Paralytic shellfish poison (PSP) profiles and toxification of short-necked clams fed with the toxic dinoflagellate Alexandrium tamarense

As a part of our studies on paralytic shellfish poison (PSP) accumulation kinetics in bivalves, short-necked clam Tapes japonia was experimentally contaminated with PSP by being fed with the toxic dinoflagellate Alexandrium tamarense for 2, 4, 6, 8 and 10 days, and the processes of PSP accumulation and bioconversion were investigated: the toxicity level was determined by mouse bioassay and toxin components were identified by high-performance liquid chromatography (HPLC). The strain of A. tamarense used in this study possessed a specific toxicity of 186.7 +/- 81 (mean +/- S.D., n = 5) x 10(-6) MU/cell. Total toxin concentration of this strain was 140.4 +/- 61 (mean S.D., n = 5) fmol/cell. The toxicity level of short-necked clams increased almost in parallel with the abundance of A. tamarense, reaching 1.8, 3.2, 3.8, 3.5 and 4.6 MU/g meat for 2, 4, 6, 8 and 10 days of feeding, respectively. The accumulation rates of PSP toxins, which are the ratio of the total amount of toxins accumulated in the bivalves to the estimated intake in each feeding experiment, were 7.5, 8.1, 5.7, 4.2 and 4.4% for 2, 4, 6, 8 and 10 days, respectively. At the end of each exposure period, many undigested algal cells were found in pseudofeces under microscopic observation. There was a remarkable difference in the relative proportions of the predominant toxin components between A. tamarense and short-necked clams. The most notable difference was the change in the relative amounts of C2 (carbamoyl-N-sulfo-11beta-hydroxysaxitoxin sulfate), GTX1 and GTX 4 during the first two days. In the toxic bivalves, the amount of C2, which is dominant in A. tamarense, decreased to below half a percent after being ingested. Subsequently, the amount of GTX1 in the shellfish meat reached 50.1 mol%, while that of GTX4 decreased to about half of that in A. tamarense. As for the configuration of 11-hydroxysulfate, PSP components in A. tamarense exist almost exclusively as beta-epimers (GTX3, GTX4, C2 and C4), accounting for 72.8 mol% of the total. This contrasts with the case of the short-necked clams, where the beta-epimers represented 25.8, 33.8, 30.8, 36.8 and 28.5 mol% of the total after 2, 4, 6, 8 and 10 days, respectively. PSP components seemed to be converted rapidly at an early stage of the feeding of A. tamarense.     

Occurrence of paralytic shellfish poison (PSP)-producing dinoflagellate Alexandrium tamarense in Hiroshima Bay, Hiroshima Prefecture, Japan, during 1993-2004 and its PSP profiles

To assess levels of shellfish intoxication by the paralytic shellfish poison (PSP)-producing dinoflagellate Alexandrium tamarense, potential health risks to human shellfish consumers and the possible need for regulatory intervention, yearly variations of maximum cell density of this species were examined from 1993 to 2004 in Kure Bay and Kaita Bay, which are located within Hiroshima Bay, Hiroshima Prefecture, Japan. The seawater temperature was determined concomitantly. In Kure Bay, maximum concentrations of 1,400 and 1,300 cells/mL at 0 and 5 m depths were observed on 21 and 24 April 1997. In Kaita Bay, remarkably high concentrations above 1,000 cells/mL of A. tamarense were observed in two out of three years investigated. These facts suggest that the environment in both bays is favorable for the propagation of A. tamarense. The temperature range at which the natural population of A. tamarense blooms was generally from 12 to 16 degrees C. Four strains (ATKR-94, -95, -97 and -01) from Kure Bay and one strain (ATKT-97) from Kaita Bay were established. The strain ATKR-94, cultured in modified SW-2 medium at 15 degrees C for 15 days, showed a specific toxicity of 33.8 x 10(-6) MU/cell. The toxins in all five strains exist almost exclusively as beta-epimers (C2 (PX2 or GTX8), GTX3, dcGTX3 and GTX4), which accounted for 54.9 to 73.0 mol% of the total. The corresponding a-epimers (C1 (PX1 or epi-GTX8), GTX2, dcGTX2 and GTX1) accounted for 6.0 to 28.9 mol%. The toxin profiles of ATKR-97 and ATKT-97 were characterized by unusually high proportions of low-potency sulfocarbamoyl toxin, which comprised 62.4 and 68.2 mol%, respectively, of total toxins. In the toxic bivalves, the low-toxicity sulfocarbamoyl components, major components of A. tamarense, were present in amounts of only a few percent, suggesting that in vivo conversion of PSP occurs after ingestion. A comparison of the toxin profiles of the causative dinoflagellate and contaminated bivalves showed that PSP components exist in the bivalves in the form of alpha-epimers, presumably owing to accumulation or storage of the toxins.     

