title: New insights on cytological and metabolic features of Ostreopsis cf. ovata Fukuyo (Dinophyceae): a multidisciplinary approach.
abstract: The harmful dinoflagellate Ostreopsis cf. ovata has been causing toxic events along the Mediterranean coasts and other temperate and tropical areas, with increasing frequency during the last decade. Despite many studies, important biological features of this species are still poorly known. An integrated study, using different microscopy and molecular techniques, Raman microspectroscopy and high resolution liquid chromatography-mass spectrometry (HR LC-MS), was undertaken to elucidate cytological aspects, and identify main metabolites including toxins. The species was genetically identified as O. cf. ovata, Atlantic-Mediterranean clade. The ultrastructural results show unique features of the mucilage network abundantly produced by this species to colonize benthic substrates, with a new role of trichocysts, never described before. The amorphous polysaccharidic component of mucilage appears to derive from pusule fibrous material and mucocysts. In all stages of growth, the cells show an abundant production of lipids. Different developmental stages of chloroplasts are found in the peripheral cytoplasm and in the centre of cell. In vivo Raman microspectroscopy confirms the presence of the carotenoid peridinin in O. cf. ovata, and detects in several specimen the abundant presence of unsaturated lipids structurally related to docosahexaenoic acid. The HR LC-MS analysis reveals that ovatoxin-a is the predominant toxin, together with decreasing amounts of ovatoxin-b, -d/e, -c and putative palytoxin. Toxins concentration on a per cell basis increases from exponential to senescent phase. The results suggest that benthic blooms of this species are probably related to features such as the ability to create a unique mucilaginous sheath covering the sea bottom, associated with the production of potent toxins as palytoxin-like compounds. In this way, O. cf. ovata may be able to rapidly colonize benthic substrates outcompeting other species.
authors: Department of Agricultural and Environmental Sciences, University of Udine, Udine, Italy.
authors: Giorgio
authors: G
authors: Honsell
authors: Alois
authors: A
authors: Bonifacio
authors: Marco
authors: M
authors: De Bortoli
authors: Antonella
authors: A
authors: Penna
authors: Cecilia
authors: C
authors: Battocchi
authors: Patrizia
authors: P
authors: Ciminiello
authors: Carmela
authors: C
authors: Dell'aversano
authors: Ernesto
authors: E
authors: Fattorusso
authors: Silvio
authors: S
authors: Sosa
authors: Takeshi
authors: T
authors: Yasumoto
authors: Aurelia
authors: A
authors: Tubaro
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D002338:Carotenoids / Q000737:chemistry; D002736:Chloroplasts / Q000648:ultrastructure; D002852:Chromatography, Ion Exchange; D002853:Chromatography, Liquid; D003064:Cnidarian Venoms; D004141:Dinoflagellida / Q000166:cytology* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D005838:Genotype; D008387:Marine Toxins / Q000737:chemistry; D013058:Mass Spectrometry; D008856:Microscopy, Fluorescence; D010860:Pigments, Biological / Q000378:metabolism; D025341:Principal Component Analysis; D013059:Spectrum Analysis, Raman; D000095702:Polyether Toxins
chemical_list: D000178:Acrylamides; D002338:Carotenoids; D003064:Cnidarian Venoms; D008387:Marine Toxins; D010860:Pigments, Biological; C016040:peridinin; C010272:palytoxin; D000095702:Polyether Toxins