The temporal and spatial expression patterns of regulatory genes are required for building a gene regulatory network (GRN). The current ectoderm GRN model for the sea urchin embryo includes pregastrular specification functions in the oral (OE) and aboral ectoderm (AE). Unlike the OE, which is resolved into several subdomains, the AE is considered a simpler territory due to the lack of detailed gene expression studies in this territory. Here, we perform temporal and spatial gene expression studies on the eight transcription factor genes constituting the AE GRN. Based on the differential gene expression patterns, we conclude that the AE contains at least three subdomains at the mesenchyme blastula stage. We also performed immunostaining for pSmad1/5/8 to monitor the activation of the BMP signaling pathway. The dynamic changes in the expression patterns of these transcription factor genes and the nuclearization of pSmad1/5/8 may provide a foundation for resolving the AE GRN.
© 2010 Wiley-Liss, Inc.