DevelopmentPlasticityRepair Pigment Dispersing FactorDependent andIndependent Circadian L.pdf

The Journal of Neuroscience, January 2, 2008 • 28(1):217–227 • 217 Development/Plasticity/Repair Pigment Dispersing Factor-Dependent and -Independent Circadian Locomotor Behavioral Rhythms 1 1,3 2 1 2 1 Vasu Sheeba, Vijay K. Sharma, Huaiyu Gu, Yu-Ting Chou, Diane K. O’Dowd, and Todd C. Holmes 1 2 Departments of Physiology and Biophysics, and Developmental and Cell Biology, Anatomy, and Neurobiology, University of California, Irvine, California 92612, and 3Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, 560064 Bangalore, India Circadian pacemaker circuits consist of ensembles of neurons, each expressing molecular oscillations, but how circuit-wide coordination of multiple oscillators regulates rhythmic physiological and behavioral outputs remains an open question. To investigate the relationship between the pattern of oscillator phase throughout the circadian pacemaker circuit and locomotor activity rhythms in Drosophila, we perturbed the electrical activity and pigment dispersing factor (PDF) levels of the lateral ventral neurons (LNv) and assayed their combinatorial effect on molecular oscillations in different parts of the circuit and on locomotor activity behavior. Altered electrical activity of PDF-expressing LNv causes initial behavioral arrhythmicity followed by gradual long-term emergence of two concurrent short- and long-period circadian behavioral activity bouts in 60% of flies. Initial desynchrony of circuit-wide molecular oscillations is followed by the emergence of a novel pattern of period (PER) synchrony whereby two subgroups of dorsal neurons (DN1 and DN2) exhibit PER oscillation peaks coinciding with two activity bouts, whereas other neuronal subgroups exhibit a single PER pe