Marine Biotoxins in Whole and Processed Scallops from the Argentine Sea.

Harmful algal blooms are an increasing worldwide threat to the seafood industry and human health as a consequence of the natural production of biotoxins that can accumulate in shellfish. In the Argentine Sea, this has been identified as an issue for the offshore fisheries of Patagonian scallops (Zygochlamys patagonica), leading to potentially harmful effects on consumers. Here we assess spatial and temporal patterns in marine biotoxin concentrations in Patagonian scallops harvested in Argentinian waters between 2012-2017, based on analyses for paralytic shellfish toxins, lipophilic toxins, and amnesic shellfish toxins. There was no evidence for concentrations of lipophilic or amnesic toxins above regulatory acceptance thresholds, with trace concentrations of pectenotoxin 2, azaspiracid 2 and okadaic acid group toxins confirmed. Conversely, paralytic shellfish toxins were quantified in some scallops. Gonyautoxins 1 and 2 dominated the unusual toxin profiles (91%) in terms of saxitoxin equivalents with maximum concentrations reaching 3985 µg STX eq/kg and with changes in profiles linked in part to seasonal changes. Total toxin concentrations were compared between samples of the adductor muscle and whole tissue, with results showing the absence of toxins in the adductor muscle confirming toxin accumulation in the digestive tracts of the scallops and the absence of a human health threat following the processing of scallop adductor meat. These findings highlight that paralytic shellfish toxins with an unusual toxin profile can occur in relatively high concentrations in whole Patagonian scallops in specific regions and during particular time periods, also showing that the processing of scallops on board factory ships to obtain frozen adductor muscle is an effective management process that minimizes the risk of poisonings from final products destined for human consumption.

Application of Six Detection Methods for Analysis of Paralytic Shellfish Toxins in Shellfish from Four Regions within Latin America.

With the move away from use of mouse bioassay (MBA) to test bivalve mollusc shellfish for paralytic shellfish poisoning (PSP) toxins, countries around the world are having to adopt non-animal-based alternatives that fulfil ethical and legal requirements. Various assays have been developed which have been subjected to single-laboratory and multi-laboratory validation studies, gaining acceptance as official methods of analysis and approval for use in some countries as official control testing methods. The majority of validation studies conducted to date do not, however, incorporate shellfish species sourced from Latin America. Consequently, this study sought to investigate the performance of five alternative PSP testing methods together with the MBA, comparing the PSP toxin data generated both qualitatively and quantitatively. The methods included a receptor binding assay (RBA), two liquid chromatography with fluorescence detection (LC-FLD) methods including both pre-column and post-column oxidation, liquid chromatography with tandem mass spectrometry (LC-MS/MS) and a commercial lateral flow assay (LFA) from Scotia. A total of three hundred and forty-nine shellfish samples from Argentina, Mexico, Chile and Uruguay were assessed. For the majority of samples, qualitative results compared well between methods. Good statistical correlations were demonstrated between the majority of quantitative results, with a notably excellent correlation between the current EU reference method using pre-column oxidation LC-FLD and LC-MS/MS. The LFA showed great potential for qualitative determination of PSP toxins, although the findings of high numbers of false-positive results and two false negatives highlighted that some caution is still needed when interpreting results. This study demonstrated that effective replacement methods are available for countries that no longer wish to use the MBA, but highlighted the importance of comparing toxin data from the replacement method using local shellfish species of concern before implementing new methods in official control testing programs.

Paralytic shellfish toxins and associated toxin profiles in bivalve mollusc shellfish from Argentina.

