A detection method of typical toxic mixed red tide algae in Qinhuangdao based on three-dimensional fluorescence spectroscopy.

Red tides occur every year in the Qinhuangdao sea area of China, including a variety of toxic algae and non-toxic algae. Toxic red tide algae have caused great damage to the marine aquaculture industry in China and seriously endangered human health, but most of non-toxic algae are important bait for marine plankton. Therefore, it is very important to identify the type of mixed red tide algae in Qinhuangdao sea area. In this paper, three-dimensional fluorescence spectroscopy and chemometrics were applied to the identification of typical toxic mixed red tide algae in Qinhuangdao. Firstly, the three-dimensional fluorescence spectrum data of typical mixed red tide algae in Qinhuangdao sea area were measured by f-7000 fluorescence spectrometer, and the contour map of algae samples was obtained. Secondly, the contour spectrum analysis is carried out to find the excitation wavelength of the peak position of the three-dimensional fluorescence spectrum and form the new three-dimensional fluorescence spectrum data selected by the feature interval. Then, the new three-dimensional fluorescence spectrum data are extracted by principal component analysis (PCA). Finally, the feature extraction data and the data without feature extraction are used as the input of the genetic optimization support vector machine (GA-SVM) and particle swarm optimization support vector machine (PSO-SVM) classification models, respectively, to obtain the classification model of mixed red tide algae, and the two feature extraction analysis methods and two classification algorithms are compared. The results show that the classification accuracy of the test set using the principal component feature extraction and GA-SVM classification method is 92.97 %, when the excitation wavelengths are 420 nm, 440 nm, 480 nm, 500 nm and 580 nm, and the emission wavelengths are 650-750 nm. Therefore, it is feasible and effective to apply the three-dimensional fluorescence spectrum characteristics and genetic optimization support vector machine classification method to the identification of toxic mixed red tide algae in Qinhuangdao sea area.

Dietary exposure assessment of paralytic shellfish toxins through shellfish consumption in Shenzhen population, China.

Paralytic shellfish toxins (PSTs) produced by certain marine dinoflagellates accumulate in filter-feeding marine bivalves. We used LC-MS/MS to detect and quantify 13 PSTs in 188 shellfish samples of 14 species collected from Shenzhen city's Buji seafood wholesale market from March 2019 to February 2020. Twenty-six of 188 shellfish samples (13.8%) were PSTs detectable. Within 14 species, 10 out of 34 noble clam Chlamys nobilis samples contain detectable PSTs with the highest detection rate 29.4%. Seven out of 17 samples from Nan'ao island contained detectable PSTs with the highest detection rate 41.2% among 11 origins. Samples containing PSTs were concentrated in spring and winter, with the highest levels in March>December>January. Among PSTs detected, C1 was dominant. Acute dietary exposure assessment for Shenzhen residents were based on mean adult body weight, 99th percentile daily shellfish consumption of Shenzhen food consumption survey 2008 and maximum PSTs concentration for each shellfish species. The outcome for Chlamys nobilis was 2.4~3.7-fold higher than recommended ARfDs. Mean PSTs concentration, P99, and mean shellfish consumption were used to assess chronic dietary exposure. The results were lower than recommended ARfDs. In conclusion, residents in Shenzhen are at risk for acute PSTs poisoning, while relatively safe from chronic PSTs exposure.

Identification of ichthyotoxic red tide algae based on three-dimensional fluorescence spectra and particle swarm optimization support vector machine.

Acccurate identification whether red tide has ithyotoxicity is very significant for microalgae monitoring. In order to realize the rapid and non-destructive detection of ichthyotoxic red tide algae, a detection method combining three-dimensional (3D) fluorescence spectrum and particle swarm optimization support vector machine (PSO-SVM) was developed to monitor the ichthyotoxic red tide algae with cell concentrations from 104 cells/mL to 106 cells/mL. The contour maps contracted form three-dimensional fluorescence spectra of six common species of ichthyotoxic algae and eight common species of non-ichthyotoxic algae,which are analyzed to select the optimal emission and excitation wavelength span. The new feature data are acquired by using the emission spectrum data at 480 nm and 510 nm excitation wavelengths. The new feature data are used as the input of particle swarm optimization support vector machine to establish the optimal classification model of ichthyotoxic algae, which achieves an classification accuracy of 100% for the test set. The optimal classification model is successfully applied to identify the ichthyotoxicity of different algae including Heterosigma akashiwo, Chattonella marina, Phaeocystis globosa, Prorocentrum donghaiense, Karenia dunnii, Isoscelina galbana, Isosceles globosa and Skeletonema costatum.