First paralytic shellfish poison (PSP) infestation of bivalves due to toxic dinoflagellate Alexandrium tamiyavanichii, in the southeast coasts of the Seto Inland Sea, Japan

The mussel Mytilus edulis and the cultured ark shell Anadara broughtonii in the southeast coasts of the Seto Inland Sea were contaminated with paralytic shellfish poison (PSP) following the appearance of the dinoflagellate Alexandrium tamiyavanichii in early December 1999. A. tamiyavanichii plankton collected around the Straits of Naruto on December 3, 1999 showed PSP toxicity, of which 83 mol% was accounted for by GTX2, GTX3 and GTX4. Its specific toxicity was 112.5 fmol/cell, and one MU was equivalent to 7,200 cells. Toxicity values at the beginning of toxification were 4.7 MU/g for the ark shell and 7.3 MU/g for the mussel. In the former, the value remained at almost 4 MU/g, resulting in prohibition of marketing for about two months. In the latter, it sharply decreased to less than 4 MU/g. These bivalves collected during the toxification period were dissected into five tissues, mantle, adductor muscle, hepatopancreas, gills and "others", and submitted to high-performance liquid chromatography (HPLC). The cultured ark shell accumulated GTX2, GTX3 and STX as major components and GTX1, GTX4, GTX5, neoSTX, dcSTX and PX1-3 (C1-C3) as minor ones. The amount of GTX3 decreased with time, while STX tended to increase. At the early stage of PSP toxification, toxins were accumulated in the gills and "others", most of which were quickly detoxified. On the other hand, PSP of the toxified mussel consisted of GTX4 as a main component, and GTX1, GTX2, GTX3, GTX5, STX and PX1-2 (C1-C2) as minor ones. Its toxin composition pattern was similar to that of the ingested causative plankton. Its total toxin decreased soon after disappearance of the dinoflagellate. During the decrease of toxicity, PSP tended to be retained in the hepatopancreas, resulting in accumulation of 50 mol% of total toxin.     

Accumulation and elimination profiles of paralytic shellfish poison in the short-necked clam Tapes japonica fed with the toxic dinoflagellate Gymnodinium catenatum

The paralytic shellfish poison (PSP)-producing dinoflagellate Gymnodinium catenatum (Gc) was fed to the short-necked clam Tapes japonica, and the accumulation, transformation and elimination profiles of PSP were investigated by means of high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC-FLD). The short-necked clams ingested most of the Gc cells (4 x 10(6) cells) supplied as a bolus at the beginning of the experiment, and accumulated a maximal amount of toxin (181 nmol/10 clams) after 12 hr. The rate of toxin accumulation at that time was 16%, which rapidly decreased thereafter. During the rearing period, a variation in toxin composition, derived presumably from the transformation of toxin analogues in the clams, was observed, including a reversal of the ratio of C2 to C1, and the appearance of carbamate (gonyautoxin (GTX) 2, 3) and decarbamoyl (dc) derivatives (decarbamoylsaxitoxin (dcSTX) and dcGTX2, 3), which were undetectable in Gc cells. The total amount of toxin contained in clams and residue (remaining Gc cells and/or excrement in the rearing tank) gradually declined, and only about 1% of the supplied toxin was detected at the end of the experiment.     

