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PubMed1989

Domoic acid poisoning and mussel-associated intoxication: preliminary investigations into the response of mice and rats to toxic mussel extract.

Consumption of cultivated blue mussels from Prince Edward Island was recently associated with episodes of gastro-intestinal and neurological distress. Extracts of the toxic mussels, tested in the mouse bioassay for paralytic shellfish poison, caused an atypical response characterized by scratching, convulsions and death. The present investigation shows that the domoic acid present in toxic mussels can produce in mice and rats signs identical to those induced by mussel extracts. These studies, preliminary in nature by virtue of the scarcity of domoic acid, gave ip no-effect levels in mice of 0.59 mg/kg body weight based on the behavioural response (scratching) and 2.4 mg/kg for death. These levels correspond to levels of 24 and 94 ppm in mussels. When administered orally doses of between 35 and 70 mg domoic acid/kg body weight were required to produce toxicity in mice and rats. This reduced toxicity is consistent with a lack of absorption from the gastro-intestinal tract: faecal excretion accounted for 102 +/- 17% and 98 +/- 12% (mean +/- SE) of the domoic acid administered to mice and rats, respectively. Since human intoxication occurred at an estimated 1-5 mg domoic acid/kg body weight, susceptible individuals appear to be more sensitive than rodents to the oral toxicity of domoic acid.

Animals↗

PubMed2001

A functional assay for paralytic shellfish toxins that uses recombinant sodium channels.

Saxitoxin (STX) and its derivatives are highly toxic natural compounds produced by dinoflagellates commonly present in marine phytoplankton. During algal blooms ("red tides"), shellfish accumulate saxitoxins leading to paralytic shellfish poisoning (PSP) in human consumers. PSP is a consequence of the high-affinity block of voltage-dependent Na channels in neuronal and muscle cells. PSP poses a significant public health threat and an enormous economic challenge to the shellfish industry worldwide. The standard screening method for marine toxins is the mouse mortality bioassay that is ethically problematic, costly and time-consuming. We report here an alternative, functional assay based on electrical recordings in cultured cells stably expressing a PSP target molecule, the STX-sensitive skeletal muscle Na channel. STX-equivalent concentration in the extracts was calibrated by comparison with purified STX, yielding a highly significant correlation (R=0.95; N=30) between electrophysiological determinations and the values obtained by conventional methods. This simple, economical, and reproducible assay obviates the need to sacrifice millions of animals in mandatory paralytic shellfish toxin screening programs.

Animals↗

PubMed2002

First evidence on occurrence of gymnodimine in clams from Tunisia.

Among several batches of clams harvested in Tunisia and imported to France, a small number of them were found to be neurotoxic to mice (intraperitoneal injection) as determined by the diarrhetic shellfish poisoning (DSP) bioassay developed by Yasumoto et al. (1978). The present study was conducted to confirm the nature of the toxic agent, suspected to be gymnodimine. Liquid chromatography tandem mass spectrometry analyses unequivocally revealed the presence of gymnodimine in the shellfish, making Tunisia the second country, after New Zealand, where shellfish contamination with this phycotoxin is reported. Gymnodimine B and C analogues were not detected in the clam samples. Gymnodimine preferentially accumulates in the digestive gland of the Tunisian clams, although substantial amounts are also found in the meat.

Animals↗

PubMed2006

Ecological characterization of toxic phytoplankton species (Dinophysis spp., Dinophyceae) in Slovenian mariculture areas (Gulf of Trieste, Adriatic Sea) and the implications for monitoring.

