Role of Ï54 in the regulation of genes involved in biogenesis of type I and type IV pili in Xylella fastidiosa
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ABSTRACT:
ORGANISM(S): Xylella fastidiosa
SUBMITTER: Tie Koide
PROVIDER: E-GEOD-8097 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Publications
Role of sigma54 in the regulation of genes involved in type I and type IV pili biogenesis in Xylella fastidiosa.
da Silva Neto José F JF Koide Tie T Abe Cecília M CM Gomes Suely L SL Marques Marilis V MV
Archives of microbiology 20071106 3
The phytopathogen Xylella fastidiosa produces long type IV pili and short type I pili involved in motility and adhesion. In this work, we have investigated the role of sigma factor sigma(54) (RpoN) in the regulation of fimbrial biogenesis in X. fastidiosa. An rpoN null mutant was constructed from the non-pathogenic citrus strain J1a12, and microarray analyses of global gene expression comparing the wild type and rpoN mutant strains showed few genes exhibiting differential expression. In particul ...[more]
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Project description:Background: Xylella fastidiosa, a Gram-negative fastidious bacterium, grows exclusively in the xylem of several plants, causing diseases such as citrus variegated chlorosis. As the xylem sap contains low concentrations of amino acids and other compounds, X. fastidiosa needs to cope with nitrogen limitation in its natural habitat. Results: In this work, we performed a whole-genome microarray analysis of the X. fastidiosa nitrogen starvation response. A time-course experiment (2, 8 and 12 hours) revealed many differentially expressed genes under nitrogen starvation, such as genes related to transport, nitrogen assimilation, amino acid biosynthesis, transcriptional regulation, and many genes encoding hypothetical proteins. In addition, a decrease in the expression levels of many genes involved in carbon metabolism and energy generation pathways was also observed. Comparison of gene expression profiles between the wild type strain and the rpoN null mutant allowed the identification of genes induced by nitrogen starvation in a ?54-dependent manner. A more complete picture of the ?54 regulon was achieved by combining the transcriptome data with an in silico search for potential ?54-dependent promoters, using a position weight matrix approach. One of these ?54-predicted binding sites, located upstream of the glnA gene (encoding a glutamine synthetase), was validated by primer extension assays, confirming that this gene has a ?54-dependent promoter and contains a predicted NtrC binding site. Conclusions: Together, these results show that nitrogen starvation causes intense changes in the X. fastidiosa transcriptome and some of these differentially expressed genes belong to the ?54 regulon. For time-course studies, cells cultivated at late-exponential phase in PWG medium were used to inoculate a culture in 100 ml XDM2 medium to an optical density at 600 nm (OD600 nm) of 0.1. Cells were grown during 12 days in the XDM2 medium (mid-log phase) and harvested by centrifugation. Then, the culture was divided into two 6 portions and cells were washed with XDM2 medium (zero time) or XDM2 medium lacking all nitrogen sources (XDM0), respectively. The cultivation was continued for 2h, 8h and 12h in XDM0 to establish nitrogen starvation conditions. For each time point, cells in a 25-ml culture were collected by centrifugation and rapidly frozen in dry ice, until RNA isolation. Three RNA samples isolated from independently grown cultures of the cells at each starvation period (2h, 8h and 12h) were examined, and each preparation was subjected to microarray analysis. As the genes were spotted at least in duplicate, we obtained six replicates for each gene from three independent data sets per gene per starvation period. Comparison of gene expression profiles between the wild type strain and the rpoN null mutant allowed the identification of genes induced by nitrogen starvation in a ?54-dependent manner. To determine the effect of rpoN inactivation on gene expression after nitrogen starvation, the transcriptomes of the wild type and the rpoN strains were compared using DNA microarrays, with both strains grown on XDM2 medium and submitted to nitrogen starvation (XDM0) during 2 hours. Three RNA samples isolated from independently grown cultures of the cells were examined. Due to the platform design, each microarray slide was divided into "LEFT" and "RIGHT", allowing the probing of two technical replicates per slide.
