Worm Breeder's Gazette 12(5): 82 (February 1, 1993)
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.
TGF-ß-like proteins are important players in both vertebrate and invertebrate development. We have used degenerate PCR to look for C. elegans TGF-ß homologs. Following the approach of Wharton, et al. (PNAS 88: 92149218, 1991), we took advantage of the extensive sequence information available to group the TGF-ß-like proteins into subfamilies and thereby minimize primer degeneracy by making sets of primers specific to each subfamily.
To date, using genomic DNA as template, we have recovered one homolog and have tentatively named the gene ceg-1 (for C. elegans growth factor 1). Sequencing of the PCR product and prediction of the processed mRNA and encoded amino acid sequence revealed a high degree of similarity to the bone morphogenetic protein (BMP) subfamily of TGF-ß-like proteins (see below). The indicated intron positions were based on predicted splice donor and acceptor sites with excellent match to the C. elegans consensus sequences, flanking regions with no significant TGF-ß similarity.
Hybridization of the PCR product to the YAC grid located this sequence on three overlapping YACs just to the left of the cluster on chromosome V. This position was confirmed and refined by using PCR to map the gene to a single cosmid. Hybridization of labeled PCR product to Northern blots of RNA from different stages detected a transcript of about 2 kb, in the expected size range for a TGF-ß-like mRNA, which was abundant in embryos and less abundant in adults.
We are continuing to characterize ceg-1 molecularly. We are also using PCR to test for its presence in embryos homozygous for appropriate deficiencies in order to map it relative to the several lethals in this region, which could be candidates for future transformation rescue experiments. It seems likely that there may be more than one TGF-ß homolog in C elegans, and we are continuing to search for others.