Pristionchus pacificus has been established as a satellite organism for studying developmental processes and comparing them to C. elegans. Cell fate specification during vulva formation evolved substantially between these two nematodes. Most vulva defective mutants in Pristionchus pacificus cannot be assigned for gene functions from the knowledge of C. elegans. To facilitate the cloning of these mutants we generated genetic and physical maps of Pristionchus pacificus (Srinivasan et al., 2002). The genetic and physical map projects are complemented by a genetic screen for dpy mutants. We screened 50,000 gametes and identified 47 dpy mutants. After mapping these 47 mutants, 43 could be assigned to one of the six chromosomes (Srinivasan et al., 2002). Complementation analysis showed that they fall into 12 complementation groups, called
dpy-1 to
dpy-12. The four remaining mutants show inter-genic non-complementation, a phenomenon also known for some C. elegans collagen mutants (Kusch and Edgar, 1985). We are currently fine-mapping these dpy genes with regard to the SNP markers. In C. elegans, 6 of the 26 dpy complementation groups are located on the X chromosome. In contrast, in Pristionchus pacificus we find only one complementation group with one allele to be located on the X chromosome. Since dpy mutants often result from mutations in collagen genes or collagen-modifying enzymes, we are interested in the molecular nature of the mutants in hands. Therefore, we used sequence data originated from the EST, BAC end and BAC shotgun projects in Pristionchus pacificus, searching in silico for known homologs of C. elegans genes, which when mutated might result in a dpy phenotype. We found 12 homologous representatives of all four collagen families that exist in C. elegans. Furthermore, we also hit enzymes, which are involved in cuticle assembly. For instance, we got a
dpy-18 homolog that encodes a prolyl-4-hydroxylase subunit. In addition, we could identify a protein disulfide isomerase subunit. Other non-collagen genes which result in dpy phenotypes were also detected, e.g.
dpy-19 that encodes a novel protein and
dpy-30, a gene involved in dosage compensation. Kusch M, Edgar RS. Genetic studies of unusual loci that affect body shape of the nematode Caenorhabditis elegans and may code for cuticle structural proteins. Genetics 1986 Jul;113(3):621-39. Srinivasan J, Sinz W, Lanz C, Brand A, Nandakumar R, Raddatz G, Witte H, Keller H, Kipping I, Pires-daSilva A, Jesse T, Millare J, de Both M, Schuster SC, Sommer RJ. A bacterial artificial chromosome-based genetic linkage map of the nematode Pristionchus pacificus. Genetics. 2002 Sep;162(1):129-34.