Project description:The existence of two separate lineages of Escherichia coli O157:H7 has previously been reported, and research indicates that one of these lineages (lineage I) might be more pathogenic towards human hosts. We have previously shown that the more pathogenic lineage expresses higher levels of Shiga toxin 2 (Stx2) than the non-pathogenic lineage II. To evaluate why lineage 2 isolates do not express appreciable levels of toxin, two lineage 2 isolates (FRIK966 and FRIK2000) were chosen as representatives of lineage 2 and whole genome microarrays were performed using Agilent microarrays using the E. coli O157:H7 EDL933 lineage I clinical type isolate as a reference. Microarray results were utilized to evaluate what genes and pathways might be missing or differentially expressed. Quantitative RT-PCR was utilized to validate the microarray data. Based upon the transcriptome of Escherichia coli O157:H7 EDL933 an oligonucleotide microarray, made up of 60 mers was designed. A total of 4873 genes in an 8 x 15K Agilent microarray design. Designed using a custom script, specifications for gene specific oligos were based upon various design characteristics such as temperature of melting, 3’ location, specificity, lack of repeat nucleotides, etc. (Charbonnier et al., 2005). Arrays were manufactured using Agilent Sure-print technology. Each array consisted of duplicate elements for each gene randomly distributed with Agilent control elements included. All procedures were performed according to respective manufacturer protocols. Lineage I and lineage II strains were grown overnight as described, a total of 10e7 cells were washed twice in fresh media, normalized based upon optical density, inoculated into fresh media, incubated at 37oC shaking 120 x g for 3 hours and then suspended in RNAprotect bacteria reagent (Qiagen Inc., Valencia, CA.). Total RNA was extracted using RNeasy Bacteria Mini Kit (Qiagen Inc., Valencia, CA.) and trace amounts of DNA were removed using RNase-Free DNase Set (Qiagen Inc., Valencia, CA.). RNA was quantified using Nanodrop system (NanoDrop Technologies, Wilmington, DE) and quality confirmed by electrophoresis on a Bio-rad Experion system (BioRad XXX). For each sample, 10 ug of RNA were labeled with either CyDye3-dCTP or CyDye5-dCTP (Perkin Elmer) using the LabelStar kit (Qiagen Inc., Valencia, CA.) and Random nonamers (Integrated DNA Technologies ). Labeled cDNA were hybridized to the microarray using Agilent Hi-RPM hybridization solution in an Agilent Hybridization chamber (Agilent.). A total of 8 arrays, each with duplicate elements for each gene, alternating dye swap for each replicate (4 biological replicates), were analyzed to obtain genes that were consistently and differentially regulated in comparison to EDL933, while limiting false discover rate (FDR) below a stringent 5% (Benjamini and Hochberg, 1995).

Project description:Tropospheric ozone causes severe oxidative stress in plants. To investigate the transcriptional responsiveness of adult trees to ozone, fully-expanded sun and shade leaves of mature beech trees were harvested at four time points over the entire vegetation period in 2005 and 2006. Microarray analyses were conducted on leaves from trees grown in the field under ambient and twice-ambient ozone concentrations at Kranzberger Forst (Bavarian). Beech trees changed their transcript levels in response to ozone. In the years 2005 and 2006 different transcription patterns were observed; this may have been a result of different weather conditions and ozone uptake. Furthermore, we obtained differences in mRNA expression patterns between shade and sun leaves. In the ozone-treated sun leaves of 2005, slightly up- and down-regulated transcript levels were detected, particularly in the spring and autumn, whereas shade leaves clearly exhibited reduced mRNA-levels, particularly at the end of the vegetation period. In 2006, this pattern could not be confirmed, and in the autumn, four other transcripts were slightly up-regulated in ozone-treated shade leaves. In addition, two additional transcripts were found to be influenced in sun leaves in the spring/summer. While we detected changes in the levels of only a few transcripts, the observed effects were not identical in both years. In conclusion, elevated ozone exhibited very small influence on the transcription levels of genes of mature beech trees. The study was carried out at the Kranzberger Forst research site (near Freising, Germany: 48°25’08’’N, 11°39’41’””E, 485m (Pretzsch et al., 1998) in a mixed 60-year old stand (closed canopy) with about 30m high European beech (Fagus sylvatica) and Norway spruce (Picea abies) trees. Free-air ozone fumigation started in May 2000 at double the ambient ozone concentrations with a cut-off at 150 nl l-1 (Werner and Fabian, 2002), thereby avoiding acute damage to the leaves. The ozone concentrations were measured at four heights within the fumigated space and were additionally monitored with 200 passive samplers (Werner and Fabian, 2002). In 2005 the AOT40 value under twice ambient ozone was 64.3 μmol mol-1 h and in 2006 69.0 μmol mol-1 h. Detailed ozone concentration data over the growing seasons have been reported elsewhere (Gielen et al., 2007; Kitao et al., 2009). Sun and shade leaves from 60-year-old European beech trees were harvested in a total of 8 sampling campaigns in 2005 and 2006. Using scaffolding, five leaves of sun crown (height of about 25 m) and five shade (height of about 19 m) leaves were taken from each of five control and ozone-treated trees. The sampling was carried out in May, June, August, and September of 2005 and in June, August, September and October of 2006. To avoid diurnal effects, the samples were always taken around 11 a.m. For each tree, the four leaves (sun or shade) were combined, frozen in liquid nitrogen and stored at -80 °C until RNA isolation. For one time point we had five microarrays and five dye-swaps for each of sun and shade leaves. The probes of the trees under ambient ozone were labelled with Cy3 and probes of the trees under 2x ambient were labelled with Cy5. For every pair of trees a dye control were carried out, where the control trees were labelled with Cy5 and the ozone-treated one with Cy3. For statistical analysis a coefficient of variation about all microarrays of one time point was calculated using Acuity 4.0 microarray informatics software [Axon Instruments]. We used only those spots that had a coefficient of variation < 50 and were present on at least half of identical slides. The ozone-changed transcript level of genes were expressed in the median values as log2 ratios.

