title: Parallel Evolution and Lineage-Specific Expansion of RNA Editing in Ctenophores.
abstract: RNA editing is a process of targeted alterations of nucleotides in all types of RNA molecules (e.g., rRNA, tRNA, mRNA, and miRNA). As a result, the transcriptional output differs from its genomic DNA template. RNA editing can be defined both by biochemical mechanisms and by enzymes that perform these reactions. There are high levels of RNA editing detected in the mammalian nervous system, suggesting that nervous systems use this mechanism to increase protein diversity, because the post-transcription modifications lead to new gene products with novel functions. By re-annotating the ctenophore genomes, we found that the number of predicted RNA-editing enzymes is comparable to the numbers in mammals, but much greater than in other non-bilaterian basal metazoans. However, the overall molecular diversity of RNA-editing enzymes in ctenophores is lower, suggesting a possible "compensation" by an expansion of the ADAT1-like subfamily in this lineage. In two genera of ctenophores, Pleurobrachia and Mnemiopsis, there are high levels of expression for RNA-editing enzymes in their aboral organs, the integrative center involved in control of locomotion and geotaxis. This finding supports the hypothesis that RNA editing is correlated with the complexity of tissues and behaviors. Smaller numbers of RNA-editing enzymes in Porifera and Placozoa also correlates with the primary absence of neural and muscular systems in these lineages. In ctenophores, the expansion of the RNA-editing machinery can also provide mechanisms that support the remarkable capacity for regeneration in these animals. In summary, despite their compact genomes, a wide variety of epigenomic mechanisms employed by ctenophores and other non-bilaterian basal metazoans can provide novel insights into the evolutionary origins of biological novelties.
authors.affiliation: *The Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Blvd, St Augustine, FL 32080, USA;
authors.forename: Andrea B
authors.initials: AB
authors.lastname: Kohn
authors.affiliation: *The Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Blvd, St Augustine, FL 32080, USA; Department of Neuroscience, University of Florida, Gainesville, FL 32611, USA;
authors.forename: Rachel S
authors.initials: RS
authors.lastname: Sanford
authors.affiliation: *The Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Blvd, St Augustine, FL 32080, USA; Research fellow of the Japan Society for the Promotion of Science; Center for Information Biology, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan;
authors.forename: Masa-aki
authors.initials: MA
authors.lastname: Yoshida
authors.affiliation: *The Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Blvd, St Augustine, FL 32080, USA; Department of Neuroscience, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA moroz@whitney.ufl.edu.
authors.forename: Leonid L
authors.initials: LL
authors.lastname: Moroz
mesh_terms: D000818:Animals; D037302:Ctenophora / Q000235:genetics*; D019143:Evolution, Molecular; D017393:RNA Editing / Q000502:physiology*