Molecular characterization of the apical organ of the anthozoan Nematostella vectensis.
Bottom Line: 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.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.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.
Affiliation: Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, 5008 Bergen, Norway.Show MeSH
Mentions: The 52 putative cilia-related genes can be considered in several categories. The first category includes genes involved in ciliogenesis. The forkhead domain containing gene NvFoxJ1(ao194) is among the few transcription factors that were recovered in the analysis. FoxJ1 has been characterized as a key regulator of the development of motile cilia in vertebrates and this function has been suggested to be conserved across metazoans (Thomas et al., 2010; Vij et al., 2012). The onset of NvFoxJ1 expression at the aboral pole of Nematostella coincides with the differentiation of the apical organ at early planula stage (Sinigaglia et al., 2013). The assembly and maintenance of cilia depends on conserved structural proteins and an intraflagellar transport (IFT) system. Genes falling into this category are Nvβ-tubulin (ao162), NvTektin (ao90), NvPACRG-like (Parkin-co-regulared gene (ao101, ao137; (Dawe et al., 2005), and the motor protein components NvDynein heavy chain-like (ao35) and NvDynein light chain-like (ao77) (Fig. 2A–D). Kinesins are microtubule-binding motor proteins that have diverse cellular functions including intraflagellar transport (Hirokawa et al., 2009; Verhey et al., 2011). Two Nematostella kinesins, NvKif9-like (ao113) and NvKif16-like (ao74), are expressed in the apical organ; however, members of these particular kinesin families have not been implicated in intraflagellar transport (see the Discussion section).
Affiliation: Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, 5008 Bergen, Norway.