Hemolytic Activity in Relation to the Photosynthetic System in Chattonella marina and Chattonella ovata.

Chattonella species, C. marina and C. ovata, are harmful raphidophycean flagellates known to have hemolytic effects on many marine organisms and resulting in massive ecological damage worldwide. However, knowledge of the toxigenic mechanism of these ichthyotoxic flagellates is still limited. Light was reported to be responsible for the hemolytic activity (HA) of Chattonella species. Therefore, the response of photoprotective, photosynthetic accessory pigments, the photosystem II (PSII) electron transport chain, as well as HA were investigated in non-axenic C. marina and C. ovata cultures under variable environmental conditions (light, iron and addition of photosynthetic inhibitors). HA and hydrogen peroxide (H2O2) were quantified using erythrocytes and pHPA assay. Results confirmed that% HA of Chattonella was initiated by light, but was not always elicited during cell division. Exponential growth of C. marina and C. ovata under the light over 100 µmol m-2 s-1 or iron-sufficient conditions elicited high hemolytic activity. Inhibitors of PSII reduced the HA of C. marina, but had no effect on C. ovata. The toxicological response indicated that HA in Chattonella was not associated with the photoprotective system, i.e., xanthophyll cycle and regulation of reactive oxygen species, nor the PSII electron transport chain, but most likely occurred during energy transport through the light-harvesting antenna pigments. A positive, highly significant relationship between HA and chlorophyll (chl) biosynthesis pigments, especially chl c2 and chl a, in both species, indicated that hemolytic toxin may be generated during electron/energy transfer through the chl c2 biosynthesis pathway.

Shellfish contamination with lipophilic toxins and dietary exposure assessments from consumption of shellfish products in Shenzhen, China.

Lipophilic shellfish toxins (LSTs) can cause human illness and therefore represent a serious threat to public health. Shellfish are the main dietary source of LSTs, but very few studies have appraised dietary exposure to LSTs through shellfish consumption in China. We measured levels of multiple LSTs in shellfish samples sold in the principal wholesale seafood market in the southern coastal city of Shenzhen, and we estimated the potential for acute and chronic LST exposure of the Shenzhen population via ingestion of shellfish. LST contamination data were obtained from a total of 14 species of 188 commercial samples. Eleven individual LSTs, namely okadaic acid (OA), dinophysis toxin-1 and -2 (DTX1 and DTX2), pectenotoxin-2 (PTX2), yessotoxin and homo yessotoxin (YTX and hYTX), azaspiracid-1, -2 and -3 (AZA1, AZA2, AZA3), spirolides (SPXs), and gymnodimine (GYM), were determined using liquid chromatography electrospray-ionization tandem mass spectrometry (LC-ESI-MS/MS). More than two thirds of samples showed undetectable LSTs, while the detection rates (the proportion of samples with detectable LSTs) of individual LSTs ranged from 0% to 45.7%. Most shellfish samples had lower levels of LST contamination than the corresponding limits of detection (LODs), while some samples had levels of hYTX and GYM that exceeded the limits of quantification (LOQs). Overall, levels of LSTs in the 188 samples were below the regulatory limits set by most countries. Acute and chronic exposures of LST were estimated by a point-estimate modeling method that combined sample contamination data with consumption data from dietary survey of Shenzhen residents and consumption figures proposed by EFSA, the European Food Safety Authority. Seasonal variations in LST concentrations were noted in some instances. Overall, the estimated acute exposure to LSTs based on consumption of large-size shellfish portions and the maximum LSTs contamination level were below the provisional acute reference doses (ARfDs) proposed by the EFSA. Chronic exposure estimates based on mean and 99th percentile consumption of shellfish by Shenzhen residents and mean LSTs contamination levels in the collected samples were from 2452 to 74 times lower than those associated with estimated acute exposure levels.

