Ciprofibrate stimulated gene expression in rats
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ABSTRACT:
ORGANISM(S): Rattus norvegicus
PROVIDER: GSE335 | GEO | 2003/03/31
SECONDARY ACCESSION(S): PRJNA84809
REPOSITORIES: GEO
Similar Datasets
Project description:Samples and RNA preparation: The series is composed of 4 hybridizations for analysis of differentially expressed genes in the liver of ciprofibrate dosed vs. control rats. Rats (200-250 g) were given (by gastric intubation) tap water (control group, n=5) or ciprofibrate (50 mg/kg body weight, once daily for 60 days, n=4). Liver total RNA extraction was performed first by ultracentrifugation on a cesium chloride cushion and then using TRIZOL Reagent (GIBCO BRL Life Technologies, New York, NY). Labeling and hybridization: One microgram of total RNA from the control pool (n=5), and from each ciprofibrate dosed rat was reverse transcribed and labeled with Cy3- and Cy5-attached dendrimer, respectively, using 3DNA Array Detection Submicro kit as described in the manufacturer's protocols (Genisphere, Montvale, NJ). The labeling reactions were also spiked with exogenous control RNAs (Stratagene) at expected Cy5/Cy3 ratios of 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 0.5, 0.33, 0.25 and 0.125 for control spike 1, 2, 3, 4, 5, 6, 8, 9, 10 and 7, respectively. The Cy3 and Cy5 labeled samples (combined volume 5 microliter) were mixed with 30 microliter of the hybridization solution containing 0.25 M NaPO4, 1 mM EDTA, 4.5% SDS, 1 x SSC, 2 x Denhardt's solution, 0.25 microliter antifade reagent (Genisphere) and 0.2 microgram mouse COT-1 DNA (GIBCO BRL Life Technologies), added onto the array and covered with 22 x 50mm cover slip. The array was assembled into humidified hybridization chamber (Corning) and hybridized at 65oC for 18 h by submerging in a water bath. Post-hybridization washes were done once in 2 x SSC, 0.2% SDS at 55oC for 15 min, then in 2 x SSC at room temperature for 15 min, and finally with 0.2 x SSC at room temperature for 15 min. Scanning, image analysis and data processing: Arrays were scanned at 10 micrometer resolution with a confocal laser scanner constructed in-house in collaboration with NEMKO (Trondheim, Norway) according to a prototype developed at NHGRI (http://www.nhgri.gov/DIR/LCG/15K(HTML/). Microarray image analysis was done with MicroArray Suite software version 2.1 with globally normalization (Scanalytics, Inc., Fairfax VA). First, spots undetected (target intensity=1) in at least one array were excluded. Then, spots with signal intensity (averages of the 4 arrays) less than 300 in both channels were removed. The fluorescence intensity ratios (Cy5/Cy3) for genes measured from probes spotted in duplicate were averaged for each slide. Then, mean ratios of the 4 hybridizations were calculated for each gene, and differentially regulated genes were determined using 1.4 fold change cutoff values (1.4 for up-regulated or 0.7 for down-regulated genes).
