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SUMMARY:From apical organs to the bilaterian forebrain: Duplication and di
 vergence of neural circuits in central nervous system evolution - Detlev A
 rendt\, EMBL Heidelberg\, Germany.
DTSTART:20120613T120000Z
DTEND:20120613T130000Z
UID:TALK37724@talks.cam.ac.uk
CONTACT:Vera Hunnekuhl
DESCRIPTION:From apical organs to the bilaterian forebrain: Duplication an
 d divergence of neural circuits in central nervous system evolution\n\nNeu
 ral circuits\, composed of interconnected neurons\, represent the basic\nu
 nit of the nervous system. The highly complex arrangement of\ncross-talkin
 g\, serial and parallel circuits in bilaterian brains can\nonly be underst
 ood if we gain insight into its evolutionary emergence.\nIn my seminar I w
 ill focus on the neural circuits controlling the\nrelease of serotonin and
  melatonin in bilaterian brains. Melatonin\, the\n“hormone of darkness
 ”\, is synthesized from serotonin that likewise\nmodulates locomotor act
 ivity. To elucidate the evolutionary origin of\nthe serotonin – melatoni
 n-releasing photosensory-secretory circuits\, we\ninvestigated locomotor c
 ontrol in the swimming ciliated larvae of the\nmarine annelid Platynereis\
 , a new molecular model species for marine\nzooplankton. We identify a sma
 ll set of serotonin and\nmelatonin-releasing light-sensitive neurons and s
 how that serotonin and\nmelatonin have opposite effects on ciliary beating
  frequency\, mimicking\nday and night conditions\, respectively. As in ver
 tebrates\, the\nPlatynereis larval serotonin - melatonin locomotor control
  system acts\ndownstream of the circadian clock\, which is present in the 
 same cells\,\nand its development critically depends on functional rx (ret
 ina\nhomeobox) transcription factor that specifies retina\, pineal and\nhy
 pothalamus\, known sites of serotonin and melatonin production in the\nver
 tebrates. We propose that the vertebrate circadian control system\nevolved
  from a simple serotonin – melatonin system for the circadian\ncontrol o
 f ciliary locomotion in marine larvae.
LOCATION:Main Lecture Theatre\, Department of Zoology
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