Identification of paralytic shellfish poison producing algae based on three-dimensional fluorescence spectra and quaternion principal component analysis.

In view of the problem of the paralytic shellfish poison producing algae on-line measurement and identification, a new feature extraction method of paralytic shellfish poison producing algae measurement and identification based on quaternion principal component analysis (QPCA) is investigated. The three-dimensional (3D) fluorescence spectra of three common species of paralytic shellfish poison producing algae and eight species common of non paralytic shellfish poison producing algae are analyzed. The quaternion parallel representation model of algae three-dimensional fluorescence spectrum data is established, then the features of quaternion principal component is extracted to use as the input of k-nearest neighbor (KNN) classifier, and the identification of paralytic shellfish poison producing algae is realized by the three-dimensional fluorescence spectra coupled with quaternion principal component analysis. The results show that under the quaternion parallel representation model, the recognition accuracy rate of multiplication feature, modulus feature and summation feature is 90%, 95% and 100% respectively. Compared with that of the principal component analysis feature extraction method, the recognition accuracy rate in pure samples by summation feature of quaternion principal component is improved by 10%. This study provides an experimental basis for the accurate monitoring technology of three-dimensional fluorescence spectrum of paralytic shellfish poison producing algae.

A comparative study of phytoplankton community structure and biomass determined by HPLC-CHEMTAX and microscopic methods during summer and autumn in the central Bohai Sea, China.

As the largest inland sea of China, the Bohai Sea has confronted significant environmental changes in recent decades, and a shift of phytoplankton community from diatoms to dinoflagellates was observed by microscopic method in previous studies. However, the counting of some small-sized non-diatoms (e.g., flagellates and cyanobacteria) have long been neglected due to the limitation of this method. In this study, we measured the phytoplankton community structure and abundance in the central Bohai Sea in summer and autumn of 2015 by employing both microscopic method and high-performance liquid chromatography (HPLC) pigments - CHEMTAX analysis. The results of microscopic counting showed that the phytoplankton community was characterized by diatoms, dinoflagellates, and chrysophytes, which contained a total of 107 species. Dinoflagellates and diatoms co-dominated in summer while the latter became the dominant group in autumn. Compared with microscopic counting, CHEMTAX analysis allowed identification of a larger number of phytoplankton groups (including 8 phyla). The results of CHEMTAX analysis showed that besides diatoms and dinoflagellates, the small-sized non-diatoms (i.e., flagellates and cyanobacteria) also played an important role. Diatoms and cyanobacteria dominated the total Chl a (contributing 32.5% and 17.1%, respectively), followed by cryptophytes, dinoflagellates, and prasinophytes in the summer. A short-term summer to autumn variability of phytoplankton abundance and community was observed. Temperature and nutrient availability affected the succession of the phytoplankton community from diatoms and non-diatoms co-dominance in the summer to absolute diatoms dominance in the autumn. A direct comparison of algal cell abundance and CHEMTAX biomass showed that a significant positive correlation was observed only for dinoflagellates (P < 0.01) in the autumn. Our work provides some basic information on the dynamics of small-sized flagellates and cyanobacteria in this area, and also suggests that a combination of both the methods is needed in future investigations to better understand the current status as well as the future changes of phytoplankton community.

Hemolytic and cytotoxic activity from cultures of Aureococcus anophagefferens-a causative species of brown tides in the north-western Bohai Sea, China.

Brown tides were first observed in 2009 in the north-western Bohai Sea (Qinhuangdao sea area), China, and blooms have occurred at different scales in late spring every year since then. Although the detrimental effects on marine organisms of the causative phytoplankton species Aureococcus anophagefferens have been extensively studied, the mechanism remains poorly understood. We used erythrocytes and adrenal gland chromaffin tumor cells (PC12) to explore the hemolytic activity and cytotoxicity, respectively, of chloroform and methanol extracts of cultured A. anophagefferens isolated from the north-western Bohai Sea area. The methanol extracts showed no hemolytic or cytotoxic activity. Chloroform extracts had a potent hemolytic effect on rabbit erythrocytes; thin layer chromatography (TLC) indicated that the hemolysin was a kind of glycolipid compound. Erythrocyte lysis assay showed that erythrocytes of sea bream were sensitive to the hemolysin, whereas those of human and chicken erythrocytes were insensitive. The hemolytic effects were elevated as temperatures rose from 4 °C to 37 °C. Hemolytic blocking experiments showed that sphingomyelin and d-xylose can inhibit hemolysis significantly, while osmotic protectants with different hydrated molecular diameters had no inhibition, and the hemolysins had no obvious phospholipase activity. The chloroform extracts of A. anophagefferens had significant inhibitory effects on the viability of PC12 cells, and can induce efflux of lactic dehydrogenase (LDH) of PC12 cells and lead to their necrosis.

