A HOMEOTIC GENE-CLUSTER PATTERNS THE ANTEROPOSTERIOR BODY AXIS OF C-ELEGANS

In insects and vertebrates, clusters of Antennapedia class homeobox (H OM-C) genes specify anteroposterior body pattern. The nematode C. eleg ans also contains a small cluster of HOM-C genes, one of which has bee n shown to specify positional identity. Here we show that two addition al C. elegans HOM-C genes also specify positional identity and that to gether these three HOM-C genes function along the anteroposterior axis in the same order as their homologs in other organisms. Thus, HOM-C-b ased pattern formation has been conserved in nematodes despite the man y differences in morphology and embryology that distinguish them from other phyla. Each C. elegans HOM-C gene is responsible for a distinct body region; however, where their domains overlap, two HOM-C genes can act together to specify the fates of individual cells.