Why Sequence Capitella capitata?

Capitella capitata is a polychaete annelid (a bristle worm) and will be among the first of the Lophotrochozoa (a large superphylum comprising about 1/3 of animal life) to have its genome sequenced. This species has a simple external anatomy that represents well the common body plan of an annelid worm.  It is small, adults ranging from 6 to 10 mm in length; has a cosmopolitan distribution; and is heavily cited as a bioindicator of disturbed marine habitats. It is easy to raise in the lab, with a generation time of only six weeks. Capitella develops indirectly, that is, through a trochophore larva intermediate, and has been studied extensively as a model of annelid development.  It offers many experimental advantages. For example, the eggs are large (200 µm in diameter), facilitating their manipulation. Embryos and larvae are continuously available and do not feed. The animals produce large brood sizes of up to 250 embryos. Embryonic and larval development has been described in detail. The embryos develop rapidly, taking only eight days from fertilization to metamorphosis, and all stages are easily grown, manipulated, and observed in a lab dish. Adults are experimentally accessible since they do not secrete hard tubes (in contrast to many marine polychaetes). 

In addition to serving as a model of early development, they are studied for their robust regenerative capacity.  This is in contrast to the condition in leeches (also to be sequenced at JGI), so a comparison between these two organisms may reveal insight into the mechanisms of regeneration. Capitella capitata has a small genome size of only 240 Mb distributed across 10 chromosomes.  Isogenic laboratory strains are available, as are cDNA libraries from various developmental stages.  A variety of techniques are available for studying the cellular, molecular, and developmental biology of this animal, including in-situ hybridization and immunohistochemistry, intracellular injections for cell lineage tracing, and functional gene knockdowns.

CSP project participants: Elaine Seaver (Univ. of Hawaii), Jeffrey Boore (JGI and UC Berkeley), and Rob Savage (Williams College).