Seasonal variability of Protoceratium reticulatum and yessotoxins in Japanese scallop Patinopecten yessoensis in northern Yellow Sea of China.

This paper reports a toxic strain of Protoceratium reticulatum, its morphology, phylogeny, yessotoxins (YTXs) production and abundance in northern Yellow Sea of China from 2011 to 2015 was investigated. YTXs in hepatopancreas and edible parts of bottom sowing cultured Japanese scallop Patinopecten yessoensis in this sea area were determined weekly for 5 years. Other potential producers of YTXs, Gonyaulax spinifera and Lingulodinium polyedrum, were also investigated. Results revealed that Protoceratium reticulatum strain from the northern Yellow Sea belongs to a geographically widely distributed species. Motile cells of Protoceratium reticulatum contribute to YTXs in Japanese scallop, and G. spinifera may also be a potential contributor. Resting cysts of Protoceratium reticulatum, G. spinifera, and L. polyedrum in sediments were possibly important origins of YTXs in scallop cultured at sea bottom. YTXs in scallop decreased from 2011 to 2015, most toxins were concentrated in hepatopancreas, while a small portion in edible parts which was safe for consumption the whole year around.

Occurrence of marine algal toxins in oyster and phytoplankton samples in Daya Bay, South China Sea.

The occurrence and seasonal variations of marine algal toxins in phytoplankton and oyster samples in Daya Bay (DYB), South China Sea were investigated. Two Dinophysis species, namely, D. caudata and D. acuminata complex, were identified as Okadaic acid (OA)/pectenotoxin (PTX) related species. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis demonstrated that 2.04-14.47 pg PTX2 per cell was the predominant toxin in single-cell isolates of D. caudata. D. acuminata was not subjected to toxin analysis. The occurrence of OAs in phytoplankton concentrates of net-haul sample coincided with the presence of D. accuminata complex, suggesting that this species is most likely an OA producer in this sea area. OA, dinophysistoxins-1 (DTX1), PTX2, PTX2sa, gymnodimine (GYM), homoyessotoxin (homoYTX), and domoic acid (DA) demonstrated positive results in net haul samples. To our best knowledge, this paper is the first to report the detection of GYM, DA, and homoYTX in phytoplankton samples in Chinese coastal waters. Among the algal toxins, GYM demonstrated the highest frequency of positive detections in phytoplankton concentrates (13/17). Five compounds of algal toxins, including OA, DTX1, PTX2, PTX2sa, and GYM, were detected in oyster samples. DA and homoYTX were not detected in oysters despite of positive detections for both in the phytoplankton concentrates. However, neither the presence nor absence of DA in oysters can be determined because extraction conditions with 100% methanol used to isolate toxins from oysters (recommended by the EU-Harmonised Standard Operating Procedure, 2015) would likely be unsuitable for this water-soluble toxin. In addition, transformation of DA during the digestion process of oysters may also be involved in the negative detections of this toxin. GYM exhibited the highest frequency of positive results in oysters (14/17). OAs were only detected in the hydrolyzed oyster samples. The detection rates of PTX and PTX2sa in oysters were lower than those in the net haul samples.

A plasmonic ELISA for the naked-eye detection of chromium ions in water samples.

