The synaptic connectivity of the PDF circuit with clock and non-clock cells undergoes circadian structural remodeling

PÍREZ, N.; BERNABEI CORNEJO, S.G.; CERIANI, M.F.

Cold Spring Harbor

Conferencia; Neurobiology of Drosophila Meeting; 2015

Cold Spring Harbor Laboratory

In our laboratory we are interested in understanding the relevance of specific neuronal circuits in the circadian control of behavior in Drosophila. We have previously shown 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. This remodeling implies daily changes in presynaptic markers of active zones, opening the possibility that the connectivity is indeed changing daily. To map this connectivity, we employed a membrane-tethered splitGFP strategy, which 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 in a circadian fashion, by means of these structural changes. To test this hypothesis we are performing live whole brain optical imaging experiments to corroborate if the synaptic partners identified through GRASP are indeed functional. Additionally, we are testing what functional role the putative post synaptic cells identified by the GRASP screen have on the circadian control of activity. This is achieved by means of ectopically expressing ions channels that hyperpolarize or depolarize the membrane potential of these neuronal groups, allowing us to chronically alter the activity of these clusters. Results from these experiments will enable us to continue mapping the connectivity of the Drosophila circadian network.