Stage specific Northern analysis reveals that the
dpy-5 gene is expressed at low levels in embryos and Ll larvae, but is expressed at increased levels in I2 larvae through to adults. This pattern of expression correlates well with the onset of the mutant Dpy-5 phenotype that begins at the L2 larval stage and persists through to the adult. Two lines of evidence suggest that the
dpy-5 message is expressed at relatively high levels: hybridization to Northern blots detects a strong signal and
dpy-5 clones appear at a frequency of about 1 in 5000 in Bob Barstead's lambda ZAP cDNA library. Size estimates based on Northern analysis suggest that the
dpy-5 gene encodes a message that is approximately 950 bp in size. Genomic and cDNA sequence data have been obtained for the
dpy-5 gene in C. elegans. The
dpy-5 gene contains six exons measuring 277 bp, 105 bp, 105 bp, 90 bp, 83 bp, and 114 bp in size that code for a 257 arnino acid protein. The five introns in
dpy-5 measure 416 bp, 170 bp, 54 bp, 233 bp, and 47 bp in length. Unlike
dpy-2,
dpy-10, (Levy et al., WBG 11- 5:36) and
dpy-13 (von Mende et al., Cell 55:567-576),
dpy-5 is not a collagen gene. In addition,
dpy-5 does not share significant sequence identity with another non-collagen dpy,
dpy-20 (D. Clark, Ph.D. thesis) . Searches against the EMBL database have not revealed significant identity to any other sequences at either the DNA or protein level. The
dpy-5 homolog in C. bnggsae has also been cloned and sequenced. Analysis of this sequence reveals a high degree of conservation between G briggsae and C. elegans. This conservation is particularly evident in the last three exons in which 84% homology exists at the amino acid level. Low stringency genomic hybridization with
dpy-5 as a probe suggests that the gene is present in only one copy in the C. elegans genome. Analysis of the amino acid sequence shows strong evidence of a signal peptide, suggesting that the
dpy-5 gene product may be a secreted protein. Supported by an NSERC scholarship and a University Graduate Fellowship to J.M.B and an MRC grant to A.M.R.