Transfer of paralytic shellfish toxins via marine food chains: a simulated experiment.
OBJECTIVE
To study the transfer of paralytic shellfish toxins (PST) using four simulated marine food chains: dinoflagellate Alexandrium tamarense --> Artemia Artemia salina --> Mysid shrimp Neomysis awatschensis; A. tamarense --> N. awatschensis; A. tamarense --> A. salina --> Perch Lateolabrax japonicus; and A. tamarense --> L. japonicus.


METHODS
The ingestion of A. tamarense, a producer of PST, by L. japonicus, N. awatschensis, and A. salina was first confirmed by microscopic observation of A. tamarense cells in the intestine samples of the three different organisms, and by the analysis of Chl.a levels in the samples. Toxin accumulation in L. japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly through the vector of A. salina was then studied. The toxicity of samples was measured using the AOAC mouse bioassay method, and the toxin content and profile of A. tamarense were analyzed by the HPLC method.


RESULTS
Both A. salina and N. awatschensis could ingest A. tamarense cells. However, the ingestion capability of A. salina exceeded that of N. awatschensis. After the exposure to the culture of A. tamarense (2000 cells x mL(-1)) for 70 minutes, the content of Chl.a in A. salina and N. awatschensis reached 0.87 and 0.024 microg x mg(-1), respectively. Besides, A. tamarense cells existed in the intestines of L. japonicus, N. awatschensis and A. salina by microscopic observation. Therefore, the three organisms could ingest A. tamarense cells directly. A. salina could accumulate high content of PST, and the toxicity of A. salina in samples collected on days 1, 4, and 5 of the experiment was 2.18, 2.6, and 2.1 MU x g(-1), respectively. All extracts from the samples could lead to death of tested mice within 7 minutes, and the toxin content in artemia sample collected on the 1st day was estimated to be 1.65 x 10(-5) microg STX equal/individual. Toxin accumulation in L. japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly from the vector of A. salina was also studied. The mice injected with extracts from L. japonicus and N. awatschensis samples that accumulated PST either directly or indirectly showed PST intoxication symptoms, indicating that low levels of PST existed in these samples.


CONCLUSIONS
Paralytic shellfish toxins can be transferred to L. japonicus, N. awatschensis, and A. salina from A. tamarense directly or indirectly via the food chains.
Tan
Zhi-Jun
ZJ
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, Shandong, China. zhijuntandy@hotmail.com
Yan
Tian
T
Yu
Ren-Cheng
RC
Zhou
Ming-Jiang
MJ
D000818:Animals; D001156:Artemia / Q000187:drug effects; D002452:Cell Count; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D056890:Eukaryota / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects; D005399:Fishes; D020387:Food Chain; D006868:Hydrolysis; D008387:Marine Toxins / Q000032:analysis* / Q000378:metabolism* / Q000633:toxicity; D051379:Mice; D008954:Models, Biological; D008974:Mollusca / Q000737:chemistry*; D010243:Paralysis / Q000139:chemically induced
D008387:Marine Toxins; D002734:Chlorophyll; D000077194:Chlorophyll A