title: Molecular characterization of the apical organ of the anthozoan Nematostella vectensis.
abstract: Apical organs are sensory structures present in many marine invertebrate larvae where they are considered to be involved in their settlement, metamorphosis and locomotion. In bilaterians they are characterised by a tuft of long cilia and receptor cells and they are associated with groups of neurons, but their relatively low morphological complexity and dispersed phylogenetic distribution have left their evolutionary relationship unresolved. Moreover, since apical organs are not present in the standard model organisms, their development and function are not well understood. To provide a foundation for a better understanding of this structure we have characterised the molecular composition of the apical organ of the sea anemone Nematostella vectensis. In a microarray-based comparison of the gene expression profiles of planulae with either a wildtype or an experimentally expanded apical organ, we identified 78 evolutionarily conserved genes, which are predominantly or specifically expressed in the apical organ of Nematostella. This gene set comprises signalling molecules, transcription factors, structural and metabolic genes. The majority of these genes, including several conserved, but previously uncharacterized ones, are potentially involved in different aspects of the development or function of the long cilia of the apical organ. To demonstrate the utility of this gene set for comparative analyses, we further analysed the expression of a subset of previously uncharacterized putative orthologs in sea urchin larvae and detected expression for twelve out of eighteen of them in the apical domain. Our study provides a molecular characterization of the apical organ of Nematostella and represents an informative tool for future studies addressing the development, function and evolutionary history of apical organ cells.
authors.affiliation: Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, 5008 Bergen, Norway.
authors.forename: Chiara
authors.initials: C
authors.lastname: Sinigaglia
authors.affiliation: Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, 5008 Bergen, Norway.
authors.forename: Henriette
authors.initials: H
authors.lastname: Busengdal
authors.affiliation: Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Avi
authors.initials: A
authors.lastname: Lerner
authors.affiliation: Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Paola
authors.initials: P
authors.lastname: Oliveri
authors.affiliation: Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, 5008 Bergen, Norway. Electronic address: fabian.rentzsch@sars.uib.no.
authors.forename: Fabian
authors.initials: F
authors.lastname: Rentzsch
mesh_terms: D000818:Animals; D002923:Cilia / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D019143:Evolution, Molecular; D005346:Fibroblast Growth Factors / Q000378:metabolism; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D008675:Metamorphosis, Biological / Q000235:genetics; D009420:Nervous System / Q000196:embryology*; D009474:Neurons / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D012615:Sea Anemones / Q000196:embryology* / Q000502:physiology*; D012617:Sea Urchins / Q000196:embryology / Q000502:physiology; D012679:Sense Organs / Q000196:embryology*; D015398:Signal Transduction; D013045:Species Specificity; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D014157:Transcription Factors; D005346:Fibroblast Growth Factors
keywords: Apical organ; Cilia; FGF; Life cycle; Nematostella; Sea urchin