2010-12-21 | E-GEOD-21647 | biostudies-arrayexpress
Project description:Due to its aquatic saprophytic lifestyle, the fungus Blastocladiella emersonii seems to be adapted to low aerated environments and thus can be an interesting model of study of the hypoxic stress response. Iron deprivation, a hypoxia-mimicking stimulus due to HIF-1 stabilization, and geldanamycin, that causes HIF-1 depletion by HSP90 inhibition, are helpful parameters to find an evidence of an oxygen-dependent regulatory mechanism in B. emersonii similar to the metazoan HIF-1 pathway. Direct transcript comparison between cells grown under normoxic conditions (70%sat. O2 in air) and cells submitted to oxygen deprivation (direct and gradual) and iron (II) deprivation. It was also compared transcripts of cells submitted to direct 1-hour hypoxia (1%sat. O2) with cells treated with geldanamycin for 1 hour, followed to 1-hour hypoxia (1%sat. O2). There are at least 3 biological replicates (independent harvest) and 2 technical replicates of each array (L - left and R - right).
2010-06-24 | E-GEOD-17524 | biostudies-arrayexpress
Project description:The global transcriptional response of the phytopathogenic bacterium X. fastidiosa to a sudden increase in salinity and osmolarity of the medium was investigated using DNA microarrays. Time-course experiments were carried out by exposing bacterial cells to high salinity (250 mM NaCl) and high osmolarity (300 mM sucrose) conditions revealing 142 upregulated genes under both stresses, including pathogenicity related genes, genes encoding transcriptional regulators, as well as genes related to DNA metabolism and mobile genetic elements. In addition, 38 genes were downregulated under both conditions, most of them related to ribosomal and heat shock proteins. A total of 192 genes were upregulated exclusively in the presence of NaCl, including genes encoding transporters, genes involved in oxidative-stress response and genes related to cell structure. A smaller number of genes (44 genes) were induced only in the presence of sucrose, most of them encoding hypothetical and conserved hypothetical proteins. Interestingly, 57% of the genes differentially expressed under both stress conditions have no putative function assigned, emphasizing the importance of high-throughput experiments to start the characterization of these genes in X. fastidiosa. Keywords: stress response, osmotic and salt stress Direct comparison between osmotic or salt stress condition and control (29oC) condition. Some hybridizations are dye-swaped. There are at least 3 biological replicates (independent harvest) and 2 technical replicates of each array (L - left and R - right).
2014-05-25 | E-GEOD-7126 | biostudies-arrayexpress
Project description:Blastocladiella emersonii life cycle presents a number of drastic biochemical and morphological changes, mainly during two cell differentiation stages: the germination and the sporulation. To investigate the transcriptional changes taking place during the sporulation phase, which culminates with the production of the zoospores, motile cells responsible for the dispersal of the fungus, microarray experiments were performed. Transcription comparisons between cell at the begining of the sporulation phase (zero min.) and at different time points throughout zoospore differentiation were performed in order to associate the gene expression profile with the morphologial changes which culminate with zoospore differentiation. Microarray experiments along the sporulation phase were also realized in the presence of 1% glucose, once such carbohydrate is able to block zoospore differentiation. The results obtained from both sets of experiments were compared in order to understand the glucose effect on sporulation. There are at least 3 biological replicates (independent harvest) and 2 technical replicates of each array (L - left and R - right).