Diarrhetic shellfish poisoning (DSP) events are often registered in Slovenian mariculture areas (Gulf of Trieste, Adriatic Sea) and are related to the occurrence of Dinophysis spp. The annual dynamic of this genus and succession of the most important species were studied at two shellfish farms during monitoring fieldwork in the period 1995-2003. Results indicate that the Dinophysis genus maintains a relatively stable inter-annual dynamic at both sites. The Dinophysis community is characterized by two surface maxima in June and September, while in the middle layer only the autumn peak is pronounced (peak median 92 cells l(-1)). Occasional abundance maxima of around 2000 cells l(-1) in the surface layer indicate that potential outbursts of toxic species are less predictable than their seasonal dynamic. On the basis of multivariate analysis, Dinophysis sacculus was characterized as a typical late spring-early summer species, and Dinophysis caudata and Dinophysis fortii as autumn species. Correlation analysis revealed the influence of stratified conditions only on the most abundant species, D. sacculus. Ecological characteristics of the species were combined with shellfish safety requirements towards a more effective monitoring.

Animals↗

PubMed2000

Paralytic shellfish toxins in the freshwater cyanobacterium Aphanizomenon flos-aquae, isolated from Montargil reservoir, Portugal.

Montargil reservoir, located in a dry flat area in the centre of Portugal, was filled in 1958 to fulfil agricultural, electric and industrial requirements. In May 1996, an intensive bloom of phytoplankton was detected. The algal community was strongly dominated by cyanobacteria with predominance of Aphanizomenon flos-aquae from May to June and Microcystis aeruginosa from July to August. Extracts of samples collected during the bloom period showed high toxicity by mouse bioassay. During the M. aeruginosa predominance period, the toxicity was ascribed to the presence of hepatotoxins, but clear symptoms of paralytic shellfish poison were observed when A. flos-aquae was the dominant species. In order to confirm the production of neurotoxins a strain of A. flos-aquae was isolated and established in culture. In this manuscript, we show the morphological characteristics and confirm paralytic shellfish toxins production by the strain isolated and maintained in culture. Identification of the saxitoxin analogs was achieved using high performance liquid chromatography with postcolumn fluorescence derivatization (HPLC-FLD) and liquid chromatographic mass spectrometry technique (LC-MS). The toxins found in the culture extract were GTX5 (64.5 mol%), neoSTX (23.0 mol%), dcSTX (6.1 mol%), STX (5.4 mol%) and GTX6 (1.1 mol%). This is, to our knowledge, the first report of unambiguous evidence of paralytic shellfish toxins produced by freshwater cyanobacteria in Portugal. The toxin profile is rather different from the previously reported PSP producing A. flos-aquae and demonstrates its diversity in terms of toxin production.

Animals↗

PubMed2003

Comparison of different fluorimetric HPLC methods for analysis of acidic polyether toxins in marine phytoplankton.

The human toxic syndrome, diarrhetic shellfish poisoning (DSP), is caused by polyether toxins that are present in bivalve molluscs but originate from some species of marine phytoplankton. During the last few years different HPLC methods with fluorescence detection (FLD) have been proposed for analysis of marine toxins, including polyether toxins, in shellfish and phytoplankton. Several derivatization reagents have been proposed in the literature, with the aim of converting the acidic DSP toxins into their corresponding fluorescent derivatives. In this work we report results obtained from HPLC-FLD analysis of extracts from phytoplankton, including Dinophysis spp.,harvested off the south-west coast of Ireland. Three different reagents were used for fluorescent derivatization: 3-bromomethyl-6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone (BrDMEQ), 9-chloromethylanthracene (CA), and "in situ" 9-anthracenyldiazomethane (ADAM). Derivatization was performed under conditions previously optimised. The DSP derivatives were cleaned using different SPE procedures then analysed by HPLC-FLD. In this study, the use of BrDMEQ, CA, and "in situ" ADAM was compared in terms of sensitivity and selectivity. Evaluation of HPLC methods for analysis of DSP toxin derivatives was also conducted; the presence of okadaic acid (OA), dinophysistoxin-2 (DTX-2), and pectenotoxin-2 seco acids (PTX1SAs) was detected in the sample extracts studied.

Animals↗

PubMed2001

Influence of amino acids on okadaic acid production.

