Transcription profiling of wheat cultivars after cold treatment
ABSTRACT: Different wheat cultivars may be classified as either winter or spring varieties depending on whether they require exposure to an extended period of cold in order to become competent to flower. Using a growth regime that mimics the conditions that occur during a typical winter in Britain, we wished to survey the genes that are involved in phase transition as well as those involved in cold-acclimation. Experiment Overall Design: We wished to study the profiles of expression of genes involved in both phase transition (vegetative to reproductive growth transition) and cold-acclimation. To that end we we exposed plants to a gradual, stepped decline in both temperature and light. We sampled plants at three time points (3 weeks post-germination, 5 weeks post germination and 9 weeks post germination). We took samples from two separate tissues (crown and leaf) to se whether responses were different. We used two biological reps for each time point and tissue. Control plants were exposed to a delined in day-length and light intensity, but not in temperature.
Project description:In this study we used the Affymetrix Barley 1 GeneChip to investigate transcriptome responses of barley cv. Morex to low temperature, including triplicated measurements of cold, freeze/thaw cycles and de-acclimation over 33 days. Experiment Overall Design: Plants were grown at 20ºC for seven days and subject to a symmetrical cycle of acclimation, cold, freeze-thaw, and deacclimation. Chilling began by decreasing the temperature overnight from 20ºC to 4ºC at a rate of 1.3ºC•h-1 and maintaining temperatures of 4 ºC in the day and 2ºC at night for 5 days. Freeze-thaw cycling lasted 12 days with day temperatures of 4ºC and night temperatures gradually decreasing from -2ºC the first night to -4ºC for three nights and -10ºC for four nights, then recovering to -4ºC for three nights and -2ºC for one night. This treatment was designed to allow daily freeze-thaw cycling and protein synthesis. Chilling conditions (4ºC day, 2ºC night) were resumed for five days, followed by deacclimation with increasing temperature to 20ºC overnight and maintaining for three days. Sampling was done at four different times, each at the 11th hour of light to avoid circadian effects: 1) before chilling treatment, 2) five days after initiation of chilling treatment, 3) eight days into freeze-thaw treatment and 4) three days into de-acclimation.
Project description:In this study, we used GC-MS analysis in combination with flux analysis and the Affymetrix ATH1 GeneChip to survey the metabolome and transcriptome of Arabidopsis leaves in response to manipulation of the thiol-disulfide status. Feeding low concentrations of the sulfhydryl reagent dithiothreitol (DTT) for one hour at the end of the dark period led to post-translational redox-activation of ADP-glucose pyrophosphorylase and major alterations in leaf carbon partitioning, including an increased flux into major respiratory pathways, starch- cell-wall-, and amino-acid synthesis and a reduced flux to sucrose. This was accompanied by a decrease in the levels of hexose-phosphates, while metabolites in the second half of the TCA cycle and various amino acids increased, indicating a stimulation of anaplerotic fluxes reliant on α-ketoglutarate. There was also an increase in shikimate as a precursor of secondary plant products and marked changes in the levels of the minor sugars involved in ascorbate synthesis and cell wall metabolism. Transcript profiling revealed a relatively small number of changes in the levels of transcripts coding for components of redox-regulation, transport processes and cell wall, protein and amino acid metabolism, while there were no major alterations in transcript levels coding for enzymes involved in central metabolic pathways. These results provide a global picture of the effect of redox and reveal the utility of transcript and metabolite profiling as systemic strategies to uncover the occurrence of redox-modulation in vivo. Experiment Overall Design: Leaf discs were incubated with or without 5mM DTT for one hour to affect the redox status of the cells. The effect of this treatment on global gene expression was analysed using affymetrix ATH1 microarrays. The experiments contains one control (-DTT) and one treatment (+DTT) and is performed with 2 biological replicas.
Project description:The effect of sucrose feeding on gene expression in Arabidopsis thaliana leaves was investigated using affymetrix ATH1 microarrays. For this, petioles of detached leaves were put in a solution containing either sucrose or sorbitol (control). Sugars were taken up into the leaf via the respiration stream for 13 hours. After that, leaves were frozen in liquid nitrogen and RNA was extracted for analysis. Experiment Overall Design: The effect of sucrose feeding on gene expression was investigated using affymetrix ATH1 microarrays. For this, petioles of detached leaves were put in a solution containing either sucrose or sorbitol (control). Sugars were taken up into the leaf via the respiration stream for 13 hours. After that, leaves were frozen in liquid nitrogen and RNA was extracted for analysis.