2009-10-27 | E-GEOD-18718 | biostudies-arrayexpress
Project description:Xylella fastidiosa is the etiologic agent of a wide range of plant diseases including citrus variegated chlorosis (CVC), a major threat to the Brazilian citrus industry. Genome sequences of several strains of this phytopathogen are accessible, enabling large-scale functional studies. Transcript levels in different iron availabilities were assessed with DNA microarrays representing 2608 (91.6%) coding sequences (CDS) of X. fastidiosa CVC strain 9a5c. When treated with the iron chelator 2,2-dipyridyl, 193 CDS were considered as up-regulated and 216 as down-regulated. In the presence of 100uM of ferric pyrophosphate, 218 and 256 CDS were considered as up- and down-regulated, respectively. Differential expression for a subset of 44 CDS was further evaluated by reverse transcription - quantitative PCR that showed a Pearson correlation of 0.77 with array results. The CDS differentially expressed upon the iron concentration shift participate in diverse cellular functions. Many CDS involved with regulatory functions, pathogenicity and cell structure, were modulated in both conditions tested suggesting that major changes in cell architecture and metabolism occur when X. fastidiosa cells are exposed to extreme variations in iron concentration. Interestingly, the modulated CDS include those related to colicin V-like bacteriocin synthesis and secretion and to pili/fimbriae functions. We also investigated the contribution of the ferric uptake regulator Fur to the iron regulon of X. fastidiosa. The promoter regions of strain 9a5c genome were screened for putative Fur boxes and candidates were analyzed by electrophoretic mobility shift assays. Taken together, our data support the hypothesis that Fur is not solely responsible for the modulation of the iron regulon of X. fastidiosa and present novel evidence for iron regulation of pathogenicity determinants. Keywords: stress response; response to iron-depleted condition Direct comparison between low iron content (200uM 2,2-dipyridyl) and control condition. Hybridizations are dye-swaped. There are 2 biological replicates (independent harvest) and 2 technical replicates of each array (L - left and R - right).
2007-08-31 | E-GEOD-5888 | biostudies-arrayexpress
Project description:Xylella fastidiosa is the etiologic agent of a wide range of plant diseases including citrus variegated chlorosis (CVC), a major threat to the Brazilian citrus industry. Genome sequences of several strains of this phytopathogen are accessible, enabling large-scale functional studies. Transcript levels in different iron availabilities were assessed with DNA microarrays representing 2608 (91.6%) coding sequences (CDS) of X. fastidiosa CVC strain 9a5c. When treated with the iron chelator 2,2-dipyridyl, 193 CDS were considered as up-regulated and 216 as down-regulated. In the presence of 100uM of ferric pyrophosphate, 218 and 256 CDS were considered as up- and down-regulated, respectively. Differential expression for a subset of 44 CDS was further evaluated by reverse transcription - quantitative PCR that showed a Pearson correlation of 0.77 with array results. The CDS differentially expressed upon the iron concentration shift participate in diverse cellular functions. Many CDS involved with regulatory functions, pathogenicity and cell structure, were modulated in both conditions tested suggesting that major changes in cell architecture and metabolism occur when X. fastidiosa cells are exposed to extreme variations in iron concentration. Interestingly, the modulated CDS include those related to colicin V-like bacteriocin synthesis and secretion and to pili/fimbriae functions. We also investigated the contribution of the ferric uptake regulator Fur to the iron regulon of X. fastidiosa. The promoter regions of strain 9a5c genome were screened for putative Fur boxes and candidates were analyzed by electrophoretic mobility shift assays. Taken together, our data support the hypothesis that Fur is not solely responsible for the modulation of the iron regulon of X. fastidiosa and present novel evidence for iron regulation of pathogenicity determinants. Direct comparison between high iron content (100uM ferric pyrophosphate) and control condition. Hybridizations are dye-swaped. There are 2 biological replicates (independent harvest) and 2 technical replicates of each array (L - left and R - right).