Analysis of paralytic shellfish toxins and their metabolites in shellfish from the North Yellow Sea of China

Samples of toxic scallop (Patinopecten yessoensis) and clam (Saxidomus purpuratus) collected on the northern coast of China from 2008 to 2009 were analysed. High-performance liquid chromatography with post-column oxidation and fluorescence detection was used to determine the profile of the main paralytic shellfish poisoning (PSP) toxins in these samples and their total toxicity. Hydrophilic interaction liquid ion chromatography with mass spectrometric detection confirmed the toxin profile and detected several metabolites in the shellfish. Results show that C1/2 toxins were the most dominant toxins in the scallop and clam samples. However, GTX1/4 and GTX2/3 were also present. M1 was the predominant metabolite in all the samples, but M3 and M5 were also identified, along with three previously unreported presumed metabolites, M6, M8 and M10. The results indicate that the biotransformation of toxins was species specific. It was concluded that the reductive enzyme in clams is more active than in scallops and that an enzyme in scallops is more apt to catalyse hydrolysis of both the sulfonate moiety at the N-sulfocabamoyl of C toxins and the 11-hydroxysulfate of C and GTX toxins to produce metabolites. This is the first report of new metabolites of PSP toxins in scallops and clams collected in China.     

Analysis of paralytic shellfish toxins and their metabolites in shellfish from the North Yellow Sea of China

Samples of toxic scallop (Patinopecten yessoensis) and clam (Saxidomus purpuratus) collected on the northern coast of China from 2008 to 2009 were analysed. High-performance liquid chromatography with post-column oxidation and fluorescence detection was used to determine the profile of the main paralytic shellfish poisoning (PSP) toxins in these samples and their total toxicity. Hydrophilic interaction liquid ion chromatography with mass spectrometric detection confirmed the toxin profile and detected several metabolites in the shellfish. Results show that C1/2 toxins were the most dominant toxins in the scallop and clam samples. However, GTX1/4 and GTX2/3 were also present. M1 was the predominant metabolite in all the samples, but M3 and M5 were also identified, along with three previously unreported presumed metabolites, M6, M8 and M10. The results indicate that the biotransformation of toxins was species specific. It was concluded that the reductive enzyme in clams is more active than in scallops and that an enzyme in scallops is more apt to catalyse hydrolysis of both the sulfonate moiety at the N-sulfocabamoyl of C toxins and the 11-hydroxysulfate of C and GTX toxins to produce metabolites. This is the first report of new metabolites of PSP toxins in scallops and clams collected in China.     

桑沟湾养殖牡蛎中贝类毒素监测及预警

利用高效液相色谱-串联质谱(high performance liquid chromatography-tandem mass spectrometry,HPLCMS/MS)方法监测养殖牡蛎中5种腹泻性贝类毒素与6种麻痹性贝类毒素含量变化及分布特征,分别利用HP20大孔型吸附树脂与SP700吸附树脂作为富集树脂,富集养殖海域海水中5种腹泻性贝类毒素与6种麻痹性贝类毒素,利用HPLC-MS/MS检测方法分析其中毒素含量,同步监测了养殖海域内牡蛎与海水中毒素含量,探究了两者之间的关系,建立了牡蛎内贝类毒素含量随海水内贝类毒素含量之间的变化规律。结果显示:在该海域内一共监测到OA、DTX-1、GYM、PTX-2 4种腹泻性贝类毒素与STX、dc STX两种麻痹性贝类毒素;在整个监控期内,海水中所监测贝类毒素随时间变化呈现先增长,达到峰值后逐渐降低趋势。牡蛎中毒素含量与海水中毒素含量呈正相关关系,即牡蛎内毒素的增长随海水内毒素的增长而增长,但牡蛎内毒素含量的峰值出现时间在海水中毒素含量出现峰值之后,延后时间为14 d。根据固相吸附毒素跟踪技术原理,可以提前14 d预警牡蛎内毒素含量。     

Thermal Degradation of Partially Purified Paralytic Shellfish Poison Toxins at Different Times, Temperatures, and pH

