Climate Change Stressors, Phosphate Limitation, and High Irradiation Interact to Increase Alexandrium minutum Toxicity and Modulate Encystment Rates.

The changes in the cell physiology (growth rate, cell size, and cell DNA content), photosynthetic efficiency, toxicity, and sexuality under variable light and nutrient (phosphates) conditions were evaluated in cultures of the dinoflagellate Alexandrium minutum obtained from a red tide in the Ría de Vigo (NW Spain). The cells were grown at low (40 and 150 µE m-2 s-1), moderate (400 µE m-2 s-1), and high (800 µE m-2 s-1) light intensities in a medium with phosphate (P+) and without (P-). Cultures were acclimated to the irradiance conditions for one week, and the experiment was run for ~1 month. The cell size and DNA content were monitored via flow cytometry. Two different clonal strains were employed as a monoculture (in a P- or P+ medium) or, to foster sexuality and resting cyst formation, as a mixed culture (only in a P- medium). A. minutum growth was favored by increasing light intensities until 400 µE m-2 s-1. The DNA content analyses indicated the accumulation of S-phase cells at the highest light intensities (400 and 800 µE m-2 s-1) and therefore the negative effects on cell cycle progression. Only when the cells were grown in a P- medium did higher light intensities trigger dose-dependent, significantly higher toxicities in all the A. minutum cultures. This result suggests that the toxicity level is responsive to the combined effects of (high) light and (low) P stress. The cell size was not significantly affected by the light intensity or P conditions. The optimal light intensity for resting cyst formation was 150 µE m-2 s-1, with higher irradiances reducing the total encystment yield. Encystment was not observed at the lowest light intensity tested, indicative of the key role of low-level irradiance in gamete and/or zygote formation, in contrast to the stressor effect of excessive irradiance on planozygote formation and/or encystment.

Response of the toxic dinoflagellate Alexandrium minutum to exudates of the eelgrass Zostera marina.

Biotic interactions are a key factor in the development of harmful algal blooms. Recently, a lower abundance of planktonic dinoflagellates has been reported in areas dominated by seagrass beds, suggesting a negative interaction between both groups of organisms. The interaction between planktonic dinoflagellates and marine phanerogams, as well as the way in which bacteria can affect this interaction, was studied in two experiments using a non-axenic culture of the toxic dinoflagellate Alexandrium minutum exposed to increasing additions of eelgrass (Zostera marina) exudates from old and young leaves and to the presence or absence of antibiotics. In these experiments, A. minutum abundance, growth rate and photosynthetic efficiency (Fv/Fm), as well as bacterial abundance, were measured every 48 h. Toxin concentration per cell was determined at the end of both experiments. Our results demonstrated that Z. marina exudates reduced A. minutum growth rate and, in one of the experiments, also the photosynthetic efficiency. These results are not an indirect effect mediated by the bacteria in the culture, although their growth modify the magnitude of the negative impact on the dinoflagellate growth rate. No clear pattern was observed in the variation of toxin production with the treatments.

Targeted and non-targeted mass spectrometry to explore the chemical diversity of the genus Gambierdiscus in the Atlantic Ocean.

Dinoflagellates of the genus Gambierdiscus have been associated with ciguatera, the most common non-bacterial fish-related intoxication in the world. Many studies report the presence of potentially toxic Gambierdiscus species along the Atlantic coasts including G. australes, G. silvae and G. excentricus. Estimates of their toxicity, as determined by bio-assays, vary substantially, both between species and strains of the same species. Therefore, there is a need for additional knowledge on the metabolite production of Gambierdiscus species and their variation to better understand species differences. Using liquid chromatography coupled to mass spectrometry, toxin and metabolomic profiles of five species of Gambierdiscus found in the Atlantic Ocean were reported. In addition, a molecular network was constructed aiming at annotating the metabolomes. Results demonstrated that G. excentricus could be discriminated from the other species based solely on the presence of MTX4 and sulfo-gambierones and that the variation in toxin content for a single strain could be up to a factor of two due to different culture conditions between laboratories. While untargeted analyses highlighted a higher variability at the metabolome level, signal correction was applied and supervised multivariate statistics performed on the untargeted data set permitted the selection of 567 features potentially useful as biomarkers for the distinction of G. excentricus, G. caribaeus, G. carolinianus, G. silvae and G. belizeanus. Further studies will be required to validate the use of these biomarkers in discriminating Gambierdiscus species. The study also provided an overview about 17 compound classes present in Gambierdiscus, however, significant improvements in annotation are still required to reach a more comprehensive knowledge of Gambierdiscus' metabolome.

Documento de consenso y conclusiones. La metodología de las encuestas alimentarias, estudios nutricionales, de estimación de la actividad física y otros estilos de vida / No disponible

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Ingesta de grasas trans; situación en España / Intake of trans fats; situation in Spain

Las recomendaciones nutricionales actuales incluyen la disminución de la ingesta de ácidos grasos trans (AGt), ya que existe una evidencia científica suficiente de su relación con la enfermedad cardiovascular. Durante las últimas décadas, en muchos países Europeos ha disminuido considerablemente la ingesta de AGt gracias a la legislación establecida y a los cambios en los procesos tecnológicos desarrollados por la industria alimentaria. En España únicamente 2,1 g/día, 0,7 % de la energía ingerida proviene de AGt, valor inferior al valor máximo recomendado (<1%) según los datos del estudio TRANSFAIR. En nuestro país, el contenido en AGt de los productos procesados, como las margarinas, bollería etc, ha disminuido a lo largo de los últimos años y es inferior al 1% en más del 90% de estos productos. Es necesario, sin embargo, desarrollar y aplicar normativas que regulen el contenido en AGt en los productos comercializados en nuestro país, incluyendo la obligatoriedad de incluir este dato en el etiquetado (AU)

Current nutritional recommendations include decreasing the intake of trans fatty acids (TFA), since there exists sufficient scientific evidence of its influence to cardiovascular disease. During the last decades, in many European countries the TFA intake has considerably decreased through the established legislation and changes in the technological processes developed by the food industry. In Spain, just 2.1 g/day, a 0.7% of the daily energy intake comes from TFA, a lower value than the recommended maximum (<1%), according to data from TRANSFAIR study. The TFA content of processed products such as margarines, factory-baked goods and etc, has declined over recent years and is less than 1% in more than 90% of all these products in Spain. However, it is necessary to develop and implement regulations, governing the TFA content in the products sold in our country, in which there should be the requirement to include this information in the label too (AU)

Methodology of dietary surveys, studies on nutrition, physical activity and other lifestyles

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Café y diabetes mellitus / No disponible

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