Rhythmic structural plasticity in the circuit controlling rest-activity cycles in Drosophila

MARÍA PAZ FERNÁNDEZ; JIMENA BERNI; MARÍA FERNANDA CERIANI

Sandestin, Florida, USA

Congreso; XI meeting Society for Biological Rhythms Research; 2008

Clock output pathways are central to convey timing information from the circadian clock to a diversity of output systems, ranging from cell-autonomous processes to physiology and behavior. While the molecular mechanisms that generate and sustain rhythmicity at the cellular level are well understood, how this information is further structured to control specific behavioral outputs remains an open question. Rhythmic release of pigment dispersing factor (PDF) has been proposed to propagate the ¨time of day¨ information from core pacemaker cells to downstream targets underlying rhythmic locomotor activity. Indeed, such circadian changes in PDF intensity represent the only known mechanism through which the PDF circuit could communicate with its output. In this work we describe a novel circadian phenomenon involving extensive remodeling in the axonal terminals of the PDF circuit which display higher complexity during the day and significantly lower complexity at nighttime, both under daily cycles and constant conditions. In support to its circadian nature, cycling is lost in bonafide clock-less mutants. We propose this clock-controlled structural plasticity as a candidate mechanism contributing to the transmission of the information downstream of pacemaker cells.