BOOSTING CLOCK`S COMPLEXITY: AN INHIBITORY HAND IN THE CIRCADIAN PACEMAKER OF DROSOPHILA

LIA FRENKEL; GUILLERMO BERNABÓ; NARA I MURARO ; M. FERNANDA CERIANI

Huerta Grande, Córdoba

Congreso; Reunión Anual de la Sociedad Argentina de Neuroiencia; 2013

Sociedad Argentina de Neuroiencia

The internal time-keeping mechanism, the circadian clock, generates daily oscillations in physiology that enable the anticipation to reoccurring daily events. Among the 150 clock neurons in the Drosophila´s brain, the small ventral lateral neurons (sLNvs) constitute the major pacemaker since under constant conditions they guide the temporal organization of daily locomotor activity. In addition to PDF-(pigment dispersing factor)-filled vesicles, they also contain small clear vesicles putatively packed with a fast neurotransmitter potentially involved in synchronizing the circadian network. Here we identify this neurotransmitter by evaluating flies? locomotor activity pattern after disrupting either membrane or vesicular neurotransmitter transporters (NTT) function, specifically within PDF neurons. We found that downregulating glycine transporter expression increases period length in almost an hour without affecting rhythmicity. A decrease in intracellular glycine availability seems to underlie period lengthening as disrupting glycine synthesis has a similar effect. Daily oscillations in PDF levels at the sLNvs axonal termini are decreased under such conditions. The pursuit of glycinergic targets by immunohistochemistry revealed that PDF neurons express glycine receptor. Behaviorally, downregulating glycine receptor in PDF neurons decreases rhythmicity. Whether sLNvs glycinergic transmission entails cluster synchronization is still unknown. Current experiments will shed light on this issue.