2010-06-05 | E-GEOD-335 | biostudies-arrayexpress
Project description:Omeprazole stimulated gene expression in rats Samples and RNA preparation: The series is composed of 9 hybridizations for analysis of differentially expressed genes in the gastric mucosa of omeprazole dosed vs. control rats. Nine rats (200-250 g) were given (by gavage) 400 micromol/kg of the proton pump inhibitor omeprazole (Astra AB, Gothenburg, Sweden) in Methocel (Dow Corning, Midland, MI) daily for 10 weeks. Seven rats received vehicle only. After 10 weeks the stomachs were removed for sampling of full-thickness corpus from the upper part of the greater curvature. Total RNA extraction was performed first by ultrasentrifugation on a cesium chloride cushion and then using TRIZOL Reagent (GIBCO BRL Life Technologies, New York, NY). Labeling and hybridization: Total RNA from 7 untreated rats were pooled and used as a common control. Three micrograms of total RNA from the control pool, and three micrograms of total RNA from each omeprazole dosed rat were reverse transcribed and labeled with capture sequences for subsequent attachment of Cy3- and Cy5-attached dendrimer, respectively, using 3DNA Array 350 Expression Array Detection kit as described in the manufacturer's protocols (Genisphere, Montvale, NJ). The labeling reactions were also spiked with exogenous control RNAs (Stratagene) at ratios of 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 0.5, 0.33, 0.25 and 0.125 for control spike 1, 2, 3, 4, 5, 6, 8, 9, 10 and 7, respectively. The slides were pre-washed in 2xSSC, 0.2% SDS at 55oC for 20 min, then 0.2x SSC at room temperature for 3 min, and deionized sterile filtered H2O at room temperature for 2 min. The Cy3 and Cy5 labeled samples (combined volume 9 microliter) were mixed with 25 microliter of the hybridization solution containing 0.25 M NaPO4, 1 mM EDTA, 4.5% SDS, 1 x SSC, 2 x Denhardt's solution and 2 microliter LNA dT Blocking reagent (Genisphere). A total hybridization volume of 50 microliter was added onto the array and covered with 24 x 60 mm cover slip. The array was assembled into humidified hybridization chamber (Corning) and hybridized at 60 oC for 18 h by submerging in a water bath. Post-hybridization washes were done once in 2 x SSC, 0.2% SDS at 55 oC for 15 min, then in 2 x SSC at room temperature for 15 min, and finally with 0.2 x SSC at room temperature for 15 min. After washing the fluorescent 3DNA reagent was hybridized to the cDNA at 60 oC for 3 h as described in the manufacturer's protocols. After dendrimer hybridization the slides were washed as described above. Scanning, image analysis and data processing: Arrays were scanned at 10 micrometer resolution with a ScanArray Express HT scanner (Packard BioSciences, Billerica, MA). The microarrays were analyzed using GenePix™ Pro 4.1 (Axon Instruments, Inc., Union City, CA). All subsequent statistical analyses were performed using the statistical package R, R Development Core Team. A signal intensity based criterion was applied to remove the spots with median spot signal intensity less than 200. A spot area based criterion was applied to remove the spots with the area less than 50 pixels in either channel. Spots with more than 40% of the pixels saturated in either channel were also removed. Print tip-dependent normalization was applied to the data in order to compensate for systematic errors. The normalized ratios of the duplicated spots were averaged. Further analysis was done on the log2 transformed ratios. In order to assess the significance of up- or downregulation of the genes, tests for differential expression were performed using moderated T-tests, as implemented in the Limma R package of Smyth. Keywords: repeat sample
2004-10-20 | GSE1808 | GEO
Project description:Omeprazole stimulated gene expression in rats Samples and RNA preparation: The series is composed of 9 hybridizations for analysis of differentially expressed genes in the gastric mucosa of omeprazole dosed vs. control rats. Nine rats (200-250 g) were given (by gavage) 400 micromol/kg of the proton pump inhibitor omeprazole (Astra AB, Gothenburg, Sweden) in Methocel (Dow Corning, Midland, MI) daily for 10 weeks. Seven rats received vehicle only. After 10 weeks the stomachs were removed for sampling of full-thickness corpus from the upper part of the greater curvature. Total RNA extraction was performed first by ultrasentrifugation on a cesium chloride cushion and then using TRIZOL Reagent (GIBCO BRL Life Technologies, New York, NY). Labeling and hybridization: Total RNA from 7 untreated rats were pooled and used as a common control. Three micrograms of total RNA from the control pool, and three micrograms of total RNA from each omeprazole