Unknown,Transcriptomics,Genomics,Proteomics

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Comparisons of gene expressions in zebrafish (Danio rerio) brain and gill after cold acclimation

ABSTRACT: Ambient temperature affects organisms comprehensively, however cold responses are different among tissues. Here, we adopt a transcript screening approach to explore and compare the cold responses in zebrafish gills and brain. Zebrafish were exposed to cold and the oligonucleotide-based microarray was used to identify cold-induced genes. Principle component analysis (PCA) of the gene expression profiles indicated that gills develop different strategies for the increasing of exposure period while brain relatively remained stable. Combining statistic and clustering methods, we found that gills showed higher protein metabolism and cell activity while brain showed higher stress responses and detoxification during cold acclimation. According to the microarray data sets, we extended the study on ionocyte- and isotocin neuron-related genes in gills and brain, respectively, and found these genes were broadly stimulated by cold. These data suggest that cold activates specific physiological functions in different tissues. Taken together, our results provide molecular evidences to elucidate the cold acclimation in zebrafish gills and brain. Keywords: Time course, Tissue types After the low-temperature treatment, brain and gill tissues dissected from 10 individuals were pooled as a sample and then homogenized in 0.8 ml Trizol reagent (Invitrogen, Carlsbad, CA). 120 individuals (60 for low-temperature treatment and 60 for control) were sacrificed for each microarray hybridization experiment, and another 200 individuals were used for quantitative reverse-transcription polymerase chain reaction. After chloroform extraction, RNA precipitation and ethanol washing, the RNA samples were purified and treated with DNase1 to remove the genomic DNA by using RNeasy Mini Kit (Qiagen, Huntsville, Alabama). The quantity and quality of total RNA were assessed by spectrophotometry and Bioanalyzer (Aglient Technologies, Foster City, CA). The commercial zebrafish 14K oligonucleotides set (MWG Biotech AG, Ebersbach, Germany) were obtained and were printed on UltraGAPS Coated slide (Corning, New York, NY ) with use of the OmniGrid 100 microarrayer (Genomic Solutions, Ann Arbor, MI) according to the manufactureâ??s instructions. The 14,067 oligonucleotides represent 9666 genes (7009 singlet genes and 2657 redundant genes), and the redundancy of this chip is 31 %. The detailed description of the oligonucleotides information can be obtained on the Ocimun Biosolution website. cDNA probes were synthesized and purified by reverse transcription of 20 Î¼g total RNA using a SuperScript indirect cDNA labeling system (Invitrogen) and MinElute PCR purification kit (Qiagen) and were labeled with Alexa 647 dye (cold treatment groups) and Alexa 555 dye (control groups)(Invitrogen), respectively. The zebrafish 14K OciChip array chip was pretreated with 1% bovine serum albumin (BSA) (fraction V), 4x saline-sodium citrate (SSC), and 1% sodium dodecylsulfate (SDS) at 42 Â°C for 45 min, and then hybridized overnight in a cocktail containing 5x Denhardt's solution, 6x SSC, 0.5% SDS, 50% formamide, 50 mM sodium phosphate, and 2 Âµg/Âµl yeast tRNA. Slides were washed with 2x SSC and 0.1% SDS (5 min), 1x SSC and 0.1% SDS (5 min), 0.5x SSC (5 min), and twice with 0.1x SSC (2 min each). Scanning was performed with a Genepix scanner (Molecular Devices, Sunnyvale, CA). The acquired images were analyzed using Genepix and Genespring software (Aglient Technologies, Foster City, CA). The measurements of spots were filtered by flags, and the Lowess normalization was performed after subtraction of the median background. Each experiment contained 3 biological replicates (including 1 dye swap) with different samples. The differentially expressed genes were selected from those with at least 2 of 3 significant signals (ratio > 2 or < 0.5), and then the Significant Analysis of Microarray method (SAM 3.02) was used to determine statistical significances.

