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Accumulation of paralytic shellfish poison (PSP) and biotransformation of its components in oysters, Crassostrea gigas, fed with the toxic dinoflagellate Alexandrium tamarense.

As a part of our studies on the mechanism of uptake of paralytic shellfish poison (PSP) and the kinetics of its accumulation in bivalves, oysters Crassostrea gigas were experimentally contaminated with PSP by being fed with the toxic dinoflagellate Alexandrium tamarense for 2, 4, 6, 8 and 10 days. Temporal variations in the PSP contents and their profiles in oysters during the feeding experiment were monitored by high-performance liquid chromatography (HPLC) and the toxin profile of the oysters was compared with that of A. tamarense. Toxins excreted from the infested oysters into the seawater for 2 and 10 days were recovered and analyzed by HPLC. PSP toxicity rapidly appeared in the tissues of oysters and their toxicity levels reached 0.6 (0.3), 2.2 (1.1), 1.0 (0.5), 3.4 (1.6) and 1.1 (0.5) MU/g (nmol/g) shucked meat at 2, 4, 6, 8 and 10 days, respectively. The accumulation rates of toxin, calculated from the total amount (nmol) of toxins expressed by the total cell number fed during the exposure period and the toxicity of the oysters, were 14.1, 18.7, 5.1, 14.9 and 3.2% for 2, 4, 6, 8 and 10 days. During feeding experiments, the toxin profile of oysters changed substantially, showing marked differences from the proportions found in the toxigenic dinoflagellate used as food. The toxin components in this strain existed almost exclusively as beta-epimers, which accounted for 66.3 mol% of the total. This contrasts with the case of the oysters, where the beta-epimers represented 24.8, 29.8, 25.1, 27.3 and 25.2 mol% of the total at 2, 4, 6, 8 and 10 days, respectively. The amount of gonyautoxin-1 (GTX1) accumulated in oysters increased linearly and slowly for 8 days and the maximum content of GTX1 reached 51.3 mol%. The composition of GTX group compounds recovered from the seawater in which the oysters had been reared was a little different from that within the oyster tissues.

Animals↗

Characteristics of paralytic shellfish poisoning toxins derived from short-necked clams (Tapes japonica) in Mikawa Bay.

A "red tide" bloom of Alexandrium tamarense occurred in Mikawa Bay in April 1991. In association with this, paralytic shellfish poisoning toxin was detected in short-necked clams by mouse bioassay. High performance liquid chromatography analysis demonstrated large quantities of the N-sulfocarbamoyl toxins, C1, and C2 (approximately 90% of the total toxins), whose latent potency was confirmed by treatment with boiling at low pH.

Animals↗

New strategy for the determination of microcystins and diarrhetic shellfish poisoning (DSP) toxins, two potent phosphatases 1 and 2A inhibitors and tumor promoters.

A new analytical strategy was established to improve the determination and identification performance during analyses of microcystins and diarrhetic shellfish poisoning (DSP) toxins in different matrices. Automated high performance size exclusion chromatography (gel permeation chromatography, SEC) was applied for the clean-up of raw extracts from algae and mussel tissue containing either microcystins or DSP toxins. The cleaned raw extracts are well suited for the direct determination of microcystins and DSP toxins by HPLC/MS. The analyses of cleaned raw extracts containing microcystin by HPLC and UV/diode array detection (DAD) revealed chromatograms without interfering peaks. Additionally, methods for the identification of unknown microcystins and those not available as standards were developed and established. The proposed strategy is exemplarily demonstrated for the analyses of a natural algae community from a lake in Slowakia and a naturally contaminated mussel from Portugal.

Carcinogens↗

Paralytic shellfish poisoning toxins accumulation in purple clam Hiatula rostrata and toxic effect on milkfish Chanos chanos larval fish.

In an attempt to feed purple clams (Hiatula rostrata) with dinoglagellate Alexandrium minutum, the maximal accumulation toxicity of paralytic shellfish poisoning (PSP) toxins reached 40.6 MU/g on day 5 of feeding. Subsequently, the toxicity increased no further, although purple clams ingested more toxic algae. Furthermore, when milkfish (Chanos chanos) larvae were treated with toxic, nontoxic A. minutum or PSP toxin-containing extract in the water medium, it was found that the mortality of fish increased with the increasing concentrations of toxic algae. PSP toxin-containing extract did not show any toxic effect on milkfish larvae.