Paralytic Shellfish Poisoning is a potentially fatal syndrome, resulting from the filter-feeding activities of marine molluscs accumulating harmful neurotoxins naturally occurring in microalgae. Outbreaks are well recognised throughout most regions of the world, but with the highest levels of toxicity to date recorded in mussels from Argentina. Whilst toxicity has been documented for selected outbreaks over the years, testing has been conducted using a mouse bioassay. Consequently there is a need to establish baseline data utilising modern chemical detection methods, which also facilitate the quantification of individual toxin analogues, giving useful data on toxin profiles as well as total sample toxicity. In this study, 151 shellfish samples harvested from the marine waters of Argentina between 1980 and 2012 were subjected to analysis by liquid chromatography with fluorescence detection, since Jan 2019 the European Union reference method for PSP determination. Total PST concentrations were found to vary enormously throughout the coastline of Argentina, with higher levels of toxins found in the central regions of Rio Negro and Chubut. Toxin profiles in terms of molar percentage of total concentrations were dominated by the gonyautoxins GTX1&4 and GTX2&3, followed by C1&2, STX and dcGTX2&3, with minor levels of other analogues previously not reported in the country. Profiles were found to vary significantly, with statistical clusters of profile types associated with a wide range of factors, including species, spatial and temporal differences, as well as likely source microalgae species and potential toxin transformation pathways. Overall application of the chemical detection method has confirmed both the significant risk to shellfish consumers in Argentina with periodic outbreaks of extremely high toxin levels and a large variability in toxin profiles relating in part to previously reported variabilities in microalgal toxin content. The study has demonstrated the potential for the method to systematically study the relationships between toxicity, toxin profile, source phytoplankton and other environmental factors.

Occurrence and profiles of lipophilic toxins in shellfish harvested from Argentina.

The presence of phytoplankton responsible for the production of lipophilic marine biotoxins is well recognised throughout parts of South America. To date, the quantitation of lipophilic toxins in Argentinean shellfish has been limited to select and highly focussed geographical studies. This work reports the analysis for lipophilic marine biotoxins in shellfish harvested across five regions of Argentina between 1992 and 2012. LC-MS/MS analysis was used for the quantitation of all regulated lipophilic toxins. High concentrations of okadaic acid group toxins were quantified, with a clear dominance of the parent okadaic acid and more than 90% of the toxin present as esters. Results showed DSP toxins in shellfish from the Buenos Aires Province during 2006 and 2007, earlier than previously described. There was also strong evidence linking the presence of okadaic acid to human intoxications. Other lipophilic toxins detected were yessotoxin, pectenotoxin-2 and 13-desMeC spirolide. With evidence published recently for the presence of azaspiracid producers, this work reports the detection of low concentrations of azaspiracid-2 in shellfish. As such the data provides the first published evidence for yessotoxins and azaspiracids in Argentinean shellfish and further evidence for the continuing presence of lipophilic marine toxins in Argentinean waters.

In vitro and in vivo effects of tamoxifen against larval stage Echinococcus granulosus.

Cystic echinococcosis is a zoonotic infection caused by the larval stage of the cestode Echinococcus granulosus. Chemotherapy currently employs benzimidazoles; however, 40% of cases do not respond favorably. With regard to these difficulties, novel therapeutic tools are needed to optimize treatment in humans. The aim of this work was to explore the in vitro and in vivo effects of tamoxifen (TAM) against E. granulosus. In addition, possible mechanisms for the susceptibility of TAM are discussed in relation to calcium homeostasis, P-glycoprotein inhibition, and antagonist effects on a putative steroid receptor. After 24 h of treatment, TAM, at a low micromolar concentration range (10 to 50 µM), inhibited the survival of E. granulosus protoscoleces and metacestodes. Moreover, we demonstrated the chemotherapeutic and chemopreventive pharmacological effects of the drug. At a dose rate of 20 mg/kg of body weight, TAM induced protection against the infection in mice. In the clinical efficacy studies, a reduction in cyst weight was observed after the administration of 20 mg/kg in mice with cysts developed during 3 or 6 months, compared to that of those collected from control mice. Since the collateral effects of high TAM doses have been largely documented in clinical trials, the use of low doses of this drug as a short-term therapy may be a novel alternative approach for human cystic echinococcosis treatment.