S17-04 Acoel flatworms and the origin of bilaterian animals

related homeobox 1 gene, Prrx1, are up-regulated in the autopods of the bat wing compared to the bat hindlimb and mouse forelimb. Changes in the mRNA transcript abundance of several genes involved in retinoic acid (RA) synthesis, degradation and signaling were consistent with the down-regulation of the RA signaling pathway in the developing bat wing autopod. Signal from a microarray probe targeting the 5 0 UTR of the Meis homeobox 2 (Meis2) mRNA transcript, showed the greatest difference in expression in the bat wing compared to bat hindlimb and mouse forelimb. This difference was not seen for a probe complementary to the Meis2 C-terminal coding region. The up-regulation of a Meis2 isoform lacking a C-terminal homeodomain may play an important role in the sculpting of bat wings during development.