ORGANISM(S): Danio rerio

SUBMITTER: Ming Yi Chou

PROVIDER: E-GEOD-10958 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Ectothermic vertebrates are different from mammals that are sensitive to hypothermia and they have to maintain core temperature for survival. Why and how ectothermic animals can survive, grow and reproduce in low temperature have been for a long time a scientifically challenging and important inquiry to biologists. We used a microarray to profile the gill transcriptome in zebrafish (Danio rerio) after exposure to low temperature. Adult zebrafish were acclimated to a low temperature of 12 ï°C for 1 (1-d) and 30 d (30-d), and the gill transcriptome was compared to wild types by oligonucleotide microarray hybridization. Results showed 11 and 22 transcripts were found to be upregulated by low-temperature treatment for 1-d and 30-d respectively, while 56 and 70 transcrips were downregulated. The gill transcriptome profiles revealed that ionoregulation-related gene was highly upregulated in cold-acclimated zebrafish. This observation encouraged us to investigate the role of ionoregulatory genes in zebrafish gills during cold acclimation. Cold acclimation caused upregulation of genes that are essential for ionocyte specification, differentiation, ionoregulation, and acid/base balance, and also increased the numbers of cells expressing these genes. mRNA expression of epithelial Ca2+ channel (ECaC), one of these genes, was increased in parallel with the level of Ca2+ influx, revealing a functional compensation after long-term acclimation to cold. Phospho-histone H3 and TUNEL staining showed that the cell turnover rate was retarded in cold-acclimated gills. These results suggest that gills may sustain their functions by yielding mature ionocytes from preexisting undifferentiated progenitors in low-temperature environments. The AB strain of zebrafish (D. rerio) was originally obtained from the University of Oregon, and were kept in the zebrafish stock center at Academia Sinica, Taipei, Taiwan. Fish were reared in local tap water at 28 ï°C and a photoperiod regime of 14-h L/10-h D. Adult zebrafish were acclimated to 12 ï°C with a gradually reduced temperature at a gradient of 4 ï°C/h in order to prevent temperature shock and reduce mortality. After 30 d of acclimation, surviving (over an 80% survival rate) fish appeared to be feeding and behaving normally compared with control fish. The experimental protocols were approved by the Academia Sinica Institutional Animal Care and Utilization Committee (approval no. RFiZOOHP2006083). After the low-temperature treatment, gill tissues dissected from 6 individuals were pooled as a sample and then homogenized in 5 ml Trizol reagent (Invitrogen, Carlsbad, CA). Thirty six individuals (18 for low-temperature treatment and 18 for control) were sacrificed for each microarray hybridization experiment, and another 60 individuals were used for quantitative reverse-transcription polymerase chain reaction. After chloroform extraction, RNA precipitation and ethanol washing, the RNA samples were purified and treated with DNase1 to remove the genomic DNA by using RNeasy Mini Kit (Qiagen, Huntsville, Alabama). The quantity and quality of total RNA were assessed by spectrophotometry and agarose gel electrophoresis, respectively. The commercial zebrafish 14K oligonucleotides set (MWG Biotech AG, Ebersbach, Germany) were obtained and were printed on UltraGAPS Coated slide (Corning, New York, NY ) with use of the OmniGrid 100 microarrayer (Genomic Solutions, Ann Arbor, MI) according to the manufactureâs instructions. The 14,067 oligonucleotides represent 9666 genes (7009 singlet genes and 2657 redundant genes), and the redundancy of this chip is 31 %. The detailed description of the oligonucleotides information can be obtained on the Ocimun Biosolution website (http://www.ocimumbio.com/web/default.asp). cDNA probes were synthesized by reverse transcription of 20 Î¼g total RNA using a SuperScript indirect cDNA labeling system (Invitrogen) and were labeled with Cy5 (cold treatment groups) and Cy3 (control groups)(Amersham Bioscience, Buckinghamshire, UK) , respectively. The zebrafish 14K OciChip array chip was pretreated with 1% bovine serum albumin (BSA) (fraction V), 4x saline-sodium citrate (SSC), and 1% sodium dodecylsulfate (SDS) at 42 Â°C for 45 min, and then hybridized overnight in a cocktail containing 5x Denhardt's solution, 6x SSC, 0.5% SDS, 50% formamide, 50 mM sodium phosphate, and 2 Âµg/Âµl yeast tRNA. Slides were washed with 2x SSC and 0.1% SDS (5 min), 1x SSC and 0.1% SDS (5 min), 0.5x SSC (5 min), and twice with 0.1x SSC (2 min each). Scanning was performed with a Genepix scanner (Molecular Devices, Sunnyvale, CA). The acquired images were analyzed using ScanArray Express 3.0 (PerkinElmer, Waltham, MA) and Genespring (Aglient Technologies, Foster City, CA) software. The measurements of spots were filtered by flags, and the lowest normalization was performed after subtraction of the median background. To assess the differential expressions of genes, we identified the ratio of Cy5/Cy3 intensity > 2 or < 0.5. Each experiment contained 3 biological replicates (including 1 dye swap) with different samples, and the differentially expressed genes were selected from those with at least 2 of 3 significant signals (ratio > 2 or < 0.5).

