Meeting Abstract
The establishment of the anterior-posterior (A-P) axis is a defining characteristic of all bilaterians. While the molecular mechanisms specifying A-P axis polarity during embryogenesis are well characterized, the mechanisms utilized by asexual organisms to post-embryonically modify existing body axis polarity are not well understood. Radical alterations in axis polarity occur during reverse polarity budding in the acoel flatworm Convolutriloba macropyga when buds develop with A-P axis polarity completely reversed relative to the parent. We have identified a polarity transition zone characterized by a loss of muscle fiber organization at the base of each budding site. Unlike other regions, tissues excised from within this region fail to regenerate suggesting a transient loss of axis polarity. Chemical genetic screens have identified Hedgehog and Wnt signaling proteins as candidates for functioning in this disruption and reversal of the A-P axis during asexual reproduction in C. macropyga. By characterizing the spatiotemporal expression and function of specific Hedgehog and Wnt signaling components, we show that alterations in Hedgehog signals likely mediate a loss of axial polarity in the polarity transition zone and subsequent upregulation of Wnt signals allow for patterning of novel, reversed axes at the bud site.
