title: Increased potential for wound activated production of Prostaglandin E2and related toxic compounds in non-native populations of Gracilaria vermiculophylla.
abstract: The capacity of the East Asian seaweed Gracilaria vermiculophylla ("Ogonori") for production of prostaglandin E2from arachidonic acid occasionally causes food poisoning after ingestion. During the last two decades the alga has been introduced to Europe and North America. Non-native populations have been shown to be generally less palatable to marine herbivores than native populations. We hypothesized that the difference in palatability among populations could be due to differences in the algal content of prostaglandins. We therefore compared the capacity for wound-activated production of prostaglandins and other eicosatetraenoid oxylipins among five native populations in East Asia and seven non-native populations in Europe and NW Mexico, using a targeted metabolomics approach. In two independent experiments non-native populations exhibited a significant tendency to produce more eicosatetraenoids than native populations after acclimation to identical conditions and subsequent artificial wounding. Fourteen out of 15 eicosatetraenoids that were detected in experiment I and all 19 eicosatetraenoids that were detected in experiment II reached higher mean concentrations in non-native than in native specimens. Wounding of non-native specimens resulted on average in 390% more 15-keto-PGE2, in 90% more PGE2, in 37% more PGA2and in 96% more 7,8-di-hydroxy-eicosatetraenoic acid than wounding of native specimens. Not only PGE2, but also PGA2and dihydroxylated eicosatetraenoic acid are known to deter various biological enemies of G. vermiculophylla that cause tissue or cell wounding, and in the present study the latter two compounds also repelled the mesograzer Littorina brevicula. Non-native populations of G. vermiculophylla are thus more defended against herbivory than native populations. This increased capacity for activated chemical defense may have contributed to their invasion success and at the same time it poses an elevated risk for human food safety.
authors.affiliation: Helmholtz-Zentrum für Ozeanforschung GEOMAR, Düsternbrooker Weg 20, D-24105 Kiel, Germany.
authors.forename: Mareike
authors.initials: M
authors.lastname: Hammann
authors.affiliation: Institute for Inorganic and Analytical Chemistry, Instrumental Analytics/Bioorganic Analytics, Friedrich Schiller University, Lessingstraße 8, D-07743 Jena, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Rempt
authors.affiliation: Institute for Inorganic and Analytical Chemistry, Instrumental Analytics/Bioorganic Analytics, Friedrich Schiller University, Lessingstraße 8, D-07743 Jena, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Pohnert
authors.affiliation: College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, 266003 Qingdao, China.
authors.forename: Gaoge
authors.initials: G
authors.lastname: Wang
authors.affiliation: Department of Biology, Chungnam National University, Daejeon 305-764, Korea.
authors.forename: Sung Min
authors.initials: SM
authors.lastname: Boo
authors.affiliation: Helmholtz-Zentrum für Ozeanforschung GEOMAR, Düsternbrooker Weg 20, D-24105 Kiel, Germany. Electronic address: fweinberger@geomar.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Weinberger
keywords: Gracilaria; Metabolomics; Ogonori; Oxylipin; Prostaglandin; Seaweed invasion