title: Analysis of soluble protein contents from the nematocysts of a model sea anemone sheds light on venom evolution.
abstract: The nematocyst is one of the most complex intracellular structures found in nature and is the defining feature of the phylum Cnidaria (sea anemones, corals, jellyfish, and hydroids). This miniature stinging organelle contains and delivers venom into prey and foe yet little is known about its toxic components. In the present study, we identified by tandem mass spectrometry 20 proteins released upon discharge from the nematocyst of the model sea anemone Nematostella vectensis. The availability of genomic and transcriptomic data for this species enabled accurate identification and phylogenetic study of these components. Fourteen of these proteins could not be identified in other animals suggesting that they might be the products of taxonomically restricted genes, a finding which fits well their origin from a taxon-specific organelle. Further, we studied by in situ hybridization the localization of two of the transcripts encoding the putative nematocyst venom proteins: a metallopeptidase related to the Tolloid family and a cysteine-rich protein. Both transcripts were detected in nematocytes, which are the cells containing nematocysts, and the metallopeptidase was found also in pharyngeal gland cells. Our findings reveal for the first time the possible venom components of a sea anemone nematocyst and suggest their evolutionary origins.
authors.affiliation: Department of Molecular Evolution and Development, Centre for Organismal Systems Biology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria. yehu.moran@univie.ac.at
authors.forename: Yehu
authors.initials: Y
authors.lastname: Moran
authors.forename: Daniela
authors.initials: D
authors.lastname: Praher
authors.forename: Ami
authors.initials: A
authors.lastname: Schlesinger
authors.forename: Ari
authors.initials: A
authors.lastname: Ayalon
authors.forename: Yossi
authors.initials: Y
authors.lastname: Tal
authors.forename: Ulrich
authors.initials: U
authors.lastname: Technau
mesh_terms: D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D003064:Cnidarian Venoms / Q000235:genetics*; D018076:DNA, Complementary; D019143:Evolution, Molecular; D017403:In Situ Hybridization; D016013:Likelihood Functions; D045726:Metalloproteases / Q000235:genetics / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D058894:Nematocyst / Q000737:chemistry*; D021141:Nucleic Acid Amplification Techniques; D010802:Phylogeny; D011506:Proteins / Q000235:genetics*; D012615:Sea Anemones / Q000737:chemistry / Q000235:genetics*; D053719:Tandem Mass Spectrometry
chemical_list: D003064:Cnidarian Venoms; D018076:DNA, Complementary; D011506:Proteins; D045726:Metalloproteases