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Gene Expression Omnibus (GEO) . http://www.ncbi.nlm.nih.gov/geo /. Microarrays in gene expression. A typical gene expression analysis experiment: Differential systems – e.g. cancer vs. normal, drug vs. no drug Choose/prepare the microarray Extract total mRNA (transcriptome)
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Gene Expression Omnibus (GEO) http://www.ncbi.nlm.nih.gov/geo/
Microarrays in gene expression • A typical gene expression analysis experiment: • Differential systems – e.g. cancer vs. normal, drug vs. no drug • Choose/prepare the microarray • Extract total mRNA (transcriptome) • Reverse transcription/dye labeling • Combine equal amounts • Hybridize • Scan • ANALYSE AND INTERPRET THE RESULTS – this is the tricky part…
GeneExpressionOmnibus(GEO): Gene Expression and Molecular Abundance Data Repository • A public repository for the archiving and distribution of gene expression data submitted by the scientific community. • Curated, online resource for gene expression data browsing, query, analysis and retrieval. • Convenient for deposition of gene expression data, as required by funding agencies and journals.
GEO Architecture GEO has four kinds of data records • Platform (GPL) = the technology used and the features detected. • Sample (GSM) = preparation and description of the sample. • Series (GSE) defines a set of samples and how they are related. • DataSets (GDS) sample data collections assembled by GEO staff.
GEO Architecture Submitted by Experimentalists Curated by NCBI Submitted by Manufacturer GDS Grouping of experiments GSE Grouping of slide/chip data “a single experiment” GPL Platform descriptions GSM Raw/processed spot intensities from a single slide/chip
GEO Home Page • Simple interface to: • show status • find documentation • query data • browse data
Platform Accession Page • Platform details: • Description • Type • Organism • Manufacturer • Related samples and series • NOTE THE TOP BAR (SCOPE)
Sample Accession Page • Sample details: • Description • Type • Organism • Source • Related platforms and series
Sample File Data Table Data table field descriptions Truncated data table from Quick view Total data rows and file size
Series Accession Page • Biological sample summary • Design summary • Publication information • Related platforms and samples
DATASET or GENE PROFILE search GEO data can be queried as: • Datasets: experiment-centric view using Entrez GEO DataSets • Gene profiles: gene-centric view using Entrez GEO Profiles Selecting either takes you to a similar Entrez introduction page
Querying GEO DataSets • Start a GEO DataSets search with the Query>DataSets text box • This brings up an Entrez GEO DataSets results form
Querying GEO with IDs from Papers • A common way to access GEO data is through accessions from papers. • Online journals include hyperlinks to the GEO accession page. • Or, at the GEO home page enter the accession into the Query>GEO accession text box
GEO Links in PubMed Search Results • One option for displaying PubMed search results is GEO DataSet links. • When present, the results page is actually from Entrez GEO DataSets.