Here, we describe the development of a triangular silver nanoprism (AgNPR) etching-based plasmonic ELISA for the colorimetric determination of Cr(III) levels in environmental water samples. This involved the creation of a novel signal generation system (substrate reaction solution) for a competitive ELISA in which hydrogen peroxide (H2O2) is used to etch triangular AgNPRs, inducing a change in color. This is achieved by controlling the H2O2 concentration that remains after degradation by catalase, which is conjugated to the secondary antibody of the ELISA. Because the degree of color change and the shift in the absorption spectrum of the substrate reaction solution are closely correlated with the Cr(III) concentration, this plasmonic ELISA can be used not only for the quantification of Cr(III) concentrations ranging from 3.13 to 50 ng/mL, with a limit of detection (LOD) of 3.13 ng/mL, but also for the visual detection (indicated by a color change from blue to mauve) of Cr(III) with a sensitivity of 6.25 ng/mL by the naked eye. Therefore, the plasmonic ELISA developed in this work represents a new strategy for heavy metal ion detection and has high potential applicability in resource-constrained areas. Graphical Abstract Schematic diagram of triangular silver nanoprism etching-based signal generation system.

Silver nanoparticle enhanced Raman scattering-based lateral flow immunoassays for ultra-sensitive detection of the heavy metal chromium.

We report a simple and ultra-sensitive surface enhanced Raman scattering (SERS) strip sensor based on silver nanoparticles (AgNPs) and lateral flow immunoassays (LFIAs). LFIAs are inexpensive, simple, portable and robust, thus making them commonplace in medicine, agriculture and food safety. However, their applications are limited due to the low signal intensity of the color-formation reaction based on the label accumulation. SERS is a powerful molecular spectroscopy technique for ultra-detection, which is based on the enhancement of the inelastic scattering from molecules located near nanostructured metallic surfaces when the molecules are illuminated and the surface plasmons are excited. Because of the rapidity and robustness of LFIAs and the high sensitivity of SERS, we introduce SERS into LFIAs (SERS-LFIA). Our SERS-LFIA demonstrates fast, excellent performance and is suitable for the semiquantitative examination of ultratrace analytes (Cr(3+)), with the limit of the detection (LOD) as low as 10(-5) ng mL(-1), which is 10(5)-fold more highly sensitive than those previously used to detect Cr(3+) within 15 min.

[Identification of ichthyotoxic microalgae species and its hemolytic activity by three-dimensional fluorescence spectra].

To identify ichthyotoxic microalgae species and its hemolytic activity by three-dimensional fluorescence spectra, the relationship between hemolytic activity and the three-dimensional fluorescence of typical ichthyotoxic algae (Karenia mikimotoi, Chattonella marina, Chattonella ovata) cultured in different Fe2+ concentrations was investigated with methods of Coif2 wavelet and Fisher discriminant analysis. The results showed that the differences of three-dimensional fluorescence spectra between ichthyotoxic algae and non-ichthyotoxic algae were within the 1 to 10 data points (wavelength lambda(em) = 650-680 nm) and 35 to 47 data points (wavelength lambda(em) = 725-750 nm, lambda(ex) = 400-425 nm). Fisher discriminant analysis showed that the correct discrimination ratios of ichthyotoxic algae and non-ichthyotoxic species are 91.7% and 100%, respectively, and the ratio of algae with medium hemolytic activity (> or = 10 HU, < 20 HU) was 70% and that of algae with low hemolytic activity (< 10 HU) and high hemolytic activity (> or = 20 HU) are both of above 80%.

[Production of peroxide hydrogen in Chattonella ovata Hong Kong strain].

The growth characteristics of Chattonellea ovata Hong Kong strain (COHK) under different salinity and nutrient conditions and production of peroxide hydrogen (H2O2) in different growth phase were investigated in laboratory unialgal culture experiment. The results showed that high concentration of H2O2 was reached during the logarithmic phase from 4th to 8th days, corresponding to the maximum value of 2.91 x 10(-4) nmo x cell(-1) on the 6th day. When the N: P ratios were 16: 1, 32:1 and 64: 1, COHK possessed the relatively high growth rate and cell concentration, however, growth rate of COHK was lower with the N: P ratios of 4: 1 and 8: 1. The H2O2 concentration reached the highest (1.26 x 10(-4) nmol x cell(-1)) with the N: P ratio of 4: 1, which suggested that production of H2O2 was reversely related to the growth of COHK. The optimum salinities for COHK were 20 and 25. When the salinities were 10, 15 and 30, the growth rate of COHK was lower, showing lower and higher salinities inhibited the growth of COHK. Salinity also influenced the production of H2O2. The highest concentration of H2O2 among the experiments, 2. 2 x 10(-4) nmol x cell(-1), was observed at the salinity of 10, while there was no significant difference of H2O2 concentration from the salinity range of 15 to 30. The optimal Fe(3+) concentration for the growth of COHK was from 0.2 x 10(-8) to 1 x 10(-8) mol x L(-1), where growth rate were relatively higher. Growth rate of COHK was depressed in absence (0 mol x L(-1)) and high concentration of Fe3+ (5 x 10(-8) mol x L(-1)), with which H2O2 concentration was 0.97 x 10(-4) and 0.95 x 10(-4) nmol x cell(-1), respectively.

