Revisiting the HPLC-FLD method to quantify paralytic shellfish toxins: C3,4 quantification and the first steps towards validation

Paralytic shellfish toxins (PSTs) are a large group of biotoxins that cause paralytic shellfish poisoning. Their appearance in natural waters and their ingestion by aquatic species have a huge socio-economic impact, whereby their monitoring is of the upmost relevance to minimize the consequences. For earlier detection and faster response/action by stakeholders, validation of adjusted analytical methods, particularly for lower concentration levels, is important. This work proposes a derived High-Performance Liquid Chromatography method, with fluorescence detection (HPLC-FLD). The main differences from the official method are the size of the HPLC column and the gradient elution conditions. It covers the current eleven certified reference materials (CRM) available on the market, including the most recent—C3,4. This first calibration report for C3,4 suggests limits of detection (LOD) and limits of quantification (LOQ) of 6 nM and 19 nM (~5 µg STX.2HCl eqv./kg and 17 µg STX.2HCl eqv./kg), respectively. For the remaining CRM, LODs ranged between 3 and 28 nM (~0.9 and 127 µg STX.2HCl eqv./kg), while LOQs varied between 11 and 94 nM (~3 and 409 µg STX.2HCl eqv./kg, considering toxicity equivalency factors (TEFs) reported by EFSA).info:eu-repo/semantics/publishedVersio

Cation-exchange resin applied to paralytic Shellfish toxins depuration from Bivalves exposed to Gymnodinium catenatum

The accumulation of marine biotoxins in shellfish and their consumption causes serious food safety problems, threatening human health and compromising the availability of protein-based food. It is thus urgent to develop methodologies for the detoxification of live bivalves, avoiding their economic and nutritional devaluation. In this context, we tested an adsorption mechanism of paralytic shellfish toxins (PST) based on a cation-exchange resin. The first studies using cultures of Gymnodinium catenatum (natural producers of PST) showed a decrease of about 80% in overall toxicity after 48 h. Interestingly, we found that the toxins are adsorbed differently, with toxins’ structural features playing a part in the adsorption capacity via steric hindrance, electronic effects, or the extent of positive charge density (e.g., dcSTX). The positive effect of the resin in accelerating PST clearance from live mussels (Mytilus edulis) is not evident when compared to resin-free clearance; nevertheless, relevant information could be gathered that will facilitate further in vivo studies. Several factors appear to be at play, namely the competition of natural substances (e.g., salts, organic matter) for the same binding sites, the blocking of pores due to interactions between molecules, and/or difficulties in resin absorption by mussels. Additionally, the present work revealed the ability of mussels to neutralize pH and proposes bioconversion reactions among the PST molecules.LA/P/0101/2020MAR-01.03.01-FEAMP0049info:eu-repo/semantics/publishedVersio

The influence of surface modified poly(L-lactic acid) films on the differentiation of human monocytes into macrophages

