title: PDFR and CRY signaling converge in a subset of clock neurons to modulate the amplitude and phase of circadian behavior in Drosophila.
abstract: BACKGROUND
  To synchronize their molecular rhythms, circadian pacemaker neurons must input both external and internal timing cues and, therefore, signal integration between sensory information and internal clock status is fundamental to normal circadian physiology.
  
  
  RESULTS
  We demonstrate the specific convergence of clock-derived neuropeptide signaling with that of a deep brain photoreceptor. We report that the neuropeptide PDF receptor and the circadian photoreceptor CRYPTOCROME (CRY) are precisely co-expressed in a subset of pacemakers, and that these pathways together provide a requisite drive for circadian control of daily locomotor rhythms. These convergent signaling pathways influence the phase of rhythm generation, but also its amplitude. In the absence of both pathways, PER rhythms were greatly reduced in only those specific pacemakers that receive convergent inputs and PER levels remained high in the nucleus throughout the day. This suggested a large-scale dis-regulation of the pacemaking machinery. Behavioral rhythms were likewise disrupted: in light:dark conditions they were aberrant, and under constant dark conditions, they were lost.
  
  
  CONCLUSIONS
  We speculate that the convergence of environmental and clock-derived signals may produce a coincident detection of light, synergistic responses to it, and thus more accurate and more efficient re-setting properties.
authors.affiliation: Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, United States of America.
authors.forename: Seol Hee
authors.initials: SH
authors.lastname: Im
authors.forename: Weihua
authors.initials: W
authors.lastname: Li
authors.forename: Paul H
authors.initials: PH
authors.lastname: Taghert
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D001683:Biological Clocks; D056926:CLOCK Proteins / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology; D003433:Crosses, Genetic; D056931:Cryptochromes / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D005136:Eye Proteins / Q000378:metabolism*; D007150:Immunohistochemistry / Q000379:methods; D008027:Light; D009474:Neurons / Q000378:metabolism*; D010641:Phenotype; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; C507073:PDFR protein, Drosophila; D043562:Receptors, G-Protein-Coupled; C119828:cry protein, Drosophila; D056926:CLOCK Proteins