Identification of New CTX Analogues in Fish from the Madeira and Selvagens Archipelagos by Neuro-2a CBA and LC-HRMS.

Ciguatera Poisoning (CP) is caused by consumption of fish or invertebrates contaminated with ciguatoxins (CTXs). Presently CP is a public concern in some temperate regions, such as Macaronesia (North-Eastern Atlantic Ocean). Toxicity analysis was performed to characterize the fish species that can accumulate CTXs and improve understanding of the ciguatera risk in this area. For that, seventeen fish specimens comprising nine species were captured from coastal waters inMadeira and Selvagens Archipelagos. Toxicity was analysed by screening CTX-like toxicity with the neuroblastoma cell-based assay (neuro-2a CBA). Afterwards, the four most toxic samples were analysed with liquid chromatography-high resolution mass spectrometry (LC-HRMS). Thirteen fish specimens presented CTX-like toxicity in their liver, but only four of these in their muscle. The liver of one specimen of Muraena augusti presented the highest CTX-like toxicity (0.270 ± 0.121 µg of CTX1B equiv·kg-1). Moreover, CTX analogues were detected with LC-HRMS, for M. augusti and Gymnothorax unicolor. The presence of three CTX analogues was identified: C-CTX1, which had been previously described in the area; dihydro-CTX2, which is reported in the area for the first time; a putative new CTX m/z 1127.6023 ([M+NH4]+) named as putative C-CTX-1109, and gambieric acid A.

Addressing the Analytical Challenges for the Detection of Ciguatoxins Using an Electrochemical Biosensor.

The importance of ciguatoxins (CTXs) in seafood safety and their emerging occurrence in locations far away from tropical areas highlight the need for simple and low-cost methods for the sensitive and rapid detection of these potent marine toxins to protect seafood consumers. Herein, an electrochemical immunosensor for the detection of CTXs is presented. A sandwich configuration is proposed, using magnetic beads (MBs) as immobilization supports for two capture antibodies, with their combination facilitating the detection of CTX1B, CTX3C, 54-deoxyCTX1B, and 51-hydroxyCTX3C. PolyHRP-streptavidin is used for the detection of the biotinylated detector antibody. Experimental conditions are first optimized using colorimetry, and these conditions are subsequently used for electrochemical detection on electrode arrays. Limits of detection at the pg/mL level are achieved for CTX1B and 51-hydroxyCTX3C. The applicability of the immunosensor to the analysis of fish samples is demonstrated, attaining detection of CTX1B at contents as low as 0.01 µg/kg and providing results in correlation with those obtained using mouse bioassay (MBA) and cell-based assay (CBA), and confirmed by liquid chromatography coupled to high-resolution mass spectrometry (LC-ESI-HRMS). This user-friendly bioanalytical tool for the rapid detection of CTXs can be used to mitigate ciguatera risk and contribute to the protection of consumer health.

Simultaneous analysis of 11 haloacetic acids by direct injection-liquid chromatography-electrospray ionization-triple quadrupole tandem mass spectrometry and high resolution mass spectrometry: occurrence and evolution in chlorine-treated water.

A fast, simple, selective, and sensitive method for the analysis of 11 haloacetic acids (HAAs) in chlorine-treated water has been developed. The method is based on liquid chromatography-electrospray ionization-triple quadrupole tandem mass spectrometry (LC/ESI-QqQ-MS/MS) with direct injection of the aqueous sample. The main novelty of this method over the previously published procedures based on different techniques of mass spectrometry with direct injection is the combination of the simultaneous analysis of three types of HAAs (chlorinated, brominated, and iodinated) with its simplicity and low LODs (0.01-0.6 µg/L), avoiding the use of ion-pairing reagents for LC as well as the complexity and high cost of other techniques such as ion chromatography and capillary electrophoresis coupled to tandem mass spectrometry (IC-MS/MS and CE-MS/MS). The developed method was compared with another procedure carried out in our laboratory based on direct injection-liquid chromatography-electrospray ionization-high-resolution mass spectrometry with an Orbitrap analyzer (LC/ESI-Orbitrap-HRMS). The application of this technique to HAA analysis had not been previously described. LODs achieved by LC-HRMS (0.01-2 µg/L) were higher than the ones obtained by LC-MS/MS. Therefore, the LC/ESI-QqQ-MS/MS method was applied to the analysis of real samples. Quality parameters were calculated with satisfactory results and real samples related to three drinking water treatment plants (DWTPs), tap water, and the drinking water distribution system of Barcelona area (Catalonia, NE Spain) were analyzed. Furthermore, the evolution of HAA concentration along time in a DWTP-treated water sample was studied.

