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Confirmation of okadaic acid, dinophysistoxin-1 and dinophysistoxin-2 in shellfish as their anthrylmethyl derivatives using UV radiation.

A rapid and simple method for confirmation of the diarrhetic shellfish poisons (DSP): okadaic acid (OA), dinophysistoxin-1 (DTX-1) and dinophysistoxin-2 (DTX-2) using fluorescence detection following derivatization with 9-chloromethylanthracene, has been established as an alternate to LC/MS. Exposure of the anthrylmethyl derivatives of OA, DTX-1 and DTX-2 to near UV light (300-400 nm) resulted in the loss of these compounds to below detection limits within 30 min, with a concurrent appearance of two additional compounds. Based on the mass spectral evidence, we propose that these newly formed compounds are the decarboxylation products of the derivatized diarrhetic shellfish poisons. UV radiation is, therefore, proposed as a rapid and simple confirmation technique for these DSP in mussel samples.

Animals↗

Protein phosphatase in neuroblastoma cells: [3H]cantharidin binding site in relation to cytotoxicity.

Protein phosphatase 2A (PP2A) plays a central role in essential phosphorylation-dependent signal transduction pathways. It is also a principal target for many natural toxicants (cantharidin, microcystins, diarrhetic shellfish poisons) and a synthetic herbicide (endothall). This study develops a cellular model to explore the toxicology of PP2A inhibitors by use of a [3H]cantharidic acid ([3H]CA) ligand binding assay to quantify interactions at the toxicant site and cell viability to evaluate in vivo toxicity. Mouse neuroblastoma (N1E-115) cells are similar to mouse brain with respect to the affinity (12-15 nM), number (B(max), 9-22 pmol/mg protein) and ligand specificity of this binding site. In addition, the competitive potency of ten analogs of CA (including endothall) and two potent diarrhetic shellfish poisons (okadaic acid and calyculin A) is correlated (r2 = .9) with and therefore predictive of their cytotoxicity. The only exception is microcystin LR which is a potent inhibitor at the binding site but is not cytotoxic, possibly reflecting a lack of cellular uptake. ATP and several other phosphorus-containing bifunctional acids inhibit [3H]CA binding by phosphorylation-independent pathways; pyrophosphate apparently acts as a competitive inhibitor. Mn++ and five other divalent cations are also inhibitors with a unique action of Mn++ at 25 to 50 microM in increasing [3H]CA binding, which suggests a specific role in PP2A function. Neuroblastoma cells are therefore suitable to study the mechanisms by which the toxicant, ATP and Mn++ binding sites regulate PP2A activity and cell physiology.

Animals↗

Hydrophilic interaction liquid chromatography/mass spectrometry for determination of domoic acid in Adriatic shellfish.

This paper describes a new method for sensitive, specific and direct determination of domoic acid (DA), the causative toxin of amnesic shellfish poisoning (ASP) syndrome, in shellfish. It is based on combination of hydrophilic interaction liquid chromatography with mass spectrometry (HILIC/MS). The high percentage of organic modifier in the mobile phase and the omission of ion-pairing reagents, both favoured in HILIC, result in enhanced detection limits with MS detection. The new method was set up either on an ionspray ion trap MS instrument operating in MS and MS/MS scanning acquisition modes, or on a turboionspray triple-quadrupole MS system operating in selected ion monitoring (SIM) and multiple reaction monitoring (MRM) acquisition modes. Positive and negative ion experiments were performed. MRM experiments are recommended for screening contaminated shellfish tissue and for quantitative analyses due to highest sensitivity and selectivity. The minimum detection levels for the toxin in tissue were found to be 63 and 190 ng/g in positive and negative MRM experiments, respectively, which are well below the regulatory limit for DA in tissue (20 microg/g). Application to shellfish samples collected in the Adriatic Sea (Italy) in the period 2000-2004 demonstrated for the first time in Italy the presence of DA as a new toxin that has entered the Adriatic Mytilus galloprovincialis toxin profile.

Animals↗

[The problem of selective determination of PSP toxins in mussels].

Levels of paralytic shellfish poisoning (PSP) toxins in shellfish are routinely determined by mouse bioassay. In order to improve the qualitative and quantitative determination of PSP toxins, chromatographic techniques with fluorescence detection have been developed. These HPLC methods and the HPLC/MS coupling were used to determine a second PSP toxin which was found, in addition to saxitoxin, in canned Spanish mussels. These canned mussels were rejected in 1986 by the German food control because PSP concentrations were too high. It has been shown that these samples contained mainly dc-saxitoxin.