Animals↗

Ionspray mass spectrometry of marine toxins. III. Analysis of paralytic shellfish poisoning toxins by flow-injection analysis, liquid chromatography/mass spectrometry and capillary electrophoresis/mass spectrometry.

Ionspray mass spectrometry has been used to monitor the purification of saxitoxin, the parent compound in the family of toxins responsible for paralytic shellfish poisoning (PSP), from a strain of the dinoflagellate Alexandrium excavatum. Quantitative results obtained by flow-injection analysis are compared to those obtained by high-performance liquid chromatography with post-column oxidation and fluorescence detection. The coupling of liquid chromatography and capillary electrophoresis with ionspray mass spectrometry is described for the separation of mixtures of PSP toxins and the highly potent pufferfish toxin tetrodotoxin. Tandem mass spectrometry is used to provide the structural information, and the ability to distinguish isomeric PSP toxins both chromatographically and mass spectrometrically is demonstrated.

Chromatography, High Pressure Liquid↗

Detection of paralytic shellfish poison by rapid cell bioassay: antagonism of voltage-gated sodium channel active toxins in vitro.

Although cytotoxicity assays provide several advantages over mouse bioassays, sodium channel-blocking marine toxins, such as those associated with paralytic shellfish poison (PSP), require prolonged incubation periods of 24-48 h. This is in marked contrast to in vitro detection of sodium channel-enhancing marine toxins such as ciguatoxins or brevetoxins which can be accomplished in as few as 4-6 h. We developed a modified PSP cell bioassay that is as rapid as in vitro methods for sodium channel-enhancing toxins. The cell bioassay is based on a saxitoxin-dependent antagonism of the rapid in vitro effects of brevetoxin or ciguatoxin. Comparative analysis of naturally incurred PSP residues by both antagonism cell bioassay and the mouse bioassay demonstrated significant correlation. The simplicity, sensitivity, and enhanced kinetics of the new antagonism cell bioassay format provide the basis for development of a practical alternative to conventional mouse testing for PSP.

Animals↗

Occurrence of paralytic shellfish poison (PSP) in the starfish Asterina pectinifera collected from the Kure Bay, Hiroshima Prefecture, Japan.

Assays were made for paralytic toxicity of marine invertebrates inhabiting at the coasts of Hiroshima Bay, where the infestation of bivalves such as cultured oysters with paralytic shellfish poison (PSP) has been occurred. The starfish Asterina pectinifera collected at the estuary of Nikoh River, Hiroshima Bay, was found to contain moderate levels of paralytic toxicity. Its highest toxicities as PSP found on July 30, 1999 were 12.5 MU/g for whole body, 11.0 MU/g for integument tissues and 3.9 MU/g for viscera, respectively. The toxicity of integument was changed from 3.6 to 11.0 MU/g in 1 year. Its paralytic toxin principles were identified as PSP toxins, composing mainly from saxitoxin (STX) group toxins such as carbamoyl-N-hydroxy neosaxitoxin (hyneoSTX), and STX, by HPLC and LC-MS, accounting for over 90 mol%. The PSP toxins contained in the starfish A. pectinifera considered to be transferred from bivalves or detritus living in the same area, which were contaminated with PSP. However, the involved pathway may be different from that of Asterias amurensis which was infested directly through food chain from its food bivalves, for its toxin pattern.

Animals↗

Ionspray mass spectrometry of marine toxins. IV. Determination of diarrhetic shellfish poisoning toxins in mussel tissue by liquid chromatography/mass spectrometry.

An improved liquid chromatographic/mass spectrometric (LC/MS) method utilizing gradient elution and ion-spray ionization is described for the sensitive determination of okadaic acid and dinophysistoxin-1, the principal toxins implicated in cases of diarrhetic shellfish poisoning. The method was used to confirm the presence of both toxins, together with a recently identified isomer of okadaic acid, dinophysistoxin-2, in various samples of cultivated blue mussels (Mytilus edulis) from Canadian and European waters. The method provided a mass detection limit of 0.4 ng for each toxin, thus allowing detection of 40 ng per g of whole mussel tissue (or approximately 10 ng/g if only the digestive glands were used in the assay). Quantitative results obtained by LC/MS were in good agreement with those obtained by derivatization and high-performance liquid chromatography with fluorescence detection.