2007-09-01 | E-GEOD-5886 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the following subset Series: GSE4968: Sugarcane transcriptome - ABA treatment GSE4971: Sugarcane transcriptome - Drought response GSE14730: Expression profile in internodes 1, 5 and 9 from high and low brix plants for sucrose content GSE14731: Expression profile between internodes 1 and 9 from high and low brix plants for sucrose content Refer to individual Series
2010-06-30 | E-GEOD-14732 | biostudies-arrayexpress
Project description:The study comprises various components: We aim to screen out different gene expression profile in acute rejection on the kidney. We aim to screen out different gene expression profile in acute tubular necrosis on the kidney. We aim to screen out different gene expression profile in borderline change on the kidney. We aim to screen out different gene expression profile in non-rejection on the kidney. We aim to screen out different gene expression profile in presumed rejection on the kidney. We aim to screen out different gene expression profile in renal recipients with stable function. Results from the various study components can help to diagnose renal allograft dysfunction with different causes by distinct gene expression profile. Keywords: acute rejection, acute tubular necrosis, borderline change, non-rejection, presumed rejection, renal recipients with stable function, Samples GSM456771-GSM456800: This study has been accomplished with 15 patients of acute rejection on the kidney.Technical replicates: 2 replicates(except AR10 and AR13) Samples GSM456801-GSM456810: This study has been accomplished with 5 patients of acute tubular necrosis on the kidney. Technical replicates: 2 replicates(except ATN4) Samples GSM456811-GSM456831: This study has been accomplished with 11 patients of borderline change on the kidney.Tecnical replicates:2 replicates(except BL8 and BL11) Samples GSM456833-GSM456850: This study has been accomplished with 9 patients of non-rejection on the kidney.Technical replicates: 2 replicates Samples GSM456851-GSM456864: This study has been accomplished with 7 patients of presumed rejection on the kidney.Technical replicates: 2 replicates Samples GSM456865-GSM456894: This study has been accomplished with 15 patients of renal recipients with stable function.Technical replicates: 2 replicates
2010-06-25 | E-GEOD-19130 | biostudies-arrayexpress
Project description:Schistosomiasis continues to be a significant public health problem1. Although vaccine development against this disease has experienced more failures than successes, encouraging results have recently been obtained using membrane-spanning protein antigens from the tegument of S. mansoni. Our group recently identified Sm29, an antigen that is predominantly recognized by IgG1 and IgG3 antibodies of resistant patients2. In the present study, we show that Sm29 is located on the surface of adult worms and lung-stage schistosomula. Immunization of mice with recombinant (r) Sm29 engendered 51% reduction in adult worm burdens, 60% reduction in intestinal eggs and 55% reduction in liver granulomas. Protective immunity in mice was associated with high titers of specific IgG1 and IgG2a and elevated production of IFN-γ, TNF-α and IL-12. Further, cellular responses of infected schistosomiasis patients to rSm29 consisted of elevated IFN-γ and an absence of IL-5. Gene expression analysis of worms recovered from rSm29 vaccinated mice relative to control mice revealed a significant (q< 0.01) down-regulation of 498 genes, while no up-regulation was detected. Among down-regulated genes, many of them encode surface antigens and proteins associated with immune signals suggesting that under immune attack schistosomes reduce the expression of critical surface proteins. This study demonstrates that the membrane-bound Sm29 protein is a new molecule that has great potential as a vaccine candidate against schistosomiasis. Keywords: Schistosoma mansoni gene expression in vaccinated mice Two biological samples were used in the study, each used in two arrays (technical replicates with dye swap) and each array containing two replicates of each spot. Overall, there are eight data points data points for each spot. Only cases with more than 4 of 8 points are valid ratios were considered. Value and its respective dye swap value [after changing the log(ratio) signal] were averaged, reducing the data point to four. The average values were than used in the significance testing using SAM (Tusher et al., 2001). The samples were used to get average values using the following combination: 3000139790L with 3000139792L; 3000139790R with 3000139792R; 3000139791L with 3000139795L; 3000139791R with 3000139795R The normalized, averaged dyeswap values are provided in a supplementary file at the foot of the record.