Animals↗

Evaluation of laboratory performance of the AOAC method for PSP toxin in shellfish.

Laboratory performance of the official AOAC method for paralytic shellfish poison (PSP) toxin in shellfish was evaluated. Two series of naturally toxic shellfish split samples were distributed (15 in 1979 and 19 in 1982) to state shellfish-monitoring laboratories which participate in the National Shellfish Sanitation Program. The laboratories performed bioassays on duplicate 100 g portions of each 220 g split sample. Bioassays were consistent among the laboratories and compared favorably with those of previous studies.

Animals↗

Shellfish and fish poisoning related to the toxic dinoflagellates.

At least four different species of the toxic dinoflagellates cause shellfish and fish poisoning in the United States: Ptychodiscus brevis, neurotoxic shellfish poisoning; Protogonyaulax catenella and P tamarensis, paralytic shellfish poisoning; and Gambierdiscus toxicus, ciguatera fish poisoning. These three disorders have similar clinical manifestations, primarily neurologic and alimentary. A complete history is essential; confirmation, while dependent on specific laboratory analysis, is usually based on a history of ingestion of fish or shellfish previously associated with these types of poisonings. The principal toxins affect sodium channels; Ptychodiscus brevis toxins and ciguatoxin by stimulating these channels and saxitoxin by blocking them. Since no antidote is known, treatment is symptomatic. Public health measures and public education are necessary to prevent this form of poisoning.

Animals↗

Poisonings: food, fish, shellfish.

Not every traveler who gets sick away from home has an infection; some are poisoned. This article describes common and dangerous illnesses caused by food-borne toxins. It explores the toxic illnesses acquired from fish or seafood, including scombroid, ciguatera, pufferfish toxicity, and a variety of shellfish poisonings. It also provides a brief overview of plant toxicity. Although gastroenteritis is a common feature of many food poisonings, this article emphasizes those processes associated with neurologic manifestations, as they tend to be more dangerous to patients and less well understood by physicians. It also stresses strategies to prevent food poisoning.

Animals↗

[A new pathophysiological explanation of ciguaterra (author's transl)].

After pointing out clinical, biochemical and biological similarities between paralytic shellfish poisoning and ciguaterra fish poisoning, the authors describe their recent discoveries in regard to ciguaterra origin. The causal agent searched without results since many years, might be a dinoflagellate, of the genus Diplopsalis.

Ciguatera Poisoning↗

Use of two detection methods to discriminate ciguatoxins from brevetoxins: application to great barracuda from Florida Keys.

In Florida (USA), numerous cases of human ciguatera fish poisoning, as well as neurotoxic shellfish poisoning following consumption of local seafood products, have been reported. By using in parallel, the sodium channel receptor binding assay (RBA), and the ouabain/veratridine-dependent cytotoxicity assay (N2A assay), we established criteria to identify, detect, and quantify ciguatoxins in fish extracts, with a brevetoxin as internal standard. Results showed that the Caribbean ciguatoxin C-CTX-1 exhibited an 8-fold higher potency in the RBA than brevetoxins and, a 440 and 2300-fold higher potency in the N2A assay than PbTx-1 and PbTx-3, respectively. Moreover, a sensitivity comparison between assays revealed that the N2A assay was more sensitive (12-fold) for ciguatoxin analysis, whereas the RBA was more sensitive (3-24-fold) for brevetoxins analysis. Based on the relative potency between toxins and the opposite sensitivity of both assays we have used the RBA and the N2A assay to screen great barracuda (Sphyraena barracuda) collected from the Florida Keys for ciguatoxins and brevetoxins. Fish extract analysis showed a sodium channel-dependent activity consistent with the presence of ciguatoxins, and not brevetoxins. Among 40 barracudas analyzed, 60% contained ciguatoxin levels in their liver measurable by the N2A assay with the most toxic fish containing 2.1ppb C-CTX-1 equivalents.

Animals↗

Comparison between HPLC and a commercial immunoassay kit for detection of okadaic acid and esters in Portuguese bivalves.