Animals↗

Separation of paralytic shellfish poisoning toxins on Chromarods-SIII by thin-layer chromatography with the Iatroscan (mark 5) and flame thermionic detection.

Thin-layer chromatography (TLC) on Chromarods-SIII with the Iatroscan (Mark-5) and a flame thermionic detector (FTID) was used to develop a rapid method for the detection of paralytic shellfish poisoning (PSP) toxins. The effect of variation in hydrogen (H2) flow, air flow, scan time and detector current on the FTID peak response for both phosphatidylcholine (PC) and PSP were studied in order to define optimum detection conditions. A combination of hydrogen and air flow-rates of 50 ml/min and 1.5-2.0 l/min respectively, along with a scan time of 40 s/rod and detector current of 3.0 A (ampere) or above were found to yield the best results for the detection of PSP compounds. Increasing the detector current level to as high as 3.3 A gave about 130 times more FTID response than did flame ionization detection (FID), for PSP components. Quantities of standards as small as 1 ng neosaxitoxin (NEO), 5 ng saxitoxin (STX), 5 ng B1-toxins (B1), 2 ng gonyautoxin (GTX) 2/3, 6 ng GTX 1/4 and 6 ng C-toxins (C1/C2) could be detected with the FTID. The method detection limits for toxic shellfish tissues using the FTID were 0.4, 2.1, 0.8 and 2.5 micrograms per g tissue for GTX 2/3, STX, NEO and C toxins, respectively. The FTID response increased with increasing detector current and with increasing the scan time. Increasing hydrogen and air flow-rates resulted in decreasing sensitivity within defined limits. Numerous solvent systems were tested, and, solvent consisting of chloroform: methanol-water-acetic acid (30:50:8:2) could separate C toxins from GTX, which eluted ahead of NEO and STX. Accordingly, TLC/FTID with the Iatroscan (Mark-5) seems to be a promising, relatively inexpensive and rapid method of screening plant and animal tissues for PSP toxins.

Calibration↗

Frequent occurrence of paralytic shellfish poisoning toxins as dominant toxins in marine puffer from tropical water.

Considerably high toxicity was detected in marine puffers collected from Masinloc Bay, Philippines. The toxicity was detected in the liver, intestine, muscle and skin. Noteworthy, the specimens, the muscle of which showed high toxicity, appeared in high frequency, indicating that puffers from this area is not safe for human consumption. These puffer specimens contained paralytic shellfish poisoning (PSP) toxins, often as major toxin components, the profile of which was similar to that of freshwater puffers reported from tropical areas. These results indicate that PSP toxins are common in tropical puffers both from marine and freshwater.

Animals↗

Occurrence of paralytic shellfish poison in the starfish, Asterias amurensis in Kure Bay, Hiroshima Prefecture, Japan.

In May 1996, during surveillance on the toxicity of invertebrates such as bivalves inhabiting the coasts of Hiroshima Bay, the starfish Asterias amurensis collected in the estuary of the Nikoh River was found to contain toxins which showed strong paralytic action in mice; the maximum toxicity (as paralytic shellfish poison, PSP) was 8.0 MU/g for whole body and 28.7 MU/g for viscera throughout the monitoring period, March to July 1996. Attempts were made to identify the paralytic toxins in the starfish. They were extracted with 80% ethanol acidified with acetic acid, followed by defatting with dichloromethane. The aqueous layer obtained was treated with activated charcoal and then applied to a Sep-Pak C18 cartridge. The unbound toxic fraction was analyzed by high-performance liquid chromatography techniques. The starfish toxin was rather unexpectedly identified as PSP. It was comprised of high toxic components (gonyautoxin-1; GTX1, GTX2, GTX3, GTX4, decarbamoyl-GTX3; dcGTX3 and dcSTX) as the major components, which accounted for approximately 77 mole% of all components, along with protogonyautoxin-1, 2, 3 and 4 (PX1-4), which are N-sulfocarbamoyl derivatives. Of the high toxic components, GTX1 was present in the largest amounts. It was concluded that the toxin of starfish collected in the estuary of Nikoh River in May 1996 consisted of PSP, which supposedly came via the food chain from toxic bivalves living in the same area. To our knowledge, this is the first report of the occurrence of PSP in starfish.

