title: An ancient role for nitric oxide in regulating the animal pelagobenthic life cycle: evidence from a marine sponge.
abstract: In many marine invertebrates, larval metamorphosis is induced by environmental cues that activate sensory receptors and signalling pathways. Nitric oxide (NO) is a gaseous signalling molecule that regulates metamorphosis in diverse bilaterians. In most cases NO inhibits or represses this process, although it functions as an activator in some species. Here we demonstrate that NO positively regulates metamorphosis in the poriferan Amphimedon queenslandica. High rates of A. queenslandica metamorphosis normally induced by a coralline alga are inhibited by an inhibitor of nitric oxide synthase (NOS) and by a NO scavenger. Consistent with this, an artificial donor of NO induces metamorphosis even in the absence of the alga. Inhibition of the ERK signalling pathway prevents metamorphosis in concert with, or downstream of, NO signalling; a NO donor cannot override the ERK inhibitor. NOS gene expression is activated late in embryogenesis and in larvae, and is enriched in specific epithelial and subepithelial cell types, including a putative sensory cell, the globular cell; DAF-FM staining supports these cells being primary sources of NO. Together, these results are consistent with NO playing an activating role in induction of A. queenslandica metamorphosis, evidence of its highly conserved regulatory role in metamorphosis throughout the Metazoa.
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Ueda
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Gemma S
authors.initials: GS
authors.lastname: Richards
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Bernard M
authors.initials: BM
authors.lastname: Degnan
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Alexandrea
authors.initials: A
authors.lastname: Kranz
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Maja
authors.initials: M
authors.lastname: Adamska
authors.affiliation: Department of Physiology &Biophysics, Dalhousie University, Halifax NS B3H 4R2, Canada.
authors.forename: Roger P
authors.initials: RP
authors.lastname: Croll
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Sandie M
authors.initials: SM
authors.lastname: Degnan
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000235:genetics / Q000378:metabolism*; D005075:Biological Evolution; D007814:Larva / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D008018:Life Cycle Stages / Q000235:genetics; D008675:Metamorphosis, Biological / Q000235:genetics*; D009569:Nitric Oxide / Q000235:genetics / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics; D011161:Porifera / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics
chemical_list: D009569:Nitric Oxide; D019001:Nitric Oxide Synthase