Unité mixte de recherche
Stress Environnementaux et BIOsurveillance des milieux aquatiques
Parc Technologique ALATA - BP2
Over the last decades, there has been great interest in the scientific community regarding the possible alterations in the functioning of the endocrine system of humans and wildlife as a result of chemical exposure. Many reports showed deleterious effects of these endocrine disrupting compounds (EDCs) on the reproductive health of wildlife (invertebrates, fish, birds or reptiles), farmed animals and humans. The aquatic environment is the final sink for most of those chemicals, leading to exposure of aquatic organisms, including fish. Exposure of fish to EDCs has been associated with reproductive adverse effects at both individual and population level in a variety of fish species.
One key physiological process targeted by these EDCs is steroidogenesis. Steroidogenesis is the process responsible for steroid biosynthesis such as sexual hormones (estrogens, androgens, progestins) that are essentials for a proper reproduction, and is supported by numerous enzymes including aromatase.
The focus of my research is thus to investigate fish steroidogenesis and reproduction and the impact of EDCs on those processes. For that, we work with zebrafish (Danio rerio), a small cyprinid fish native from India and nearby countries that is currently the most widely used aquatic organism in laboratories. By using this small fish, we acquired knowledge on the steroidogenic process (steroidogenic enzymes localizations, steroidogenic genes expression and enzyme activities) and on fish reproduction (vitellogenesis, spermatogenesis, fecundity, embryos survival) in normal conditions and highlighted the deleterious effects of exposure to different kinds of EDCs such as natural and synthetic hormones, pesticides or pharmaceuticals, alone or in mixtures.
Concern about the effects of EDCs to fish (and humans) reproductive health has stimulated the development and implementation of screening and testing procedures for EDCs, notably within the perspective of the European regulatory framework for chemicals REACH (registration, evaluation, authorization and restriction of chemicals). The development of tests to identify endocrine active substances and quantify their effects in fish has thus become a challenge these years. In this regard, transgenic fish could be relevant tools allowing the detection of endocrine effects while possibly reducing the number of animals needed and the costs. In the lab, different transgenic zebrafish lines, expressing fluorescent protein under the control of steroidogenic genes promoters, were developed. Our recent projects were dedicated to the characterization and optimization of the use of these models for the assessment of endocrine disrupting potency of chemicals.