title: The dynamically evolving nematocyst content of an anthozoan, a scyphozoan, and a hydrozoan.
abstract: Nematocytes, the stinging cells of cnidarians, are the most evolutionarily ancient venom apparatus. These nanosyringe-like weaponry systems reach pressures of approximately 150 atmospheres before discharging and punching through the outer layer of the prey or predator at accelerations of more than 5 million g, making them one of the fastest biomechanical events known. To gain better understanding of the function of the complex, phylum-specific nematocyst organelle, and its venom payload, we compared the soluble nematocyst's proteome from the sea anemone Anemonia viridis, the jellyfish Aurelia aurita, and the hydrozoan Hydra magnipapillata, each belonging to one of the three basal cnidarian lineages which diverged over 600 Ma. Although the basic morphological and functional characteristics of the nematocysts of the three organisms are similar, out of hundreds of proteins identified in each organism, only six are shared. These include structural proteins, a chaperone which may help maintain venon activity over extended periods, and dickkopf, an enigmatic Wnt ligand which may also serve as a toxin. Nevertheless, many protein domains are shared between the three organisms' nematocyst content suggesting common proteome functionalities. The venoms of Hydra and Aurelia appear to be functionally similar and composed mainly of cytotoxins and enzymes, whereas the venom of the Anemonia is markedly unique and based on peptide neurotoxins. Cnidarian venoms show evidence for functional recruitment, yet evidence for diversification through positive selection, common to other venoms, is lacking. The final injected nematocyst payload comprises a mixture of dynamically evolving proteins involved in the development, maturation, maintenance, and discharge of the nematocysts, which is unique to each organism and potentially to each nematocyst type.
authors.affiliation: Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel.
authors.forename: Tamar
authors.initials: T
authors.lastname: Rachamim
authors.affiliation: Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel Proteomics Resource Center, Langone Medical Center, New York University.
authors.forename: David
authors.initials: D
authors.lastname: Morgenstern
authors.affiliation: Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel.
authors.forename: Dikla
authors.initials: D
authors.lastname: Aharonovich
authors.affiliation: Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel.
authors.forename: Vera
authors.initials: V
authors.lastname: Brekhman
authors.affiliation: Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel lotant@univ.haifa.ac.il dsher@univ.haifa.ac.il.
authors.forename: Tamar
authors.initials: T
authors.lastname: Lotan
authors.affiliation: Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel lotant@univ.haifa.ac.il dsher@univ.haifa.ac.il.
authors.forename: Daniel
authors.initials: D
authors.lastname: Sher
mesh_terms: D000818:Animals; D003063:Cnidaria / Q000378:metabolism*; D003064:Cnidarian Venoms / Q000032:analysis / Q000378:metabolism*; D019143:Evolution, Molecular; D058894:Nematocyst / Q000378:metabolism*; D020543:Proteome / Q000032:analysis / Q000378:metabolism*; D059467:Transcriptome
chemical_list: D003064:Cnidarian Venoms; D020543:Proteome
keywords: anemone; cnidaria; hydra; jellyfish; mass spectrometry; nematocyst; protein domain; toxin; transcriptome; venom