The first stages in the sea urchin genome project have been reported. Significance and context This paper represents the culmination of two years of work by five laboratories, making the first inroads on the problem of deciphering the sea urchin genome. These spiny ocean denizens occasionally serve as a model organism in developmental biology and are sometimes used to study gene regulation. As echinoderms, they also have a potentially informative phylogenetic relationship to chordates, and thus

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... to the vertebrates. The California purple sea urchin, Strongylocentrotus purpuratus, was the organism selected for this genomic study. Key results The cornerstone of the sea urchin project was the construction of a contiguous set of bacterial artificial chromosomes (BACs) spanning the entire genome. To create a genomic scaffold, BAC clones were aligned using overlapping end sequences and additional sequence-tagged sites, then checked by comparing restriction enzyme digests. Analysis of the end sequences allowed the authors to estimate that the sea urchin genome contains about 27,000 genes, consistent with the urchin's genome being about one quarter the size of a human's. In addition to the BAC map, cDNA libraries were generated from several developmental stages and from particular organs. Each library was arrayed onto filters that are now available for hybridization screening. The genome project also includes a cDNA database that will expand as data from analyzed cDNAs become available. Links Further information about the Sea urchin genome project is available.