Evaluation of tetrodotoxins in puffer fish caught along the Mediterranean coast of Spain. Toxin profile of Lagocephalus sceleratus.

Although consumption of Tetraodontidae species is prohibited in the EU, intoxications are still reported. The evaluation of tetrodotoxins (TTXs) by mass spectrometry (LC-MS/MS and LC-HRMS) and a screening immunoassay (mELISA) in tetraodontid fishes caught along the Western Mediterranean Sea revealed high concentrations of TTXs in Lagocephalus sceleratus while no TTXs were identified in L. lagocephalus and Sphoeroides pachygaster individuals. The high TTXs content found in the L. sceleratus analysed herein demonstrate the occurrence of highly toxic puffer fish in the Western Mediterranean Sea. Being L. sceleratus a recent invasive species in the Mediterranean, surveillance, risk assessment and risk management measures are necessary. The strategy used within this research work could be a valuable tool for future food safety monitoring.

Fungal biodegradation of anthracene-polluted cork: A comparative study.

The efficiency of cork waste in adsorbing aqueous polycyclic aromatic hydrocarbons (PAHs) has been previously reported. Biodegradation of contaminated cork using filamentous fungi could be a good alternative for detoxifying cork to facilitate its final processing. For this purpose, the degradation efficiency of anthracene by three ligninolytic white-rot fungi (Phanerochaete chrysosporium, Irpex lacteus and Pleurotus ostreatus) and three non-ligninolytic fungi which are found in the cork itself (Aspergillus niger, Penicillium simplicissimum and Mucor racemosus) are compared. Anthracene degradation by all fungi was examined in solid-phase cultures after 0, 16, 30 and 61 days. The degradation products of anthracene by P. simplicissimum and I. lacteus were also identified by GC-MS and a metabolic pathway was proposed for P. simplicissimum. Results show that all the fungi tested degraded anthracene. After 61 days of incubation, approximately 86%, 40%, and 38% of the initial concentration of anthracene (i.e., 100 µM) was degraded by P. simplicissimum, P. chrysosporium and I. lacteus, respectively. The rest of the fungi degraded anthracene to a lesser extent (<30%). As a final remark, the results obtained in this study indicate that P. simplicissimum, a non-ligninolytic fungi characteristic of cork itself, could be used as an efficient degrader of PAH-contaminated cork.

Fragmentation studies for the structural characterization of marine dissolved organic matter.

High-resolution tandem mass spectrometry by collision-induced dissociation with a linear ion trap-Orbitrap has been performed on marine dissolved organic matter (DOM). Product ion spectra of selected precursor ions (m/z 359-375) have been acquired to obtain structural information, after method development. To evaluate the performance of the method, the Suwannee River fulvic acid (SRFA) reference standard was also analyzed. By reconstructing the individual product ion spectrum of marine DOM, several fragments were assigned to the different precursor ions indicating the presence of carboxyl, hydroxyl, lactones, quinones, esters, and structures more similar to lignin-degraded molecules. On the basis of these findings, coastal marine DOM molecules, although structurally homogeneous, might be more rich in diversity of functional groups than previously described.

Occurrence of cytostatic compounds in hospital effluents and wastewaters, determined by liquid chromatography coupled to high-resolution mass spectrometry.

The occurrence of 26 commonly used cytostatic compounds in wastewaters was evaluated using an automated solid-phase extraction (SPE) method with liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Detection was optimized using Oasis HLB SPE cartridges at pH 2. Two hospital effluents and their two receiving wastewater treatment plants were sampled over five days. In hospital effluents, eight cytostatics were detected at levels up to 86.2 µg L(-1) for ifosfamide, 4.72 µg L(-1) for cyclophosphamide, and 0.73 µg L(-1) for irinotecan, the three most relevant compounds identified. Cyclophosphamide and megestrol acetate were found in wastewaters at concentrations up to 0.22 µg L(-1) for the latter. The predicted environmental concentrations (PEC) in sewage effluents of ifosfamide (2.4-4.3 ng L(-1)), capecitabine (11.5-14.2 ng L(-1)), and irinotecan (0.4-0.6 ng L(-1)), calculated from consumption data in each hospital, published excretion values for the target compounds, and wastewater elimination rates, were in agreement with experimental values.