Macrophages play a crucial role in the biological performance of biomaterials, as key factors in defining the optimal inflammation-healing balance towards tissue regeneration and implant integration. Here, we investigate how different surface modifications performed on poly(L-lactic acid) (PLLA) films would influence the differentiation of human monocytes into macrophages. We tested PLLA films without modification, surface-modified by plasma treatment (pPLLA) or by combining plasma treatment with different coating materials, namely poly(L-lysine) and a series of proteins from the extracellular matrix: collagen I, fibronectin, vitronectin, laminin and albumin. While all the tested films are non-cytotoxic, differences in cell adhesion and morphology are observed. Monocyte-derived macrophages (MDM) present a more rounded shape in non-modified films, while a more elongated phenotype is observed containing filopodia-like and podosome-like structures in all modified films. No major differences are found for the expression of HLA-DR+/CD80(+) and CD206(+)/CD163(+) surface markers, as well as for the ability of MDM to phagocytize. Interestingly, MDM differentiated on pPLLA present the highest expression of MMP9. Upon differentiation, MDM in all surface modified films present lower amounts of IL-6 and IL-10 compared to non-modified films. After stimulating MDM with the potent pro-inflammatory agent LPS, pPLLA and poly(L-lysine) and fibronectin-modified films reveal a significant reduction in IL-6 secretion, while the opposite effect is observed with IL-10. Of note, in comparison to non-modified films, all surface modified films induce a significant reduction of the IL-6/IL-10 ratio, a valuable prognosticator of the pro-versus anti-inflammatory balance. These findings provide important insights into MDM-biomaterial interactions, while strengthening the need for designing immune-informed biomaterials.project NORTE-01-0145-FEDER-000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement through the European Regional Development Fund (FEDER). C. R. Correia and J. F. Mano acknowledge the funding from the European Research Council for project ATLAS with the grant agreement number ERC-2014-ADG-669858. J. Gaifem, M.B. Oliveira and R. Silvestre acknowledge the Portuguese Foundation for Science and Technology (FCT) for the doctoral (PD/BD/106053/2015), post-doctoral (SFRH/BPD/111354/2015) and FCT Investigator (IF/00021/2014) grants, respectively. The authors also acknowledge Hospital de Braga for providing the buffy coatsThis work was developed under the scope of the project NORTE-01-0145-FEDER-000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement through the European Regional Development Fund (FEDER). C. R. Correia and J. F. Mano acknowledge the funding from the European Research Council for project ATLAS with the grant agreement number ERC-2014-ADG-669858. J. Gaifem, M.B. Oliveira and R. Silvestre acknowledge the Portuguese Foundation for Science and Technology (FCT) for the doctoral (PD/BD/106053/2015), post-doctoral (SFRH/BPD/111354/2015) and FCT Investigator (IF/00021/2014) grants, respectively. The authors also acknowledge Hospital de Braga for providing the buffy coats.info:eu-repo/semantics/publishedVersio

Toxin profile of two Gymnodinium catenatum strains from Iberian Coastal Waters

Gymnodinium catenatum has been the main species responsible for paralytic shellfish poisoning events along the Portuguese coast (Iberian Peninsula), causing bans on bivalve harvesting that result in huge economic losses. This work presents the characterization of two novel isolates of G. catenatum regarding their growth and toxin profiles. Laboratory growth experiments revealed that, although low growth rates were obtained during cultivation, the cell yields were high compared to those reported in the literature. Evaluation of the toxin profiles, by HPLC-FLD, essentially confirmed the typical composition of toxins of this regional population (Iberian Peninsula), namely, the absence or low representation of the toxins dcNEO, GTX1,4 and NEO and a higher ratio of the toxins C1,2, GTX6 and GTX5. However, the percentage of the identified toxins varied among the strains of this study (under the same isolation, growth, and analysis conditions), and also differed from that of other strains described in the literature. Interestingly, we found a comparatively high abundance of dcSTX in both strains, relative to the other toxins, and an unquantifiable amount of C3,4 toxins. In addition to the geographic relationship between toxin profiles, chemical conversions among toxins may explain some differences encountered in the toxin profiles of G. catenatum strains.info:eu-repo/semantics/publishedVersio

On the development of selective chelators for Cadmium: Synthesis, structure and chelating properties of 3-((5-(trifluoromethyl)-1,3,4-thiadiazol-2-yl)amino)benzo[d]isothiazole 1,1-dioxide, a novel Thiadiazolyl Saccharinate

Aquatic contamination by heavy metals is a major concern for the serious negative consequences it has for plants, animals, and humans. Among the most toxic metals, Cd(II) stands out since selective and truly efficient methodologies for its removal are not known. We report a novel multidentate chelating agent comprising the heterocycles thiadiazole and benzisothiazole. 3-((5-(trifluoromethyl)-1,3,4-thiadiazol-2-yl)amino)benzo[d]isothiazole 1,1-dioxide (AL14) was synthesized from cheap saccharin and characterized by different techniques, including single crystal X-ray crystallography. Our studies revealed the efficiency and selectivity of AL14 for the chelation of dissolved Cd(II) (as compared to Cu(II) and Fe(II)). Different spectral changes were observed upon the addition of Cd(II) and Cu(II) during UV-Vis titrations, suggesting different complexation interactions with both metals.UIDB/04326/2020, UIDB/04564/2020, ALG-01-0145-FEDER-022121, SFRH/BD/130407/2017info:eu-repo/semantics/publishedVersio

