To examine whether a BMP signaling pathway functions in specification of cell fates in sea urchin embryos, we have cloned sea urchin BMP2/4, analyzed its expression in time and space in developing embryos and assayed the developmental consequences of changing its concentration through mRNA injection experiments. These studies show that BMP4 mRNAs accumulate transiently during blastula stages, b...

Brivanlou and Melton, 1992; Kessler and Melton, 1994; Schulte-Merker et al., 1994). At a later stage, signals Clare Hudson, Debbie Clements, Rosalind V. Friday, David Stott, and Hugh R. Woodland* originating in the dorsal organizer region (e.g., noggin, Department of Biological Sciences chordin, and nodal-related molecules) and local signalUniversity of Warwick ing molecules in the ventral and ...