Liquid chromatography (HPLC), used to identify diarrhoeic shellfish poisoning (DSP) toxins in Portuguese shellfish, has detected okadaic acid (OA), dinophysistoxin-2 (DTX2) and esters of both of these. In Donax clams, a surprisingly high level of esters has been recently associated with some outbreaks of diarrhoea in shellfish consumers. In view of these events, we have proposed that screening for esters must be included in monitoring programmes for DSP toxins. HPLC is laborious, time-consuming and suffers from some interferences at low detection levels in total meat extracts. An enzyme-linked immunosorbent assay (ELISA) based on the procedure of Usagawa et al. ('DSP-Check' kit) was tested against HPLC. The 'DSP-Check' kit was capable of quantitatively detecting DSP toxins in all the tested contaminated samples containing only okadaic acid, provided that the parent toxins were within the range of detection and were not in the ester form. A high correlation was observed between the two methods when appropriate dilutions were performed. The immunoassay kit tested appeared to be more sensitive, specific and faster than HPLC for determination of DSP in total shellfish meat extracts. No problems were found when using hydrolysed semi-purified extracts in order to detect esters of okadaic acid. In view of the results obtained so far, Donax clams appeared to be an excellent indicator of shellfish contamination with diarrhoeic toxins. On sandy beaches of the Portuguese southern coast, were rock mussels are not so abundant, they should be screened more often than other species in order to prevent diarrhoea in humans.

Calibration↗

Poisonous marine morsels.

Consumption of seafood is increasing and physicians should know more about ichthyosarcotoxism, or fish-flesh poisoning. It appears in a variety of forms: poisoning, ciguatera, tetrodotoxin and scombroid poisoning. Ingestion of certain marine turtles and mammals also has been incriminated as the cause of illness. Paralytic shellfish poisoning can be deadly. In addition, red tide may cause respiratory problems.

Animals↗

[Poisoning by paralytic molluscan toxins in Oaxaca].

Toxic Red Tides are caused by marine dinoflagellates which synthesize neurotoxins that accumulate in bivalve mollusks. Upon ingestion, these shellfish can cause paralysis and death. During the month of December, 1989, 99 cases of Paralytic Shellfish Poisoning in the areas of Salina Cruz and Huatulco, Oaxaca, were reported; three of which died. The majority of the cases involved the ingestion of oysters and clams. A short time later, the Red Tide was reported appearing. One hundred and fifteen seafood samples were analyzed through a biologic test in mice to determine the quantity of saxitoxin. Oysters and clams showed levels reaching 4 000 U.R. Laboratory analysis of seawater found very high quantities of Gimnodinium catenatum and Gonyaulax catenella. The control measures consisted of the prohibition of the harvest and sale of all bivalve mollusks as well as a public warning to avoid the consumption of such shellfish.

Animals↗

Oliva vidua fulminans, a marine mollusc, responsible for five fatal cases of neurotoxic food poisoning in Sabah, Malaysia.

This is the first report in which a marine mollusc, Oliva vidua fulminans (olives), generally not known to be poisonous, was responsible for death in five children after consuming boiled olives with tamarind. The onset of symptoms was rapid 10 to 20 min after consumption of the olives. Signs and symptoms included nausea, vomiting, abdominal pain, tingling sensation around the lips, numbness around the mouth, drowsiness, lethargy and generalized weakness with paraesthesia in the limbs. The five deaths occurred within 3 to 4 hours after eating the poisoned olives and resulted from respiratory failure. Left-over olives from the affected household and freshly collected live olives had a toxicity of 14,200 mouse units (M.U.) and 15,000 M.U. per 100 g meat respectively. No other common chemical poison and organophosphorus insecticides were detected. The neurotoxic agent was acid and heat stable and was toxic at pH less than 4. Its action was similar to that of paralytic shellfish poisoning which was caused by toxins from certain dinoflagellates.

Adolescent↗

Pectenotoxins--an issue for public health: a review of their comparative toxicology and metabolism.

Pectenotoxins (PTXs) are a group of toxins associated with diarrhetic shellfish poisoning (DSP) and isolated from DSP toxin-producing dinoflagellate algae. Consumption of shellfish contaminated with PTXs has been associated with incidences of severe diarrhetic illness resulting in hospitalisation. Concern has been raised for public health following the discovery that these toxins are not only hepatotoxic and can cause diarrhetic effects in mammals, but that they are potently cytotoxic to human cancer cell lines and have been found to be tumour promoters in animals. With advances in knowledge and technology, more PTXs are being identified, but little is known of their toxicology and the potential impact these toxins may have on public health in the long term. Without such information, adequate health-risk assessments for the consumption of shellfish contaminated with PTXs cannot be performed. This review gives a brief introduction to diarrhetic shellfish toxins, details the known toxicology and metabolism of PTXs in animals, and discusses known incidences of PTX poisoning in humans.