Project description:To identify genes associated with lung cancer progression, we examined gene expression profiles of tumor cells from 20 patients with primary, untreated non-small cell lung cancer (10 adenocarcinomas (AC) and 10 squamous cell carcinomas (SCC)) in comparison to lung tissue of 23 patients with stage IIIB or stage IV non-small cell lung cancer (15 AC and 8 SCC). Bronchoscopical biopsies from patient with recurrent lung tumor were taken after initial treatment. Cancer cells were isolated using laser capture microdissection in order to obtain pure samples of tumor cells. For expression analysis, microarrays covering 8793 defined genes (Human HG Focus Array, Affymetrix) were used. Array data were normalized and analysed for significant differences using variance stabilizing transformation (VSN) and significance analysis of microarrays (SAM), respectively. Genes were considered to be up- or down-regulated when the ratio between primary and recurrent tumor samples were at least 1.5-fold differentially expressed with an estimated false discovery rate: < 5%. Based on differentially expressed genes, primary cancer samples could be separated from recurrent tumor samples. We identified 115 and 124 significantly regulates genes in AC and SCC, respectively. For example, in recurrent AC we found increased expression of genes related to the wingless (FZD6, RYK, MYC) and calcium (CALM1, ATB2B1, S100A2) signalling pathways which might play a role in metastasis of tumor cells. Other differentially expressed genes were related to cell cycle (CCND1, CDK2), transcription factors (TTF1, TAF2, YY1), nuclear mRNA splicing and mRNA processing (SFRS1, HNRPL), protein-nucleus import (NUTF2, KPNB1, NUP50) and chromatin modification (HIST1H4C, SMARCC1). In SCC, we found an increased expression of CTNNB1, an important mediator in wingless signalling pathway. Among the down-regulated genes in SCC, the utmost fraction belonged to genes coding for ubiquitin mediated proteolysis (UCHL1, PSMA3, COPS6) and ribosomal proteins (RPS26, RPL7A, RPS15). Other down regulated genes were related to transcription factors (TCEA2, TAF10), nuclear mRNA splicing and mRNA processing (SNRPD2, HNRPM). In conclusion, a distinct pattern of gene expression is found during the progression from primary carcinoma to recurrent NSCLC. Our microarray-based expression profiling revealed interesting novel candidate genes and pathways that may contribute to lung cancer progression. Experiment Overall Design: - 20 patients with primary, untreated non-small cell lung cancer (10adenocarcinomas (AC) and 10 squamous cell carcinomas (SCC)) in comparison to lung tissue of 23 patients with stage IIIB or stage IV non-small cell lung cancer (15 AC and 8 SCC) Experiment Overall Design: - Human HG Focus Array, Affymetrix) were used Experiment Overall Design: - Array data were normalized and analysed for significant differences using variance stabilizing transformation (VSN) and significance analysis of microarrays (SAM) Experiment Overall Design: - Genes were considered to be up- or down-regulated when the ratio between primary and recurrent tumor samples were at least 1.5-fold differentially expressed with an estimated false discovery rate: < 5%
Project description:Lung cancers are a heterogeneous group of diseases with respect to biology and clinical behavior. So far, diagnosis and classification are based on histological morphology and immunohistological methods for discrimination between two main histologic groups: small cell lung cancer (SCLC) and non-small cell lung cancer which account for 20% and 80% of lung carcinomas, respectively. While SCLCs express properties of neuroendocrine cells, NSCLCs, which are divided into the three major subtypes adenocarcinoma, squamous cell carcinoma and dedifferentiated large cell carcinoma, show different characteristics such as the expression of certain keratins or production of mucin and lack neuroedocrine differentiation. The molecular pathogenesis of lung cancer involves the accumulation of genetic und epigenetic alterations including the activation of proto-oncogenes and inactivation of tumor suppressor genes which are different for lung cancer subgroups. The development of microarray technologies opened up the possibility to quantify the expression of a large number of genes simultaneously in a given sample. There are several recent reports on expression profiling on lung cancers but the analysis interpretation of the results might be difficult because of the heterogeneity of cellular components. A contamination of the tumor sample with normal epithelia, blood vessels, stromal cells, leucocytes and tumor necrosis may confound the true expression profile of the tumor. The use of laser capture microdissection (LCM) greatly improves the sample preparation for microarray expression analysis. Consequently, we used advanced technology including LCM and microarray analysis. In detail, we examined gene expression profiles of tumor cells from 29 previously untreated patients with lung cancer (10 adenocarcinomas (AC), 10 squamous cell carcinomas (SCC), 9 small cell lung cancer (SCLC)) in comparison to normal lung tissue (LT) of 5 control patients without tumor. Bronchoscopical biopsies from the primary lung tumor were taken before treatment. Biopsies