Final Report Summary - GLISFCO (Glia, Smell, Food & Courtship in Drosophila) Odors are key components for sensory communication involved in behaviors such as social communication or food search. Recently, molecular receptors, neuronal architecture, physiological regulation, and behavioral consequences underlying these biological processes have started to be revealed in an increasing number of animal models. But more and more breakthroughs are highlighting some unexpected results asking for deeper studies. Drosophila melanogaster has proven to be a particular powerful tool to understand, to test, and to manipulate the complex neurogenetical interactions between molecular and cellular partners controlling such behaviors. We had shown that a subset of glia is mastering the activity of a population of neurons involved in chemoperception in Drosophila (e.g. glutamatergic neurons). We had also uncovered a striking molecular and neuronal architecture regulating courtship using food odors instead of classical pheromones in fruit flies. We have expanded these pioneer works to understand how the nervous system can govern behavior in order to interact with the environment. For this aim, we have presented how odors can influence mating behavior in Drosophila melanogaster (Ziegler et al., 2013). We have described a simple method to test Drosophila olfactory preferences (Simonnet et al., 2014). We have uncovered that the lack of dietary polyunsaturated fatty acids causes synapse dysfunction in the Drosophila visual system (Ziegler et al., 2015). We found that the amino acid transporter JhI-21 coevolves with glutamate receptors, impacts NMJ physiology, and influences locomotor activity in Drosophila larvae (Ziegler et al., 2016). We discovered that direct sensing of nutrients via a LAT1-like transporter in Drosophila insulin-producing cells is similarly happening compared to humans (Manière et al., 2016; Manière et al., 2017). We described how chemicals and chemoreceptors are ecologically relevant signals driving behavior in Drosophila (Depetris-Chauvin et al., 2015). And we found that olfactory detection of a bacterial short-chain fatty acid acts as an orexigenic signal in Drosophila melanogaster larvae (Depetris-Chauvin et al., 2017).These collected data represent a solid step toward the understanding of animal interaction with their environment, and to suggest new strategies to treat neuronal disorders in humans.