Exploring the contribution of Evening cells to the circadian pacemaker of Drosophila.

DUHART, J.; CERIANI, M. F.; DE LA CRUZ, G.; PÍREZ, N.

Valparaiso

Simposio; Latin American Symposium on Chronobiology; 2017

LASC

The circadian clock of Drosophila is composed of 150 cells, which can be divided into 7 clusters. Under laboratory conditions, daily locomotor activity is condensed in morning and evening bouts. Each activity peak has been linked to a specific group of neurons: the PDF-positive small ventral lateral neurons (sLNv) control the morning component (M-cells), and the dorsal lateral neurons plus the 5th sLNv control the evening component (E-cells). While M-cells have long been considered as the main pacekeepers of the circadian clock, there is increasing evidence pointing to the contribution of E-cells in sustaining a coherent rhythmic output, although the mechanisms underlying their role are not fully described yet. Our first aim was to characterize the neurotransmitters secreted by E-cells, as well as their impact in the generation of a robust behavioral rhythm. To do so, we genetically manipulated the expression of different neurotransmitter transporters in a subset of E-cells, and monitored locomotor activity rhythms. Next, to characterize possible circuital mechanisms by which E-cells could mediate such influence on the behavioral output, we focused on the relation between E-cells and M-cells. Structural analysis of pre- and post-synaptic markers revealed a possible E- to M-cells communication, which was functionally corroborated using genetically encoded calcium reporters. This work contributes to shape a detailed map of the functional and structural characteristics of the pacemaker network, which is essential for understanding the neural basis of the circadian control of behavior.