CONICET | Buscador de Institutos y Recursos Humanos

The circadian clock of Drosophila is composed of 150 cells, which can be divided into 6-7 clusters, based on neuropeptide expression and anatomical location. Among these groups, the small ventral lateral neurons (sLNvs) are determinant in the ability of the fly to sustain rhythms in the absences of environmental cues, and have long been characterized as the main pace keepers of the clock. Moreover, axonal terminals of sLNv cells undergo extensive remodeling on daily basis, including changes in the number of synaptic contacts between this cluster and other circadian and non-circadian neurons. However, the contribution of other neuronal clusters to the generation of a robust rhythmic output has been less studied. We focused in the dorsal lateral neurons (LNd) cell group, which is important for the day-night transition rise in locomotor activity, and exhibit rapid and coherent phase resetting following light stimulus. Our aim is to characterize the neurotransmitters secreted by these cells, and the impact of them in the generation of a robust rhythmic output. To do so, we genetically manipulated the expression of the different neurotransmitters transporters in these cells, by means of expression of specific RNAi, and monitored locomotor activity rhythms of these flies. In addition, we will assess the structural connections between LNds and sLNvs cells with GRASP (GFP reconstitution across synaptic partners) technique, as well as the functional connection between these clusters using genetically encoded calcium imaging. These work will allow us to validate a detailed map of the functional and structural characteristics of the pacemaker circuit, which is essential for understanding the neural basis of the circadian control of behavior.