Toxin profile of Alexandrium ostenfeldii (Dinophyceae) from the Northern Adriatic Sea revealed by liquid chromatography-mass spectrometry.

This paper reports on the first occurrence of fairly high numbers of Alexandrium ostenfeldii along the Emilia Romagna coasts (Italy). Detailed liquid chromatography-mass spectrometry (LC-MS) analyses of the toxin profile were performed on a strain of the organism collected in November 2003, isolated during the event and grown in culture. Selected ion monitoring (SIM) and multiple reaction monitoring (MRM) experiments were carried out for detection of spirolides and paralytic shellfish poisoning (PSP) toxins. They revealed that the Adriatic A. ostenfeldii produces mainly spirolide 13-desmethyl C at levels of 3.7 pg/cell but not PSP toxins. Interestingly, low levels of some spirolide isomers that have not been reported so far in other strains of the dinoflagellate were also detected. This represents the first report of spirolide-type toxins in the Adriatic Sea.

Relevance of the dinoflagellate Gonyaulax fragilis in mucilage formations of the Adriatic Sea.

Oceanographic cruises were carried out monthly from June 1999 to July 2002 to follow the mucilage formation process in the Northern Adriatic Sea. Results show that in correspondence with these events the dinoflagellate Gonyaulax fragilis (Schütt) Kofoid was observed both in the water column and within mucilage aggregates. In the water column, increasing abundances were observed from May until July, with values never exceeding 8500 cells l(-1). Much higher densities were observed within superficial gelatinous aggregates (22800-3400000 cells l(-1)). In mucilage samples, a large number of decomposing cells were present, together with abundant alive cells, enveloped in exudates. G. fragilis isolated from mucilage samples was cultured in three different culture media; it was characterized by a low growth rate but it produced a high amount of polysaccharides. The highest yield both in terms of cell number and carbohydrate production was observed in the medium having the highest nitrogen and phosphorus content and the lowest N/P ratio. The monomeric composition of G. fragilis carbohydrates, compared with that of mucilage samples, showed that in both natural and cultured samples galactose was the most abundant sugar; in addition, an overall good correlation, especially between the monomeric carbohydrate composition of G. fragilis grown in f/2 medium and that of a mucilage sample in which this species was present in high density, was observed.

Complex yessotoxins profile in Protoceratium reticulatum from north-western Adriatic sea revealed by LC-MS analysis.

While the occurrence of yessotoxin (YTX) has been reported worldwide from Protoceratium reticulatum, the biogenetic origin of some YTX analogues is still unknown, thus raising an issue whether they are metabolites of YTX formed in mussels or true products of different dinoflagellate species. Findings reported herein suggest that P. reticulatum from the north-western Adriatic sea is responsible for production, together with YTX (1), of homoYTX (2), 45-OHYTX (3), carboxyYTX (5), and noroxoYTX (7). YTX and its analogues have been determined by high performance liquid chromatography coupled with electrospray ion trap mass spectrometry (HPLC-MS and HPLC-MSn experiments). The result is the first to confirm production of these YTX analogues from this species and indicate it as a producing organism of homoYTX, 45-OHYTX, carboxyYTX, and noroxoYTX found in shellfish.