Okadaic acid (OA) (1)) was the first example of a group of polyether toxins known to be produced by marine microalgae, which are responsible for the natural phenomena known as Diarrhetic Shellfish Poisoning (DSP) red tides. It is also a highly selective inhibitor of protein phosphatases type 1 (PP1) and 2A (PP2A), as well as being a potent tumour promoter. For these reasons, OA is an extremely useful tool for studying cellular processes and an important standard for polluted shellfish control. In this paper, we report on a double objective: to improve the production of toxins and verify the apparent participation of amino acids in the formation of these polyethers by monitoring their influence on the promotion of growth, total cell yield and increased in toxicity in Prorocentrum lima of the PL2V strain in batch cultures, in a modified K medium.

Amino Acids↗

PubMed2006

Saxitoxin puffer fish poisoning in the United States, with the first report of Pyrodinium bahamense as the putative toxin source.

BACKGROUND: From January 2002 to May 2004, 28 puffer fish poisoning (PFP) cases in Florida, New Jersey, Virginia, and New York were linked to the Indian River Lagoon (IRL) in Florida. Saxitoxins (STXs) of unknown source were first identified in fillet remnants from a New Jersey PFP case in 2002. METHODS: We used the standard mouse bioassay (MBA), receptor binding assay (RBA), mouse neuroblastoma cytotoxicity assay (MNCA), Ridascreen ELISA, MIST Alert assay, HPLC, and liquid chromatography-mass spectrometry (LC-MS) to determine the presence of STX, decarbamoyl STX (dc-STX), and N-sulfocarbamoyl (B1) toxin in puffer fish tissues, clonal cultures, and natural bloom samples of Pyrodinium bahamense from the IRL. RESULTS: We found STXs in 516 IRL southern (Sphoeroides nephelus), checkered (Sphoeroides testudineus), and bandtail (Sphoeroides spengleri) puffer fish. During 36 months of monitoring, we detected STXs in skin, muscle, and viscera, with concentrations up to 22,104 microg STX equivalents (eq)/100 g tissue (action level, 80 microg STX eq/100 g tissue) in ovaries. Puffer fish tissues, clonal cultures, and natural bloom samples of P. bahamense from the IRL tested toxic in the MBA, RBA, MNCA, Ridascreen ELISA, and MIST Alert assay and positive for STX, dc-STX, and B1 toxin by HPLC and LC-MS. Skin mucus of IRL southern puffer fish captive for 1-year was highly toxic compared to Florida Gulf coast puffer fish. Therefore, we confirm puffer fish to be a hazardous reservoir of STXs in Florida's marine waters and implicate the dinoflagellate P. bahamense as the putative toxin source. CONCLUSIONS: Associated with fatal paralytic shellfish poisoning (PSP) in the Pacific but not known to be toxic in the western Atlantic, P. bahamense is an emerging public health threat. We propose characterizing this food poisoning syndrome as saxitoxin puffer fish poisoning (SPFP) to distinguish it from PFP, which is traditionally associated with tetrodotoxin, and from PSP caused by STXs in shellfish.

Animals↗

PubMed2001

A cytotoxicity assay for the detection and differentiation of two families of shellfish toxins.

There is an urgent need for an alternative to the mouse bioassay for the detection of algal toxins in shellfish on both analytical and animal welfare grounds. Several alternative methodologies have been described, but have not gained widespread acceptance to date, because each assay measures only one or a small number of related phycotoxins out of the increasing range that needs to be detected. A simple cytotoxicity assay using either the HepG2 or ECV-304 cell lines is described with two end-point measurements, which can detect and distinguish between two unrelated classes of phycotoxins. Morphological examination following 3h exposure to the sample enables the detection of the diarrhetic shellfish poisons, including okadaic acid and related toxins. Viability testing using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide), following 24h exposure of the same cells to the sample, reveals a second class of toxin, which is most probably the newly-described toxin, azaspiracid. This assay should play an important role in shellfish monitoring in the future.

