BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-3006
DTSTART:20130416T170500Z
DURATION:PT1H0M0S
DTSTAMP:20260420T005230Z
LAST-MODIFIED:20130405T160954Z
LOCATION:4274 Chamberlin (refreshments will be served)
SUMMARY:The Ascaris nervous system - a simple nervous system.  Hah!\, 
 Chaos & Complex Systems Seminar\, Tony Stretton\, UW Department of Zoo
 logy
DESCRIPTION:Numerically\, nematodes have very simple nervous systems. 
  The female parasitic nematode Ascaris suum has only 298 neurons\, and
  the hermaphroditic free-living Caenorhabditis elegans has 302.  A. su
 um is large (ca 35 cm)\, and has large neurons suitable for electrophy
 siological recording.   We assembled a functional circuit from the mor
 phological synapses\, scored by electron microscopy\, and the physiolo
 gical properties of the neurons and their synapses.  The predicted act
 ivity of this circuit matched that actually recorded from neurons in d
 issected preparations that were opened to allow microelectrode penetra
 tion.  However\, it differed dramatically from the activity recorded f
 rom these same neurons in semi-intact behaving preparations.  Somethin
 g was missing from the circuit description.  We have now shown that th
 ere are numerous neuropeptides (at least 250) present in A. suum\, and
  the ones we have sequenced have potent activity on individual neurons
 .   We think that they were washed out of the dissected preparations\,
  thus losing their modulatory activity on individual neurons.  For pep
 tide identification\, initially peptides were purified by HPLC and seq
 uenced by Edman degradation.  Now we are using mass spectrometry\, whi
 ch has speeded up the discovery process more than one hundred-fold.   
 In particular\, we are now dissecting single identified neurons and su
 bjecting them to MALDI-TOF MS and tandem MS for sequence determination
 .  All neurons examined so far contain peptides.  Most contain previou
 sly unknown peptides\, and the unknown peptides often outnumber the kn
 own peptides.   This is a powerful method of peptide discovery.   It h
 as the distinct advantage that it simultaneously solves the identity a
 nd the cellular expression of the peptide.  It also has the advantage 
 that it identifies the peptide actually expressed by a particular neur
 on\, rather than relying on predictions from cDNA or genomic DNA seque
 nces\, and on reporter constructs for expression patterns.  Neuropepti
 des are processed from precursor proteins\, and the rules of the prote
 olytic cleavage are not yet robust enough for accurate prediction of p
 rocessing.
URL:https://www.physics.wisc.edu/events/?id=3006
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