NOVEL GENE CONTAINING MULTIPLE EPIDERMAL GROWTH FACTOR-LIKE MOTIFS TRANSIENTLY EXPRESSED IN THE PAPILLAE OF THE ASCIDIAN TADPOLE LARVAE

We have investigated molecular mechanisms of the embryonic development of an ascidian, a primitive chordate which shares features of both in vertebrates and vertebrates, with a view to identifying genes involved in development and metamorphosis, We isolated 12 partial cDNA sequenc es which were expressed in a stage-specific manner using differential display, We report here the isolation of a full-length cDNA sequence f or one of these genes which was specifically expressed during the tail bud and larval stages of ascidian development, This cDNA, 1213 bp in l ength, is predicted to encode a protein of 337 amino acids containing four epidermal growth factor (EGF)-like repeats and three novel cystei ne-rich repeats, Characterization of its spatial expression pattern by in situ hybridisation in late tailbud and larval embryos demonstrated strong expression localised throughout the papillae and anteriormost trunk and weaker expression in the epidermis of the remainder of the e mbryo, As recent evidence indicates that the signal for metamorphosis originates in the anterior trunk region, these results suggest that th is gene may have a role in signalling the initiation of metamorphosis. (C) 1997 Wiley-Liss, Inc.