Developmental expression of the hemichordate otx ortholog

The phylogenetic location of hemichordates is unique because they seem to f ill an evolutionary gap between echinoderms and chordates. We report here c haracterization of Pf-otx, a hemichordate ortholog of otx, with its embryon ic and larval expression pattern. Pf-otx is initially expressed in the vege tal plate of the blastula. Expression remains evident in the archenteron th rough gastrulation and then disappears. A new expression domain appears nea r the mouth along the preoral and postoral ciliated bands in the early torn aria larva. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.