Identification and developmental expression of Ci-isl, a homologue of vertebrate islet genes, in the ascidian Ciona intestinalis

Here we describe the cloning and expression pattern of Ci-isl, a homologue of vertebrate islet genes, in the ascidian Ciona intestinalis. Early in dev elopment, Ci-isl expression occurs in the primordia of palps and brain vesi cle, then in the tailbud embryo it is transiently extended to the notochord cells. At larva stage, the expression is down-regulated in the notochord, and it persists predominantly in the compartments of the nervous system. Th ese observations indicate that also in invertebrates, islet genes show an e xpression pattern during differentiation of the nervous system. (C) 1998 El sevier Science Ireland Ltd. All rights reserved.