Reevaluation of Drosophila Melanogaster's Neuronal Circadian Pacemakers Reveals New Neuronal Classes

J Comp Neurol. 2006 Sep 10;498(2):180-93. doi: 10.1002/cne.21021.


In the brain of the fly Drosophila melanogaster, approximately 150 clock-neurons are organized to synchronize and maintain behavioral rhythms, but the physiological and neurochemical bases of their interactions are largely unknown. Here we reevaluate the cellular properties of these pacemakers by application of a novel genetic reporter and several phenotypic markers. First, we describe an enhancer trap marker called R32 that specifically reveals several previously undescribed aspects of the fly's central neuronal pacemakers. We find evidence for a previously unappreciated class of neuronal pacemakers, the lateral posterior neurons (LPNs), and establish anatomical, molecular, and developmental criteria to establish a subclass within the dorsal neuron 1 (DN1) group of pacemakers. Furthermore, we show that the neuropeptide IPNamide is specifically expressed by this DN1 subclass. These observations implicate IPNamide as a second candidate circadian transmitter in the Drosophila brain. Finally, we present molecular and anatomical evidence for unrecognized phenotypic diversity within each of four established classes of clock neurons.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Clocks*
  • Biomarkers / metabolism
  • Circadian Rhythm / physiology
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / anatomy & histology*
  • Drosophila melanogaster / physiology
  • Genes, Reporter
  • Medulla Oblongata / anatomy & histology
  • Neural Pathways / anatomy & histology
  • Neurons* / classification
  • Neurons* / cytology
  • Neurons* / metabolism
  • Neuropeptides / metabolism
  • Nuclear Proteins / metabolism
  • Period Circadian Proteins


  • Biomarkers
  • Drosophila Proteins
  • Neuropeptides
  • Nuclear Proteins
  • PER protein, Drosophila
  • Period Circadian Proteins
  • tim protein, Drosophila