Worm Breeder's Gazette 13(5): 47 (February 1, 1995)

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

A semaphorin (aka fasciclin IV or collapsin) Gene in C. elegans.

Peter Roy, Joe Culotti

Samuel Lunenfeld Research Institute of Mt. Sinai Hospital Toronto, Ontario MSG 1X5 Canada

The Semaphorins (aka Fasciclin IV in Drosophila or Collapsin
in chicken) are a group of related proteins that provide
guidance cues for migrating axon growth cones. The chicken
Semaphorin has been shown to induce growth cone collapse
in vitro. We identified a semaphorin gene from C. elegans
using degenerate oligonucleotides (based on known Semaphorin
sequences, Kolodkin et al., Cell 7;: 1389-99, 1993) for
RT-PCR. After trying several combinations of PCR primers
and sequencing over 60 different PCR products, we found
a single clone that encodes a real Semaphorin. After identifying
genomic clones, we read (in the last WBG) that Y. Kohara's
group had identified a fasciclin IV-related gene in the
large cDNA sequencing project that they are carrying out.
We have since obtained his cDNA from them and shown that
it is the same semaphorin that we cloned. This cDNA hybridizes
to a 2.7 kb mRNA on Northern blots and encodes a protein of
at least 600 amino acids. Because of possible uncertainties
in our sequence analysis we do not yet know if this semaphorin
gene encodes a transmembrane or immunoglobulin domain,
as is found in the Semaphorins of other species.
The C. elegans semaphorin gene was mapped by Y. Kohara to
cosmid F14B11 on LGI just left of unc-54. We have verified
this location by sequencing subclones from this cosmid.
We are currently attempting to determine the expression
pattern of the C elegans semaphorin gene.