Identification of genes involved in oral/pharyngeal nervous system development in Cnidaria, Nematostella vectensis.
Members of the phylum Cnidaria, the closest sister group of Bilateria, is an informative metazoan lineage for the understanding of the earliest assembly processes of the nervous system. Although cnidarin Nematostella vectensis has a diffuse nervous system that lacks distinct neural tissue, they develop neural assembly around oral/pharyngeal region. From our comprehensive in silico survey using published RNA-seq data (1, 2), we identified a series of genes related to bilaterian neurosecretory systems was also expressed in N. vectensis oral/pharyngeal neurons. Among them, we focused on one of the transcription factors, Orthopedia (Otp) gene. To understand the function of Otp in N. vectensis oral/pharyngeal nervous system, we performed RNA-sequencing analysis utilizing knock-downed larvae of Otp. The goals of this project are clarify the Otp-dependent mechanisms underlying the oral/pharyngeal nervous system and compare the cnidarian and bilaterian nervous systems at the molecular/functional levels, to provide hints to understand why and how initial neural centralization had begun during nascent phase of metazoan evolution.  (1) Sebe-Pedros, A. et al. Cnidarian Cell Type Diversity and Regulation Revealed by Whole-Organism Single-Cell RNA-Seq. Cell 173, 1520-1534 e1520, doi:10.1016/j.cell.2018.05.019 (2018). (2) Warner, J. F. et al. NvERTx: a gene expression database to compare embryogenesis and regeneration in the sea anemone Nematostella vectensis. Development 145, doi:10.1242/dev.162867 (2018).