In vitro bioassays for monitoring drinking water quality of tap water, domestic filtration and bottled water.

BACKGROUND: Location-specific patterns of regulated and non-regulated disinfection byproducts (DBPs) were detected in tap water samples of the Barcelona Metropolitan Area. However, it remains unclear if the detected DBPs together with undetected DPBs and organic micropollutants can lead to mixture effects in drinking water. OBJECTIVE: To evaluate the neurotoxicity, oxidative stress response and cytotoxicity of 42 tap water samples, 6 treated with activated carbon filters, 5 with reverse osmosis and 9 bottled waters. To compare the measured effects of the extracts with the mixture effects predicted from the detected concentrations and the relative effect potencies of the detected DBPs using the mixture model of concentration addition. METHODS: Mixtures of organic chemicals in water samples were enriched by solid phase extraction and tested for cytotoxicity and neurite outgrowth inhibition in the neuronal cell line SH-SY5Y and for cytotoxicity and oxidative stress response in the AREc32 assay. RESULTS: Unenriched water did not trigger neurotoxicity or cytotoxicity. After up to 500-fold enrichment, few extracts showed cytotoxicity. Disinfected water showed low neurotoxicity at 20- to 300-fold enrichment and oxidative stress response at 8- to 140-fold enrichment. Non-regulated non-volatile DBPs, particularly (brominated) haloacetonitriles dominated the predicted mixture effects of the detected chemicals and predicted effects agreed with the measured effects. By hierarchical clustering we identified strong geographical patterns in the types of DPBs and their association with effects. Activated carbon filters did not show a consistent reduction of effects but domestic reverse osmosis filters decreased the effect to that of bottled water. IMPACT STATEMENT: Bioassays are an important complement to chemical analysis of disinfection by-products (DBPs) in drinking water. Comparison of the measured oxidative stress response and mixture effects predicted from the detected chemicals and their relative effect potencies allowed the identification of the forcing agents for the mixture effects, which differed by location but were mainly non-regulated DBPs. This study demonstrates the relevance of non-regulated DBPs from a toxicological perspective. In vitro bioassays, in particular reporter gene assays for oxidative stress response that integrate different reactive toxicity pathways including genotoxicity, may therefore serve as sum parameters for drinking water quality assessment.

Molecular characterization of dissolved organic matter through a desalination process by high resolution mass spectrometry.

The effect of different water treatments such as ultrafiltration (UF) and reverse osmosis (RO) on dissolved organic matter (DOM) is still unknown. Electrospray ionization Fourier transform orbitrap mass spectrometry has been used to provide valuable information of marine DOM evolution through a desalination process on a molecular scale. In the present manuscript, the characterization of four real composite water samples from a desalination pilot plant installed in the coast of Barcelona (Spain) has been carried out. The sampling was performed on each point of the pilot plant: raw seawater (RSW), UF effluent, brine RO and permeate RO. The mass spectra of the different samples show several thousand peaks, however for the present screening study, only the mass range m/z 200-500 and the main signals in this mass range (relative intensities ≥1%) have been considered. The analysis of RSW and UF samples reveal that there is little effect on DOM by the UF pilot. However, when the water is treated on the RO an important change on DOM has been observed. The recurring periodical patterns found in RSW and UF are lost in Permeate RO sample. Compounds with more aliphatic character, with higher H/C ratio (H/Cav 1.72) are present in the Permeate and some of them have been tentatively identified as fatty acids.

Magnetic particle-based enzyme assays and immunoassays for microcystins: from colorimetric to electrochemical detection.