Animals↗

PubMedDate not supplied

Determination of diarrheic shellfish toxins in mussels by microliquid chromatography-tandem mass spectrometry.

A fast, sensitive, and specific procedure for determining toxins that cause diarrheic shellfish poisoning (DSP) using microliquid chromatography coupled with tandem mass spectrometry (micro-LC-MS-MS) is reported. The lipophylic polyether acidic toxins okadaic acid (OA), its isomer dinophysistoxin-2 (DTX-2), the 35-methylokadaic acid dinophysistoxin-1 (DTX-1), and the novel toxin dinophysistoxin-1B (DTX-2B; recently isolated from Irish mussels) were extracted from shellfish tissues with acetone and chromatographed by isocratic elution at 10 microL/min with CH3 CN-H2O, 80 + 20 (v/v), containing 0.1% trifluoroacetic acid, through a C18 reversed-phase column (1.0 mm id). The chromatograph is coupled via an ion spray interface to an atmospheric pressure ionization source. Collision-induced-dissociation (CID) ion mass spectra of the protonated molecule, [M + H]+, at m/z 805 for OA, DTX-2, and DTX-2B and at m/z 819 for DTX-1, were obtained in MS-MS experiments to identify 2 diagnostic fragment ions for each analyte that could be used for selected-reaction-monitoring (SRM) micro-LC-MS-MS analysis. The CID spectrum of DTX-2B confirmed it to be a new OA isomer, like DTX-2. Standard curves obtained by SRM micro-LC-MS-MS were linear (r2 > or = 0.9992) over the range 0.05-1.00 micrograms/mL (i.e., 0.10-2.00 micrograms toxin/g hepatopancreas), and a detection limit of 15 pg/injection was obtained for each DSP toxin. Average recoveries ranged from 95 to 101%, and coefficients of variation ranged from 1.8 to 3.4%. This novel SRM micro-LC-MS-MS method was used to confirm acidic DSP toxins in Irish and Italian toxic mussels. It offers a high degree of specificity because analyte confirmation is based on retention time, molecular weight, structural information obtained from the presence of 2 diagnostic fragments for each analyte, and ion ratios. OA was found in both Irish (< or = 0.7 micrograms/g hepatopancreas) and Italian (< or = 1.5 micrograms/g hepatopancreas) mussels. DTX-1 was found only in Italian mussels (< or = 0.3 micrograms/g hepatopancreas). DTX-2 (< or = 6.1 micrograms/g hepatopancreas) and DTX-2B (< or = 0.08 micrograms/hepatopancreas) were unique to Irish shellfish.

Animals↗

PubMed1985

Occurrence of a water soluble toxin in a parrotfish (Ypsiscarus ovifrons) which is probably responsible for parrotfish liver poisoning.

The liver of the parrotfish Ypsiscarus ovifrons sometimes causes severe muscle pain, paralysis and dyspnea when ingested by humans. Individual livers, ovaries and digestive tracts and their contents were examined for lethal potency in mice. They were all toxic, except for livers obtained from April to June. Lethal potency ranged from 0.25 to 5.0 MU/g tissue. Livers were extracted with acidic aqueous ethanol and the extracts purified by charcoal treatment, gel filtration and partition and reversed phase column chromatography. Both the crude and partially purified toxin showed chemical and/or pharmacological properties different from those of tetrodotoxin or paralytic shellfish poisons.

Animals↗

PubMed2001

Ciguatera poisoning: a global issue with common management problems.

