MAYBRAIN · Brain remodeling during sexual differentiation and water to air transition in a hemimetabolous insect

The evolution of the brain deeply transformed the animal kingdom leading to extraordinary animal diversity. Brain evolution and plasticity were necessary for many major evolutionary changes (e.g. terrestrialization of tetrapods, evolution of sociality) as well as developmental changes within an organism's life span (e.g. metamorphosis). In this project, I propose to study the brain remodeling in the mayfly Cloeon dipterum whose biology has the advantage of offering us multiple perspectives and insights on brain plasticity: (i) evolutionary perspective: mayflies are part of the insect lineage in which wings originated. This project will shed light on brain processes controlling wings and flight.(ii) developmental perspective: mayflies are hemimetabolous insects that present a gradual metamorphosis that nonetheless accompanies a major lifestyle transition from an aquatic juvenile form to an aerial winged adult.(iii) sexual dimorphism: the species C. dipterum displays significant sexual dimorphism as males have an extra pair of eyes (turbanate eyes), whose sensory signals need to be processed by the brain.Using a combination of single cell transcriptomics (sc-RNA-seq), in situ hybridisations and drug treatments, this project will yield a gene expression atlas of the brain of C. dipterum separately for both male and female individuals, across multiple points of its life cycle (two nymphal stages and two adult stages). This atlas will give us information on the brain processes necessary for the water to land evolutionary transition, those associated with flight and the acquisition of wings and those underlying the appearance of a new sensory organ - the turbanate eyes - in males, with the data conveniently navigable along annotated chromosomes. This study will also establish C. dipterum as a model for studying hemimetabolous insect brains and provide a reference for future studies.