In this work, magnetic particles (MPs) are used as supports for the immobilization of biorecognition molecules for the detection of microcystins (MCs). In one approach, a recombinant protein phosphatase 1 (PP1) has been conjugated to MPs via coordination chemistry, and MC-LR detection has been based on the inhibition of the enzyme activity. In the other approach, a monoclonal antibody (mAb) against MC-LR has been conjugated to protein G-coated MPs, and a direct competitive enzyme-linked immunoparticle assay (ELIPA) has been then performed. Conjugation of biomolecules to MPs has been first checked, and after optimization, MC detection has been performed. The colorimetric PPIA with PP1-MP and the best ELIPA strategy have provided limits of detection (LOD) of 7.4 and 3.9 µg/L of MC-LR, respectively. The electrochemical ELIPA has decreased the LOD to 0.4 µg/L, value below the guideline recommended by the World Health Organisation (WHO). The approaches have been applied to the analysis of a cyanobacterial culture and a natural bloom, and MC equivalent contents have been compared to those obtained by conventional assays and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results have demonstrated the viability of the use of MPs as biomolecule immobilization supports in biotechnological tools for MCs monitoring.

Yeast-yeast interactions revealed by aromatic profile analysis of Sauvignon Blanc wine fermented by single or co-culture of non-Saccharomyces and Saccharomyces yeasts.

There has been increasing interest in the use of selected non-Saccharomyces yeasts in co-culture with Saccharomyces cerevisiae. The main reason is that the multistarter fermentation process is thought to simulate indigenous fermentation, thus increasing wine aroma complexity while avoiding the risks linked to natural fermentation. However, multistarter fermentation is characterised by complex and largely unknown interactions between yeasts. Consequently the resulting wine quality is rather unpredictable. In order to better understand the interactions that take place between non-Saccharomyces and Saccharomyces yeasts during alcoholic fermentation, we analysed the volatile profiles of several mono-culture and co-cultures. Candida zemplinina, Torulaspora delbrueckii and Metschnikowia pulcherrima were used to conduct fermentations either in mono-culture or in co-culture with S. cerevisiae. Up to 48 volatile compounds belonging to different chemical families were quantified. For the first time, we show that C. zemplinina is a strong producer of terpenes and lactones. We demonstrate by means of multivariate analysis that different interactions exist between the co-cultures studied. We observed a synergistic effect on aromatic compound production when M. pulcherrima was in co-culture with S. cerevisiae. However a negative interaction was observed between C. zemplinina and S. cerevisiae, which resulted in a decrease in terpene and lactone content. These interactions are independent of biomass production. The aromatic profiles of T. delbrueckii and S. cerevisiae in mono-culture and in co-culture are very close, and are biomass-dependent, reflecting a neutral interaction. This study reveals that a whole family of compounds could be altered by such interactions. These results suggest that the entire metabolic pathway is affected by these interactions.

Can cyanotoxins explain the clinical features of the thermal crisis in balneotherapy?

Microbial biofilms communities in mineral waters and hot springs have a particular composition with species belonging to different groups such as epsilonproteobacteria and gammaproteobacteria or different siderobacteria and other chymoautrophic organisms, in addition to certain bacillaryophytes, chlorophytes and especially cyanobacteria. Balneotherapy can cause adverse reactions to the usual doses of application of treatments, that consists of a non-specific clinical picture, the so-called "thermal crisis" or "balneointoxication". Despite its clinical similarity (gastric discomfort, hepatic congestive outbreaks, cutaneous reactions, etc.) with that observed in acute cyanotoxin poisonings, thermal crisis has never been associated with the abundant growth of potentially toxic cyanobacteria in the mineral water sources. The aim of this work was to verify the hypothetical involvement of cyanotoxins in this clinical picture. Samples from mostly sulphurous water sources, with thermal characteristics ranging from cold to hyperthermal waters were analysed. ELISA (both in solution and in cellular matrix samples), LC-ESI-HRMS (in cellular matrix samples), and analysis of potential toxicity by means of a standardized bioassay were carried out. The toxic effect observed in the toxicity bioassays in one third of the sources may be related to the existence of microcystins and nodularins and even with other cyanobacterial peptides detected. In addition, several responses observed in the toxicity analyses reflect a pattern, probably linked to a type of hormetic response (hormesis is an adaptive response to low levels of stress, characterized by a biphasic dose-response curve).

Insights to estimate exposure to regulated and non-regulated disinfection by-products in drinking water.