dosed rat were reverse transcribed and labeled with capture sequences for subsequent attachment of Cy3- and Cy5-attached dendrimer, respectively, using 3DNA Array 350 Expression Array Detection kit as described in the manufacturer's protocols (Genisphere, Montvale, NJ). The labeling reactions were also spiked with exogenous control RNAs (Stratagene) at ratios of 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 0.5, 0.33, 0.25 and 0.125 for control spike 1, 2, 3, 4, 5, 6, 8, 9, 10 and 7, respectively. The slides were pre-washed in 2xSSC, 0.2% SDS at 55oC for 20 min, then 0.2x SSC at room temperature for 3 min, and deionized sterile filtered H2O at room temperature for 2 min. The Cy3 and Cy5 labeled samples (combined volume 9 microliter) were mixed with 25 microliter of the hybridization solution containing 0.25 M NaPO4, 1 mM EDTA, 4.5% SDS, 1 x SSC, 2 x Denhardt's solution and 2 microliter LNA dT Blocking reagent (Genisphere). A total hybridization volume of 50 microliter was added onto the array and covered with 24 x 60 mm cover slip. The array was assembled into humidified hybridization chamber (Corning) and hybridized at 60 oC for 18 h by submerging in a water bath. Post-hybridization washes were done once in 2 x SSC, 0.2% SDS at 55 oC for 15 min, then in 2 x SSC at room temperature for 15 min, and finally with 0.2 x SSC at room temperature for 15 min. After washing the fluorescent 3DNA reagent was hybridized to the cDNA at 60 oC for 3 h as described in the manufacturer's protocols. After dendrimer hybridization the slides were washed as described above. Scanning, image analysis and data processing: Arrays were scanned at 10 micrometer resolution with a ScanArray Express HT scanner (Packard BioSciences, Billerica, MA). The microarrays were analyzed using GenePix⢠Pro 4.1 (Axon Instruments, Inc., Union City, CA). All subsequent statistical analyses were performed using the statistical package R, R Development Core Team. A signal intensity based criterion was applied to remove the spots with median spot signal intensity less than 200. A spot area based criterion was applied to remove the spots with the area less than 50 pixels in either channel. Spots with more than 40% of the pixels saturated in either channel were also removed. Print tip-dependent normalization was applied to the data in order to compensate for systematic errors. The normalized ratios of the duplicated spots were averaged. Further analysis was done on the log2 transformed ratios. In order to assess the significance of up- or downregulation of the genes, tests for differential expression were performed using moderated T-tests, as implemented in the Limma R package of Smyth.
2010-06-05 | E-GEOD-1808 | biostudies-arrayexpress
Project description:This series repressents the data set from the paper "Expression microarray analysis and oligo array CGH of aquired gemcitabine resistance in mouse colon reveals selection for chromosomal aberrations". Biological material: One solid mouse tumor "Colon 26A" was routinely maintained by successive transplantation. A subset of mice with this tumor was treated at the maximum tolerable dosage of Gemcitabine and successively transplanted 5 times and similarly treated. The last passage was completly resistant and designated, "Colon 26G". Expression array: Total RNA was isolated from frozen mouse tumors using Tryzol. Single stranded cDNA was synthetized from 30 mg of total RNA by reverse transcription using aminoallyl labeled dUTP (Ambion). Labelling was performed according to the aminoallyl labeling protocol. Briefly, cDNA was incubated at room temperature for 1 h with fluorolink monofunctional cy5 or cy3 (Amersham) followed by 15 min 4 M hydroxylamine treatment. Uncoupled dyes were removed using Qiaquick PCR purification columns (Qiagen) and mixed with 12 mg poly(dA) (Amersham), 60 mg yeast tRNA (Sigma) and 24 mg Cot-1 DNA (Invitroen). The probe was dissolved in 127 ml hybridization mixture containing 46% formamide, 9.5% dextran sulfate, 2x SSC and 0.2% SDS. The probe was heated to 70°C for 10 min and annealed at 37°C for 1 h. Slides were hybridized for 14 h at 37°C over-night (HyArray 12™, Perkin Elmer). After hybridization the slides were washed in the HybArray 12™ with 50% formamide, 2x SSC, pH 7 at 35°C for 15 min, followed b PI buffer (0.1 M sodium phosphate, 0.1% Igepal Ca630, pH 8) at room temperature and 3 washes of 0.2x SSC, 0.1x SSC and 0.01x SSC at room temperature followed by centrifugation. Arrays were scanned using a laser scanner (ScanArray Express, Perkin Elmer) and analysed using ImaGene version 5.6. Cy5 cy3 ratios are calculating by taking the log2 of the signal mean of each spot minus the median background mean of all spots on the array. This is followed by a standard normalization for spot intensity and calculation of the ratios. Keywords: other