ABSTRACT: Mixtures of purified and partially purified paralytic shellfish poisoning (PSP) toxins including C1/2 and B1 toxins, gonyautoxins 1-4 (GTX), neosaxitoxin (NEO), and saxitoxin (STX) were heated at different temperatures (90 to 130 °C), heating times (10 to 120 min), and pH (3 to 7) and analyzed by HPLC. C toxins declined rapidly at low pH, and GTX 1/4 toxins decreased at high temperatures and at high pH. GTX 2/3 increased initially at low pH and then declined with subsequent heating, whereas STX increased consistently at pH 3 to 4. The integrated total specific toxicity declined at high pH (6 to 7). The kinetics of thermal destruction were 1^st order, and the efficacy of thermal destruction was highly dependent on pH, with rapid thermal destruction of carbamate compounds at higher pH. D values of carbamate toxins decreased with increasing temperature at high pH. Heating at low pH resulted in conversion of least toxic compounds to highly toxic compounds.     

Effects of exogenous polyamines on growth,toxicity, and toxin profile of dinoflagellate Alexandrium minutum

The effect of exogenous polyamines (cadaverine, putrescine, norspermidine, spermidine, and spermine) on the growth, toxicity, and toxin profile of the dinoflagellate Alexandrium minutum T1 was examined. It was found that cadaverine at concentrations of 0.1-2.0 mumol/L enhanced the growth of A. minutum T1. Putrescine and norspermidine at a low level (0.1 mumol/L) also promoted the algal growth. Spermidine depressed the algal growth. However, the cell toxicity levels of A. minutum T1 cultured with or without cadaverine, putrescine, norspermidine, and spermidine were almost the same. The toxic components of A. minutum T1 were GTXs 1-4 only, and GTXs 1 and 4 were predominant (74.6 +/- 7.1%) in all cultures. On the other hand, spermine did not effect the growth of A. minutum T1, though it decreased the cell toxicity and the ratio of GTX 2 + GTX 3 (15.0 +/- 6.6%).     

Toxins in toxic Taiwanese crabs

Abstract

A total of 459 specimens covering 51 species in 9 families was collected from October 1992 to May 1996 in Taiwan. All specimens were assayed for the presence of tetrodotoxin (TTX) and paralytic shellfish poison (PSP). The specimens of five xanthid crabs Zosimus aeneus, Lophozozymus pictor, Ategatopsis germaini, Atergatis floridus, and De‐mania reynaudi were found to contain potent toxins. Among them, A. germaini showed the highest toxicity. The toxin profile of each toxic crab species was as follows: 82% TTX and 18% PSP in Z. aeneus, 89% TTX and 11% PSP in L. pictor, 3% TTX and 97% PSP inA germaini, 85% TTX and 15% in A. floridus, and 88% TTX and 12% PSP in D. reynaudi. PSP was mainly composed of gonyautoxins (GTXs) 1–4 in Z. aeneus, L. pictor, and A. floridus, but GTX 3 and hydroxysaxitoxin in A. germaini, and neosaxitoxin in D. reynaudi. The PSP‐producing dinoflagellate plankton Alexandrium minutum and TTX‐producing bacteria including Vibrio alginolyticus and Vibrio parahaemolyticus were isolated and considered as the sources of the toxins.     

石房蛤毒素免疫亲和柱制备及柱效测试研究

目的阐明石房蛤毒素(saxitoxin, STX)免疫亲和柱对11种麻痹性贝类毒素的亲和作用。方法通过纯化的STX单克隆抗体与琼脂糖凝胶(sepharose 4B)制备STX免疫亲和柱,采用11种麻痹性贝类毒素(paralytic shellfish poisoning,PSP)标液进行过柱实验,优化上柱条件,采用液相色谱-质谱串联法进行毒素检测。结果STX免疫亲和柱对新石房蛤毒素(neosaxitoxin,neo-STX)、脱氨甲酰基新石房蛤毒素(decarbamoylneosaxitoxin dihydrochloride,dcneo-STX)、膝沟藻毒素1(gonyautoxin-1,GTX1)、膝沟藻毒素4(gonyautoxin-4, GTX4)基本没有亲和力作用;而对7种PSP的亲和力强弱顺序为:STXN-磺酰氨甲酰基类毒素5(gonyautoxin-5, GTX5)脱氨甲酰基石房蛤毒素(decarbamoylsaxitoxin dihydrochloride, dcSTX)膝沟藻毒素3(gonyautoxin-3,GTX3)脱氨甲酰基膝沟藻毒素3(decarbamoylgonyautoxin-3,dcGTX3)脱氨甲酰基膝沟藻毒素2(decarbamoylgonyautoxin-2, dcGTX2)膝沟藻毒素2(gonyautoxin-2, GTX2),其中对STX、GTX5、dcSTX、GTX3的回收率为61.2%～99.0%。结论该STX免疫亲和柱对STX、GTX5、dcSTX、GTX3有较好的吸附效果,能够满足样品检测前处理的要求,为水产品中麻痹性贝类毒素的提取方法研究提供了新技术的参考依据。     

