Circadian structural remodeling of the PDF circuit: implications on connectivity and function

DEPETRIS-CHAUVIN, A.; GOROSTIZA, E.A.; PÍREZ, N.; CERIANI, M.F.

Mendoza

Simposio; XII Latin American Symposium on Chronobiology; 2013

LASC

Our lab has previously reported that sLNvs neurons, a circuit key to control rest-activity cycles in Drosophila, undergoes circadian remodeling of its axonal projections, and we have put forward the hypothesis that this structural plasticity provides the substrate for the circadian control of activity and connectivity of the PDF circuit. Here we show that this remodeling implies daily changes in presynaptic markers of active zones, opening the possibility that the connectivity is indeed changing daily. By expressing two complementary fragments of GFP tethered to synaptic membranes, we revealed that PDF axons contact different synaptic partners along the day, extending the impact of core pacemaker neurons to circuits outside of the circadian network. We propose that this plasticity is capable of affecting the synaptic output of this circuit in a circadian fashion. In order to test this hypothesis we are currently performing live whole brain optical imaging experiments. The goal of these experiments is to test if the synaptic partnerships identified through GRASP are indeed functional. We will tackle this question by means of using two binary systems of expression such as GAL4/UAS and lexA/lexAop, that will allow us to specifically activate the PDF neurons, while concomitantly expressing a reporter of activity on the putative post synaptic partners.