ABSTRACT: To understand the survival of dormant, nonculturable H. pylori, we investigated changes in cell morphology and gene transcription associated with the loss in culturability seen under oxygen stress and nutrient deprivation. This study examined the gene transcription profiles associated with the transition to a nonculturable form under stress by microarray analysis. We examined one time point of H.pylori cells stressed by oxygen (24H) and three consecutive time points of cells stressed by nutrient deprivation (24, 72, 168H).
Project description:Ribonucleases (RNases) are central actors in post-transcriptional regulation, a major level of regulation of gene expression in all cells. This control plays an important role in the bacterial pathogen Helicobacter pylori, although only the function of RNase J was characterized so far. Here, we studied the RNase R enzyme from H. pylori, a 3’-5’ exoribonuclease whose ortholog in Escherichia coli was reported to display, in addition, helicase activity and to be able to hydrolyze RNA substrates with double stranded structures. We observed that HpRNase R protein does not carry the domains responsible for helicase activity in E. coli and accordingly that the purified protein is unable to degrade in vitro RNA molecules with secondary structures. The RNase R helicase domain loss is widespread among the Campylobacterota and occurred gradually during their evolution. Furthermore, an in vivo interaction between HpRNase R and RhpA, the sole DEAD-box RNA helicase of H. pylori, was discovered. Phylogenomics suggests that this interaction might occur in other bacteria of the phylum Campylobacterota. Purified RhpA facilitates the degradation of double stranded RNA substrates by HpRNase R, showing that this complex is functional. HpRNase R has a minor role of in 5S rRNA maturation and, as shown by RNA-Seq, few targets in H. pylori all of them being included in the RhpA regulon. In conclusion, we describe a new type of RNase R that lacks some of the features that were considered as hallmarks of RNase R proteins, but that has co-opted another RNA helicase, which we hypothesize helps it accomplish some of its functions in vivo.
Project description:Validation of an in vitro model of hypoxia using a primary cell culture of mouse embryonic fibroblasts (MEF) exposed to 1% oxygen at 37 degrees celsius. Control cells were exposed to atmospheric oxygen. Hypoxic and normoxic MEF (in 100 mm dishes, four replicates per group) were submitted to gene expression analysis using Affymetrix Exon microarrays. Differential gene expression analysis was performed with R package DEMI (http://biit.cs.ut.ee/demi/).
Project description:Helicobacter cinaedi is an emerging bacterial pathogen of immunosuppressed individuals. The species is traditionally thought to require an H2-enhanced microaerobic atmosphere for growth, although it can proliferate under aerobic conditions when co-cultured with epithelial monolayers or supplemented with certain metabolites (notably, L-lactate). The goal of this experiment was to assess the global transcription changes that occur in the H. cinaedi type strain (ATCC BAA-847) under various media and atmospheric conditions. These include bacterial monoculture, as well as co-culture with Caco-2 intestinal epithelial cells. In total, Illumina mRNA-seq (stranded, paired-end) was performed on H. cinaedi grown under 9 in vitro culture conditions (4-5 biologic replicates per condition).
Project description:We examined the transcriptomes of murine "expandable hemangioblasts" (eHBs) and their blood and endothelial progeny, comparing them to the transcriptomes of murine embryonic stem (ES) cells, primary murine endothelial cells isolated from E11.5 yolk sacs or embryos, and E14.5 fetal liver hematopoietic stem cells. Total RNAs were purified from lysates of cultured or primary cells, reverse transcribed, and sequenced on an Illumina HiSeq 2500.
