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Vale P.,Instituto Nacional dos Recursos Biologicos
Food Chemistry | Year: 2011

The paralytic shellfish poisoning (PSP) toxin producer Gymnodinium catenatum produces several hydrophobic analogues of saxitoxin (STX). These are poorly studied due to their recent discovery and lack of standards. It was previously observed these hydrophobic analogues could be partially hydrolysed, loosing its benzoate moiety during alkaline oxidation to obtain fluorescent products measurable by HPLC analysis. The hydrolysis reaction was further explored to study two practical aspects. One was the indirect measurement of these compounds through its hydrolysis products: the decarbamoyl analogues of STX. The second one was to simplify standard production of decarbamoyl analogues, which are commonly found in contaminated shellfish products.PSP analogues are unstable in alkaline media. The hydrolysis of benzoate analogues progressed rapidly with increasing base amount, but the decarbamoylgonyautoxin type hydrolysis products were short lived and converted into decarbamoylsaxitoxin type analogues. For a rapid estimation of the presence of these benzoate analogues in seafood, decarbamoylgonyautoxin type analogues can only be measured as decarbamoylsaxitoxin type equivalents.For production of standards, complete hydrolysis of hydroxybenzoate decarbamoylsaxitoxin analogues can render decarbamoylsaxitoxin and decarbamoylneosaxitoxin. Obtaining decarbamoylgonyautoxins was not suitable resorting to decarbamoylgonyautoxin type hydroxybenzoate analogues due to the prolonged reaction times required for complete hydrolysis and their instability at high pH. Hydrolysis of sulphated-benzoate analogues was best suited for obtaining decarbamoylgonyautoxins due to the very rapid hydrolysis time required. © 2010 Elsevier Ltd. Source

Vale P.,Instituto Nacional dos Recursos Biologicos
Toxicon | Year: 2010

Bivalve metabolites of saxitoxin analogues, not present in microalgae, were recently described as an important toxin fraction in mussels contaminated by Alexandrium tamarense. These possess very low fluorescence, and require mass spectrometry detection. HILIC-MS was implemented to look for these metabolites in bivalves contaminated during Gymnodinium catenatum blooms at the Portuguese coast. The presence of M1 was tentatively identified in several bivalves, ranging from estuarine (Mytilus galloprovinciallis, Cerastoderma edule and Ruditapes decussatus) to oceanic habitat (Donax trunculus and Ensis spp.). It was hypothesized that M1 could contribute to an important fraction of the profile of STX analogues. M1 was more abundant in estuarine bivalves that retain longer PSP toxins, in the following order: mussels > cockles > clams. These data highlight that the study by fluorimetry alone of the carbamoyl, N-sulfocarbamoyl, and decarbamoyl families is manifestly insufficient to fully understand toxin dynamics in bivalves feeding on G. catenatum without a proper study of hydroxybenzoate and hydroxylated M-toxins. © 2009 Elsevier Ltd. All rights reserved. Source

At Aveiro lagoon (Portuguese northwest coast) bivalve contamination with diarrhoetic shellfish poisoning toxins (DSTs), okadaic acid (OA) and dinophysistoxin-2 (DTX2), is a recurrent annual phenomenon seriously affecting seafood safety. The influence of meteorological parameters was studied to understand accumulation of DSTs in mussels, related to the blooming of the causative toxic microalgae, belonging to genus Dinophysis.Two simplified models were useful in predicting the accumulation of DSTs in blue mussels from this lagoon. Either the May river drainage or the rainfall accumulated from January through May could adequately predict the severity of OA accumulated from predation upon Dinophysis acuminata during June/July. In both cases a linear relationship was obtained, with correlation coefficients of 0.85 or greater.Winds with a west direction favour coastal concentration of Dinophysis acuta in Aveiro region. Both OA and DTX2 contamination increased exponentially in September/October with the cumulative number of days with W-wind orientation in the preceding August (correlation coefficients greater than 0.92). This relationship was attributed to the quadratic effect of wind stress on surface currents.August is a transitional month, when the continental runoff effect upon Dinophysis acuminata can still be observed and Dinophysis acuta advection may be promoted by westerly winds occurring in July. The frequency of periods with northerly winds in July can halt accumulation of toxins derived from Dinophysis acuta. © 2011 Elsevier Ltd. Source

Frias J.P.G.L.,New University of Lisbon | Sobral P.,New University of Lisbon | Ferreira A.M.,Instituto Nacional dos Recursos Biologicos
Marine Pollution Bulletin | Year: 2010

Microplastics pose a threat to coastal environments due to their capacity to adsorb persistent organic pollutants (POPs). These particles (less than 5. mm in size) are potentially dangerous to marine species due to magnification risk over the food chain. Samples were collected from two Portuguese beaches and sorted in four classes to relate the adsorption capacity of pollutants with color and age. Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and DDTs were analysed on pellets through gas chromatography mass spectrometry (GC-MS), and types of plastic were identified using Fourier transformed infra-red spectroscopy (micro-FTIR). Microplastics were mostly polyethylene and polypropylene. Regarding sizes, some fibres ranged from 1 to 5μm in diameter and were 500μm in length. The majority of samples collected had sizes above 200μm. Black pellets, unlike aged pellets, had the highest concentrations of POPs except for PAHs in Fonte da Telha beach. PAHs with higher concentrations were pyrene, phenantrene, chrysene and fluoranthene. Higher concentrations of PCBs were found for congeners 18, 31, 138 and 187. Further investigation is necessary to understand the relationship between plastic degradation and adsorption for different pollutants. © 2010 Elsevier Ltd. Source

Costa P.M.,New University of Lisbon | Caeiro S.,New University of Lisbon | Caeiro S.,University of Lisbon | Vale C.,Instituto Nacional dos Recursos Biologicos | Costa M.H.,New University of Lisbon
Environmental Pollution | Year: 2012

Surveying toxicity of complex geochemical media as aquatic sediments often yields results that are either difficult to interpret or even contradictory to acknowledged theory. Multi-level biomarkers were investigated in a benthic fish exposed to estuarine sediments through laboratory and in situ bioassays, to evaluate their employment either in ecological risk assessment or in more mechanistic approaches to assess sediment-bound toxicity. Biomarkers reflecting lesions (such as genotoxicity or histopathology), regardless of their low or absent specificity to contaminants, are efficient in segregating exposure to contaminated from uncontaminated sediments even when classical biomarkers like CYP1A and metallothionein induction are inconclusive. Conversely, proteomics and gene transcription analyses provided information on the mechanics of toxicity and aided explaining response variation as a function of metabolic imbalance and impairment of defences against insult. In situ bioassays, although less expedite and more affected by confounding factors, produced data better correlated to overall sediment contamination. © 2011 Elsevier Ltd. All rights reserved. Source

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