ReadXplorer--visualization and analysis of mapped sequences.

MOTIVATION: Fast algorithms and well-arranged visualizations are required for the comprehensive analysis of the ever-growing size of genomic and transcriptomic next-generation sequencing data. RESULTS: ReadXplorer is a software offering straightforward visualization and extensive analysis functions for genomic and transcriptomic DNA sequences mapped on a reference. A unique specialty of ReadXplorer is the quality classification of the read mappings. It is incorporated in all analysis functions and displayed in ReadXplorer's various synchronized data viewers for (i) the reference sequence, its base coverage as (ii) normalizable plot and (iii) histogram, (iv) read alignments and (v) read pairs. ReadXplorer's analysis capability covers RNA secondary structure prediction, single nucleotide polymorphism and deletion-insertion polymorphism detection, genomic feature and general coverage analysis. Especially for RNA-Seq data, it offers differential gene expression analysis, transcription start site and operon detection as well as RPKM value and read count calculations. Furthermore, ReadXplorer can combine or superimpose coverage of different datasets. AVAILABILITY AND IMPLEMENTATION: ReadXplorer is available as open-source software at http://www.readxplorer.org along with a detailed manual.

RhizoRegNet--a database of rhizobial transcription factors and regulatory networks.

Sinorhizobium meliloti is a symbiotic soil bacterium that forms nitrogen-fixing nodules on roots of leguminous plants, including Medicago truncatula (barrel medic), and M. sativa (alfalfa). The Sinorhizobium-Medicago symbiosis is an important symbiosis model system. Knowledge gained from this system can be extended to other agriculturally important "rhizobial" symbioses. Since the publication of the S. meliloti genome in 2001, many new genetic, biochemical and physiological data have been generated. Effective methods to organize, store, and mine this postgenome data are crucial for continued success of the S. meliloti model system. In 2009, we introduced a portal for rhizobial genomes, RhizoGATE (Becker et al., J. Biotechnol. 140, 45-50). The RhizoGATE portal combines continuously updated S. meliloti genome annotation with postgenome data resources. Here we report integration of a new component, RhizoRegNet, to RhizoGATE. RhizoRegNet combines transcriptome data and operon predictions with published data on regulatory interactions. By allowing searching and visualisation of complex transcriptional regulatory networks, RhizoRegNet advances our understanding of transcriptional regulation in S. meliloti. The current version of RhizoRegNet is divided into 13 functional modules containing information for 114 regulators, 475 regulated genes, and 178 transcription factor binding motifs. In this report, we provide an example of how RhizoRegNet facilitates visualisation and analysis of the regulatory network for exopolysaccharide biosynthesis and motility. Presently, RhizoRegNet contains regulatory network information for S. meliloti and the closely related bacterium, S. medicae, but can be expanded to include other rhizobial species.

Visualizing post genomics data-sets on customized pathway maps by ProMeTra-aeration-dependent gene expression and metabolism of Corynebacterium glutamicum as an example.

BACKGROUND: The rapid progress of post-genomic analyses, such as transcriptomics, proteomics, and metabolomics has resulted in the generation of large amounts of quantitative data covering and connecting the complete cascade from genotype to phenotype for individual organisms. Various benefits can be achieved when these "Omics" data are integrated, such as the identification of unknown gene functions or the elucidation of regulatory networks of whole organisms. In order to be able to obtain deeper insights in the generated datasets, it is of utmost importance to present the data to the researcher in an intuitive, integrated, and knowledge-based environment. Therefore, various visualization paradigms have been established during the last years. The visualization of "Omics" data using metabolic pathway maps is intuitive and has been applied in various software tools. It has become obvious that the application of web-based and user driven software tools has great potential and benefits from the use of open and standardized formats for the description of pathways. RESULTS: In order to combine datasets from heterogeneous "Omics" sources, we present the web-based ProMeTra system that visualizes and combines datasets from transcriptomics, proteomics, and metabolomics on user defined metabolic pathway maps. Therefore, structured exchange of data with our "Omics" applications Emma 2, Qupe and MeltDB is employed. Enriched SVG images or animations are generated and can be obtained via the user friendly web interface. To demonstrate the functionality of ProMeTra, we use quantitative data obtained during a fermentation experiment of the L-lysine producing strain Corynebacterium glutamicum DM1730. During fermentation, oxygen supply was switched off in order to perturb the system and observe its reaction. At six different time points, transcript abundances, intracellular metabolite pools, as well as extracellular glucose, lactate, and L-lysine levels were determined. CONCLUSION: The interpretation and visualization of the results of this complex experiment was facilitated by the ProMeTra software. Both transcriptome and metabolome data were visualized on a metabolic pathway map. Visual inspection of the combined data confirmed existing knowledge but also delivered novel correlations that are of potential biotechnological importance.