Evolutionarily conserved coding sequences in the dpy-20-unc-22 region of Caenorhabditis elegans.

Caenorhabditis elegans provides an excellent opportunity to study the organization of a complex genome. The alignment of the genetic and molecular maps over a large stretch of the genome is an essential part of this study. The objective of this paper was the identification and characterization of coding regions in four cosmids containing DNA from the interval between dpy-20 and unc-22 on linkage group IV. These cosmids were characterized with regard to the map position and the developmental patterns of expression of coding sequences. Since an extensive genetic map already exists for this region, this detailed description of the coding sequences in the dpy-20-unc-22 region will make possible alignment of the molecular and genetic maps for this portion of the C. elegans genome. In this study, we have used interspecies cross-hybridization to localize and identify potential coding elements. We have investigated four cosmids containing approximately 150 kb of C. elegans genome adjacent to the well-characterized muscle gene, unc-22(IV). Fragments subcloned from the four cosmids were hybridized at moderate stringency to the genome of the related species, Caenorhabditis briggsae. In this way nine potential coding regions were identified. Seven of these nine fragments also hybridized to mRNA transcripts on Northern blots. Five of the seven showed maximal hybridization to RNA from L2-stage animals, a pattern that resembles that of actin transcription. It is speculated that the functions of these five may in some way be related to one another, and perhaps also to that of unc-22, which is itself a muscle gene.