Acolhimento residencial em Portugal

In Portugal there are 8000 children and young people in Residential Care (RC). The concept of RC quality emerges as the adequacy of the characteristics of the centres to the needs of children. Being a complex and multidimensional construct requires different perspectives and an evaluation by various sources, assuming the voice of children as the main reference in measuring the quality. The quality of the RC is closely related to psychological adjustment, well-being and satisfaction with life of children and adolescents. Until now it has not been performed in Portugal an assessment of the quality of the RC system. At this time there is an ongoing study that aims to assess the quality of Portuguese RC system through needs assessment and psychological adjustment of children in RC, the evaluation of the quality of services provided by centres and understanding of the relationship between these two variables. This symposium aims to present some emerging results of the pilot study of national character research, still in progress, which aims to assess the quality of the RC Portuguese system. In this sense, a brief contextualization of the RC will be in Portugal, followed by the presentation of the main methodology that is used for this assessment – A Comprehensive Evaluation System for Residential Care in Portugal (ARQUA-P). Subsequently, it will be presented the data related to the psychological adjustment of adolescents that are in RC, their self-esteem, well-being and happiness subjective, relating these variables with the quality of the RC.info:eu-repo/semantics/publishedVersio

Population Structure and Reproduction of Pseudione elongata africana (Bopyridae, Isopoda)

The population structure and reproductive fitness of Pseudione elongata africana parasitizing the shrimp Palaemon concinnus were studied in two mangroves in Mozambique. About 100 host specimens were sampled every 15 days for 12 months at Costa do Sol, a peri-urban mangrove near Maputo, and at Saco, a near pristine mangrove at Inhaca Island. Parasites were removed from the branchiostegites of the shrimp and measured. Ovigerous females were selected and the eggs and embryos removed from the brood pouch and counted after staging their level of development. At Costa do Sol, the total length of female parasites (FPTL) was about 17% higher than at Saco. Ovigerous females were also more abundant at Costa do Sol in both the dry and wet seasons. The average brood size ranged from 89 to 207 eggs mm-1 FPTL in the Saco and 177 to 357 eggs mm-1 at Costa do Sol. These data provide baseline information on the population structure and reproduction of this parasite in east African mangroves. Comparative data on these parameters in peri-urban and more isolated mangroves may also lay the groundwork for the use of parasite reproduction as an indicator of anthropogenic pressure

Global variability in seawater Mg:Ca and Sr:Ca ratios in the modern ocean

Seawater Mg:Ca and Sr:Ca ratios are biogeochemical parameters reflecting the Earth–ocean–atmosphere dynamic exchange of elements. The ratios’ dependence on the environment and organisms' biology facilitates their application in marine sciences. Here, we present a measured single-laboratory dataset, combined with previous data, to test the assumption of limited seawater Mg:Ca and Sr:Ca variability across marine environments globally. High variability was found in open-ocean upwelling and polar regions, shelves/neritic and river-influenced areas, where seawater Mg:Ca and Sr:Ca ratios range from ∼4.40 to 6.40 mmol:mol and ∼6.95 to 9.80 mmol:mol, respectively. Open-ocean seawater Mg:Ca is semiconservative (∼4.90 to 5.30 mol:mol), while Sr:Ca is more variable and nonconservative (∼7.70 to 8.80 mmol:mol); both ratios are nonconservative in coastal seas. Further, the Ca, Mg, and Sr elemental fluxes are connected to large total alkalinity deviations from International Association for the Physical Sciences of the Oceans (IAPSO) standard values. Because there is significant modern seawater Mg:Ca and Sr:Ca ratios variability across marine environments we cannot absolutely assume that fossil archives using taxa-specific proxies reflect true global seawater chemistry but rather taxa- and process-specific ecosystem variations, reflecting regional conditions. This variability could reconcile secular seawater Mg:Ca and Sr:Ca ratio reconstructions using different taxa and techniques by assuming an error of 1 to 1.50 mol:mol, and 1 to 1.90 mmol:mol, respectively. The modern ratios’ variability is similar to the reconstructed rise over 20 Ma (Neogene Period), nurturing the question of seminonconservative behavior of Ca, Mg, and Sr over modern Earth geological history with an overlooked environmental effect