Causative Organism: Ostreopsis spp.

Approximate Size: 26-65 μm in diameter to 13-50 μm in width (3)

Toxicity: 4μg of PTX is estimated to be toxic to humans (4,14*)

Mode of Activity: Acts through the Na+ and K+-ATPase  pump of cell membranes by converting the enzyme into a cation-selective ion channel (10*, 11, 12, 13)

Geographic range: Tropical–subtropical to temperate waters (15,18, 19, 20, 21, 14*)

Species:

O. heptagona, O. labens, O. lenticularis, O. mascarenensis, O. ovata, and O. siamenses (22*)

Impacts of Toxin

Marine Food Web:

Toxin is believed to be bio-magnified and/or bio-transformed up the food web (3*, 10)

Behavioral: PTX has been detected in crabs (5, 6), various fish (7, 8) and a sea anemone (9) without causing any deleterious effects (3*)

Economic:

Since 2003, restrictions on shellfish-harvesting activity in Greek coastal waters occur when positive DSP (Diarrhetic Shellfish Poisoning) samples are detected from shellfish (14)
The Italian tourism industry sustains considerable economic losses during during Ostreopsis blooms (14)
Constrains subsidence fishing and use of near-shore fisheries for export (24)

Human Health

Name of Malody: Diarrhetic Shellfish Poisoning (DSP)

Symptoms:  
Consumption: malaise, uncontrollable vomiting, diarrhea, tingling of extremities, delirium, and death (24).
Inhalation: rhinorrea, cough, fever, bronchoconstriction, mild dyspnea, and wheezing (14*, 23).
Topical Exposure: Skin irritations (3*)

Incidents: (23)

 *and references cited therein.  **MU (mouse unit): the amount of crude toxin that will kill a 20-gm in 15 minutes, or the LD50 of the population in 24 hours

References

1. Moore, R.E. & Bartolini, G., 1981. Structure of PTX. Journal of the American Chemical Society, 103(9), 2491-2494.
2. Usami, M. et al., 1995. PTX analogs from the dinoflagellate Ostreopsis siamensis. Journal of the American Chemical Society, 117(19), 5389-5390.
3. Aligizaki, K. & Nikolaidis, G., 2006. The presence of the potentially toxic genera Ostreopsis and Coolia (Dinophyceae) in the North Aegean Sea, Greece. Harmful algae, 5(6), 717–730.  
4. Taniyama, S. et al., 2002. Occurrence of a food poisoning incident by PTX from a serranid Epinephelus sp. Japan. J Nat Toxins, 11, 277–282.
5. Yasumoto, T. et al., 1986. PTX in two species of xanthid crab from the Philippines. Agricultural and Biological Chemistry, 50(1), 163–167.  
6. Lau, C.O. et al., 1995. Lophozozymus pictor toxin: a fluorescent structural isomer of PTX. Toxicon, 33(10), 1373–1377.
7. Fukui, M. et al., 1987. Occurrence of PTX in the trigger fish Melichtys vidua. Toxicon, 25(10), 1121–1124.
8. Kodama, A.M. et al., 1989. Clinical and laboratory findings implicating PTX as cause of ciguatera poisoning due to Decapterus macrosoma (mackerel). Toxicon, 27(9), 1051–1053.
9. Mahnir, V.M., Kozlovskaya, E.P. & Kalinovsky, A.I., 1992. Sea anemone Radianthus macrodactylus–a new source of PTX. Toxicon, 30(11), 1449–1456.
10. Gleibs, S. & Mebs, D., 1999. Distribution and sequestration of PTX in coral reef animals. Toxicon, 37(11), 1521-1527.
11.  Habermann, E., 1989. PTX acts through Na+, K+-ATPase. Toxicon, 27(11), 1171–1187.
12. Scheiner-Bobis, G. et al., 1994. PTX induces K+ efflux from yeast cells expressing the mammalian sodium pump. Molecular pharmacology, 45(6), 1132.
13. Hirsh, J.K. & Wu, C.H., 1997. PTX-induced single-channel currents from the sodium pump synthesized by in vitro expression. Toxicon, 35(2), 169-176.
14. Aligizaki, K. et al., 2008. First episode of shellfish contamination by PTX-like compounds from Ostreopsis species (Aegean Sea, Greece). Toxicon, 51(3), 418–427.
15. Tognetto, L. et al., 1995. Occurrence of Ostreopsis ovata (Dinophyceae) in the Tyrrhenian Sea during summer 1994. Botanica marina, 38(1-6), 291–296.
16. Faust, M.A., 1999. Three new Ostreopsis species (Dinophyceae): O. marinus sp. nov., O. belizeanus sp. nov., and O. caribbeanus sp. nov. Phycologia, 38(2), 92-99.
17. Faust, M.A., Morton, S.L. & Quod, J.P., 1996. Further SEM study of marine dinoflagellates: the genus Ostreopsis (Dinophyceae). Journal of Phycology, 32(6), 1053–1065.
18. Vila, M. et al., 2001. High Resolution Spatio-temporal Detection of Potentially Harmful Dinoflagellates in Confined Waters of the NW Mediterranean. Journal of Plankton Research, 23(5), 497-514.
19. Penna, A. et al., 2005. Characterization of Ostreopsis and Coolia (Dinophyceae) isolates in the Western Mediterranean Sea based on morphology, toxicity and internal transcribed spacer 5.8 S rDNA sequences. Journal of phycology, 41(1), 212–225.
20. Ismael, A.A. & Halim, Y., 2006. First record of Ostreopsis spp. In Egyptian waters with a description of O. mediterraneus n. sp. 12th International Conference on Harmful Algae, Copenhagen.
21. Penna, A. et al., 2010. A phylogeographical study of the toxic benthic dinoflagellate genus Ostreopsis Schmidt. Journal of Biogeography, 37(5), 830–841.
22. Rhodes, L., 2010. World-wide occurrence of the toxic dinoflagellate genus Ostreopsis Schmidt. Toxicon.
23. Ciminiello, P. et al., 2006. The Genoa 2005 Outbreak. Determination of Putative PTX in Mediterranean Ostreopsis ovata by a New Liquid Chromatography Tandem Mass Spectrometry Method. Analytical Chemistry, 78(17), 6153-6159.
24. Onuma, Y. et al., 1999. Identification of putative PTX as the cause of clupeotoxism. Toxicon, 37(1), 55-65.