Ostreopsis

Dinoflagellates Dinophysis spp., Prorocentrum lima Diatoms Pseudo-nitzschia spp. Dinoflagellates Protoperidinium spp. Epibenthic dinoflagellates Gambierdiscus toxicus Possibly Ostreopsis spp. Coolia spp. or Prorocentrum spp. 

Both known species of Ostreopsis, 0. ovata and 0. siamensis, are known to exhibit some toxic activity (5l). Like toxicus, they are also benthic and common in macroalgae, but they also occur on sand in the vicinity. Although they co-occurred with it periodically, they were often abundant when it was not, (49). They are also known from both the Atlantic and Pacific Oceans and are probably circum-tropical. 

Dinofiagellates belonging to the genus Ostreopsis have been proposed as possible biogenetic origins of palytoxin (Usami et al. 1995 Taniyama et al. 2003). This theory is further supported because of the implication of Ostreopsis siamensis in a case of clupeotoxism where the causative agent was found to be palytoxin or one of its analogues (Onuma et al. 1999). 

The term ostreocins generally describes toxirrs produced from dinoflagellates belonging to the genus Ostreopsis (Dinophyceae), although frequently some of the produced toxins are named after the producing species. Usami and co-workers were the first to establish the palytoxin-like character... 

This section will focus on the available chemical data concerning only toxic substances produced by Ostreopsis sp., shown to possess palytoxin characteristics. For reasons of convenience, toxins will be presented according to producing species. Palytoxin-like compounds have been reported for O. siamensis, O. ovata, and O. mascarenensis. The neurotoxins ostreotoxin-1 and -3 produced by O. lenticularis have not been to date characterised by use of analytical methods as palytoxin analogues, despite their reported mouse lethality and possible connection to ciguatera (Tindall et al. 1990 Mercado et al. 1994 Meunier et al. 1997). With regard to the last of the toxic species, the oidy... 

Table 5.2. Toxic Ostreopsis species and summary of reported data on properties of respective toxins produced...

Ostreopsis siamensis was first isolated by Schmidt in the Gulf of Siam, Thailand, in 1901 (Schmidt 1901). This dinoflagellate occurs in mat r tropical and subtropical areas of the world, mainly as epiphytic and less frequently as planktonic, and also in temperate areas during summertime. Until today, the presence of O. siamensis has been reported in the coastal waters of Japan (Yasumoto et al. 1987), New Zealand (Chang et al. 2000 Rhodes et al. 2000), Tasmania (Pearce et al. 2000), Spain, Italy (Vila et al. 2001 Penna et al. 2005), Greece (Aligizaki et al. 2005), and Tunisia (Turki 2005). 

O. siamensis was first characterized as a toxin producer by Nakajima et al. (1981). Some years later, Yasumoto et al. (1987) and Holmes et al. (1988) reported the lethafity and haemolytic activity of the O. siamensis toxins. Usami et al. (1995) were the first to elucidate the structure of the major ostreocin produced by O. siamensis (strain SOA 1 from Aka island, Okinawa, Japan) and point out its structural and chemical properties resemblance to palytoxin. This major constituent was named ostreocin-D and accounted for 90% of total toxicity of extracts. None of the other (more than 10) minor ostreocins present in the O. siamensis extracts were identical to palytoxin, as initially indicated by ESl-MS (Ukena et al. 2001, 2002). New Zealand O. siamensis isolates have also been reported to produce toxins exhibiting strong haemolytic activity and mouse lethality (Rhodes et al. 2000, 2002). Recently, Penna et al. (2005) have reported the presence of toxins with strong delayed haemolytic activity in Ostreopsis cf siamensis from the NW Mediterranean Sea. This haemolytic activity was inhibited by the palytoxin antagonist ouabain, indicating the palytoxin-like nature of these toxins. 

Ostreopsis ovata is the smallest species in the genus Ostreopsis. Its presence has been reported in numerous areas of the world such as the Pacific Ocean (Fukuyo 1981 Yasumoto et al. 1987), the Caribbean Sea (Tindall et al. 1990), the Brazilian coasts in the Atlantic Ocean (Graneli et al. 2002), and the Mediterranean Sea (Tognetto et al. 1995 Sansoni et al. 2003, Aligizaki et al. 2005 Penna etal. 2005). 

Ostreopsis mascarenensis was first identified in shallow (2-5 m) barrier reef enviromnents and coral reefs in the Southwest Indian Ocean and is the largest species of the genus (Quod 1994 ... 

Ostreopsis sp. have been suspected to be a source of palytoxin in cases of clupeotoxism (Yasumoto 1998 Onuma et al. 1999), and the Southwest Indian Ocean is a known clupeotoxism endemic zone (Hansen et al. 2001). It is therefore highly possible that O. mascarenensis, which is largely distributed in the western Indian Ocean, is involved in regional clupeotoxism incidents. 

