Unknown,Transcriptomics,Genomics,Proteomics

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Platform comparison and transcription profiling Arabidopsis samples on CATMA, Affymetrix and Agilent arrays

ABSTRACT: Transcript profiling is crucial to study biological systems and various platforms have been implemented to survey mRNAs at the genome scale. We have assessed the characteristics of the CATMA microarray designed for Arabidopsis thaliana transcriptome analysis, and compared it with two commercial platforms from Agilent and Affymetrix. The CATMA array consists of gene-specific sequence tags of 150 to 500 base pairs, the Agilent (Arabidopsis 2) array of 60mer oligonucleotides, and the Affymetrix gene chip (ATH1) of 25mer oligonucleotide sets. We have matched each probe repertoire with the Arabidopsis genome annotation (TIGR release 5.0) and determined the correspondence between them. Array performance was analyzed by hybridization with labeled target derived from eight RNA samples made of shoot total RNA spiked with a calibrated series of 14 control transcripts. A total of fourteen cDNA clones were thus selected and used as templates to synthesize bona fide polyadenylated spike RNAs. Each spike RNA was calibrated then mixed in equal amount with one of the other spike RNAs to obtain seven pairs at equal concentration. These seven spike RNA pairs were then combined systematically to construct seven complex spike mixes in a design similar to an ordered Latin square, each mix containing six of the seven spike pairs in staggered concentrations covering five logs. To prevent loss of spike RNA through adsorption to the plastic ware, the spike mixes were prepared in 0.5 Âµg/Âµl Col RNA, resulting in a range of concentration from 0.1 to 10,000 copies per cellular equivalent (cpc), assuming that the total RNA contained 1% polyadenalated mRNA and that a cell contained on average 300,000 transcripts. These seven RNA samples included equal amounts of combined spike RNA . To convert the spike hybridization signals to ratios, an eighth sample was prepared, called the reference sample, consisting of the base Col RNA completed with all spike RNAs at a concentration of 100 cpc. The results from the eight experiments using the Affymetrix gene chips (ATH1) are available for analysis or download from this site.

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: unknown unknown

PROVIDER: E-NASC-43 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Transcript profiling is crucial to study biological systems and various platforms have been implemented to survey mRNAs at the genome scale. We have assessed the characteristics of the CATMA microarray designed for Arabidopsis thaliana transcriptome analysis, and compared it with two commercial platforms from Agilent and Affymetrix. The CATMA array consists of gene-specific sequence tags of 150 to 500 base pairs, the Agilent (Arabidopsis 2) array of 60mer oligonucleotides, and the Affymetrix gene chip (ATH1) of 25mer oligonucleotide sets. We have matched each probe repertoire with the Arabidopsis genome annotation (TIGR release 5.0) and determined the correspondence between them. Array performance was analyzed by hybridization with labeled target derived from eight RNA samples made of shoot total RNA spiked with a calibrated series of 14 control transcripts. A total of fourteen cDNA clones were thus selected and used as templates to synthesize bona fide polyadenylated spike RNAs. Each spike RNA was calibrated then mixed in equal amount with one of the other spike RNAs to obtain seven pairs at equal concentration. These seven spike RNA pairs were then combined systematically to construct seven complex spike mixes in a design similar to an ordered Latin square, each mix containing six of the seven spike pairs in staggered concentrations covering five logs. To prevent loss of spike RNA through adsorption to the plastic ware, the spike mixes were prepared in 0.5 µg/µl Col RNA, resulting in a range of concentration from 0.1 to 10,000 copies per cellular equivalent (cpc), assuming that the total RNA contained 1% polyadenalated mRNA and that a cell contained on average 300,000 transcripts. These seven RNA samples included equal amounts of combined spike RNA . To convert the spike hybridization signals to ratios, an eighth sample was prepared, called the reference sample, consisting of the base Col RNA completed with all spike RNAs at a concentration of 100 cpc. The results from the eight experiments using the Affymetrix gene chips (ATH1) are available for analysis or download from this site. Experimenter name = Jim Beynon Experimenter phone = 01798 470382 Experimenter fax = 01789 470552 Experimenter department = Horticulture Research International Experimenter institute = Warwick University Experimenter address = Horticulture Research International Experimenter address = Wellesbourne Experimenter address = Warwick Experimenter zip/postal_code = CV34 6QJ Experimenter country = UK Keywords: unknown_experiment_design_type

Project description:Transcript profiling is crucial to study biological systems and various platforms have been implemented to survey mRNAs at the genome scale. We have assessed the characteristics of the CATMA microarray designed for Arabidopsis thaliana transcriptome analysis, and compared it with two commercial platforms from Agilent and Affymetrix. The CATMA array consists of gene-specific sequence tags of 150 to 500 base pairs, the Agilent (Arabidopsis 2) array of 60mer oligonucleotides, and the Affymetrix gene chip (ATH1) of 25mer oligonucleotide sets. We have matched each probe repertoire with the Arabidopsis genome annotation (TIGR release 5.0) and determined the correspondence between them. Array performance was analyzed by hybridization with labeled target derived from eight RNA samples made of shoot total RNA spiked with a calibrated series of 14 control transcripts. A total of fourteen cDNA clones were thus selected and used as templates to synthesize bona fide polyadenylated spike RNAs. Each spike RNA was calibrated then mixed in equal amount with one of the other spike RNAs to obtain seven pairs at equal concentration. These seven spike RNA pairs were then combined systematically to construct seven complex spike mixes in a design similar to an ordered Latin square, each mix containing six of the seven spike pairs in staggered concentrations covering five logs. To prevent loss of spike RNA through adsorption to the plastic ware, the spike mixes were prepared in 0.5 Âµg/Âµl Col RNA, resulting in a range of concentration from 0.1 to 10,000 copies per cellular equivalent (cpc), assuming that the total RNA contained 1% polyadenalated mRNA and that a cell contained on average 300,000 transcripts. These seven RNA samples included equal amounts of combined spike RNA . To convert the spike hybridization signals to ratios, an eighth sample was prepared, called the reference sample, consisting of the base Col RNA completed with all spike RNAs at a concentration of 100 cpc. The results from the eight experiments using the Affymetrix gene chips (ATH1) are available for analysis or download from this site. Experimenter name = Jim Beynon; Experimenter phone = 01798 470382; Experimenter fax = 01789 470552; Experimenter department = Horticulture Research International; Experimenter institute = Warwick University; Experimenter address = Horticulture Research International; Experimenter address = Wellesbourne; Experimenter address = Warwick; Experimenter zip/postal_code = CV34 6QJ; Experimenter country = UK Experiment Overall Design: 8 samples were used in this experiment