Animals↗

[Domoic acid and human health].

Domoic acid (DA), structurally related to glutamic and kainic acid, mainly generated by Pseudo nitzschia diatom. It often contaminates halobios such as fish and seashell and cause the Amnesic Shellfish Poisoning in human beings with the consumption of foods contaminated by DA. DA has been detected from seafoods worldwide. As the frequent occurrence of red tide and outbreak of human poisoning, more and more studies focus on DA, especially on its excitotoxicity. The producing alga, physico - chemical properties, natural contamination of seafoods, information on human poisoning, toxicity and analytical methods of DA are reviewed.

Animals↗

Microalgal blooms: a global issue with negative impact in Chile.

Ecological and health problems posed by microalgal blooms (red tides) occurring in the Southern part of Chile are reviewed. Out of the six human illnesses provoked by microalgal toxins, paralytic shellfish poisoning is the most important, because of its high mortality rate and the high levels of phycotoxins found in contaminated molluscs. Saxitoxin and its analogues bind to a receptor in the voltage-gated sodium channel of neural membranes. The most important toxin-producer microalgae are Alexandrium catenella and Dinophysis acuta. Phycotoxins become concentrated by filter-feeding shellfish, like Mytilus chilensis. Highly sensitive methods available for detection of microalgal toxins are analyzed.

Animals↗

Cloning, expression and characterisation of a single-chain Fv antibody fragment against domoic acid in Escherichia coli.

Domoic acid is a potent neuroexcitatory toxin that causes amnesic shellfish poisoning in humans through ingestion of contaminated shellfish. The variable regions of the heavy chain (V(H)) and light chain (V(L)) of an antibody specific for domoic acid were cloned from a mouse hybridoma cell line and used to construct single-chain antibody fragments (scFvs) in a variety of formats. V(H)-linker-V(L) scFvs were expressed better in Escherichia coli than the V(L)-linker-V(H) format, while use of the commonly used (Gly4Ser)3 inter-domain linker resulted in higher yields than a longer (Gly4Ser)6 linker variant. Higher soluble protein yields were achieved in E. coli TOP 10 than in E. coli XL1-Blue cells and co-production of the E. coli disulfide bond isomerase enzyme DsbC allowed higher cell densities to be attained during scFv production, leading to increased yields of recombinant protein. The purified scFv exhibited binding similar to the parent monoclonal antibody and is being used to develop an immunosensor to detect domoic acid in contaminated shellfish samples.

Animals↗

Optimisation of production of a domoic acid-binding scFv antibody fragment in Escherichia coli using molecular chaperones and functional immobilisation on a mesoporous silicate support.

Domoic acid is a potent neurotoxin that can lead to amnesic shellfish poisoning in humans through ingestion of contaminated shellfish. We have produced and purified an anti-domoic acid single-chain Fragment variable (scFv) antibody fragment from the Escherichia coli periplasm. Yields of functional protein were increased by up to 100-fold upon co-production of E. coli DnaKJE molecular chaperones but co-overproduction of GroESL led to a reduction in solubility of the scFv. Co-production of the peptidyl-prolyl isomerase trigger factor resulted in accumulation of unprocessed scFv in the E. coli cytoplasm. This was due to an apparent bottleneck in translocation of the cytoplasmic membrane by the recombinant polypeptide. Co-expression of the E. coli disulfide bond isomerase dsbC increased scFv yields by delaying lysis of the host bacterial cells though this effect was not synergistic with molecular chaperone co-production. Meanwhile, use of a cold-shock promoter for protein production led to accumulation of greater amounts of scFv polypeptide which was predominantly in insoluble form and could not be rescued by chaperones. Purification of the scFv was achieved using an optimised metal affinity chromatography procedure and the purified protein bound domoic acid when immobilised on a mesoporous silicate support. The work outlines the potential benefit of applying a molecular chaperone/folding catalyst screening approach to improve antibody fragment production for applications such as sensor development.

Cloning, Molecular↗