Aligizaki, K., Koukaras, K., and Nikolaidis, G. 2005. The genus Ostreopsis in Greek coastal waters. International Workshop Ostreopsis Is It a Problem in the Mediterranean Sea Genova, Italy. 

Chang, F.H., Shimizu, Y, Hay, B., Stewart, R., Mackay, G., and Tasker, R. 2000. Three recently recorded Ostreopsis spp. (Dinophyceae) in New Zealand temporal and regional distribution in the upper North Island from 1995 to 1997. New... 

Faust, M.A., Morton, S.L., and Quod, JP 1996. Further SEM study of marine dinoflagellates the genus Ostreopsis (Dinophyceae). Journal ofPhycology 32(6) 1053-1065. 

Graneli, E., Ferreira, C.E.L., Yasumoto, T, Rodrigues, E., Maria, H., and Neves, B. 2002. Sea urchins poisoning by the benthic dinoflagellate Ostreopsis ovata on the Brazilian Coast. Book of A bstracts, 10th International Conference on Harmful Algae, Florida, USA, p. 113. 

Holmes, M.J., Gillepsie, N.C., and Lewis, R.J. 1988. Toxicity and morphology of Ostreopsis cf siamensis cultured from a ciguatera endemic region of Queensland, Australia. Proceedings of the 6th International Coral Reef Symposium 3 49-54. 

Lenoir, S., Ten-Hage, L., Turquet, J., Quod, J.-P., Bernard, C., and Hennion, M.C. 2004. First evidence of palytoxin analogues from an Ostreopsis mascarenensis (Dinophyceae) benthic bloom in southwestern Indian Ocean. Journal of Phycology 40(6) 1042-1051. 

Mercado, J.A., Viera, M., Escalona de Motta, G., Tosteson, T.R., Gonzalez, L, and Silva, W. 1994. An extraction procedure modification changes the toxicity, chromatographic profile and pharmacologic action of Ostreopsis lenticularis extracts. Toxicon 32(3) 256. 

Meunier, F.A., Mercado, J.A., Molg6, J., Tosteson, T.R., and Escalona de Motta, G. 1997. Selective depolarization of the muscle membrane in frog nerve-muscle preparations by a chromatographically purified extract of the dinoflagellate Ostreopsis lenticularis. British Journal of Pharmacology 121(6) 1224 —1230. 

Norris, D.R., Bomber, J. W, and Balech, E. 1985. Bendiic dinoflagellates associated widi ciguatera from die Florida Keys. I. Ostreopsis heptagona sp. nov. In Toxic Dinoflagellates, ed. Anderson, D.M., White, A.W., and Baden, D.G. New York Elsevier Scientific, 39-44. 

Penna, A., Vila, M., Fraga, S., Giacobbe, M.G., Andreoni, E, Riobo, P., and Vemesi, C. 2005. Characterization of Ostreopsis and Coolia (Dinophyceae) isolates in the western Mediterranean sea based on morphology, toxicity and internal h an-scribed spacer 5.8S rDNA sequences. Journal ofPhycology A y.2 2—225. 

Quod, IP. 1994. Ostreopsis mascarenensis sp. nov (Dinophyceae), dinoflagelle toxique associe a la ciguatera dans I Ocean Indien. CryptogamieAlgologie 15(4) 243-251. 

Rhodes, L., Towers, N., Briggs, L., Munday, R., and Adamson, J. 2002. Uptake of palytoxin-like compounds by shellfish fed Ostreopsis siamensis (Dinophyceae). New Zealand Journal of Marine and Freshwater Research 36(3) 631-636. 

Simoni, E, Gaddi, A., Di Paolo, C., Lepri, L., Mancino, A., and Falaschi, A. 2004. Further investigation on blooms of Ostreopsis ovata, Coolia monotis, Prorocentrum lima on the macroalgae of artificial and natural reefs in the Northern Tyrrhenian Sea. Harmful Algae News 26 5-7. 

Taniyama, S., Arakawa, O., Terada, M., Nishio, S., Takatani, T, Mahmud, Y, and Noguchi, T. 2003. Ostreopsis sp., a possible origin of palytoxin in parrotfish Scarus ovifrons. Toxicon 42(l) 29-33. 

Tindall, D.R., Miller, DM., and Tindall, PM. 1990. Toxicity of Ostreopsis lenticularis from the British and United States Virgin Islands. In Toxic Marine Phytoplankton, ed. Graneli, E., Sundstrom, B., Edier, L., and Anderson, DM. New York Elsevier, pp. 424 - 429. 

Tognetto, L., Bellato, S., Moro, L, and Andreoli, C. 1995. Occurrence of Ostreopsis ovata (Dinophyceae) in the Tyrrhenian... 

Ukena, T, Satake, M., Usami, M., Oshima, Y, Fujita, T, Kan, Y, and Yasumoto, T. 2001. Structure elucidation of ostreocin-D, a palytoxin analog isolated from the dinoflagellate Ostreopsis siamensis. Bioscience, Biotechnology and Biochemistry 65(ll) 2585-2588. 

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