2005-12-21 | GSE2352 | GEO
Project description:To identify Six1 target genes, we chose the mK4 cell line that represents later metanephric mesenchyme of the embryonic kidney. The cells were infected with adenovirus vectors (AxCAwt) overexpressing VP16-Six1wt or VP16-Six1W171R and cultured for 24h. Total RNA was extracted using Isogen reagent (Nippon Gene), treated with RNase-free DNase (Roche Diagnostics) and purified with RNeasy Midi Kit (QIAGEN). Poly A+ RNA was selected using Oligotex-dT30 latex beads (TaKaRa). Poly A+ RNA (20 µg) was reverse transcribed using an oligo(dT) primer in the presence of aminoallyl dUTP without the addition of spike-in controls. Then, single-stranded cDNAs were coupled with Cy3 (AxCAwt VP16-Six1wt infected sample) or Cy5 (AxCAwt VP16-Six1W171R infected sample) dyes, and the labeled probes were purified with QIAquick PCR Purification kit (QIAGEN). Hybridization to the microarray was carried out at 65°C for 17h according to the manufacturer's instruction. The arrays were washed, dried and scanned using ScanArray 5000 (GSI Lumonics) at two different PMT voltage settings (high and low) to avoid signal saturation. Cy3 and Cy5 intensities for each spot on the array were determined by QuantArray software (Version 3.0.0.0, GSI Lumonics). The raw data thus obtained was processed and the Cy3 to Cy5 ratios were calculated as follows: 1) subtraction of the fluorescence intensity of negative control spots as background from the intensity of each of the Cy3 and Cy5 spots, 2) normalization of the entire data set using the global normalization method, 3) elimination of spots with high background intensity for either dye, and 4) determination of the Cy3 to Cy5 ratios. To identify Six4 target genes, we chose the mK4 cell line that represents later metanephric mesenchyme of the embryonic kidney. The cells were infected with adenovirus vectors (AxCAwt) overexpressing VP16-Six4wt or VP16-Six4W263R and cultured for 24h. Total RNA was extracted using Isogen reagent (Nippon Gene), treated with RNase-free DNase (Roche Diagnostics) and purified with RNeasy Midi Kit (QIAGEN). Poly A+ RNA was selected using Oligotex-dT30 latex beads (TaKaRa). Poly A+ RNA (20 µg) was reverse transcribed using an oligo(dT) primer in the presence of aminoallyl dUTP without the addition of spike-in controls. Then, single-stranded cDNAs were coupled with Cy3 (AxCAwt VP16-Six4wt infected sample) or Cy5 (AxCAwt VP16-Six4W263R infected sample) dyes, and the labeled probes were purified with QIAquick PCR Purification kit (QIAGEN). Hybridization to the microarray was carried out at 65°C for 17h according to the manufacturer's instruction. The arrays were washed, dried and scanned using ScanArray 5000 (GSI Lumonics) at two different PMT voltage settings (high and low) to avoid signal saturation. Cy3 and Cy5 intensities for each spot on the array were determined by QuantArray software (Version 3.0.0.0, GSI Lumonics). The raw data thus obtained was processed and the Cy3 to Cy5 ratios were calculated as follows: 1) subtraction of the fluorescence intensity of negative control spots as background from the intensity of each of the Cy3 and Cy5 spots, 2) normalization of the entire data set using the global normalization method, 3) elimination of spots with high background intensity for either dye, and 4) determination of the Cy3 to Cy5 ratios. Keywords: other
2005-07-20 | GSE2043 | GEO
Project description:Chickens were kept under a regimen of 12 hours of light and 12 hours of dark for 7 days. At LD2, 2 hours into the light cycle on the 8th day, 3 chickens were sacrificed by decapitation and their retinas dissected and pooled. Similarly, at LD18, 6 hours into the dark cycle on the 8th day, retinas were harvested from 3 chickens. Total RNA was extracted from each set of retinas using Trizol Reagent (Invitrogen). The total RNA samples were amplified to produce aRNA using the Message Amp Kit (Ambion). Randomly primed fluorescent probes were produced from the aRNA samples using a Genisphere 3DNA Array 900MPX expression array detection kit. The fluorescent dye on the probe derived from the experimental aRNA (LD2) was Cy5 while the dye on the control probe (LD18) was Cy3. Hybridizations and washes were as suggested by Genisphere. Labeled arrays were scanned in an Affymetrix 428 array scanner. The images obtained were subsequently analyzed by GenePixPro software (Axon Instruments). The GenePix results (.gpr) file was further analyzed by GeneSpring 5 (Silicon Genetics) which applied intensity dependent LOWESS normalization to the results and calculated normalized Cy5 to Cy3 ratios.