2010-05-15 | E-GEOD-10777 | biostudies-arrayexpress
Project description:Background: The parasitic trematode Schistosoma mansoni is one of the major causative agents of human schistosomiasis, which afflicts 200 million people worldwide. Praziquantel is still the only drug used for schistosomiasis treatment and reduction in drug efficiency has prompting the search for new therapeutic compounds against this disease. Our group has demonstrated that heme crystallization into hemozoin (Hz) within S. mansoni gut is a major heme detoxification route involving lipid droplets in this process and acting as a potential chemotherapeutical target. In the present work, we investigated the effects of the antimalarial quinine (QN) in a murine schistosomiasis model by using a combination of biochemical, cell biology and molecular biology approaches. Methodology/Principal Findings: Treatment of S. mansoni-infected female Swiss mice with daily intraperitoneal injections of QN (75mg/kg/day) from 11th to 17th day after infection decreased not only total, males and females worm burden (46.2 %-51.0 %), eggs production, but also the granulomatous reaction to parasite eggs trapped in the liver. These effects correlated with a significant impairment of Hz production (40%) specifically in S. mansoni females, being parallel to remarkable ultrastructural changes in female worms, particularly in the gut epithelium. Microarray gene expression analysis indicated that QN treatment increased the expression of transcripts related to musculature, protein synthesis and repair mechanisms. Conclusions: The overall significant reduction in several disease burden parameters by QN treatment indicates that interference of Hz formation in S. mansoni is a valid chemotherapeutical target for development of new antischistosomal drugs. The perfused adult female worms were incubated with cold RNAlater solution (Ambion) and kept at 4 0C until RNA extraction. Total RNA was extracted using Trizol reagent (Invitrogen) according to the manufacture's instructions. RNA was quantified using Nanodrop ND-1000 UV/Vis spectrophotometer and its quality was assured with Agilent 2100 Bioanalyzer, a micro fluidics-based electrophoresis platform. 1 μg total RNA from each sample was amplified using the T7-RNA polymerase based SuperScript Indirect RNA amplification system (Invitrogen) and subsequently 3 μg of aminoallyl-modified amplified RNA was labeled using Cy3 or Cy5 by indirect labeling (General Electric). Amplification and labeling were done according to manufacturer specifications. The Cy3 and Cy5 labeled samples were then combined, dried and re-suspended in hybridization buffer (50 % formamide, 25 % RNase free water and 25 % Microarray Hybridization buffer 4x) (General Electric). Pools of RNA from worms treated with QN were hybridized against RNA from control worms. In order to ensure the uniformity of data, all experiments were performed using slides from the same printing batch and dyes from the same lot. The same washing protocol was used and immediately after washing we scanned the slides using the same parameters. Technical and biological replicates were performed. Dye swap was employed in order to account for dye biases. A total of eight different replicated data values were obtained for each probe on the array. The samples were hybridized overnight to cDNA microarray slides containing 4,000 elements in duplicate (GEO accession: GPL3929) using ASP hybridization chambers (GE, USA) at 42 °C. Slides were washed once for 3 minutes in low stringency wash solution at 45 °C (1 x SSC + 0.2 % SDS), followed by one wash for 5 minutes in medium stringency wash solution (0.1 x SSC + 0.2%SDS) and one wash of 1 minute in high stringency wash solution (0.1 x SSC). Moreover, slides were air dried and scanned using a microarray dual channel laser scanner (GenePix 4000B, Molecular Devices, USA) at 5 μm resolution, 100 % laser power and PMT levels were adjusted in order to obtain similar average intensities of red and green signal. Data were extracted using Array Vision 8.0 program. To correct for systematic biases on the data originated from small differences in the labeling and/or detection efficiencies between the fluorescent dyes, expression ratios were logged (base 2) and normalized using a locally weighted linear regression (LOWESS) algorithm [60]. Normalized log2 (ratios) were further analyzed with the Significance Analysis of Microarrays tool (SAM) [61] using a 0.1 % false discovery rate (FDR) to find differentially expressed genes. The genes identified in the previous step were filtered using a 1.7 fold change cut-off in at least 4 out of the 8 data points. This step is critical in identifying more biological relevant changes. It is important to stress that the fold change filter was used after the identification of differentially expressed genes, and our results are not influenced by the potentially misleading effects caused by the use of arbitrary thresholds to trim data sets before significance testing .
2010-06-24 | E-GEOD-14751 | biostudies-arrayexpress