[en] In cnidarian-Symbiodiniaceae symbioses, the presence of photosynthetic dinoflagellates inside the host tissues causes daily local hyperoxia and promotes the generation of reactive oxygen species (ROS), which can damage cellular components, trigger cell death and, under certain conditions, lead to the collapse of the symbiotic interaction (bleaching). This implies that the establishment and maintenance of a symbiotic relationship with algae relies in part on regulatory mechanisms that maintain redox homeostasis at the holobiont level. This project aims to better understand how ROS and redox changes affect the development and maintenance of the cnidarian-Symbiodiniaceae symbiosis. Specifically, using the Aiptasia model, we propose to (I) detect and monitor in vivo intracellular H₂O₂ production across different stages of symbiosis by developing a genetically encoded biosensor (HyPer7) and introducing it into larvae and pedal lacerates of our anemones; (II) assess the importance of redox homeostasis for the establishment of the symbiosis by comparing the antioxidant capacity of the host according to its symbiotic state and by modifying the balance between ROS production and its antioxidant capacity. A better understanding of these processes is necessary if we are to conserve coral reefs in the coming decades. In addition, the developments in this project will provide a powerful methodological platform to study the dynamics of H2O2 in complex processes in cnidarians such as development, regeneration, interactions with pathogens and symbionts, and stress responses.