2010-12-10 | GSE25992 | GEO
Project description:A single-domain globin (cgb) mutant strain of Campylobacter jejuni NCTC11168 was grown in 2 homemade, parallel chemostats. Cells were grown in 125 ml volumes of Mueller-Hinton Broth where the growth rate was controlled by the dilution rate (0.1 h-1). A gas mix of 80% nitrogen, 10% carbon dioxide and 10% oxygen was pumped into the head-space of the vessels at a rate of 0.25 l/min to obtain a microaerobic environment and the culture was maintained at 42 ºC via a water jacket. Cells were grown as above until steady-state had been reached. At steady-state one of the cultures was exposed to 0.25 mM GSNO (final concentration) for a period of 10 min. Samples of both the control and stressed cultures were harvested into phenol/ethanol to stabilize the RNA and total RNA was purified using Qiagen’s RNeasy Mini kit (as recommended by the suppliers) prior to use in microarray analysis. Equal quantities of RNA from control and GSNO-supplemented cultures were labelled using nucleotide analogues of dCTP containing either Cy3 or Cy5 fluorescent dyes. The average signal intensity and local background correction were obtained using a commercially available software package from Biodiscovery, Inc (Imagene, version 4.0 and GeneSight, version 4). The mean values from each channel were log2 transformed and normalised using the Lowess method to remove intensity-dependent effects in the log2(ratios) values. The Cy3/Cy5 fluorescent ratios were calculated from the normalized values. Keywords: Stress-response to GSNO
2007-12-31 | GSE5396 | GEO
Project description:This series repressents the data set from the paper "Expression microarray analysis and oligo array CGH of aquired gemcitabine resistance in mouse colon reveals selection for chromosomal aberrations". Biological material: One solid mouse tumor "Colon 26A" was routinely maintained by successive transplantation. A subset of mice with this tumor was treated at the maximum tolerable dosage of Gemcitabine and successively transplanted 5 times and similarly treated. The last passage was completly resistant and designated, "Colon 26G". Expression array: Total RNA was isolated from frozen mouse tumors using Tryzol. Single stranded cDNA was synthetized from 30 mg of total RNA by reverse transcription using aminoallyl labeled dUTP (Ambion). Labelling was performed according to the aminoallyl labeling protocol. Briefly, cDNA was incubated at room temperature for 1 h with fluorolink monofunctional cy5 or cy3 (Amersham) followed by 15 min 4 M hydroxylamine treatment. Uncoupled dyes were removed using Qiaquick PCR purification columns (Qiagen) and mixed with 12 mg poly(dA) (Amersham), 60 mg yeast tRNA (Sigma) and 24 mg Cot-1 DNA (Invitroen). The probe was dissolved in 127 ml hybridization mixture containing 46% formamide, 9.5% dextran sulfate, 2x SSC and 0.2% SDS. The probe was heated to 70°C for 10 min and annealed at 37°C for 1 h. Slides were hybridized for 14 h at 37°C over-night (HyArray 12â¢, Perkin Elmer). After hybridization the slides were washed in the HybArray 12⢠with 50% formamide, 2x SSC, pH 7 at 35°C for 15 min, followed b PI buffer (0.1 M sodium phosphate, 0.1% Igepal Ca630, pH 8) at room temperature and 3 washes of 0.2x SSC, 0.1x SSC and 0.01x SSC at room temperature followed by centrifugation. Arrays were scanned using a laser scanner (ScanArray Express, Perkin Elmer) and analysed using ImaGene version 5.6. Cy5 cy3 ratios are calculating by taking the log2 of the signal mean of each spot minus the median background mean of all spots on the array. This is followed by a standard normalization for spot intensity and calculation of the ratios.