[Study on hemolytic activity of Chattonella marina Hong Kong strain].

Hemolytic activity of Chattonella marina Hong Kong strain (CMHK) in different growth phase and nutrients structure was studied under laboratory conditions. According to the growth curve of CMHK, cells in culture were collected in logarithmic phase, stationary phase and decline phase, respectively, to determine hemolytic activity. Hemolytic activity of CHHK, which was cultured in different nutrients structure, was also determined. Furthermore, acute toxicity test of CMHK on Artemia salina was performed in early logarithmic phase (5 d), late logarithmic phase (13 d), stationary phase (15 d) and decline phase (17 d). The results showed that the highest hemolytic activity was detected in early logarithmic phase. After 5 d culture, the hemolytic activity reached 1.80 x 10(-7) HU/cell, then decreased gradually with culture time increasing. Hemolytic activity of total cells in culture in different growth phase coincided with the growth curve with the maximum reaching 5.32 HU/L in late logarithmic phase. Growth rate of CMHK was greatly depressed by Fe limitation while hemolytic activity per cell was enhanced to 8.37 x 10(-7) HU/cell, nearly 6.5 times higher than that with no Fe limitation (1.33 x 10(-7)HU/cell). Similarly, N, Mn and P limitation could also increase the hemolytic activity of CMHK. Acute toxicity test of CMHK on A. salina showed that the maximum toxicity of the algae appeared at late logarithmic phase. It was found that death rate of A. sinica reached to 77% in 48 h when exposed to the algal culture at late logarithmic phase with algae density being 4.0 x 10(4) cells/mL, and the lowest toxicity on A. sinica appeared in early logarithmic phase with death rate of 20%.

[Population dynamics of Alexandrium tamarense and its relations with environmental factors in Nanji Islands sea area of Zhejiang Province].

Based on the investigation in Nanji Islands sea area of Zhejiang Province from April 2006 to March 2007, the dynamics of Alexandrium tamarense and its relations with environmental factors were studied. In the study sea area, A. tamarense cells could only be found in spring (from April to June), and the cell abundance was of single peak curve, with the highest (12250 cells x L(-1)) in surface water on 8th of May. Higher cell abundance of A. tamarense was found at the water temperature of 18.5 degrees C - 19.5 degrees C, salinity of 29.5 per thousand - 31.0 per thousand, and lower PO4-P concentration, but no correlation was observed between A. tamarense cell abundance and water dissolved inorganic N concentration. Linear stepwise regression revealed that there was a significant positive correlation between the cell abundance of A. tamarense and the ratio of water dissolved inorganic N to PO4-P.

[Relationships between pollutants discharge and red tide occurrence in Shenzhen eastern coast].

The study on the effects of pollutants discharge on red tide occurrence in eastern sea area of Shenzhen showed that the occurrence frequency of dinoflagellate red tide had significant positive correlations with the net discharge of total nitrogen (TN) and total phosphorous (TP) as well as the N/P ratio of the discharge. The thresholds of net discharged TN and TP were estimated to be 3.917 x 10(3) t and 2.123 x 10(4) t, respectively. No significant correlation was observed between diatom red tide and alongshore pollutants discharge. An example was given to illustrate the means of pollutants discharge control.

Trophic transfer of paralytic shellfish toxins from the cladoceran (Moina mongolica) to larvae of the fish (Sciaenops ocellatus).