Ciguatera poisoning, a toxinological syndrome comprising an enigmatic mixture of gastrointestinal, neurocutaneous and constitutional symptoms, is a common food-borne illness related to contaminated fish consumption. As many as 50000 cases worldwide are reported annually, and the condition is endemic in tropical and subtropical regions of the Pacific Basin, Indian Ocean and Caribbean. Isolated outbreaks occur sporadically but with increasing frequency in temperate areas such as Europe and North America. Increase in travel between temperate countries and endemic areas and importation of susceptible fish has led to its encroachment into regions of the world where ciguatera has previously been rarely encountered. In the developed world, ciguatera poses a public health threat due to delayed or missed diagnosis. Ciguatera is frequently encountered in Australia. Sporadic cases are often misdiagnosed or not medically attended to, leading to persistent or recurrent debilitating symptoms lasting months to years. Without treatment, distinctive neurologic symptoms persist, occasionally being mistaken for multiple sclerosis. Constitutional symptoms may be misdiagnosed as chronic fatigue syndrome. A common source outbreak is easier to recognize and therefore notify to public health organizations. We present a case series of four adult tourists who developed ciguatera poisoning after consuming contaminated fish in Vanuatu. All responded well to intravenous mannitol. This is in contrast to a fifth patient who developed symptoms suggestive of ciguatoxicity in the same week as the index cases but actually had staphylococcal endocarditis with bacteraemia. In addition to a lack of response to mannitol, clinical and laboratory indices of sepsis were present in this patient. Apart from ciguatera, acute gastroenteritis followed by neurological symptoms may be due to paralytic or neurotoxic shellfish poisoning, scombroid and pufferfish toxicity, botulism, enterovirus 71, toxidromes and bacteraemia. Clinical aspects of ciguatera toxicity, its pathophysiology, diagnostic difficulties and epidemiology are discussed.

Adult↗

PubMed1998

Occurrence of okadaic acid-producing Prorocentrum lima on the Sanriku coast, northern Japan.

Prorocentrum lima was found to be distributed on the surface of the algae, Sargassum confusum and Carpopeltis flabellata collected at the Sanriku coast, northern Japan. Chemical analysis of cultured cells revealed that Sanriku strains of P. lima produce okadaic acid, a toxin responsible for diarrhetic shellfish poisoning. The Sanriku strain grew well in T1 medium at 15 degrees C at which tropical strains do not grow, indicating that it is a local strain which adapts to cooler environments.

Adaptation, Biological↗

PubMed2000

New fluorimetric method of liquid chromatography for the determination of the neurotoxin domoic acid in seafood and marine phytoplankton.

Domoic acid (DA) is a neurotoxic amino acid that is responsible for the human toxic syndrome, amnesic shellfish poisoning (ASP). A new rapid, sensitive liquid chromatographic (LC) method has been developed for the determination of DA in various marine samples. DA in marine biological materials was derivatised with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and analysed using isocratic reversed-phase LC with fluorimetric detection. The calibration, based on standard DA solutions, was linear in the range 0.04-2 microg/ml (r2=0.998) and the detection limit (3:1, signal/noise) was better than 1 ng/ml. Using the certified reference material (MUS-1B), recoveries of DA from shellfish tissue were >95% (n=5). When a strong anion exchange SPE cartridge was used for sample clean-up the detection limit was 6 ng DA/g mussel tissue. Good reproducibility was achieved with RSD values ranging from 3% for 8 microg DA/g (n=5), to 5% for 0.04 microg DA/g (n=5). This new method was successfully applied to the determination of DA in naturally contaminated shellfish and in marine phytoplankton cultures of Pseudonitzschia sp.

Chromatography, Liquid↗

PubMed1982

Gonyautoxin associated with RNA-containing fraction in the toxic scallop digestive gland.

A nontoxic high molecular substance associated with some paralytic shellfish poisons was separated by Sephadex G-50 gel filtration from the toxic digestive glands of the scallop Patinopecten yessoensis fed the causative plankton Protogonyaulax tamarensis. Unlike the corresponding fraction from the nontoxic digestive glands, the substance released gonyautoxins II and III on digestion with RNase T2, suggesting that it is associated with an RNA of P. tamarensis. It is possible that the toxification of scallop is partly due to the toxins already accumulated in Protogonyaulax cells, and partly due to incorporation of this precursor, which releases the toxins as a result of enzymic processes in the shellfish.

