Sphedgehog is expressed by pigment cell precursors during early gastrulation in Strongylocentrotus purpuratus

We have sequenced the Sphedgehog ( Sphh ) gene from the sea urchin Strongylocentrotus purpuratus . Sphh transcripts are detected first at the mesenchyme blastula stage, and they accumulate throughout early embryogenesis. The Sphh protein is produced by precursor pigment cells during early and midgastrulation. NiCl 2 inhibits pigment cell differentiation in sea urchins. Here, we show that, in S. purpuratus , nickel affects a process(es) between 17 and 24 hr of development, corresponding to the time period when Sphh mRNA is first detected. However, nickel treatment does not alter the early expression of Sphh . Developmental Dynamics 231:370–378, 2004. © 2004 Wiley‐Liss, Inc.