Expression analysis of Salmonella typhimurium LT2 TA100 upon exposure to C60
ABSTRACT: Investigation of gene expression level changes in Salmonella typhimurium LT2 TA100 upon exposure to C60, compared to unexposed controls. The mutations engineered into this strain make it susceptile to mutagenic compounds. The Salmonella typhimurium TA100 strain used in this study is further described in Pedersen P, Thomsen E, Stern RM. 1983. Detection by Replica Plating of False Revertant Colonies Induced in the Salmonella Mammalian Microsome Assay by Hexavalent Chromium. Environmental health perspectives 51: 227-230. A 4 x 72K array study using total RNA recovered from triplicate cultures of Salmonella typhimurium LT2 TA100 exposed to C60 and triplicate cultures of controls that were not exposed to C60. Each 72K array measures the expression level of 4,504 genes from Salmonella typhimurium LT2 with seven 45 to 60-mer probe pairs per gene.
Project description:To explore the mechanisms of Salmonella desiccation resistance, we studied the transcriptomic responses in Salmonella Tennessee (Tennessee), using S. Typhimurium LT2 (LT2), a strain weakly resistant to desiccation, as a reference strain. In response to 2 h air-drying at 11% equilibrated relative humidity, approximately one-fourth of the ORFs in the Tennessee genome and one-fifth in LT2 were differentially expressed (> 2-fold). Among all differentially expressed functional groups (>5-fold) in both strains, the expression fold change associated with fatty acid metabolism was the highest, and constituted 51 and 35% of the total expression fold change in Tennessee and LT2, respectively. Tennessee showed greater changes in expression of genes associated with stress response and envelope modification than LT2, while showing lesser changes in protein biosynthesis expression. Expression of flagella genes was significantly more inhibited in stationary phase cells of Tennessee than LT2 both before and after desiccation. Salmonella Typhimurium LT2 ATCC strain 19585 (LT2) and Tennessee strain K4643 (Tennessee) were grown in TSB at 37 ºC with shaking for 20 h. Cells (~8 log CFU) for each strain were added on the discs and either stored at -80ºC directly, as control samples; or kept at 11% ERH at 25°C for 2 h and then transferred into -80 ºC, as desiccation treated samples. Three independent experiments were carried out for each condition.
Project description:Investigation of whole genome gene expression level changes in a Salmonella enterica serovar Typhimurium UK1 delta-iacP mutant, compared to the wild-type strain. IacP is resoponsible for the secretion of virulence effector proteins via the type III secretion system, thereby contributing the virulence of S. Typhimurium. The mutants analyzed in this study are further described in Kim et al. 2011. Role of Salmonella Pathogenicity Island 1 Protein IacP in Salmonella enterica Serovar Typhimurium Pathogenesis. Infection and Immunity 79(4):1440-1450 (PMID 21263021). A chip study using total RNA recovered from two separate wild-type cultures of Salmonella enterica serovar Typhimurium UK1 and two separate cultures of a mutant strain, Salmonella enterica serovar Typhimurium UK1 delta-iacP. Each chip measures the expression level of 4,302 genes from Salmonella enterica serovar Typhimurium.
Project description:Obacunone is a limonoids present in Citrus species. We previously reported that obacunone was inhibitory to the cell-cell signaling in Vibrio harveyi and Escherichia coli O157:H7. In the present work we evaluated the effect of obacunone on the food borne pathogen Salmonella Typhimurium LT2 using cDNA microarray. The results demonstrate that obacunone exerts an antivirulence effect on S. Typhimurium LT2 by repressing SPI1 and SPI2. Furthermore, the effect of obacunone seems to be dependent upon EnvZ. One condition experiment, obacunone treated versus DMSO treated. Biological replicates: 3 control, 3 treatment, hybridized in dye-swapped design
Project description:Salmonella spp. biofilms have been implicated in persistence in the environment and plant surfaces. In addition, Salmonella is able to form biofilms on the surface on cholesterol gallstones. The ability of Salmonella spp. on these surfaces is superior to biofilm formation on surfaces on glass or plastic. Thus, we hypothesized that Salmonella gene expression is specific during biofilm development on cholesterol surfaces. Flow through assays were performed whereby S. Typhimurium was inoculated into chambers coated with glass or cholesterol. At 24h post-inoculation, planktonic (from the flow through), biofilms (from glass or cholesterol) were collected. Thus we had 4 samples: Planktonic (2) and Biofilms (2), each with 2 biological replicates
