The genome of the sea urchin Strongylocentrotus purpuratus

We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotuspurpuratus, a model for developmental and systems biology. The sequencing strategy combinedwhole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones,aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome.The genome encodes about 23,300 genes, including many previously thought to be vertebrateinnovations or known only outside the deuterostomes. This echinoderm genome provides anevolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes.