230 likes | 247 Views
Learn about microarray technology in gene expression experiments, from sample preparation to data analysis. Explore GEO, a repository for gene expression data, and access curated datasets for research and discovery.
E N D
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 labelling • 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 Supplementary raw data file
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.