Formation of body appendages during caudal regeneration in Platynereis dumerilii: adaptation of conserved molecular toolsets

摘要

BackgroundPlatynereis and other polychaete annelids with homonomous segmentation are regarded to closely resemble ancestral forms of bilateria. The head region comprises the prostomium, the peristomium, a variable number of cephalized body segments and several appendages, like cirri, antennae and palps. The trunk of such polychaetes shows numerous, nearly identical segments. Each segment bears a parapodium with species-specific morphology on either side. The posterior end of the trunk features a segment proliferation zone and a terminal pygidium with the anus and anal cirri. The removal of a substantial part of the posterior trunk is by no means lethal. Cells at the site of injury dedifferentiate and proliferate forming a blastema to regenerate both the pygidium and the proliferation zone. The pygidium forms new anal cirri, and the proliferation zone generates new segments at a rapid pace. The formation of body appendages like the cirri and the segmental parapodia can thus be studied in the caudal regenerate of Platynereis within only a few days.