DRomics: a turnkey tool to support the use of the dose-response framework for OMICs data in ecological risk assessment . DRomics: a turnkey tool to support the use of the dose-response framework for OMICs data in ecological risk assessment

Omics approaches (e.g. transcriptomics, metabolomics) are promising for ecological risk assessment (ERA) since they provide mechanistic information and early warning signals. A crucial step in the analysis of omics data is the modelling of concentration-dependency which may have different trends including monotonic (e.g. linear, exponential) or biphasic (e.g. U shape, bell shape) forms. The diversity of responses raises several challenges concerning modelling and effect concentration (EC) derivation. Furthermore, handling high-throughput datasets is time-consuming and requires effective and automated processing routines. Thus, we developed a freely available tool (DRomics, available as an R-package and as a web-based service) which, after elimination of molecular responses (e.g. differential gene expressions from microarrays) with no concentration-dependency and/or high variability, identifies the best model for concentration-response curve description. Subsequently, an effect concentration (e.g. a benchmark dose) is estimated from each curve and curves are classified based on their model parameters. This tool is especially dedicated to manage data obtained from an experimental design favoring a great number of tested doses rather than a great number of replicates and also to handle properly monotonic and biphasic trends. The tool finally restitutes a table of results that can be directly used to perform ERA approaches. Overall design: Scenedesmus vacuolatus cultures were exposed for 14 hours to five concentrations of triclosan (0.690, 1.22, 2.15, 3.77 and 6.63µg/L) and one solvent control (final DMSO concentration of 0.1 %) with 5 replicates. After sampling, the RNA was extracted, labelled and hybridised to an Agilent one-color array.