were cut into 8µm sections and from each section cancer cells were isolated using laser capture microdissection in order to obtain pure samples of tumor cells. Total RNA was extracted, reversely transcribed, in-vitro transcribed, labelled and hybridized to the array. For expression analysis, microarrays covering 8793 defined genes (Human HG Focus Array, Affymetrix) were used. Following quality control, array data were normalized and analysed for significant differences using variance stabilizing transformation (VSN) and significance analysis of microarrays (SAM), respectively. Based on differentially expressed genes cancer samples could be clearly separated from non cancer samples using hierarchical clustering. Comparing AC, SCC and SCLC with normal lung tissue, we found 205, 335 and 404 genes, respectively, that were at least 2-fold differentially expressed with an estimated false discovery rate < 2.6%. Each histological subtype showed a distinct expression profile. Further, using a genetic programming approach we constructed a classificator to discriminate AC, SCC, NT and SCLC. To this end, the 50 genes with the greatest signal-to-noise ratio were selected to train the classificator. By leave-one-out cross validation all 34 samples were correctly classified in this training set. In order to validate the 50-gene-classificator on a test set, further 13 microdissected lung cancer samples were used and correctly classified in concordance to pathologic finding. In conclusion, the different lung cancer subtypes have distinct molecular phenotypes which reflect biological characteristics of the tumor cells and which might be the basis for development of targeted therapy. Moreover, gene expression profiling and genetic programming is a suitable tool for classification and discrimination of different histological subtypes in lung cancer in comparison to normal lung tissue. Experiment Overall Design: Comparison of gene expression profiles of normal lung tissues, adenocarcinomas, squamous cell carcinomas and small cell lung cancers.
Project description:Seed storage proteins (SSP) play a central role in providing carbon (C), nitrogen (N), and sulfur (S) resources during seed germination. Their content and composition are essential determinants shaping wheat end-use value. Molecular mechanisms underlying the developmental and nutritional regulation of SSP accumulation in wheat grain are as yet poorly understood. We were interested to elucidate the effects of N and S supplies on the gene expression of the entire system of wheat grain. For this purpose, we performed microarray analysis using a custom T.aestivum NimbleGen 40k microarray (ref. A-MEXP-1928) in wheat grains of 8 developmental stages and four N and S treatments.
Project description:Nine accessions of Arabidopsis were sampled before and after 14d of cold acclimation at 4°C. Transcript data were combined with metabolite data and related to quantitative measurement of plant freezing tolerance as determined by leaf electrolyte leakage assays.
Project description:Medicago truncatula endogenous small RNAs The dataset contains Medicago truncatula Gaertn. cv. Jemalong endogenous small RNA sequences in the range 18-28 nucleotides. High-throughput Solexa/Illumina sequencing was carried out at the Sainsbury Laboratory, Norwich, UK. Please see www.illumina.com for details of the technology. Small RNA sequences were mapped to Medicago truncatula genome release 2.0 (http://www.medicago.org/genome/), the number of matches to the unfinished genome, if any, is recorded in the Series supplementary file GSE13761_sequence_annotations.txt.gz. Size fractionated small RNA from total RNA extracts was ligated to adapters, purified again and reverse transcribed. After PCR amplification the sample was subjected to Solexa/Illumina high throughput pyrosequencing. Please see www.illumina.com for details of the sequencing technology.
Project description:Usually starch is nearly depleted at the end of the night. To induce a gradual depletion of carbon, we have analysed the global response of transcripts during an extension of the night, where carbon becomes severely limiting from about four hours onwards. Experiment Overall Design: Arabidopsis thaliana rosettes were harvested in successive timpoints in an extended night situation.
Project description:Crown rot of wheat, caused by Fusarium pseudograminearum and other Fusarium species is an important disease globally. To understand the host response to challenge by Fp, we examined gene exression changes in the stem base of the wheat variety Kennedy, following inoculation with macroconidia using the Affymetrix GeneChip Wheat Genome Array. Induced genes included mainly those with defensive functions such as genes encoding anti-microbial proteins as well as oxidative stress-related proteins, signalling molecules, and proteins involved in both primary and secondary metabolism. This study is the first comprehensive analysis of the wheat transcriptome during crown rot infection and provides new insights into the host processes involved in plant defence against this pathogen. Experiment Overall Design: There are six samples, three F. pseudograminearum inoculated samples and three mock inoculated samples. Each sample consists of 2cm of stem base from approximately 20 plants.