Project description:To identify mRNAs associated with human PUM2 protein, we used a modified Ribonucleoprotein-ImmunoPrecipitation Microarray (RIP-Chip) approach on HeLa S3 cancer cells that express PUM2. PUM ribonucleoprotein (RNP) complexes were captured from cell-free extracts with specific anti PUM2 antibody coupled to protein A sepharose beads, and then eluted with SDS-EDTA. To control for non-specifically enriched RNAs, the same procedure was performed with beads that were not coupled with immunoprecipitating antibodies (mock samples). Total RNA was isolated from cell extracts and immunopurified samples with the mirVanaTM PARISTM kit (Ambion). RNA was quantified with a NanoDrop device (Witeg AG). Poly-adenylated RNAs were amplified in the presence of aminoallyl-UTP with Amino Allyl MessageAmp II aRNA kit (Ambion). For this purpose, 500 ng total RNA from extracts and half (50-100 ng) of the immunopurified RNAs were used for amplification. 8 ug of the amplified RNAs (aaRNA) were fluorescently labeled with NHS-monoester Cy3 and Cy5 dyes (GE HealthSciences), except for mock RNA samples, where an aaRNA amount proportional to the yield obtained from corresponding PUM affinity isolates was used.For PUM2 RIPs, we performed four biological replicates but omitted the dye swaps due to the lower aaRNA obtained after amplification (~10 ug aaRNA from PUM2 RIPs, 9 ug aaRNA from mock RIPs). The Cy3- and Cy5-labeled aaRNA samples were mixed and hybridized to human cDNA microarrays. Detailed methods for microarray experiments are available at http://cmgm.stanford.edu/pbrown/protocols/index.html. cDNA microarrays were produced by the Stanford Functional Genomic Facility and contained 43,197 human probes representing 26,524 Unigene cluster IDs (12,466 ENSEMBL annotated genes) spotted on Corning Ultra GAPS slides. Spotted cDNAs were cross-linked with 65 mJ of UV irradiation on slides, which were then post-processed for 1 hour at 42°C in pre-hybridization solution (5x SSC, 0.1% SDS, 0.1 mg/ml BSA), washed twice in 400 ml of 0.1x SSC for 5 min, dunked in 400 ml ultrapure water for 30 sec, and dried by centrifugation at 550 rpm for 5 min. Slides were used the same day. Cy3- and Cy5-labeled aaRNA probes were mixed and applied to arrays in hybridization solution (3x SSC, 20 ug poly(A) RNA [Invitrogen], 20 ug yeast tRNA [Invitrogen], 20 ug Human Cot-1 DNA [Invitrogen], 20 mM HEPES [pH 7.0] and 0.3% SDS) for 18 h at 65°C. The arrays were then washed sequentially in 400 ml of 2x SSC with 0.1% SDS, 1x SSC, and 0.2x SSC. The first wash was performed for 5 min at 65°C, the subsequent washes were performed for 5 min at RT. The arrays were dried by centrifugation and immediately scanned with an AxonScanner 4200A (Molecular Devices). Data were collected using GENEPIX 5.1 (Molecular Devices). Arrays were normalized computationally by the Stanford Microarray Database (SMD). The data were filtered for signal over background of greater than 1.5 in the channel measuring aaRNA from extract, and only features that met these criteria in > 50% of the arrays were included for further analysis. Log2 median ratios were retrieved and exported into Microsoft Excel. To identify transcripts that were specifically enriched by association with PUM2, we performed two class Significance Analysis of Microarrays (SAM) on median centered arrays. A replicate experimental design type is where a series of replicates are performed to evaluate reproducibility or as a pilot study to determine the appropriate number of replicates for a subsequent experiments. Antibody used in IP: 50 ug rabbit anti-PUMILIO 2 (Bethyl Laboratories, #300-202A) Keywords: replicate_design Computed