Animals↗

Differences between the effects of saxitoxin (paralytic shellfish poison) and tetrodotoxin on the frog neuromuscular junction.

1. End-plate potentials (e.p.p.) have been recorded from the neuromuscular junctions of frog sartorius and extensor longus dig. IV muscles, using intracellular micropipettes. Either curare or MgCl(2) were present in the Ringer solution, to keep the e.p.p. amplitude below the threshold for a muscle action potential and contraction.2. It has been shown that saxitoxin (paralytic shellfish poison) usually caused a progressive reduction in the amplitude of the e.p.p. Occasionally, when it was applied in the presence of MgCl(2), the e.p.p. disappeared abruptly.3. Tetrodotoxin usually caused the e.p.p. to disappear abruptly. Occasionally, when applied in the presence of curare, the e.p.p. declined progressively for a short time before disappearing abruptly.4. It is concluded that at the frog neuromuscular junction the preferential site of action of saxitoxin is at the nerve terminals, but tetrodotoxin preferentially blocks nerve conduction at a site proximal to the junction.5. It is suggested that this preparation would be a convenient and reliable test object for distinguishing saxitoxin from tetrodotoxin.

Animals↗

Development of reference materials for paralytic shellfish poisoning toxins.

A project was undertaken to develop mussel reference materials that were certified for their mass fractions of saxitoxin and decarbamoyl-saxitoxin. Fifteen laboratories from various European countries participated. Three of these had major responsibility for substantial parts of the work and overall coordination of the project. The project involved 4 main activities: (1) procurement and characterization of calibrants; (2) improvement of analytical methodology; (3) preparation of reference materials, including homogeneity and stability studies; (4) 2 interlaboratory studies and a certification exercise. The joint activities resulted in 3 homogeneous and stable reference materials: 2 lyophilized mussel materials with and without naturally incurred paralytic shellfish poisoning (PSP) toxins, and a saxitoxin enrichment solution. The reference materials were certified with respect to their saxitoxin and decarbamoyl-saxitoxin content. The lyophilized mussel material with PSP toxins (CRM 542) contained <0.07 mg saxitoxin x 2HCl/kg and 1.59 +/- 0.20 mg decarbamoyl-saxitoxin x 2HCl/kg. The lyophilized mussel material without PSP toxins (CRM 543) contained <0.07 mg saxitoxin x 2HCl/kg and <0.04 mg decarbamoyl-saxitoxin x 2HCl/kg. The certified value of the saxitoxin mass fraction in the saxitoxin enrichment solution (CRM 663) was 9.8 +/- 1.2 microg/g.

Animals↗

Paralytic shellfish poison (saxitoxin family) bioassays: automated endpoint determination and standardization of the in vitro tissue culture bioassay, and comparison with the standard mouse bioassay.

Mouse neuroblastoma cells swell and eventually lyse upon exposure to veratridine, which, when added together with ouabain, enhances sodium ion influx. In the presence of saxitoxin (STX), which blocks sodium channels, the action of the other two compounds is inhibited and the cells remain morphologically normal. A tissue culture bioassay using mouse neuroblastoma cells, developed by Kogure and colleagues, takes advantage of these principles; in this bioassay, the fraction of the cells protected from the actions of ouabain and veratridine is in direct proportion to the concentration of STX and its analogues. We have modified this bioassay, improving its convenience and speed by eliminating the need to count individual cells to determine the saxitoxin equivalents, and instead have employed a microplate reader for automated determinations of absorbances of crystal violet from stained neuroblastoma cells. When these changes and other minor technical modifications were tested in the tissue culture bioassay systematically, we found the lower detection limit to be around 10 ng STX equivalents (eq) per ml of extract ( = 2.0 micrograms STX eq/100 g shellfish tissue). Our version of the tissue culture bioassay was compared with the standard mouse bioassay using 10 acid extracts of dinoflagellates (Alexandrium excavata and A. fundyense) and 47 AOAC extracts of shellfish tissues. The tissue culture bioassay provided results virtually identical to those obtained with the mouse bioassay (r > 0.96), and moreover, was considerably more sensitive. The results gained from high performance liquid chromatographic (HPLC) analysis of 12 of the same extracts were less consistent when compared with the results from both bioassay methods. The automated tissue culture (neuroblastoma cell) bioassay may be a valid alternative to live animal testing for paralytic shellfish poisoning.

Animals↗