BACKGROUND: Knowledge about human exposure and health effects associated with non-routinely monitored disinfection by-products (DBPs) in drinking water is sparse. OBJECTIVE: To provide insights to estimate exposure to regulated and non-regulated DBPs in drinking water. METHODS: We collected tap water from homes (N = 42), bottled water (N = 10), filtered tap water with domestic activated carbon jars (N = 6) and reverse osmosis (N = 5), and urine (N = 39) samples of participants from Barcelona, Spain. We analyzed 11 haloacetic acids (HAAs), 4 trihalomethanes (THMs), 4 haloacetonitriles (HANs), 2 haloketones, chlorate, chlorite, and trichloronitromethane in water and HAAs in urine samples. Personal information on water intake and socio-demographics was ascertained in the study population (N = 39) through questionnaires. Statistical models were developed based on THMs as explanatory variables using multivariate linear regression and machine learning techniques to predict non-regulated DBPs. RESULTS: Chlorate, THMs, HAAs, and HANs were quantified in 98-100% tap water samples with median concentration of 214, 42, 18, and 3.2 µg/L, respectively. Multivariate linear regression models had similar or higher goodness of fit (R2) compared to machine learning models. Multivariate linear models for dichloro-, trichloro-, and bromodichloroacetic acid, dichloroacetonitrile, bromochloroacetonitrile, dibromoacetonitrile, trichloropropnanone, and chlorite showed good predictive ability (R 2 = 0.8-0.9) as 80-90% of total variance could be explained by THM concentrations. Activated carbon filters reduced DBP concentrations to a variable extent (27-80%), and reverse osmosis reduced DBP concentrations ≥98%. Only chlorate was detected in bottled water samples (N = 3), with median = 13.0 µg/L. Creatinine-adjusted trichloroacetic acid was the most frequently detected HAA in urine samples (69.2%), and moderately correlated with estimated drinking water intake (r = 0.48). SIGNIFICANCE: Findings provide valuable insights for DBP exposure assessment in epidemiological studies. Validation of predictive models in a larger number of samples and replication in different settings is warranted. IMPACT STATEMENT: Our study focused on assessing and describing the occurrence of several classes of DBPs in drinking water and developing exposure models of good predictive ability for non-regulated DBPs.

Accurate mass measurements and ultrahigh-resolution: evaluation of different mass spectrometers for daily routine analysis of small molecules in negative electrospray ionization mode.

Six mass spectrometers based on different mass analyzer technologies, such as time-of-flight (TOF), hybrid quadrupole-TOF (Q-TOF), orbitrap, Fourier transform ion cyclotron resonance (FT-ICR), and triple quadrupole (QqQ), installed at independent laboratories have been tested during a single day of work for the analysis of small molecules in negative electrospray ionization (ESI) mode. The uncertainty in the mass measurements obtained from each mass spectrometer has been determined by taking the precision and accuracy of replicate measurements into account. The present study is focused on calibration processes (before, after, and during the mass measurement), the resolving power of the mass spectrometers, and the data processing for obtaining elemental formulae. The mass range between m/z 100 and 600 has been evaluated with a mix of four standards. This mass range includes small molecules usually detected in food and environmental samples. Negative ESI has been tested as there is almost no data on accurate mass (AM) measurements in this mode. Moreover, it has been used because it is the ESI mode for analysis of many compounds, such as pharmaceutical, herbicides, and fluorinated compounds. Natural organic matter has been used to demonstrate the significance of ultrahigh-resolution in complex mixtures. Sub-millidalton accuracy and precision have been obtained with Q-TOF, FT-ICR, and orbitrap achieving equivalent results. Poorer accuracy and precision have been obtained with the QqQ used: 11 mDa root-mean-square error and 6-11 mDa standard deviation. Some advice and requirements for daily AM routine analysis are also discussed here.

A large scale survey of trace metal levels in coastal waters of the Western Mediterranean basin using caged mussels (Mytilus galloprovincialis).

