Gene expression profile in the anterior regeneration of the earthworm using expressed sequence tags

In order to gain insight into the gene expression profiles associated with anterior regeneration of the earthworm, Perionyx excavatus, we analyzed 1,159 expressed sequence tags (ESTs) derived from cDNA library early anterior regenerated tissue. Among the 1,159 ESTs analyzed, 622 (53.7%) ESTs showed significant similarity to known genes and represented 338 genes, of which 233 ESTs were singletons and 105 ESTs manifested as two or more ESTs. While 663 ESTs (57.2%) were sequenced only once, 308 ESTs (26.6%) appeared 2 to 5 times, and 188 ESTs (16.2%) were sequenced more than 5 times. A total of 803 genes were categorized into 15 groups according to their biological functions. Among 1,159 ESTs sequenced, we found several gene encoding signaling molecules, such as Notch and Distal-less. The ESTs used in this study should provide a resource for future research in earthworm regeneration.