Reductions of Vibrio parahaemolyticus in Pacific oysters (Crassostrea gigas) by depuration at various temperatures

Consumption of raw oysters has been linked to several outbreaks of Vibrio parahaemolyticus infection in the United States. This study investigated effects of ice storage and UV-sterilized seawater depuration at various temperatures on reducing V. parahaemolyticus in oysters. Raw Pacific oysters (Crassostrea gigas) were inoculated with a mixed culture of five clinical strains of V. parahaemolyticus (10290, 10292, 10293, BE 98-2029 and 027-1c1) at levels of 10⁴⁻⁶ MPN/g. Inoculated oysters were either stored in ice or depurated in recirculating artificial seawater at 2, 3, 7, 10, 12.5, and 15 °C for 4–6 days. Holding oysters in ice or depuration of oysters in recirculating seawater at 2 or 3 °C for 4 days did not result in significant reductions (P > 0.05) of V. parahaemolyticus in the oysters. However, depuration at temperatures between 7 and 15 °C reduced V. parahaemolyticus populations in oysters by >3.0 log MPN/g after 5 days with no loss of oysters. Depuration at refrigerated temperatures (7–15 °C) can be applied as a post-harvest treatment for reducing V. parahaemolyticus in Pacific oysters.     

Matrix effect on paralytic shellfish toxins quantification and toxicity estimation in mussels exposed to Gymnodinium catenatum

Paralytic shellfish toxins were quantified in whole tissues of the mussel Mytilus galloprovincialis exposed to blooms of the dinoflagellate Gymnodinium catenatum in Portuguese coastal waters. A validated liquid chromatography method with fluorescence detection, involving pre-chromatographic oxidation was used to quantify carbamoyl, N-sulfocarbamoyl and decarbamoyl toxins. In order to test for any matrix effect in the quantification of those toxins, concentrations obtained from solvent and matrix matched calibration curves were compared. A suppression of the fluorescence signal was observed in mussel extract or fraction in comparison to solvent for the compounds dcGTX2 + 3, GTX2 + 3 and GTX1 + 4, while an enhancement was found for C1 + 2, dcSTX, STX, B1, dcNEO and NEO. These results showed that a matrix effect varies among compounds. The difference of concentrations between solvent and matrix matched calibration curves for C1 + 2 (median = 421 ng g?1) exceeded largely the values for the other quantified compounds (0.09-58 ng g?1). Those differences were converted into toxicity differences, using Oshima toxicity equivalence factors. The compounds C1 + 2 and dcNEO were the major contributors to the differences of total toxicity in the mussel samples. The differences of total toxicity were calculated in ten mussel samples collected during a 10-week blooming period in Portuguese coastal lagoon. Values varied between 53 and 218 μg STX equivalents kg?1. The positive differences mean that the estimated toxicity using solvent calibration curves exceed the values taking into account the matrix. For the toxicity interval 200-800 μg STX equivalents kg?1 an increase was found between 44 and 28%.     

