Integrated Approach to Propose PRoteomics for biOmonitoring: accumulation, fate and multi-markers – APPROve

The EU Water Framework Directive recently encouraged the development of innovative ecotoxicological tools. However and due to the lack of reference genome in most environmentally relevant invertebrates species, as Gammarus fossarum, the biomarkers currently used are indirect assays previously developed and validated in vertebrates. Nevertheless molecular divergence and diversity of protein functions acquired through animal evolution rules out the possibility and the relevance to directly use many vertebrates-derived biomarkers. Moreover, the fact that each assay is specific to only each biomarker makes difficult their routinely use. At last, biomarker measurements are currently performed on whole organism (or pools of organisms), leading to a decrease in its sensitivity due to biological dilution and/or specific tissue responses and making impracticable to predict and provide information on impaired physiological functions (organ).
Based on a multidisciplinarity and complementary consortium (high-throughput proteomics, ecotoxicology, TK/TD modelling, analytical chemistry and regulatory), the objective of the APPROve project is to define, through a case-study with metals, a framework to formalize the fate and effects of contaminants in a sentinel species, Gammarus fossarum, in order to improve water quality monitoring with an effective transfer of new tools to the operational sphere. The APPROve project has two mains objectives: 1) producing knowledge on accumulation and fate of metals in G. fossarum and their associated responses at organs level, in order to propose specific and relevant biomarkers and, 2) improving diagnostic tools currently available with caged G. fossarum for the assessment of contamination and toxicity in aquatic systems through TK/TD models.
Based on advanced analytical approaches (radioelements and mass spectrometry), critical lack of knowledge will be addressed about i) bioaccumulation and fate (organotropism) of metals in an invertebrate species and the identification of the organ playing a major role in the underlying processes, ii) the molecular physiology in G. fossarum to better describe and understand the impact of metals, in order to propose relevant biomarkers and to establish links with life trait impairments. The bioaccumulation dynamic of Ag, Cd, and Zn within the different organs of G. fossarum will be formalized by a TK model for each metal that will take into account the contributions of the different bioaccumulation pathways and the concentration-dependence. Then, the effects measured on biological endpoints will be linked to internal concentrations through a TD model (DEBtox model).
Based on outputs of modeling and proteomic approaches, diagnostic tools currently available with caged G. fossarum for the assessment of contamination levels and toxicity impacts of aquatic systems will be improved, and at last transferred to the operational sphere. On one hand, based on TK/TD models, metal contamination levels in caged G. fossarum could be also used i) to check the compliance to water-EQS and ii) to predict a toxic risk. On the other hand, based on field-expertise and experiment capacity of the SME BIOMAE, threshold values will be defined for new molecular biomarkers, in order to validate their use as diagnostic tools for field biomonitoring.
APPROve will (i) develop and calibrate models, allowing to better formalize accumulation and fate of metals into organisms, (ii) bridge the gap in molecular ecophysiology of a sentinel species, giving strong information and data on key organs involved in the toxicity of metallic contaminants, (iii) propose benchmark values for each new targeted-organ biomarker validated and at last (iv) highlight the originality of coupling proposed methodologies to develop TK/TD models and of their used to propose integrated diagnostic tools (molecular and physiological) for environmental monitoring.