Project description:B. cenocepacia J2315 was grown on LB medium to mid-stationary phase at OD 0.3 under full aeration and then transferred into a 50 ml centrifuge tube and placed upright into a CampyGen Compact (Oxoid, Basingstoke, UK) plastic pouch containing the gas generating paper sachet. The pouch was sealed immediately and then the cap of the centrifuge tube loosened to allow exchange of atmosphere between centrifuge tube and pouch. <br>The culture was further incubated at 37 degrees centigrade and 150 rpm for 2-3 hours until it reached OD 0.5. The centrifuge tube was sealed before opening the pouch and then snap-cooled before harvest to minimise exposure to atmospheric oxygen and to ensure expression profiles reflect the lower oxygen concentration.<br>The expression profile was compared to cells grown to OD 0.5 at atmospheric oxygen concentrations.<br>
Project description:Therapeutic hypothermia is a clinically effective treatment for various hypoxic and ischemic conditions, but the associated molecular mechanisms remain unclear. To gain insight into hypothermia-induced transcriptional response, mouse embryonic fibroblasts were exposed to mild hypothermia (32°C) or normothermia (37°C) for increasing time periods. We aimed to identify genes with temporally near-monotonic response as the most obvious candidates for mediating the therapeutic effects of hypothermia. Hypothermia was compared against normothermia at seven different time-points. Hypothermic and normothermic mouse embryonic fibroblasts (MEF, in 100 mm dishes, one array per time-point) were submitted to gene expression analysis using Mouse Gene 1.0 ST GeneChip® (Affymetrix) microarrays. Differential gene expression analysis was performed with R package DEMI (http://biit.cs.ut.ee/demi/).
Project description:In this study, a whole-genome CombiMatrix Custom oligonucleotide tiling microarray with 90000 probes covering six sequenced Helicobacter pylori(H. pylori) genomes was designed and utilized for comparative genomic profiling of eight unsequenced strains isolated from patients with different gastroduodenal diseases in Heilongjiang province of China. Since significant genomic variation were found among these strains, an additional 76 H. pylori stains with different clinical outcomes isolated from various provinces of China were further tested by PCR to demonstrate this distinction. We observed several highly variable regions among strains of gastritis, gastric ulceration and gastric cancer. They are involved in genes associated with bacterial type I, type II and type III R-M system as well as in a virB gene neighboring the well studied cag pathogenic island. Previous studies have reported the diverse genetic characterization of this pathogenic island, but it is conserved in the strains tested by microarray in this study. Moreover, a number of genes involved in the type IV secretion system related to DNA horizontal transfer between H. pylori strains were identified based on the comparative analysis of the strain specific genes. These findings may provide new insights for discovering biomarkers for prediction of gastric diseases. Here we describe the design and use of a high-density oligonucleotide microarray covering six sequenced H. pylori genomes as well as several sequenced plasmids. The performance of this microarray is evaluated, and its utility is illustrated for the hybridization of genomic DNA in order to compare eight uncharacterized H. pylori strains which have not been sequenced with the six known, sequenced strains. We utilize this microarray to identify variable genomic region among H. pylori strains isolated from patients with different gastroduodenal diseases in a Chinese patient population. H. pylori isolates from 2 patients with chronic superficial gastritis, 2 patients with atrophic gastritis, 2 patients with gastric ulcer, and 2 patients with gastric cancer were studied. All eight strains were isolated from Heilongjiang province of China. A number of variable regions with high genetic diversity was identified. 26 selected genes were validated by large scale PCR in both microarray tested strains while an additional 76 strains were isolated from eight provinces.
Project description:Comparison of B. bronchiseptica strains RB50 and 761 grown in either atmospheric concentrations of oxygen and carbon dioxide (normal conditions) or in atmospheric levels of oxygen with the addition of 5% carbon dioxide into a sealed incubator (5% CO2 conditions).
Project description:rpoE1 encodes an extracytoplasmic function (ECF) sigma factor to initiate the transcription of the genes responsible for general stress responses. This experiment is quantifying transcription in two Brucella strains: B. abortus 2308 wild type and rpoE1 in-frame deletion strains (gene bab1_1672).
Project description:Reaeration timecourse from a defined hypoxia model in Mycobacterium tuberculosis. The mechanism by which mycobacteria return to a replicating state upon re-exposure to favorable conditions is not well understood. In this study, we utilized reaeration from a defined hypoxia model to characterize the adaptive response of Mycobacterium tuberculosis (MTB) following a return to favorable growth conditions. Global transcriptional analysis identified the ~100 gene Reaeration Response, induced relative to both log-phase and hypoxic MTB. This response includes chaperones and proteases, as well as the transcription factor Rv2745c, a Clp protease gene regulator (ClgR) orthologue. During reaeration, genes repressed during hypoxia are also upregulated in a wave of transcription that includes genes crucial to transcription, translation and oxidative phosphorylation. Each reaerating culture compared at multiple timepoints to a sample from the same culture at seven days of hypoxia. Three or more replicates at each timepoint.