Project description:Tropospheric ozone causes severe oxidative stress in plants. To investigate the transcriptional responsiveness of adult trees to ozone, fully-expanded sun and shade leaves of mature beech trees were harvested at four time points over the entire vegetation period in 2005 and 2006. Microarray analyses were conducted on leaves from trees grown in the field under ambient and twice-ambient ozone concentrations at Kranzberger Forst (Bavarian). Beech trees changed their transcript levels in response to ozone. In the years 2005 and 2006 different transcription patterns were observed; this may have been a result of different weather conditions and ozone uptake. Furthermore, we obtained differences in mRNA expression patterns between shade and sun leaves. In the ozone-treated sun leaves of 2005, slightly up- and down-regulated transcript levels were detected, particularly in the spring and autumn, whereas shade leaves clearly exhibited reduced mRNA-levels, particularly at the end of the vegetation period. In 2006, this pattern could not be confirmed, and in the autumn, four other transcripts were slightly up-regulated in ozone-treated shade leaves. In addition, two additional transcripts were found to be influenced in sun leaves in the spring/summer. While we detected changes in the levels of only a few transcripts, the observed effects were not identical in both years. In conclusion, elevated ozone exhibited very small influence on the transcription levels of genes of mature beech trees. The study was carried out at the Kranzberger Forst research site (near Freising, Germany: 48°25’08’’N, 11°39’41’””E, 485m (Pretzsch et al., 1998) in a mixed 60-year old stand (closed canopy) with about 30m high European beech (Fagus sylvatica) and Norway spruce (Picea abies) trees. Free-air ozone fumigation started in May 2000 at double the ambient ozone concentrations with a cut-off at 150 nl l-1 (Werner and Fabian, 2002), thereby avoiding acute damage to the leaves. The ozone concentrations were measured at four heights within the fumigated space and were additionally monitored with 200 passive samplers (Werner and Fabian, 2002). In 2005 the AOT40 value under twice ambient ozone was 64.3 μmol mol-1 h and in 2006 69.0 μmol mol-1 h. Detailed ozone concentration data over the growing seasons have been reported elsewhere (Gielen et al., 2007; Kitao et al., 2009). Sun and shade leaves from 60-year-old European beech trees were harvested in a total of 8 sampling campaigns in 2005 and 2006. Using scaffolding, five leaves of sun crown (height of about 25 m) and five shade (height of about 19 m) leaves were taken from each of five control and ozone-treated trees. The sampling was carried out in May, June, August, and September of 2005 and in June, August, September and October of 2006. To avoid diurnal effects, the samples were always taken around 11 a.m. For each tree, the four leaves (sun or shade) were combined, frozen in liquid nitrogen and stored at -80 °C until RNA isolation. For one time point we had five microarrays and two dye-swaps for shade leaves, and three microarrays and two dye-swaps for sun leaves. The probes of the trees under ambient ozone were labelled with Cy3 and probes of the trees under 2x ambient were labelled with Cy5. For every pair of trees a dye control were carried out, where the control trees were labelled with Cy5 and the ozone-treated one with Cy3. For statistical analysis a coefficient of variation about all microarrays of one time point was calculated using Acuity 4.0 microarray informatics software [Axon Instruments]. We used only those spots that had a coefficient of variation < 50 and were present on at least half of identical slides. The ozone-changed transcript level of genes were expressed in the median values as log2 ratios.

Dataset Information

MicroRNA and aging

Publications

MicroRNA 217 modulates endothelial cell senescence via silent information regulator 1.

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