Meeting Abstract
Head and central nervous system (CNS) regeneration has proven to be an elusive trait in the deuterostomes. No chordate has been shown to be able to regenerate a complete anterior head or CNS. The hemichordate Ptychodera flava, on the other hand, has been shown to reliably regenerate all anterior structures, including their anterior proboscis and their hollow, dorsal neural tube. Both structures have been shown to have homologies with the chordate head and CNS, so insight into their regeneration may allow insight into chordate brain and CNS regeneration. Solitary hemichordates are marine invertebrates that have a tripartite body plan. The anterior proboscis is used for digging and burrowing in the sand and mud and the mouth is found at the proboscis-collar boundary. The middle collar or neck region houses the neural tube and the posterior trunk contains dorsal and ventral nerve cords that run the full length of the trunk. We have carefully analyzed anterior regeneration in P. flava and report the spatial and temporal formation of internal and external structures. Furthermore, we have sequenced, assembled, and analyzed the transcriptome for eight different stages of anterior regeneration and show that several chordate forebrain genes are expressed very early during regeneration, as the proboscis is beginning to form. Hemichordates are a key link between the deuterostome ancestor and the chordates and as such, may reveal vital steps to unlocking more extensive CNS regeneration in the chordates.
