Possibility of Toxin Profiles From Paralytic Shellfish Poisoning

Possibility of Toxin Profiles From Paralytic Shellfish Poisoning as Geographical Markers in Algae Populations Jenny Mc. Cartney

Paralytic Shellfish Poisoning n Definition – Paralytic shellfish poisoning (PSP) is a nervous system disease caused by eating cooked or raw shellfish that contain environmental toxins. – The toxins are not destroyed by cooking, freezing or pickling. – It persists due to the life cycle of algae, they form dormant cysts that sink into the sediment when conditions are unfavorable and then bloom when the conditions become favorable again.

Paralytic Shellfish Poisoning n n n There about 1600 cases of PSP reported per year with about 300 resulting in death (~19% mortality). PSP occurs primarily in temperate seas but it is quickly spreading and outbreaks have been reported in tropical to boreal waters. PSP affects more coastline than any other harmful algae bloom problem.

Map of PSP events 1988 -1998

Symptoms of PSP n n Neurological symptoms dominate because the algae produce neurotoxins that block sodium conductance in nerve and muscle tissue. Symptoms include tingling or burning sensations of lips, face and extremities that may progress to numbness and lightheadedness, a floating sensation, weakness, incoherence, thirst, headache, temporary blindness, respiratory failure due to paralysis and death.

Cause of PSP n Dinoflagellates in the genera: – Alexandrium – Gymnodinium – Pyrodinium – Gonyaulax n Primary toxins they produce: – Saxitoxin – Brevetoxin – Ciguatoxin

Alexandrium n Alexandrium cysts Alexandrium catenella Alexandrium tamarense

Gymnodinium n Gymnodinium spp. Gymnodinium catenatum

How does PSP affect you? n n Shellfish Industry – Our rate of consumption of mollusks is increasing and probably will continue to increase due to the rapidly increasing population and the growing demand for protein food resources. Closure of fisheries and beaches – Costs money, not only to be closed but to fix the problem, not to mention it ruins these leisurely activities.

Shellfish Warning Sign

How does it affect you? , cont. n n Public Health – People get sick (the maximum safe level is 80 µg toxin/100 g fish = 0. 8 ppm). – PSP bioaccumulates in the food chain (not only has it been documented in filter feeding bivalves but also in crabs, gastropods, mackerel and planktivorous fish). Costs – Shellfish and algae monitoring programs, health care costs, money lost due to fisheries and beaches being closed, and losses to the shellfish industry.

Paralytic Shellfish Poisoning n The geographic distribution of PSP is increasing. n Suspected reasons for this are: – Long term climatic variability that affects the temperature, upwelling and currents that allow cysts to survive in areas where they did not before. – Coastal currents carrying them to new places. – Traveling in ship ballast water.

Paralytic Shellfish Poisoning n n Due to all of the ways this problem affects people it is becoming increasingly essential for us to determine how to trace global dispersal’s of these different populations of dinoflagellates causing PSP. Why? -To find a solution.

Papers Studied to Provide Evidence for the Possibility of Toxin Profiles as Geographical Markers in Algae Populations n “Geographic Differences in Paralytic Shellfish Poisoning Toxin Profiles Among Japanese Populations of Alexandrium tamarense and A. catenella (Dinophyceae)” by Yoshido, Sako and Uchida published in the journal Phycological Research in 2001. n “Singapore Isolates of the Dinoflagellate Gymnodinium catenatum (Dinophyceae) Produce A Unique Profile of Paralytic Shellfish Poisoning Toxins” by Holmes, Bolch, Green, Cembella and Teo published in the Journal of Phycology in 2002. n “Paralytic Shellfish Poisoning In Northwest Spain: The Toxicity Of The Dinoflagellate Gymnodinium catenatum” by Anderson, Sullivan and Reguera published in the journal Toxicon in 1989.

Summary of Findings of Support From All Three Studies n n A. tamarense and A. catenella toxin profiles were rather constant within a geographical area and divergent among different geographical areas. Only a few groups of isolates with different toxin profiles were observed in a geographical area (suggesting that several representative isolates express the genotype in a given region). Toxin composition has been found to have a genetic basis. Diversity of toxin profile related to regional populations has been reported in isolates from Japan, North America, the northeastern Pacific, eastern Canada, Portugal, UK and New Zealand.

Summary of Findings of Support From All Three Studies, cont. n n Toxin profile was conserved within a region, and major toxin components of isolates within a region were almost identical (although their ratios varied). Comparison of planktonic isolates from Australia, China, Japan, the Philippines, Portugal, Spain and Uruguay indicate minor but geographically consistent differences in the toxin profiles. Genetic and morphological analysis of laboratory cultures of G. catenatum in the Singapore isolate illustrated that it exhibited a unique toxin profile that is distinguishable from those of other known global populations of this species. The mixture of saxitoxin and its derivatives in a dinoflagellate strain does not vary significantly with growth stage or nutrient status.

Summary of Observations Illustrating Toxicity Is Not A Foolproof Marker For Specific Geographic Populations n n n Differences in cellular toxicity of populations among neighboring geographical regions were rather small. Toxin contents, which are positively correlated to cellular toxicity, have been reported to vary dependent on growth phase or environmental factors. Relatively few investigations of diversity within a geographical region in the same year or among different years have been conducted.

Conclusions n n Since PSP outbreaks are a major problem and are only increasing in both incidence and geographical spread, a solution is becoming imminently necessary. Improved surveillance on specific dinoflagellate populations to better understand how and where they are spreading will more effectively and quickly lead us to strategies for the prevention and control of PSP. This is why there has been a fairly new focus on examining whether toxin profiles can be used as markers to track populations from specific geographical areas. From these papers the use of toxin profiles as geographic markers looks promising, although not foolproof, and in the absence of an appropriate molecular technique it has proven to be the finest biochemical marker to discriminate between populations from different geographical areas so far.

Literature Cited n n n Anderson, Donald M. , John J. Sullivan and Beatriz Reguera. “Paralytic Shellfish Poisoning In Northwest Spain: The Toxicity of the Dinoflagellate Gymnodinium catenatum. ” Toxicon 27 No. 6 (1989): 665 -674. Falconer, Ian R, ed. Algal Toxins in Seafood and Drinking Water. London: Academic Press, 1993. Halstead, Bruce W and E. J. Schantz. Paralytic Shellfish Poisoning. Geneva: World Health Organization, 1984. Holmes, Michael J. , Christopher J. S. Bolch, David H. Green, Allan D. Cembella and Serena Lay Ming Teo. “Singapore Isolates of the Dinoflagellate Gymnodinium catenatum (Dinophyceae) Produce A Unique Profile of Paralytic Shellfish Poisoning Toxins. ” Journal of Phycology 38 No. 1 (2002): 96 -106. Sze, Philip. A Biology of the Algae. Boston: WCB/Mc. Graw-Hill, 1998. Yoshido, Takashi, Yoshihiko Sako and Aritsune Uchida. “Geographic differences in paralytic Shellfish poisoning toxin profiles among Japanese populations of Alexandrium tamarense and A. catenella (Dinophyceae). ” Phycological Research 49 No. 1 (2001): 13 -21.