Circadian control of behavioral outputs in Drosophila

CERIANI, MF

Cancún

Congreso; I Reunión de la Federación de Asociaciones Latinoamericanas y del Caribe de Neurociencias (FALAN); 2012

Circadian rhythms regulate physiology and behavior through the action of self-sustained transcriptional feedback loops of clock genes. In Drosophila, over 150 neurons in the fly brain are implicated in the circadian regulation of rest-activity cycles, but a small subset -so-called small ventral lateral neurons (sLNvs)- are clearly crucial. Preservation of molecular oscillations within the sLNvs is key to command rhythmic behavior under free running conditions. The sLNvs transmit this ¨time of day¨ information releasing a neuropeptide known as pigment dispersing factor (PDF). Over the years a reasonably clear picture of how the molecular clock is assembled within a cell has emerged; however, little is known about how this molecular clock communicates with other clocks in the brain and the body to ensure a coherent response to daily changes in the environment, which is the focus of our laboratory. In the search for additional mechanisms employed by the central pacemaker neurons (sLNvs) to transmit time of day information to the rest of the network we uncovered 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 (Fernandez et al. PLoS Biol. 2008). We then proposed that such circadian remodeling of axonal terminals could imply synaptogenesis taking place on daily basis, and, as a consequence, determine a potential change in synaptic partners.  The molecular mechanisms underlying this structural plasticity will be discussed.