Meeting Abstract
Metazoans establish the bilateral body plan early in embryogenesis by patterning orthogonal body axes with polarity that is unaltered during the lifetime of most animals. While some organisms re-establish/modify body axes during regeneration and asexual reproduction, the acoel flatworm Convolutriloba longifissura is unusual in its ability to modify left-right (L-R) axis polarity during longitudinal fission. We have developed C. longifissura as a model for studying the mechanisms of L-R polarity modification during postembryonic development. Regeneration experiments have elucidated the temporal dynamics of midline re-specification, suggesting that parallel L-R axes replace the pre-existing midline prior to longitudinal fission. We have characterized the spatiotemporal expression of genes encoding ligands and receptors of signaling pathways with conserved functions in polarity specification and axial patterning. Expression domains of BMP, Hedgehog, Notch, and Slit/Robo signaling components are dynamic prior to and during longitudinal fission. RNAi-mediated gene knockdown and/or pharmacological perturbation of BMP, Notch, and Slit/Robo signals disrupt longitudinal fission and normal midline patterning suggesting a role in modulating changes in L-R axis polarity.
