The major aim of my laboratory is to understand the
way the nervous system controls behavior. We
now know that the "simple nervous system" of
the nematode Ascaris has much more complexity
than was ever imagined--the chemical signaling system
it uses are very diverse, and we are sorting them out.
These signaling systems include the neuropeptides,
which we are devoting a major effort towards identifying
and sequencing; other signaling systems that we have
worked on include serotonin and glutamate, both of
which play an important role in the motor nervous system.
These signaling systems typically are involved in the
process of neuromodulation, and each chemical involved
affects the system in a different way. Some produce
profound effects on the neurons they influence, and
others have subtle effects. Different chemicals affect
different subsets of neurons. Neuromodulation is a
matter of details, but the details matter.
We are developing new techniques for identifying
peptides in a complex mixture. I am currently excited about a new class
of antibodies that we are developing. These are generic antibodies that
recognize specific C-terminal dipeptide sequences, and we have found many new
types of neurons that contain peptides recognized by these antibodies, implying
that they contain novel peptides. We are also using MALDI-TOF mass spectroscopy
to search for new classes of neuropeptides. The most significant advance
this year has been the use of dissected nervous tissue from single worms as the
immediate target in the mass spectrometer. This has provided amazing sensitivity
and specificity, and several new peptides have been detected and sequenced. We
are now raising antibodies to study their cellular localization. The overall
conclusion we have reached is that there is a large number of as-yet undescribed
peptides in Ascaris. We have also successfully implemented for the first
time in Ascaris an in-situ hybridization method, and have determined the
location of the transcripts of 5 peptide-encoding genes.
One recent result that we think is of profound importance
is that although the neurons of Ascaris and C. elegans
are morphologically the same (C. elegans is a miniature
version of Ascaris), and although many of the neuropeptides
found or predicted from gene sequences are identical
or very similar in the 2 species, the cells in which
the peptides are expressed are almost completely
used 3 techniques (in situ hybridization, immunocytochemistry and mass spectrometry)
to detect peptide expression in Ascaris, and obtained congruent results with
each technique. Expression of peptide encoding genes in C. elegans has
been reported using GFP constructs. Out of 16 cellular comparisons, 15
are different. Only one neuron so far has shown the same peptide expression
in the 2 species. We conclude that the cellular expression pattern of peptides
may be an important part of the way a nearly identical structure can produce
Yew, J.Y., Davis, R., Dikler, S.,Nanda, J., Reinders, B.,
and Stretton, A. (2007) Products of the afp-6 gene of
the nematode Ascaris suum have different biological actions. J
Comp. Neurol. In press
Yew, JY, Davis R, Dikler S, Nanda J, Reinders B, and Stretton
AO (2006) Identification, cellular localization, and physiological
activity of neuropeptides AF21, 22, and 23, the products of
the afp-6 transcript in the nematode Ascaris suum.
Yew, J.Y., Kutz, K.K., Dikler, S., Messinger, L., Li. L., and
Stretton, A.O. (2005) A mass spectrometric map of neuropeptide
expression in Ascaris suum. J Comp. Neurol. In
Chevere, I., Donmoyer, J.E., and Stretton, A.O.W. Cellular
localization of AF17, a FMRFamide-like peptide with CCK-like
immunoreactivity, in the nervous system of the nematode Ascaris
suum. J. Comp. Neurol. J. Comp. Neurol. Under revision.
Sithigorngul, P., and Stretton, A.O.W. Localization of AF1
and AF1-like Peptides in the Nervous System of the nematode
Ascaris suum with Specific Monoclonal Antibodies; Different
Expression Patterns of AF1 in A. suum and Caenorhabditis elegans.
J. Comp. Neurol. Under revision.
Sithigorngul, P., and Stretton, A.O.W. Under revision. Isolation
of a peptide present in a single neuron of the nematode Ascaris
Chevere, I., Donmoyer, J.E., and Stretton, A.O.W. Under revision.
Cellular localization of AF17, a FMRFamide-like peptide with
CCK-like immunoreactivity, in the nervous system of the nematode
Ascaris suum. J. Comp. Neurol.
Stretton, AOW. 2002. The first sequence: Fred Sanger and Insulin.
Genetics 162: 527-532.
Angstadt, J.D., Donmoyer, J.D., and Stretton, A.O.W. 2001.
A study of dendritic spines in the nematode Ascaris highlights
the advantages and limitations of anatomical methods in identifying
functional synaptic interactions. J. Comp. Neurol.
Davis, R.E., and Stretton, A.O.W. 2001. Structure-activity
relationships of 18 endogenous neuropeptides on the motornervous
system of the nematode Ascaris suum. Peptides.
Reinitz, C.A., Herfel, H.G., Messinger, L.A., and Stretton,
A.O.W. 2000. Changes in locomotory behavior and cAMP produced
in Ascaris suum by neuropeptides from Ascaris
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