The dynamic transmission and transformation of paralytic shellfish toxins (PSTs) from the toxic dinoflagellate Alexandrium tamarense to the cladoceran Moina mongolica and subsequently to the larvae of the fish Sciaenops ocellatus were investigated under laboratory conditions. The results showed that PSTs could be transferred to S. ocellatus when they preyed on PST-containing M. mongolica. During the experimental period, A. tamarense, M. mongolica and the digestive glands of the fish larvae contained C(1/2) toxins, and the viscera of S. ocellatus contained neoSTX. The proportion of beta toxin (C2) in C(1+2) toxins increased when PSTs were transferred from A. tamarense to M. mongolica, but in the subsequent transfer from M. mongolica to S. ocellatus the proportion of alpha toxin (C1) increased. During depuration, the contents of C1 and C2 toxins in fish larvae decreased with the duration of depuration, but neoSTX remained relatively constant. The present results indicated that, using a cladoceran as the vector, PSTs can be transferred from toxic algae to a high trophic level fish and metabolized in the fish. Future work should address the metabolic characteristics of PSTs in cladocerans and the end result when they are transferred to fishes.

Transfer and metabolism of paralytic shellfish poisoning from scallop (Chlamys nobilis) to spiny lobster (Panulirus stimpsoni).

The transfer and transformation of paralytic shellfish poisoning (PSP) from scallop Chlamys nobilis to spiny lobster Panulirus stimpsoni were investigated in the present study. The results demonstrate that transfer and transformation of PSP toxins occurred when Panulirus stimpsoni were fed with toxic viscera of Chlamys nobilis, but depurated with non-toxic squids. Additionally, only the lobster hepatopancreas were found to contain PSP, and the toxin profiles were the same with those in the viscera of the scallop, including carbamate toxins (GTX(1-3)), N-sulfocarbamoyl toxins (C(1+2) and B(1)) and decarbamoyl toxins (dcGTX(2+3)). Unlike the lobster, the scallop contained more alpha than beta toxins. After being fed with toxic Chlamys nobili for 6 d, Panulirus stimpsoni selectively accumulated N-sulfocarbamoyl toxins with low toxicity. However, when they were depurated with non-toxic squid, N-sulfocarbamoyl toxins tended to transform into carbamate toxins with higher toxicity. The concentration of dcGTX(2+3) in Panulirus stimpsoni decreased significantly and wasn't detectable after depuration for 6 d, which was likely due to their initial low accumulation of toxins. These results reveal that PSP could be transferred and transformed in Crustaceans along the given food chain under the conditions of laboratory, but there are many questions remained to be solved, and the further studies should be carried out.

[Analysis of paralytic shellfish poison of bivalves in seafood market in Guangzhou].

OBJECTIVE: The investigations of the paralytic shellfish poisoning (PSP) from Huangsha seafood market of Guangzhou was performed to assess the risk of PSP in bivalves. METHODS: The concentration and profiles of PSP toxins in bivalves were determined by mouse bioassay of AOAC and high-performance liquid chromatography (HPLC). The risk assessment of PSP in bivalves was conducted with FAO and Chinese Administration Organization of Fish Culture and Seaport. RESULTS: The content of PSP detected was lower than the safe standard (4 MU/g meat) in all of the 84 samples, one of which had the highest toxicity with 1.84 MU/g muscle. These results suggested that the bivalves in seafood market was safe to feed. It was 9 samples' gland in 2 species that be detected to have PSP in the bivalves being researched, the muscles had few PSP. The concentration of PSP in one sample's gland exceeded the threshold of FAO (4 MU/g) with 14.52 MU/g meat, and the profiles of PSP in the gland were B1, GTX2/3, GTX1/4 and C according to HPLC. CONCLUSION: These results suggested that both of the concentration and detection rate of PSP of bivalves in seafood market in Guangzhou were low as a whole, but the content and discovery rate of PSP were far higher in glands than in the muscles, and the PSP content in one gland exceeded the threshold of Standard. The levels of PSP contamination in shellfish was characteristic of season. The toxins level in shellfish were the maximum in spring, but the frequency of toxins detected in shellfish was higher in summer and autumn, so the detection and risk assessment of PSP in bivalves from seafood market was essential in the future.