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.
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.