A Caenorhabditis elegans homeobox gene expressed in the male tail, a link between pattern formation and sexual dimorphism

ceh-7 is a small Caenorhabditis elegans homeobox gene. We have shown that t his gene is transcribed. Examination of the expression pattern of ceh-7 usi ng reporter constructs revealed that it is expressed in a few cells of the male tail, which form a ring around the rectum. The most posterior member o f the C. elegans Hox cluster, egl-5, an Abd-B homologue, has previously bee n shown to be required for the proper development of several blast cells in the male tail. We have examined the expression of ceh-7 in mutant backgrou nds of egl-5 and also mab-5, an Antp/Ubx/Abd-A homologue. We find that ceh- 7 is not expressed in egl-5 mutants, but is still expressed in mab-5 mutant s.