| Institution: | 1. Center for Interdisciplinary Cardiovascular Sciences, Division of Cardiovascular Medicine, Brigham and Women''s Hospital, Harvard Medical School, Boston, MA 02115, USA;2. Channing Division of Network Medicine, Brigham and Women''s Hospital, Harvard Medical School, Boston, MA 02115, USA;1. School of Geography, Geology & Environment, Kingston University, Penrhyn Road, Kingston upon Thames KT1 2EE, UK;2. Camborne School of Mines, University of Exeter, Cornwall Campus, Penryn, Cornwall TR10 9FE, UK;3. Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK;4. Department of Earth and Planetary Sciences, Birkbeck College, Gower Street, London WC1E 7HX, UK |
| Abstract: | The capacity of the East Asian seaweed Gracilaria vermiculophylla (“Ogonori”) for production of prostaglandin E2 from 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 PGA2 and in 96% more 7,8-di-hydroxy-eicosatetraenoic acid than wounding of native specimens. Not only PGE2, but also PGA2 and 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. |
