26.8 Monday, Jan. 5 The Nuclear Receptor Complement of the Cnidarian Nematostella vectensis REITZEL, Adam R.; TARRANT, Ann M.*; Woods Hole Oceanographic Institution; Woods Hole Oceanographic Institution email@example.com
Nuclear receptors (NRs) are a superfamily of metazoan transcription factors that regulate diverse developmental and physiological processes. We have identified the complete set of seventeen nuclear receptors from a cnidarian, the starlet sea anemone Nematostella vectensis. Phylogenetic analyses support N. vectensis orthologs of four nuclear receptors subfamilies in the NR 2 family (COUP-TF, TLL, HNF4, TR2/4) and one ortholog of the NR 6 family (GCNF). Other N. vectensis genes grouped well with the NR 2 family but did not have clear orthologs with bilaterians and may represent duplications within the cnidarian lineage. Unlike the jellyfish Tripedalia cystophora, N. vectensis lacks a clear ortholog of the RXRs, and experiments are in progress to determine whether retinoids specifically bind other N. vectensis NRs. Three NRs were not well-supported within any particular NR family and thus may represent ancient NRs that later diversified into bilaterian NR families. These results reveal that NRs are well diversified in the cnidarian N. vectensis including both orthologs of bilaterian NRs and novel genes likely stemming from lineage specific duplications. NR expression varies greatly during development, suggesting diverse regulatory roles for these genes. Understanding the evolutionary relationships and developmental expression of N. vectensis nuclear receptor complement allows better characterization the evolution of this gene superfamily and provides a foundation for elucidating the functions of cnidarian nuclear receptors.