Ion Channels that regulate circadian behavior and clock neuron physiology in Drosophila melanogaster

NARA I MURARO

Ciudad Autónoma de Buenos Aires

Simposio; Max Planck International Synapses and Circuits Symposium; 2015

Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET Partner Institute of the Max Planck Society

Circadian rhythms have been extensively studied inthe fruit fly where many clock genes that interlock through negative feedbackloops and generate daily oscillations have been described. Clock genes areexpressed in approximately 150 clock neurons in the Drosophila brain, of which a particular subset, the pigmentdispersing factor-expressing lateral neurons (LNvs) have been found to play acentral role. Still,little is known on the electrical properties of Drosophila clock neurons. The firing mode of the large-LNvs (lLNvs)follows a circadian pattern, with a high activity bursting mode during the dayand a lower activity tonic mode at nighttime. This change in neuronal firingcould be crucial to confer time of day information to other neurons by alteringthe release of neurotransmitters or neuropeptides, however, the mechanisms thatallow this change in firing mode are not known. In mammalian neurons, thehyperpolarisation-activated cation current Ih has been shown toparticipate in complex neuronal behaviors such as bursting. Using genetics andpharmacology coupled to whole-cell patch clamp electrophysiology in ex-vivo Drosophila brains, we show here that Ih is also involvedin the bursting behavior of the lLNvs. Moreover, not only intrinsic, but alsosynaptic factors, such as Acetylcholine and GABA are contributing to theestablishment of the lLNvs firing mode. Finally, we are performing a behavioral genetic screenthrough the down regulation of candidate voltage-gated ion channels using RNA interferencespecifically in LNvs. We will show behavioral data that point out to severalother ion channels that may play a role in clock neuron physiology.