Expression pattern of Brachyury in the embryo of the sea urchin Paracentrotus lividus.

Brachyury is a key transcription factor whose homologs have been identified in many animal species. Different Brachyury expression patterns have been observed amongst echinoderms. We have isolated PlBra, the Brachyury ortholog from the sea urchin Paracentrotus lividus and analyzed its expression during development. PlBra is first expressed at the end of cleavage in a ring of cells at the border between the presumptive endoderm and mesoderm territories. At later stages, PlBra is expressed around the blastopore and in the stomodaeum area as in most basal deuterostomes.