type and ompR mutant grown to mil-exponential phase in LB. The goal was to define the ompR-regulated genes.
Project description:Salmonella is one of most common causes of bacterial foodborne disease and consumption of contaminated poultry products, including turkey, is one route of exposure. Minimizing colonization of commercial turkeys with Salmonella could reduce the incidence of Salmonella-associated human foodborne illness. Understanding host responses to these bacteria could lead to potential strategies to minimize colonization and thus food safety risk. In this study, we evaluated bacterial load and blood leukocyte transcriptomic responses of 3-week-old turkeys challenged with the Salmonella enterica serovar Typhimurium (S. Typhimurium) UK1 strain. Turkeys (n = 8/dose) were inoculated with 108 or 1010 colony forming units (CFU) of S. Typhimurium UK1 and fecal shedding and tissue colonization were measured across multiple days post inoculation (dpi). Fecal shedding was 1-2 log10 higher in the 1010 CFU group than the 108 CFU group, but both doses effectively colonized the crop, spleen, ileum, cecum, colon, bursa of Fabricius and cloaca without causing any overt clinical signs in either group of birds. Blood leukocytes were isolated from a subset of the birds (n =3-4/dpi) both pre-infection (0 dpi) and 2 dpi with 1010 CFU and their transcriptomic responses assayed by RNA-sequencing (RNA-seq). After 2 dpi, 647 genes had significant differential expression (DE), including large increases in expression of immune genes such as CCAH221, IL4I1, LYZ, IL13RA2, IL22RA2, and ACOD1. IL1B was predicted as a major regulator of DE in these leukocytes and this DE was predicted to activate cell migration, phagocytosis and proliferation, and to impact the STAT3 and toll-like receptor pathways. These data revealed genes and pathways by which turkey blood leukocytes responded to the pathogen and can provide potential targets for developing intervention strategies or diagnostic assays to mitigate S. Typhimurium in turkeys.
Project description:Salmonella enterica serovar Typhimurium (S. Typhimurium) infection triggers an inflammatory response that changes the concentration of luminal metabolites in the gut, resulting in a distinct environment from a healthy one. We recently demonstrated that S. Typhimurium possesses the ability to form biofilms within the host environment and responds to nitrate as a signaling molecule, enabling it to modulate the transition between sessile and planktonic states. To investigate whether S. Typhimurium utilizes additional metabolites to regulate its behavior, our study delved into the impact of inflammatory metabolites on biofilm formation. Employing a transcriptomic approach we unveiled that lactate enhances the transcription of flagella and invasion genes, highlighting the active role of lactate in modulating the transition of S. Typhimurium from biofilm to motile states. All these findings propose that, as occurring with nitrate, lactate is an inflammatory metabolite being used by S. Typhimurium to support virulence.