The purpose of this study is to characterize
dpy-14 , a gene that codes for a collagen type III(alpha1). This gene is presently annotated on the WormBase database as
col-59 . DNA sequencing analysis of the
dpy-14 canonical allele,
e188 , has revealed a mutation in the third exon, at position 747. Specifically, the codon GGA, coding for Gly, is changed to AGA, a codon for Arg. The severity of the Dpy phenotype in
e188 mutants increases with higher temperatures, ranging from a mild dumpy appearance at 15 C, to a Dpy phenotype accompanied by vulval protrusions at 20 C, and to arrested development at 25 C. This gradient of temperature sensitivity might be explained by an interplay of steric hindrance and thermal motion involving the Arg side chain and water molecules. In fact, both of them are present in the channel formed in the centre of the collagen triple helix, and are thought to be involved in trimerization of the collagen monomers. The expression pattern of the gene was determined by analyzing the Long-SAGE data ( C. elegans II Project), and by the creation of promoter GFP fusion constructs. Both methods indicated that
dpy-14 is highly expressed in embryonic neurons. In order to test whether the mutant DPY-14 protein affects the morphology of the amphids, a fluorescent dye filling experiment was performed on
e188 animals. The results indicate that this class of ciliated neurons is affected by the mutation. DPY-14 shares 72% homology in its amino acid sequence with the human collagen type III(alpha1) COL3A1. Intriguingly, a mutation in COL3A1 similar to that observed in the
e188 mutants, that is a Gly to Arg mutation within a collagen-like GXY repeat, is deemed responsible for the occurrence of a type of familial aortic aneurysm. It might be possible that the study of the C. elegans
dpy-14 gene may help better understand this class of genetic diseases.