Meeting Abstract

P3.96  Monday, Jan. 6 15:30  Relating the pentaradial starfish body plan to the bilaterian anterior posterior axis LEVINE, J.*; MCCAULEY, B.; HINMAN, V.; LOWE, C.; Stanford Univ.; Carnegie Mellon Univ.; Carnegie Mellon Univ.; Stanford Univ. levinej@stanford.edu

The echinoderms are a bilaterian phylum with a highly derived radially symmetric adult body plan. As larvae, echinoderms possess a bilateral body plan with clearly defined anteroposterior (AP) and dorsoventral axes. However, at metamorphosis larvae undergo a radical transformation to a five-fold radially symmetric adult body plan. The unusual anatomies of this derived adult body plan have hindered even basic axial comparisons with other bilaterians. Bilaterian phyla pattern their AP axes with a network of transcription factors, expressed in a highly conserved spatial sequence. This suite of developmental genetic characters could inform an investigation of the axial properties of echinoderms. We are carrying out a comprehensive analysis of AP patterning gene expression during the development of the bat star Patiria miniata to explicitly test whether 1) echinoderms have retained the ancestral bilaterian gene expression domains, which would represent a cryptic molecular axis and facilitate axial comparisons with other bilaterians, or 2) echinoderms have changed the order of these domains, indicating that they remodeled the deeply conserved network of transcription factors that pattern the bilaterian AP axis while devising novel ways to pattern their five-fold radially symmetric body plans. We produced a transcriptome from a wide range of P. miniata larval and juvenile stages, and analyzed it for orthologs of AP patterning genes. We cloned orthologs of genes with conserved roles in patterning the anterior, mid, and posterior regions of the bilaterian AP axis, performed in situ hybridization on larvae and juveniles, and present the localization of these genes in larval and adult body plans.