Meeting Abstract
Ability to regenerate is found in many groups of metazoans but the majority of research is focused on adults from just a few taxa, such as planarians and hydra. Increasing the diversity of study organisms and life stages can reveal new and interesting aspects of regeneration mechanisms. Studying regeneration in invertebrate larvae can simultaneously track cell migration and proliferation while observing the regeneration of structures and restoration of function at the organismal level. Injury for long lived planktonic larvae is likely, and therefore tissue reorganization and regeneration is expected, but very few types of marine invertebrate larvae have been surveyed for their ability to regenerate. Here we present the results of regeneration assays on the nemertean pilidium larva. The nemertean pilidium larva spends weeks to months in the plankton, during which time the juvenile worm forms inside from a series of initially isolated rudiments. The fully grown juvenile erupts from the larval body in a catastrophic metamorphosis, and many juveniles consume their larval body. As the juvenile is formed, the larval body continues to grow aided by the putative stem cells. These putative stem cells could contribute to the maintenance and successful regeneration of the larval body, but direct evidence of this is lacking. We document the capacity and timeline for regeneration after surgical removal of the larval apical organ or lappets, and use BrdU assays to test hypotheses about contribution of the larval stem cells to regenerating structures.