Project description:To identify mRNAs associated with human PUM1 protein, we used a modified Ribonucleoprotein-ImmunoPrecipitation Microarray (RIP-Chip) approach on HeLa S3 cancer cells that express PUM1. PUM ribonucleoprotein (RNP) complexes were captured from cell-free extracts with anti PUM1 specific antibody Bethyl Laboratories, #300-201A coupled to protein G (PUM1) sepharose beads, and then eluted with SDS-EDTA. To control for non-specifically enriched RNAs, the same procedure was performed with beads that were not coupled with immunoprecipitating antibody (mock samples). Total RNA was isolated from cell extracts and immunopurified samples with the mirVanaTM PARISTM kit (Ambion). RNA was quantified with a NanoDrop device (Witeg AG). Poly-adenylated RNAs were amplified in the presence of aminoallyl-UTP with Amino Allyl MessageAmp II aRNA kit (Ambion). For this purpose, 500 ng total RNA from extracts and half (50-100 ng) of the immunopurified RNAs were used for amplification. 8 ug of the amplified RNAs (aaRNA) were fluorescently labeled with NHS-monoester Cy3 and Cy5 dyes (GE HealthSciences), except for mock RNA samples, where an aaRNA amount proportional to the yield obtained from corresponding PUM affinity isolates was used. For PUM1 RIPs, we performed three biological replicates with technical (dye swap) replicates (total six arrays).(~40 ug aaRNA from PUM1 RIPs, ~9 ug aaRNA from mock RIPs). The Cy3- and Cy5-labeled aaRNA samples were mixed and hybridized to human cDNA microarrays.Detailed methods for microarray experiments are available at http://cmgm.stanford.edu/pbrown/protocols/index.html. cDNA microarrays were produced by the Stanford Functional Genomic Facility and contained 43,197 human probes representing 26,524 Unigene cluster IDs (12,466 ENSEMBL annotated genes) spotted on Corning Ultra GAPS slides. Spotted cDNAs were cross-linked with 65 mJ of UV irradiation on slides, which were then post-processed for 1 hour at 42°C in pre-hybridization solution (5x SSC, 0.1% SDS, 0.1 mg/ml BSA), washed twice in 400 ml of 0.1x SSC for 5 min, dunked in 400 ml ultrapure water for 30 sec, and dried by centrifugation at 550 rpm for 5 min. Slides were used the same day. Cy3- and Cy5-labeled aaRNA probes were mixed and applied to arrays in hybridization solution (3x SSC, 20 ug poly(A) RNA [Invitrogen], 20 ug yeast tRNA [Invitrogen], 20 ug Human Cot-1 DNA [Invitrogen], 20 mM HEPES [pH 7.0] and 0.3% SDS) for 18 h at 65°C. The arrays were then washed sequentially in 400 ml of 2x SSC with 0.1% SDS, 1x SSC, and 0.2x SSC. The first wash was performed for 5 min at 65°C, the subsequent washes were performed for 5 min at RT. The arrays were dried by centrifugation and immediately scanned with an AxonScanner 4200A (Molecular Devices). Data were collected using GENEPIX 5.1 (Molecular Devices). Arrays were normalized computationally by the Stanford Microarray Database (SMD). The data were filtered for signal over background of greater than 1.5 in the channel measuring aaRNA from extract, and only features that met these criteria in > 50% of the arrays were included for further analysis. Log2 median ratios were retrieved and exported into Microsoft Excel.To identify transcripts that were specifically enriched by association with PUM1, we performed two class Significance Analysis of Microarrays (SAM) on median centered arrays. A replicate experimental design type is where a series of replicates are performed to evaluate reproducibility or as a pilot study to determine the appropriate number of replicates for a subsequent experiments. Antibody used in IP: 20 ug goat anti-PUMILIO 1 Bethyl Laboratories, #300-201A Keywords: replicate_design Computed

