COLOMBOS v3.0 : leveraging gene expression compendia for cross-species analyses

COLOMBOS is a database that integrates publicly available transcriptomics data for several prokaryotic model organisms. Compared to the previous version it has more than doubled in size, both in terms of species and data available. The manually curated condition annotation has been overhauled as well, giving more complete information about samples' experimental conditions and their differences. Functionality-wise cross-species analyses now enable users to analyse expression data for all species simultaneously, and identify candidate genes with evolutionary conserved expression behaviour. All the expression-based query tools have undergone a substantial improvement, overcoming the limit of enforced co-expression data retrieval and instead enabling the return of more complex patterns of expression behaviour. COLOMBOS is freely available through a web application at http://colombos.net/. The complete database is also accessible via REST API or downloadable as tab-delimited text files

COLOMBOS: an ever expanding collection of bacterial expression compendia.

COLOMBOS is an publically available access portal to comprehensive organism-specific cross-platform expression compendia for bacterial organisms. It provides a suite of tools for exploring, analyzing, and visualizing the data within these compendia. The expression compendia themselves are built based on a propriety methodology that is unique in directly combining the data from different technological platforms. COLOMBOS also incorporate extensive annotations for both genes and experimental conditions; these heterogeneous data are functionally integrated in the analysis tools to interactively browse and query the compendia not only for specific genes or experiments, but also metabolic pathways, transcriptional regulation mechanisms, experimental conditions, biological processes, etc. Several improvements have been made. Content wise, we have invested in the development of a compendia creation and management system that has enabled us to greatly expand existing compendia (Escherichia coli, Bacillus subtilis, and Salmonella Typhimurium) as well as add compendia for other species. Additionally, the current version supports the inclusion of RNAseq data. Functionally, we have revamped the interface with new interactive visualization and analysis tools, a bicluster tree algortihm for discovering complex coexpression patterns around a set of query genes, and inclusion of noise models for measurement errors, enabling analysis of differential expression with measures of statistical significance. This work is relevant to a large community of microbiologists by facilitating the use of publicly available genome-wide expression data to support their research, as well as providing a useful resource for top-down systems biology application

COLOMBOS v2.0: an ever expanding collection of bacterial expression compendia

The COLOMBOS database (http://www.colombos.net) features comprehensive organism-specific cross-platform gene expression compendia of several bacterial model organisms and is supported by a fully interactive web portal and an extensive web API. COLOMBOS was originally published in PLoS One, and COLOMBOS v2.0 includes both an update of the expression data, by expanding the previously available compendia and by adding compendia for several new species, and an update of the surrounding functionality, with improved search and visualization options and novel tools for programmatic access to the database. The scope of the database has also been extended to incorporate RNA-seq data in our compendia by a dedicated analysis pipeline. We demonstrate the validity and robustness of this approach by comparing the same RNA samples measured in parallel using both microarrays and RNA-seq. As far as we know, COLOMBOS currently hosts the largest homogenized gene expression compendia available for seven bacterial model organism