MATUS, D. Q.; PANG, K.; MARTINDALE, M.Q.; Univ. Hawaii; Univ. Hawaii; Univ. Hawaii: Expression of four Pax genes in the anthozoan Nematostella vectensis.

The genome of the starlet sea anemone Nematostella vectensis has been surveyed by degenerate PCR for the presence of Pax family homeodomain transcription factors. 8-9 PAX genes are found in flies and vertebrates (respectively) that have a broad range of functions, including those involved in eye formation (e.g. Pax6/eyeless, twin of eyeless) segmentation, and neural patterning. Nematostella vectensis has all four Pax orthologs (A,B,C, and D) that have been previously identified in another anthozoan, the coral Acropora millepora (Miller et al, 2000). All four Pax orthologs are expressed in the ectoderm. Pax A and C stain individual neural-like cells beginning early after gastrulation, with most Pax A expressing cells located at the oral pole and tentacles. Pax C expressing cells are located predominantly along the aboral end, and in cells of the internal pharyngeal epithelium. Pax B is expressed globally within the entire midbody ectoderm, but absent at the oral pole. Pax D, a paired/Pax 3/7 ortholog, is expressed in a single thin circumferential stripe of ectoderm aboral to the tentacular ring throughout the planula stage. The results of these patterns will be discussed with respect to Pax gene evolution in bilaterian embryos.