Project description:Escherichia coli strain MG1655 was grown to mid-log phase in defined aerobic media. One sample was treated with 30 ÂµM CORM-3, the other sample was a control. The volume (30 ml), temperature (37oC) and shaking (200 rpm) were constant. After 15 min of exposure to CO-RM, samples were taken from treated and control cells, harvested into ice cold phenol ethanol (187 Âµl phenol, 3.56 ml ethanol) to stabilize RNA, and total RNA was purified using Qiagenâs RNeasy Mini kit as recommended by suppliers. RNA was quantified using a BioPhotometer (Eppendorf). Biological experiments were carried out four times, and a dye swap performed for each experiment, providing two technical repeats for each of the four biological repeats. Cells were grown in defined minimal medium (aerobic). Final concentrations are: glycerol (54 mM), K2HPO4 (23 mM), KH2HPO4 (7.3 mM), NH4Cl (18.7 mM), CaCl2 (69 ÂµM), and K2SO4 (15 mM). Trace elements were added at 10 ml per l; final concentrations are: 134 ÂµM EDTA, 31 ÂµM FeCl3, 6.15 ÂµM ZnO, CuCl2 0.57 ÂµM, CoNo3 0.34 ÂµM, 1.6 ÂµM H3BO3, 1 ÂµM ammonium molybdenate and 1 ÂµM sodium selenite. MgCl2 was added at 1 ml per l. All chemicals were of AnalaR grade of purity or higher. E. coli strain MG1655 was grown in 250 ml side arm flasks in 30 ml of the above defined minimal media (aerobic). CORM-3 was added at a final concentration of 30 ÂµM, chosen because it causes only a slight reduction in the growth rate. Cells were grown to mid-log (Klett values of 30-40) before addition of CO-RM. The total 30 ml volume was harvested into ice cold phenol ethanol (187 Âµl phenol, 3.56 ml ethanol) to stabilize RNA, and total RNA was purified using Qiagenâs RNeasy Mini kit as recommended by suppliers. RNA was quantified using a BioPhotometer (Eppendorf). Biological experiments were carried out four times, and a dye swap performed for each experiment, providing two technical repeats for each of the four biological repeats. Equal quantities of RNA from control and CO-RM-treated cells were labelled by using nucleotide analogues of dCTP containing either Cy3 or Cy5 fluorescent dyes (Perkin Elmer). For each microarray slide, one sample was labelled with Cy3-dCTP, while the other sample was labelled with Cy5-dCTP. RNA (approximately 9 micrograms) was annealed to 4.5 micrograms pd(N)6 random hexamers (Amersham Biosciences) by heating at 65 oC for 10 min, followed by 10 min at 22 oC and cooling on ice for 2 min. This was supplemented with 6 microlitres of 5Ã First-strand buffer (Invitrogen), 2.5 microlitres dNTP mixture (5 mM each dATP, dTTP, dGTP and 2 mM dCTP), 3 microlitres 0.1 M DTT, 2 microlitres 1 mM Cy3 or Cy5 (Perkin Elmer) and 1.5 microlitre Superscript III reverse transcriptase (200 U) (Invitrogen). This was incubated at 42 oC for 3 hours. The reaction was terminated by the addition of NaOH (7.5 microlitres of 1M) and HCl (7.5 microlitres of 1M) before the addition of TE buffer (300 microlitres). Labelled cDNA was purified using a Qiaquick PCR purification kit (Qiagen). The Cy3-dCTP-labelled sample was mixed with the Cy5-dCTP-labelled sample, vacuum dried and re-suspended in 120 microlitres salt-based hybridisation buffer (supplied with the microarray slides). This was heated at 95 oC for 3 min then cooled on ice for 3 min. The mixture was pipetted onto a microarray slide, sealed with a GeneFrame and coverslip in a hybridization chamber and incubated for 18 h at 42 Â°C. Following hybridization, microarray slides (minus GeneFrame and coverslip) were washed in a series of pre-warmed (37 Â°C) SSC buffers for 5 min each at 37oC: 2Ã SSC/0.1 % SDS, 1Ã SSC, 0.2Ã SSC and 0.01Ã SSC. Microarray slides were dried by centrifugation at 1500 Ã g for 2 min before scanning. Slides were scanned on an Affymetrix 428 scanner. 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 3.5). Spots automatically flagged as bad, negative or poor in the Imagene software were removed before the statistical analysis was carried out in GeneSight. 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. Biological experiments (i.e. a comparison of control and plus CO-RM cells) were carried out four times, and a dye swap performed for each experiment, providing two technical repeats for each of the four biological repeats. Data from the independent experiments were combined. Genes that were differentially expressed â¥ twofold and displayed and P value of < 0.05 (as determined by a t test) were defined as being statistically significantly differentially transcribed.

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Comparisons of gene expressions in zebrafish (Danio rerio) brain and gill after cold acclimation

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