A large scale study of trace metal contamination (Hg, Cd, Pb and Ni) by means of caged mussels Mytilus galloprovincialis was undertaken along the coastal waters of the Western Mediterranean Sea within the context of the MYTILOS project. Individual mussels from an homogeneous population (shell size 50 ± 5 mm) obtained from an aquaculture farm were consecutively caged and deployed at 123 sites located in the Alborán, North-Western, South-Western and Tyrrhenian sub-basins for 12 weeks (April-July) in 2004, 2005 and 2006. After cage recoveries, both the metal content in the whole mussel tissue and the allometric parameters were measured. Statistical analysis of the datasets showed significant differences in concentrations between sub-basins for some metals and mussel condition index (CI). Linear regression models coupled to the CI were revisited for the data adjustment of certain trace metals (Hg, Cd and Ni), and four level categories were statistically derived to facilitate interregional comparison. Seawater masses surrounding coastal areas impacted by run-off from land mineralised coasts and industrial activities displayed the highest concentration ranges (Hg: 0.15-0.31 mg kg(-1) dw; Cd: 1.97-2.11; Ni: 2.18-3.20 and Pb: 3.1-3.8), although the levels obtained in most of the sites fitted within moderate or low categories, and they could be considered as baseline concentrations. However, few sites considered little-influenced by human activities, at present, showed high concentrations of Cd, Ni and Pb, which constitute new areas of concern. Overall, the use of active biomonitoring (ABM) approach allowed to investigate trace metal contamination in order to support policy makers in establishing regional strategies (particularly, with regard to the European Marine Strategy Directive).

Assessment of polycyclic aromatic hydrocarbon concentrations in mussels (Mytilus galloprovincialis) from the Western basin of the Mediterranean Sea.

The Mytilos project was carried during the last 3 years (2004-2006) in order to evaluate the level of chemical contamination along the coasts of the western basin of the Mediterranean Sea. Active mussel watch consisted of caged (12 weeks) Mytilus galloprovincialis at 123 stations along the Mediterranean coasts of Spain, France, Italy, North Tunisia, Algeria and Morocco. Results indicated total PAHs levels in the range 22-106 µg/kg dry weight. All large towns or industrial areas from all countries of the basin were affected. Analysis of the origin of contamination demonstrated mainly a pyrolytic origin except in some areas such as Maddalena, Napoli, Alger, and Cornigliano (Genova). Statistical analysis of the PAHs accumulation data enabled the characterisation and ranking of each coastal area. The overall results give scientific and technical basis for large-scale monitoring of the PAH contamination in the entire western Mediterranean basin.

Western Mediterranean coastal waters--monitoring PCBs and pesticides accumulation in Mytilus galloprovincialis by active mussel watching: the Mytilos project.

In order to evaluate the contamination levels in the Western Mediterranean basin, the active mussel watch methodology has been applied. This methodology consists of mussel transplantation (Mytilus galloprovincialis) from non impacted areas to selected coastal areas, characterised by potential impact from the continent due to contaminating sources. The areas of interest were selected along the entire coastal development of the Western Mediterranean sea, 122 sites in total. The time of mussel caging exposure was 12 weeks. The project was co-financed in the frame of the Interreg IIIB Meddoc Programme, aimed at determining the overall chemical quality of the Mediterranean sea, consistent with the Water Framework Directive 2000/60. Several partners representative of the coastal Mediterranean Countries were involved in the Project, with the purpose of building up a common surveillance network, adopting shared methodologies. In this paper we present the results of three yearly monitoring campaigns (2004, 2005, 2006) carried out along the coasts of Italy, France, Spain, Morocco, Algeria and Tunisia, including the coastal environment of Baleares, Sicily, Sardinia and Corsica. The contamination levels of Pesticides (DDT and its metabolites, Hexachlorocyclohexane isomers alpha and gamma) and Polychlorinated biphenyls, are reported and discussed. Statistical elaborations performed on the original data set were mainly aimed at validating the raw sample distributions, by means of the Johnson method. Both DD and PCB species frequency distributions have been approximated to appropriate theoretical distributions, belonging to the Log-normal and Bounded families. By integrating the related Probability Density Functions (p.d.f.), different accumulation values for DDT, DDD and DDE and PCB species have been estimated, corresponding to fixed percentage points of the area under the respective curves. By choosing appropriate probability level boundaries (33rd and 66th percentile), different regional zones have been ranked in terms of low, medium and high accumulation for Pesticides and PCBs.