Project description:Glucose-lysine based Maillard reaction products (MRPs) are introduced to the human body via food ingestion or are synthesized in vivo. Depending on reaction conditions, they represent a mixture of compounds with diverse chemical structures and physiological properties. MRPs may also be a potential nutrient source for Salmonella, a major foodborne gastrointestinal pathogen. This study was designed to determine the growth and transcriptional responses of S. Typhimurium LT2 to MRPs generated at low water activity to simulate the reaction occurring during food processing and storage. Maillard reactions between N-α-acetyl-lysine and glucose were varied in time (4, 23, and 143 h) to generate sub-samples with prevailing Amadori compound, advanced glycation end products (AGEs), or melanoidines respectively. The addition of MRP up to 5 mg mL-1 to defined media with 0.4% glucose had no effect on S. Typhimurium LT2 growth. In media, where the MRP sub-samples (4 and 23 h) served as the only carbon source, MRP assimilation by S. Typhimurium LT2 was observed as secondary logarithmic growth phases (0.063 h-1 and 0.072 h-1) after the growth on glucose available in the MRP reaction mixtures (0.479 h-1). The MRPs sub-sample with the highest concentration of melanoidines (143 h) also supported S. Typhimurium LT2 growth (0.368 h-1). Of the three MRPs sub-samples, the Amadori compound was the preferred carbon source for S. Typhimurium LT2 as evidenced by its almost complete disappearance (98%). Decreases in AGEs (37%) and melanoidines (15%), when incubated with S. Typhimurium LT2, also occurred. Transcription profiles of the cells grown on the MRPs fractions revealed predominant up-regulation of genes associated with the functional groups of energy metabolism, fatty and phospholipid metabolism, cellular process, and regulatory functions, and general down-regulation of the genes in the groups of amino acid biosynthesis, protein synthesis and transcription, transport and binding proteins, and DNA metabolism. The carbon flow in tricarboxylic acid (TCA) cycle partitioned by the glyoxylate cycle appeared to play an essential role in the assimilation of glucose-lysine-derived MRPs. The high expression level of numerous genes encoding hypothetical proteins or proteins with unknown function suggested the presence of genes whose role in glucose-lysine MRPs catabolism in Salmonella remains to be determined. This study was designed to determine the growth and transcriptional responses of S. Typhimurium LT2 to MRPs generated at low water activity to simulate the reaction occurring during food processing and storage. Maillard reactions between N-α-acetyl-lysine and glucose were varied in time (4, 23, and 143 h) to generate sub-samples with prevailing Amadori compound, advanced glycation end products (AGEs), or melanoidines respectively. Total bacterial RNA was isolated as previously described and the RNA samples were then converted to fluorescently-labeled cDNA and hybridized to S. Typhimurium microarrays version 5 (NIAID's Pathogen Functional Genomics Resource Center). Real-time PCR and physiological experiments were performed to validate the microarray data. In all supplementary files channel A = Cy3, channel B = Cy5.
Project description:Investigation of whole genome gene expression level changes in a Salmonella enterica serovar Typhimurium 14028 delta GidA mutant The mutant described in this study is further analyzed in Shippy, D. C., N. M. Eakley, P. N. Bochsler, and A. A. Fadl. 2011. Biological and virulence characteristics of Salmonella enterica serovar Typhimurium following deletion of glucose-inhibited division (gidA) gene. Microb Pathog. A single chip study using three separate cultures of wild-type Salmonella enterica serovar Typhimurium 14028 and three separate cultures of a single mutant, delta GidA Salmonella enterica serovar Typhimurium 14028.
Project description:Transcriptomic analysis in a Salmonella enterica Serovar Typhimurium SL 1344 that constitutively expresses stdE and stdF compared with a strain carrying an stdEF deletion A four chip study using total RNA recovered from two separate cultures of Salmonella enterica Serovar Typhimurium SL 1344 constitutively expressing stdE and stdF and two separate cultures of Salmonella enterica Serovar Typhimurium SL 1344 lacking stdE and stdF.
Project description:Salmonella enterica serovar Typhimurium is known to synthesize and respond to the cell signaling molecule, autoinducer-2 (AI-2). The luxS gene is involved in the synthesis of AI-2. We have previously shown that luxS controls a variety of bacterial processes in S. Typhimurium. In this study we identified the genes regulated by AI-2 in the Cell-Free supernatant of S. Typhimurium using mRNA samples from isogenic luxS gene mutant of S. Typhimurium strain 87-26254 grown in LB media in the presence of S. Typhimurium wild type CFS / absence AI-2 (mutant CFS of S. Typhimurium). In the presence of AI-2 in CFS, 758 genes were significantly regulated. Interstingly, AI-2 in CFS caused the down-regulation of 39 genes in Salmonella Pathogenicity Island-1 (SPI-1). Purified cDNAs from the mutant supplemented with CFS containing AI-2 and mutant without AI-2 (Mutant CFS) were each labeled with Cy-3 mono-Reactive Dye and Cy-5 mono-Reactive Dye (GE Health Care, Piscataway, NJ) and were processed using a dye-swapping design. A total of 5 microarray arrays, each with duplicate spots for each gene.
Project description:Salmonella has various mechanisms of small RNA-mediated gene regulation. In Salmonella enterica serovar Typhimurium, a novel intergenic transcript RsiM is involved in oxidative stress response which functions as one of the powerful antimicrobials in macrophage innate immunity. We note that the ∆rsiM mutant is sensitive to hydrogen peroxide (5.0mM). This finding provides insights into the function of RsiM as a regulator of oxidative stress response. UK1 wild-type and ∆rsiM strains were grown in LB medium at 37℃ to an OD600 of 0.6, and then subjected to oxidative stress (5.0 mM hydroperoxide) for 30 min. Total RNA was extracted from three biological replicates of wild-type and ∆rsiM mutant.