Production and excretion of okadaic acid,pectenotoxin-2 and a novel dinophysistoxin from the DSP-causing marine dinoflagellate Dinophysis acuta – Effects of light,food availability and growth phase |
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| Institution: | 1. Marine Biological Section, University of Copenhagen, Strandpromenaden 5, DK-3000 Helsingør, Denmark;2. Alfred-Wegener-Institute for Polar and Marine Research, Am Handelshafen 12, D-27570 Bremerhaven, Germany;1. División Ficología, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n (B1900FWA), La Plata, Argentina;2. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917, 1033 Buenos Aires, Argentina;3. Alfred-Wegener-Institut, Helmholtz Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany;1. Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, D-27570 Bremerhaven, Germany;2. Department of Environmental Sciences, School of Tropical and Laboratory Medicine, Hainan Medical University, Haikou 571199, China;3. University of Copenhagen, Marine Biological Section, Strandpromenaden 5, 3000 Helsingør, Denmark;4. Technical University of Denmark, Department of Biotechnology and Biomedicine, Søltofts Plads, 2800 Kgs. Lyngby, Denmark;5. Technical University of Denmark, National Food Institute, Kemitorvet, 2800 Kgs. Lyngby, Denmark;1. LOHABE, Department of Oceanography, Chonnam National University, Gwangju 61186, Republic of Korea;2. Research Institute for Basic Sciences, Chonnam National University, Gwangju 61186, Republic of Korea;3. School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea;1. College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China;2. Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China;3. Ifremer, Laboratoire Phycotoxines, 44311 Nantes, France;1. Harmful Microalgae Group (VGOHAB), Centro Oceanográfico de Vigo, IEO, Vigo, Spain;2. Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Naples, Italy;1. Research Center for Marine Ecology, The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China;2. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China;3. College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China |
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| Abstract: | Diarrhetic shellfish poisoning (DSP) toxins constitute a severe economic threat to shellfish industries and a major food safety issue for shellfish consumers. The prime producers of the DSP toxins that end up in filter feeding shellfish are species of the marine mixotrophic dinoflagellate genus Dinophysis. Intraspecific toxin contents of Dinophysis spp. vary a lot, but the regulating factors of toxin content are still poorly understood. Dinophysis spp. have been shown to sequester and use chloroplasts from their ciliate prey, and with this rare mode of nutrition, irradiance and food availability could play a key role in the regulation of toxins contents and production. We investigated toxin contents, production and excretion of a Dinophysis acuta culture under different irradiances, food availabilities and growth phases. The newly isolated strain of D. acuta contained okadaic acid (OA), pectenotoxins-2 (PTX-2) and a novel dinophysistoxin (DTX) that we tentatively describe as DTX-1b isomer. We found that all three toxins were excreted to the surrounding seawater, and for OA and DTX-1b as much as 90% could be found in extracellular toxin pools. For PTX-2 somewhat less was excreted, but often >50% was found extracellularly. This was the case both in steady-state exponential growth and in food limited, stationary growth, and we emphasize the need to include extracellular toxins in future studies of DSP toxins. Cellular toxin contents were largely unaffected by irradiance, but toxins accumulated both intra- and extracellularly when starvation reduced growth rates of D. acuta. Toxin production rates were highest during exponential growth, but continued at decreased rates when cell division ceased, indicating that toxin production is not directly associated with ingestion of prey. Finally, we explore the potential of these new discoveries to shed light on the ecological role of DSP toxins. |
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