2010-06-05 | E-GEOD-2352 | biostudies-arrayexpress
Project description:The objective of the present study was to use our own fabricated bovine liver cDNA microarray to profile genome-wide expression patterns of genes in the liver of cow throughout pregnancy. Ten-microgram of pooled liver total RNA obtained from nonpregnant cycling cows was reverse transcribed in the presence of cyanine-3-fluorescent dye (Cy3)-conjugated dUTP (Amersham Pharmacia Biotech) by using Superscript II reverse transcriptase (Life Technologies, Rockville, MD) to yield Cy3 fluorescence-labeled control cDNA probe. Similarly, liver total RNA obtained from cows on days 19, 27, 49, 58, 150 and 245 of pregnancy was separately reverse transcribed in the presence of Cy5-conjugated dUTP by using Superscript II reverse transcriptase to yield Cy5 fluorescence-labeled test cDNA probe. After a 2-h reverse transcription reaction at 42oC, RNA was degraded by addition of 1.5 µl of an alkaline solution (1N NaOH / 20 mM EDTA), and neutralized by addition of 1.5 µl 1N HCl. The labeled control cDNA probe and test cDNA probe were then mixed and washed by centrifugation with TE (Tris-EDTA, pH 7.0) first and then with TE, 20 µg Salmon sperm DNA, 20 µg polyA and 20 µg yeast RNA in a Microcon YM-30 column (Millipore, Bedford, MA). The concentrated probe mix was adjusted with TE to a volume of 24.8 µl, denatured at 100oC for 2 min, spun for a few min and made to a final hybridization volume of 31 µl with 5.27 µl 20XSSC and 0.93 µl 10% SDS and kept at room temperature until used. Before hybridization, microarray glass slides were immersed in 0.2% SDS for 2 min followed by two washes each 2 min in autoclaved Milli Q water, and subjected to blocking in 180 ml of Methyl Pyrrolidinone (Aldrich) containing 2.7 g Succinic Anhydride (WAKO, Japan) and 15.3 ml 1M Boric acid (pH 8.0) solution for 20 min. Slides were then washed with autoclaved Milli Q water, and the spotted cDNA targets (microarray) were denatured in boiling water for 2 min. The slides were dehydrated in 100% ethanol for 2 min and air dried by spinning at a low speed. The mixture of labeled probes, for example, the control (Cy3) and test (Cy5), were then applied to the microarray, placed a cover slip carefully and incubated at 65oC for 14 – 16 h in a custom slide chamber with humidity maintained by a small reservoir of 3 x SSC. In addition, 3 - 6 µl of 3 x SSC was spotted at each corner of the slide, as far away from the array as possible. After incubation for 14 – 16 h at 65oC, the slides were washed in 2 x SSC / 0.03% SDS for 2 min, followed by washing in 2 x SSC, 1 x SSC and 0.2 x SSC, each for 2 min with gentle agitation, and air dried by spinning at a low speed. All hybridizations were performed in duplicate except those of days 19 and 27, where no reverse labeling was done. In addition, day 245 of pregnancy had three samples hybridized with two of them being labeled using the same dye combination and the other is reverse labeled. In the reverse labeling procedure, for example, the control liver cDNA and test liver cDNA, which had been first labeled with fluorescent dyes Cy3 and Cy5, respectively, were then labeled with Cy5 and Cy3, respectively. The microarray hybridization images were immediately scanned by GenePix 4000B (Axon Instrument, Union City, CA). The images acquired by scan were analyzed by GenePix Pro 4.0 software. The absolute feature (microarray spot) and background intensity of Cy3 and Cy5 for each feature on the array was obtained for the hybridized images. The local background intensity of each spot was smoothed by the local weight regression smoother (lowess smoother) and subtracted from feature intensity data. The subtracted intensity data were subjected to non-parametric