Geographical,temporal, and species variation of the polyether toxins,azaspiracids, in shellfish

Azaspiracid Poisoning (AZP) is a new toxic syndrome that has caused human intoxications throughout Europe following the consumption of mussels (Mytilus edulis), harvested in Ireland. Shellfish intoxication is a consequence of toxin-bearing microalgae in the shellfish food chain, and these studies demonstrated a wide geographic distribution of toxic mussels along the entire western coastal region of Ireland. The first identification of azaspiracids in other bivalve mollusks including oysters (Crassostrea gigas), scallops (Pecten maximus), clams (Tapes phillipinarium), and cockles (Cardium edule) is reported. Importantly, oysters were the only shellfish that accumulated azaspiracids at levels that were comparable with mussels. The highest levels of total azaspiracids (microg/g) recorded to-date were mussels (4.2), oysters (2.45), scallops (0.40), cockles (0.20), and clams (0.61). An examination of the temporal variation of azaspiracid contamination of mussels in a major shellfish production area revealed that, although maximum toxin levels were recorded during the late summer period, significant intoxications were observed at periods when marine dinoflagellate populations were low. Although human intoxications have so far only been associated with mussel consumption, the discovery of significant azaspiracid accumulation in other bivalve mollusks could pose a threat to human health.     

Canning process that diminishes paralytic shellfish poison in naturally contaminated mussels (Mytilus galloprovincialis).

Changes in toxin profile and total toxicity levels of paralytic shellfish poison (PSP)-containing mussels were monitored during the standard canning process of pickled mussels and mussels in brine using mouse bioassays and high-performance liquid chromatography. Detoxification percentages for canned mussel meat exceeded 50% of initial toxicity. Total toxicity reduction did not fully correspond to toxin destruction, which was due to the loss of PSP to cooking water and packing media of the canned product. Significant differences in detoxification percentages were due to changes in toxin profile during heat treatment in packing media. Toxin conversion phenomena should be determined to validate detoxification procedures in the canning industry.     

Matrix effect on paralytic shellfish toxins quantification and toxicity estimation in mussels exposed to Gymnodinium catenatum

Paralytic shellfish toxins were quantified in whole tissues of the mussel Mytilus galloprovincialis exposed to blooms of the dinoflagellate Gymnodinium catenatum in Portuguese coastal waters. A validated liquid chromatography method with fluorescence detection, involving pre-chromatographic oxidation was used to quantify carbamoyl, N-sulfocarbamoyl and decarbamoyl toxins. In order to test for any matrix effect in the quantification of those toxins, concentrations obtained from solvent and matrix matched calibration curves were compared. A suppression of the fluorescence signal was observed in mussel extract or fraction in comparison to solvent for the compounds dcGTX2?+?3, GTX2?+?3 and GTX1?+?4, while an enhancement was found for C1?+?2, dcSTX, STX, B1, dcNEO and NEO. These results showed that a matrix effect varies among compounds. The difference of concentrations between solvent and matrix matched calibration curves for C1?+?2 (median?=?421?ng?g^?1) exceeded largely the values for the other quantified compounds (0.09–58?ng?g^?1). Those differences were converted into toxicity differences, using Oshima toxicity equivalence factors. The compounds C1?+?2 and dcNEO were the major contributors to the differences of total toxicity in the mussel samples. The differences of total toxicity were calculated in ten mussel samples collected during a 10-week blooming period in Portuguese coastal lagoon. Values varied between 53 and 218?µg STX equivalents kg^?1. The positive differences mean that the estimated toxicity using solvent calibration curves exceed the values taking into account the matrix. For the toxicity interval 200–800?µg STX equivalents kg^?1 an increase was found between 44 and 28%.     

2018—2020年河北省市售贝类中麻痹性贝类毒素污染状况调查分析

目的了解2018—2020年河北省市售贝类中麻痹性贝类毒素(paralytic shellfish poison,PSP)污染状况。方法 2018年8月—2020年5月间,对河北省市售的7种双壳贝类,共508份进行检测分析。样品经0.5%乙酸水提取,石墨化碳黑固相萃取柱净化,采用高效液相色谱-串联质谱法进行检测。结果 508份样品,PSP阳性样品24份,检出率为4.7%, 15份样品超过世界卫生组织规定安全限量,超标率为3.0%。检出贝类为贻贝、毛蚶、杂色蛤、扇贝, PSP含量范围分别为217.0~13001.8μg石房蛤毒素当量(saxitoxin equivalent, STXeq/kg)、217.0~4893.2μg STXeq/kg、217.0~503.6μg STXeq/kg、217.0~11024.5μg STXeq/kg;超标贝类为贻贝、毛蚶、扇贝。贝类中检出的PSP类型有GTX1、GTX4、GTX2、GTX3、neoSTX、STX。结论河北省市售贝类麻痹性贝类毒素暴露风险整体较低,秦皇岛地区贻贝等贝类产品在4、5月份较易受到PSP污染,应持续关注,加强早期监测预警。     

