How do Drosophila clock neurons fire up?

NARA I MURARO

Huerta Grande, Cordoba

Congreso; XXIX Congreso Anual de la Sociedad Argentina de Investigación en Neurociencia; 2014

Sociedad Argentina de Investigación en Neurociencia

Circadian rhythms have been extensively studied in the fruit fly where many clock genes that interlock through negative feedback loops and generate daily oscillations have been described. Clock genes are expressed in approximately 150 clock neurons in the Drosophila melanogaster brain, of which a particular subset, the pigment dispersing factor-expressing lateral neurons (LNvs) have been found to play a central role. Still, little is known on the electrical properties of Drosophila clock neurons. The large subtype of LNvs (lLNvs) show spontaneous action potential firing organized in bursts and firing activity that follows a circadian pattern. This daily cycling of neuronal activity could be crucial to confer time of day information to other neurons by altering the release of neurotransmitters or neuropeptides, however, the mechanisms that allow this change in firing activity are not known. We have performed a behavioral genetic screen through the down regulation of candidate voltage-gated ion channels using RNA interference specifically in LNvs. Among the positive hits of the screen, the hyperpolarization-activated cation current Ih and the T-type calcium channel DmαG are being studied further. The role of these currents in Drosophila neurons has not been explored much; however, they have been shown to be key in generating complex neuronal behaviors such as bursting in mammalian neurons. We are using whole-cell patch clamp electrophysiology in ex-vivo Drosophila brains to study the role of these ion channels in the establishment of lLNvs physiology. Moreover, not only intrinsic, but also synaptic factors, such as Acetylcholine and GABA are contributing to the establishment of the lLNvs firing mode.