call for neuroanatomical data

Oliver Hobert or38 at columbia.edu
Tue Jun 8 09:07:22 EST 1999


For everyone who deals with the characterization of expression patterns in
the nervous system, the truly impressive paper of White et al. 1986
(Phil.Trans.Roy.Soc.) serves as the ultimate source of knowledge. While the
largely (but not always) invariant cell body positions described by Sulston
et al. are an essential tool in the ID of neurons, the axon morphologies
described by White et al. greatly facilitates the identification of a given
neuron.

When using GFP reporter gene fusions to analyze the shapes of single
neurons, occasional discrepancies or variations have turned up suggesting
that the axonal anatomy of two neurons are different from the description
provided by White et al.   We have 3 GFP fusions that argue that the PVT
axon goes into the nerve ring (and does NOT terminate in the posterior
body) and 2 fusions that argue that DVB terminates around the vulva (and
does NOT go to the nerve ring).  Of course, those reporter gene studies
need to be taken with caution since one could envision a theoretical
scenario in which the GFP reporter construct somewhat changes the axonal
anatomy of the neurons. If however, such discrepancies can be revealed with
different lines and even different constructs, such scenarios should be
unlikely. In any case, the additional GFP data should not be taken as the
last word, but should help to point to ambiguities, which any researcher
involved in neuron identification should use to their own judgement.

 Besides the few discrepancies  described above, valuable additions would,
for example be the description of the length of the posteriorly directed
SIA, SIB, SMB, SMD class neurons (not shown in White et al.). If there were
consistent (are they consistent ??) and distinct lengths of these axons in
the sublateral cords, described by cell specific GFP's, this information
would aid people in the identification of these neurons with new GFP
reporter genes.

The work of John White is the key to our knowledge of neuron morphology,
but GFP reporters are also going to be useful in exploring those neurons
which may show animal-to-animal variation in shape in wild type.

With the help of anybody who has data to report, I will volunteer to write
up a Worm Breeders Gazette note which compiles any significant
discrepancies or additional features that help to distinguish neurons more
exactly.

I would appreciate any kind of data, input, suggestions etc. concerning
this issue.




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Oliver Hobert, Assistant Professor
Columbia University, College of Physicians & Surgeons
Department of Biochemistry & Molecular Biophysics
701 W.168th Street; HHSC 726, Box 140
New York, NY 10032
phone: office: (212) 305 0063, lab: (212) 305 0065
fax: (212) 305 0065
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