High Levels of Anabaenopeptins Detected in a Cyanobacteria Bloom from N.E. Spanish Sau-Susqueda-El Pasteral Reservoirs System by LC-HRMS.

The appearance of a bloom of cyanobacteria in the Sau-Susqueda-El Pasteral system (River Ter, NE Spain) in the autumn of 2015 has been the most recent episode of extensive bloom detected in Catalonia. This system is devoted mainly to urban supply, regulation of the river, irrigation and production of hydroelectric energy. In fact, it is one of the main supply systems for the metropolitan area of cities such as Barcelona and Girona. An assessment and management plan was implemented in order to minimize the risk associated to cyanobacteria. The reservoir was confined and periodic sampling was carried out. Low and high toxicity was detected by cell bioassays with human cell lines. Additionally, analysis studies were performed by enzyme-linked immunosorbent assay (ELISA) and liquid chromatography-high resolution mass spectrometry (LC-HRMS). A microcystin target analysis and suspect screening of microcystins, nodularins, cylindrosperpmopsin and related cyanobacterial peptides by LC-HRMS were applied. The results for the analysis of microcystins were negative (<0.3 µg/L) in all the surface samples. Only traces of microcystin-LR, -RR and -dmRR were detected by LC-HRMS in a few ng/L from both fractions, aqueous and sestonic. In contrast, different anabaenopeptins and oscillamide Y at unusually high concentrations (µg-mg/L) were observed. To our knowledge, no previous studies have detected these bioactive peptides at such high levels. The reliable identification of these cyanobacterial peptides was achieved by HRMS. Although recently these peptides are detected frequently worldwide, these bioactive compounds have received little attention. Therefore, more studies on these substances are recommended, especially on their toxicity, health risk and presence in water resources.

Detection of tetrodotoxins in juvenile pufferfish Lagocephalus sceleratus (Gmelin, 1789) from the North Aegean Sea (Greece) by an electrochemical magnetic bead-based immunosensing tool.

Two small Lagocephalus sceleratus juveniles were captured in picarel targeting catches from North Aegean Sea (Greece) in the autumn of 2017. An electrochemical immunosensing tool using magnetic beads as immobilisation support was developed and applied to the rapid screening of tetrodotoxins (TTXs), potent neurotoxins that constitute a food safety hazard when present in seafood. This tool revealed the presence of TTXs in both individuals. Results were compared with those provided by mELISA and LC-HRMS, the latter confirming the presence of TTX. Some of the tissues contained TTX contents close to or above 2 mg/kg. L. sceleratus juveniles had been considered as non-toxic and, to our knowledge, this is the first report of high TTX levels in small L. sceleratus individuals. Such specimens can be mistaken with other edible species, posing a threat to consumers. The availability of low-cost and user-friendly tools for TTXs detection will contribute to guarantee seafood safety.

Bioaccessibility of lipophilic and hydrophilic marine biotoxins in seafood: An in vitro digestion approach.

This study aimed to assess the bioaccessibility of different marine biotoxins in naturally contaminated shellfish and fish gonads using an in vitro digestion methodology. In general, hydrophilic toxins (domoic acid, paralytic shellfish poisoning toxins and tetrodotoxins) showed higher bioaccessibility than lipophilic ones (okadaic acid and azaspiracids). The bioaccessibility of toxins from the okadaic acid group ranged from 69% (raw European razor clams) to 74% (raw donax clams). Regarding azaspiracids, 47% of the initial content was bioaccessible in steamed blue mussel. As for hydrophilic toxins, 100% of the initial content was bioaccessible after digestion in raw shellfish and puffer fish gonads. The total tetrodotoxin bioaccessibility in puffer fish gonads decreased significantly after steaming. The profile of tetrodotoxins changed during the digestion process: TTX and 11-norTTX-6S-ol analogues decreased significantly after digestion, but the 5,6,11-trideoxy TTX analogue increased in both raw and steamed puffer fish gonads. These preliminary findings confirm the need to consider bioaccessibility data in future seafood risk assessment, as such information enables a more accurate and realistic estimation of potential seafood hazards, particularly in what concerns lipophilic toxins, therefore, constituting a crucial tool in the refinement of regulatory limits for the presence of biotoxins in seafood.