Animals↗

PubMed2004

High affinity for the rat brain sodium channel of newly discovered hydroxybenzoate saxitoxin analogues from the dinoflagellate Gymnodinium catenatum.

The paralytic shellfish poison family has been recently extended by the discovery of several analogues possessing a hydoxybenzoate moiety instead of the carbamoyl group one finds in saxitoxin, the parent molecule of this toxin family. We have investigated the potency of these new analogues on a representative isoform of the pharmacological target of these toxins, the voltage gated sodium channel. These toxins were found to have K1's in the low nanomolar range, only slightly less potent than saxitoxin. The hydroxybenzoate group may increase the lipophilicity of these toxins and improve their ability to pass through epithelia and therefore its uptake and elimination in both intoxication victims and animals that bioaccumulate paralytic shellfish toxins.

Animals↗

PubMed2005

Health risk assessment of cyanobacterial (blue-green algal) toxins in drinking water.

Cyanobacterial toxins have caused human poisoning in the Americas, Europe and Australia. There is accumulating evidence that they are present in treated drinking water supplies when cyanobacterial blooms occur in source waters. With increased population pressure and depleted groundwater reserves, surface water is becoming more used as a raw water source, both from rivers and lakes/reservoirs. Additional nutrients in water which arise from sewage discharge, agricultural run-off or storm water result in overabundance of cyanobacteria, described as a 'water bloom'. The majority of cyanobacterial water-blooms are of toxic species, producing a diversity of toxins. The most important toxins presenting a risk to the human population are the neurotoxic alkaloids (anatoxins and paralytic shellfish poisons), the cyclic peptide hepatotoxins (microcystins) and the cytotoxic alkaloids (cylindrospermopsins). At the present time the only cyanobacteral toxin family that have been internationally assessed for health risk by the WHO are the microcystins, which cause acute liver injury and are active tumour promoters. Based on sub-chronic studies in rodents and pigs, a provisional Guideline Level for drinking water of 1 microg/L of microcystin-LR has been determined. This has been adopted in legislation in countries in Europe, South America and Australasia. This may be revised in the light of future teratogenicity, reproductive toxicity and carcinogenicity studies. The other cyanobacterial toxin which has been proposed for detailed health risk assessment is cylindrospermopsin, a cytotoxic compound which has marked genotoxicity, probable mutagenicity, and is a potential carcinogen. This toxin has caused human poisoning from drinking water, and occurs in water supplies in the USA, Europe, Asia, Australia and South America. An initial health risk assessment is presented with a proposed drinking water Guideline Level of 1 microg/L. There is a need for both increased monitoring data for toxins in drinking water and epidemiological studies on adverse health effects in exposed populations to clarify the extent of the health risk.

Bacterial Toxins↗

PubMed1975

Health hazards of bivalve-mollusk ingestion.

Bivalve mollusks (oysters, clans, and mussels) filter large quantities of water unselectively and thereby may concentrate a variety of aquatic contaminants pathogenic for man within edible shellfish viscera. The recognized bacterial disease associated with ingestion of contaminated bivalves include typhoid fever (not presently a public health problem), Vibrio parahemolyticus gastroenteritis, and Vibrio chloerae infection. The major known shellfish-associated viral diseases are viral hepatitis and possibly viral gastroenteritis. The ingestion of bivalves that have fed on the toxic species of dinoflagellates that produce red tides may be responsible for an uncommon and very rarely fatal illness, paralytic shellfish poisoning. Outbreaks of airborne respiratory irritation in populations exposed to red tides may be the most common public health problem associated with red tides. The health hazards resulting from industrial, agricultural, and oil pollution of bivalves in coastal waters and the hazard from improper handling of bacterially contaminated mollusks remain to be defined.

Animals↗