Meeting Abstract

S9-1.4  Saturday, Jan. 7  The evolution of a hox code: evidence from a basal metazoan MARTINDALE, Mark, Q.*; DUBUC, Tim; SIMMONS, Dave K.; Univ. Hawaii; Univ. Hawaii; Univ. Hawaii

Hox genes have played an important role in re-galvanizing a modern understanding of the role of development and body plan evolution. Comparative genomics have revealed an unexpected genomic complexity in basal metazoans, and ‘tool kits’ of homologous genes with deep evolutionary ancestry have been documented. When, and how, these genes become assembled into functional networks regulating body plan formation is a current focus of evolutionary developmental biologists. Among the more contentious issues in cnidarian evolutionary developmental biology is the role of Hox class homeodomain transcription factors on axial patterning. Many workers refuse to acknowledge the existence of Hox genes in cnidarians and fewer that they might be involved in axial patterning. We use mRNA overexpression and morpholino knockdown microinjection experiments in developing embryos in conjunction with qPCR and in situ hybridization of a variety of target genes to determine what, if any, role these gene have on axial patterning during the development of the anthozoan Nematostella vectensis. We studied posterior and anterior Hox genes and show that misexpression not only affects the development of expected domains of the target genes, but that these genes also affect the expression of each other, revealing the existence of a “hox code” initially described in bilaterians. While these observations are interpretable relative to their own expression domains, it is not clear if they provide deep insight in the evolution and expansion of Hox gene function in bilaterians.