Harmful Dinoflagellate Ostreopsis cf. ovata Fukuyo: Detection of Ovatoxins in Field Samples and Cell Immunolocalization Using Antipalytoxin Antibodies

Abstract

Ostreopsis cf. ovata, a benthic dinoflagellate often blooming along the Mediterranean coasts, has been associated with toxic events ranging from dyspnea to mild dermatitis. In late September 2009, an Ostreopsis cf. ovata bloom occurred in the Gulf of Trieste (Northern Adriatic Sea; Italy), causing pruritus and mild dermatitis in beachgoers. An integrated study was initiated to characterize Ostreopsis cells by light and confocal microscopy, PCR techniques, immunocytochemistry, and high resolution liquid chromatography-mass spectrometry (HR LC-MS). The presence of Ostreopsis cf. ovata of the Atlantic/Mediterranean clade was unambiguously established by morphological and genetic analyses in field samples. Several palytoxin-like compounds (ovatoxin-a,-b,-c,-d,-e) were identified by HR LC-MS, ovatoxin-a being the most abundant (45-64 pg/cell). Surprisingly, no palytoxin was detected. For the first time, monoclonal and polyclonal antipalytoxin antibodies revealed the intracellular cytoplasmic localization of ovatoxins, suggesting their cross-reactivity with these antibodies. Since harmful dinoflagellates do not always produce toxins, the immunocytochemical localization of ovatoxins, although qualitative, can provide an early warning for toxic Ostreopsis cells before their massive diffusion and/or concentration in seafood.

Sanitary problems related to the presence of Ostreopsis spp. in the Mediterranean Sea: a multidisciplinary scientific approach

“…Similar symptoms were observed along the Spanish and French Mediterranean coasts, accompanied by ocular irritation, headache and, in some cases, by fever [41,42]. Other anecdotal descriptions of respiratory problems following marine aerosol exposure during Ostreopsis blooms have also been reported along the Mediterranean coast [25,43,44]. The most serious sanitary problems occurred on the Liguria coast in summer of 2005 [22,40] and repeated, with a lower intensity, in 2006 [40].…”

“…The cause-effect correlation between the cases of malaise and the involvement of algal toxins has not been completely clarified: in fact palytoxins were never detected in marine aerosol so far, even though these toxins were quantified in field algal samples [31]. Furthermore, although Ostreopsis cells concentrations were determined in seawater, these data are not predictive for human risk since dinoflagellates do not always produce the same amount of toxins, if any [25]. Ostreopsis cell debris can be also present in the marine aerosol and their contribution to the ef- fects on human health cannot be excluded.…”

“…Since then, the presence of Ostreopsis spp., most often O. cf. ovata, has been recorded several times along the Italian coastline [8][9][10][11][12][13][14][15][16][17][18][19][20][21], including the northern areas, such as the Gulf of Genoa [19,22,23] and the Gulf of Trieste (Figure 1) [19,24,25].…”

The novel ovatoxin-g and isobaric palytoxin (so far referred to as putative palytoxin) from Ostreopsis cf. ovata (NW Mediterranean Sea): structural insights by LC-high resolution MSn

“…Relative abundance of each toxin was similar to that observed for most of the Mediterranean O. cf. ovata strains analyzed so far [2,3,[29][30][31]. In particular, in this representative sample, OVTX-a accounted for 52 % of the total toxin content, followed by OVTX-b (29 %), OVTX-e (7 %), OVTX-d (6 %), OVTX-c (4 %), and a pPLTX (0.5 %).…”

High Resolution LC-MSn Fragmentation Pattern of Palytoxin as Template to Gain New Insights into Ovatoxin-a Structure. The Key Role of Calcium in MS Behavior of Palytoxins

“…So, the results obtained were used for structural investigation of the main toxin produced by Ostreopsis ovata. This benthic dinoflagellate currently represents the major threat in the Mediterranean area both from an environmental and a public health perspective [11][12][13]. The most relevant episode associated to O. ovata occurred in 2005 along the Ligurian coasts (Italy) when hundreds of people required medical attention after exposure to marine aerosols [14,15].…”