Prediction of paralytic shellfish toxin based on a projected future climate scenario for South Korea

This study aimed to predict the seasonal patterns of paralytic shellfish poison (PSP) level in the next 90 years based on a future climate scenario, Representative Concentration Pathway (RCP) 8.5. To achieve this goal, we constructed a censored regression model using seawater temperature, weekly change in seawater temperature, salinity, rainfall, insolation, shell species, and areas prone to red tide as potentially influential environmental factors on PSP level in the coastal areas of South Korea. The censored regression model is used instead of the ordinary regression model because the PSP data had a large portion of non-detectable (ND) data. All of the continuous environmental covariates had significant quadratic relationships with the PSP toxin level except insolation. These results indicated that there are favorable ranges of seawater temperature, weekly change in seawater temperature, salinity, and rainfall to PSP production. To predict the future PSP distribution, we plugged the environmental condition data under a future climate scenario, RCP 8.5 scenario, in the estimated regression model. In the future, it is expected that the highest frequency of shellfish poisoning outbreaks will occur during the earlier months in the year, such as February and March, whereas most outbreaks of shellfish poisoning have occurred in April and May during recent years in South Korea.     

Comparative Toxicity and Paralytic Shellfish Poisoning Toxin Profiles in the Mussel Mytilus galloprovincialis and the Oyster Crassostrea gigas Collected from a Mediterranean Lagoon in Tunisia: A Food Safety Concern

Edible shellfish Mytilus galloprovincialis and Crassostrea gigas have been investigated for the paralytic shellfish poisons using mouse bioassay and high performance liquid chromatography with fluorescence detection. Paralytic shellfish poisons toxins were detected in mussels and oysters from September 2007 to May 2008. The level of paralytic shellfish poisons toxins in mussels reached the maximum in November with 832.9 μg saxitoxin-eq/100 g tissue. In oysters, toxins were detected with a maximum of 11.2 μg saxitoxin-eq/100 g tissue. The toxin high performance liquid chromatography profiles in mussels and oysters revealed the dominance of gonyautoxin 5 and N-sulfocarbamoyl-gonyautoxin-2 and -3 (C1-2), whereas GTX1-4, saxitoxin, and neosaxitoxin were found at low amounts. Overall, levels of paralytic shellfish poisons toxins were 20–70 times greater in mussels than in oysters. This is the first report on the qualitative and quantitative paralytic shellfish poisons content of M. galloprovincialis and C. gigas from a shellfish farming lagoon in Tunisia.     

A new analytical method for gonyautoxins based on postcolumn HPLC

A new ion-pairing high-performance liquid chromatography (HPLC) method on a C30 column with a volatile mobile phase was developed to separate the gonyautoxin group (GTXs) from contaminants, allowing the utilization of liquid chromatography/mass spectrometry (LC/MS) with higher performance. A mobile phase consisting of 5 mmol/L heptafluorobutyric acid and 2% acetonitrile in 10 mmol/L ammonium acetate was adopted for separation of GTXs because the C30 column strongly retains GTXs under acidic conditions. The newly adopted method could efficiently separate GTXs from contaminants, especially in the toxic short-necked clam, whereas the routine HPLC so far used has poor resolution to separate GTXs from unknown interfering substances. In our method, GTXs were eluted in the order of GTX5, GTX3, GTX4, GTX2 and GTX1 from the C30 column, and were successfully determined by sonic spray ionization mass spectrometry (SSI-MS) with high sensitivity. This method is characterized by the combination of HPLC using a fluorescence detection system for PSP, and SSI-MS for measurement of the mass number.