A novel guanine exchange factor increases the competence of early ectodermto respond to neural induction

Inductive interactions between different cell layers have an extremely impo rtant role in early embryogenesis. One of the most intensively studied and best characterised of these is the induction of neural tissue from ectoderm al cells by the dorsal mesoderm. The competence of ectodermal cells to resp ond to neural induction varies according to dorsal-ventral position; with d orsal ectoderm (much of which forms the neural plate) having a far higher c ompetence. Here we show that overexpression of the nucleotide exchange fact or lfc increases ectodermal competence for neural induction as well as the amount of neural tissue in the whole embryo. Lfc is expressed pan ectoderma lly soon after gastrulation and may respond to an early determinant of dors al ectoderm. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.