Project description:Regulation of expression of genes encoding chloroplast components is critical to the autotrophic plant and never more so than in the cotyledons of the de-etiolating seedling. Many chloroplast proteins are nuclear-encoded and a retrograde signal from the chloroplasts (the Plastid Signal) modulates nuclear transcription. However, not all chloroplast-targeted genes are subject to this control and not all plastid-dependent nuclear genes are chloroplast-targeted. We therefore aim to provide the most comprehensive screen yet of which genes are affected by plastid-signalling. To specifically knock-out positive plastid signalling in light-grown cotyledons, the herbicide Norflurazon (NF) is supplied in the growth medium, causing a carotenoid deficiency that leaves the chloroplasts vulnerable to photobleaching. This blocks the expression of a subset of nuclear genes, such as Lhcb and HEMA1. Two pairs of RNAs will directly compare the transcription in seedlings grown under continuous white light with and without NF. A third RNA will also be compared from a mutant that shows a degree of constitutive positive plastid signalling. These two mutants act synergistically to counteract the effect of NF on nuclear transcription. The gun1,gun5 double mutant maintains a significantly higher level of Lhcb and HEMA1 expression in the presence of photobeached chloroplasts than the NF-treated wild-type. This transcriptome set will therefore complement RNA1 (wild-type+NF) and indicate which of the genes identified from the RNA1/RNA2 comparison are subject to the particular gun1/gun5 plastid signalling pathway(s). The growth of conditions of the seedlings (namely on MS medium supplemented with 1.5% sucrose, for 3 days under continuous WL following 2 days germination in darkness) has been chosen from the results of our own recent studies using Northern blotting techniques that show these conditions to maximise the respective NF and gun mutant effects on Lhcb and HEMA1 gene expression. This experiment is part one of a two-part study to compare the transcriptional output of this NF-affected pathway with that of a newly discovered FR-mediated pathway. A subsequent array experiment will assess the nuclear response as affected by this FR/ phyA-input pathway and the two sets of array data will be compared and contrasted. Note: Col-0 wild-type (NASC code N1092). gun1,gun5 double mutant(obtained from Enriquez Lopez-Juez, Royal Holloway, University of London.(Mochizuki et al. 2001 PNAS 98: 2053-2058). This line cannot be donated by us as it is the IP of Joanne Chory (SALK Institute, USA). Treatment = a herbicide (Norflurazon) application which leads to chloroplast photobleaching and hence down regulation of nuclear genes dependent on plastid signalling from intact chloroplasts.

Project description:PCD is a highly organised process that is involved in development and in an organisms response to biotic stresses (toxins and avirulent pathogens) and abiotic stresses (such as temperature, water availability, etc.). It is a genetically regulated form of cellular suicide, however in plants the underlying process is poorly understood. Although PCD may occur in response to different stimuli; we believe once it is triggered, one core mechanism is responsible for the cellular demise. It is our aim to identify the elements of this mechanism. We will do this by expanding on the work of a previous user of GARNet's GeneChip microarray facility, Dr. Jodi Swidzinski. She utilised an Arabidopsis cell suspension system; performing microarray analysis on both senescing, and heat shock induced PCD samples. This resulted in data showing that a large number of genes were upregulated (or downregulated) in response to both treatments. We are working under the premise that some of the genes that were similarly regulated under both treatments must be core PCD genes. However because of the large amount of data generated it is difficult to choose appropriate candidate genes (with any degree of confidence that they are core genes) for further study. We propose to use a third PCD-inducing treatment, involving a mycotoxin, to generate another population of microarray results. The mycotoxin we intend to use is Fumonisin B1 (FB1). This is an extremely potent compound that induces PCD by disrupting ceramide synthesis. We have found Arabidopsis protoplasts to be much more sensitive than cells to the toxin at low concentrations. Protoplasts are treated with 20mM FB1 and RNA is extracted at time points when 0%, 20% and 40% of protoplasts have died. This RNA is then pooled. RNA from methanol treated protoplasts is used as a control. We intend for these RNA samples to be subjected to GeneChip microarray analysis. This would identify genes differentially regulated due to FB1 treatment, which would be interesting in itself. However, by combining this data with that from previous work by Swidzinski (2002) we will be able to decrease the pool of possible core genes further, and increase the chances of selecting an appropriate candidate gene. This will both improve upon existing work and add value to an existing GARNet data set.

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Platform comparison and transcription profiling Arabidopsis samples on CATMA, Affymetrix and Agilent arrays

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