regression and local variance normalization. The non-parametric regression can reduce intensity-depended biases. Compared with the linear regression, the accuracy is improved, if the points in scatter plot of Cy3 vs. Cy5 were not distributed around the straight line. The local variance normalization controls the noise (background) in the raw data to a greater extent where the normalized data, in many cases, did not show significant fold-differences in comparison with background-subtracted raw intensity ratios, which frequently displayed higher fold-differences. Thus, the variance method that we employed to bovine liver array data has produced much reliable normalized ratios. To group liver genes with similar expression patterns throughout bovine pregnancy, two clustering algorithm were employed. The hierarchical clustering algorithm was performed using the software, Cluster 3.0, created and made freely available by Dr. Michiel de Hoon (http://bonsai.ims.u-tokyo.ac.jp/~mdehoon/software/cluster/software.htm) based on the original version written by Dr. Michael Eisen (http://rana.lbl.gov/), and the software TreeView (http://rana.lbl.gov/). For hierarchical clustering, genes with either 2 or more than 2-fold induction or 2 or more than 2-fold repression at least at one point of the sampling period were selected. All ratio values were log transformed (base 2) to treat inductions or repressions of identical magnitude as numerically equal but with opposite sign, and subjected to centroid linkage clustering. Self-Organizing Maps (SOMs) algorithm was performed using the software GeneCluster 2 made freely available by Whitehead Institute Center for Genome Research (http://www-genome.wi.mit.edu/cancer/software/genecluster2/gc2.html). The SOMs were performed on the present data to better visualization of clusters of genes with their expression patterns plotted on an x-y axis. For SOMs, genes with either 1.5-fold (and above) induction or 1.5-fold (and above) repression at least at one point of the sampling period were selected. The minimum fold difference i.e., 1.5-fold, chosen for the analyses in the present study was based on the calculation that the technical variation contributing to the expression level of each individual gene due either to different labeling efficiencies of cyanine dyes or labeling procedure or both, was found to be within the range of 1.41-fold induction or repression. Therefore, either the induction or the repression of a particular gene by 1.5-fold or above was considered significant. Keywords = differential liver gene expression Keywords = bovine pregnancy Keywords = hierarchical clustering Keywords = self-organizing maps Keywords: time-course
2003-11-14 | GSE458 | GEO
Project description:Late exponential growth phase (18 h) Emericella nidulans mycelia were transferred to minimal media also supplemented with 1.8 mM diamide, 75 mM H2O2 or 0.8 mM menadione (sodium bisulfite addition compound) and transcriptome profiles were recorded at 0.25, 0.5, 1, 3, 6 and 9 h incubation times. Double printed EST-based (2x4352 spots) DNA chips were used to monitor changes in cDNA populations prepared from mRNA pools isolated from oxidative stress exposed and untreated control cultures. Gene expression ratios were estimated with Genisphere (Hatfield, PA, USA) 3DNA Submicro EX Expression Array Detection Kit. Expression data were read with a GenePix 4000B microarray scanner (Axon Instruments). Intensity ratios were calculated with GenePix Pro 3.0 software. Note, processed data after LOESS-type normalization are presented on Series GSE2085 and all the signs were also reversed during data processing to reach proper log2(treated/control) channel intensity ratios. Keywords: time-course
2006-01-05 | GSE2100 | GEO