Meeting Abstract
Severe injury to the central nervous system (CNS) of chordates often results in permanent and irreversible mental and physical challenges. While some chordates are able to repair and/or regenerate portions of their nervous system, no chordate has been shown to be able to regenerate all regions of their CNS after catastrophic injury or amputation. Some hemichordates, on the other hand, are able to efficiently regenerate all neural structures, including their dorsal, hollow neural tube after complete ablation. Hemichordates are marine acorn worms and a sister group to the echinoderms. The hemichordate, Ptychodera flava, develops from a pelagic, feeding tornaria larva to a tripartite, benthic worm with an anterior proboscis, a middle collar region, and a long posterior trunk. The adult worm regenerates all body parts when bisected in the trunk, but it was unknown whether the regeneration program was present in tornaria larvae. We have shown that P. flava larvae are capable of robust regeneration after bisection through the sagittal, coronal, and axial planes. We used immunofluorescence to show that the apical sensory organ regenerates a rich, serotonin positive complex of cells within two weeks after amputation. Cells labeled with EdU (5-ethynyl-2′-deoxyuridine) confirm that regeneration is occurring through epimorphic processes as new cells are added at the cut site and throughout the regenerating tissue. This study verifies that P. flava larvae can be used for future functional studies aimed at identifying the genetic and morphological mechanisms controlling CNS regeneration in a stem deuterostome. Biol. Bull. (2018) 234: 152–164.
