Percorrer por autor "Barreiro, Aldo"
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- Analysis of the Use of Cylindrospermopsin and/or Microcystin-Contaminated Water in the Growth, Mineral Content, and Contamination of Spinacia oleracea and Lactuca sativaPublication . Llana-Ruiz-Cabello, Maria; Jos, Angeles; Cameán, Ana; Oliveira, Flavio; Barreiro, Aldo; Machado, Joana; Azevedo, Joana; Pinto, Edgar; Almeida, Agostinho; Campos, Alexandre; Vasconcelos, Vitor; Freitas, MarisaCyanobacteria and cyanotoxins constitute a serious environmental and human health problem. Moreover, concerns are raised with the use of contaminated water in agriculture and vegetable production as this can lead to food contamination and human exposure to toxins as well as impairment in crop development and productivity. The objective of this work was to assess the susceptibility of two green vegetables, spinach and lettuce, to the cyanotoxins microcystin (MC) and cylindrospermopsin (CYN), individually and in mixture. The study consisted of growing both vegetables in hydroponics, under controlled conditions, for 21 days in nutrient medium doped with MC or CYN at 10 μg/L and 50 μg/L, or CYN/MC mixture at 5 + 5 μg/L and 25 + 25 μg/L. Extracts from M. aeruginosa and C. ovalisporum were used as sources of toxins. The study revealed growth inhibition of the aerial part (Leaves) in both species when treated with 50µg/L of MC, CYN and CYN/MC mixture. MC showed to be more harmful to plant growth than CYN. Moreover spinach leaves growth was inhibited by both 5 + 5 and 25 + 25 µg/L CYN/MC mixtures, whereas lettuce leaves growth was inhibited only by 25 + 25 µg/L CYN/MC mixture. Overall, growth data evidence increased sensitivity of spinach to cyanotoxins in comparison to lettuce. On the other hand, plants exposed to CYN/MC mixture showed differential accumulation of CYN and MC. In addition, CYN, but not MC, was translocated from the roots to the leaves. CYN and MC affected the levels of minerals particularly in plant roots. The elements most affected were Ca, K and Mg. However, in leaves K was the mineral that was affected by exposure to cyanotoxins.
- Effects of interaction and bioaccessibility of the cyanotoxins microcystin and cylindrospermopsin in aquatic and terrestrial speciesPublication . Freitas, Marisa; Azevedo, Joana; Carvalho, António Paulo; Planchon, Sébastien; Renaut, Jenny; Mendes, Vera; Manadas, Bruno; Pinto, Edgar; Barreiro, Aldo; Neves, Joana; Campos, Alexandre; Vasconcelos, VitorThe occurrence and proliferation of toxic cyanobacteria blooms as a potential consequence of eutrophication and climate change are an emergent environmental concern worldwide. Microcystin-LR (MC-LR), mainly produced by Microcystisaeruginosa is the most documented and studied cyanotoxin. Cylindrospermopsin (CYN) has been recognized of increased concern due to the invasive nature of its main producer, Cylindrospermopsisraciborskii. Recent studies support the hypothesis that MC-LR and CYN exert harmful effects on crop plants. Lettuce, Lactuca sativa, is an important commercial leafy vegetable, which supplies important components for a healthy diet (e.g., fibers, minerals and antioxidants). Therefore, it is of particular interest the knowledge of lettuce sensitivity to ecologically relevant concentrations of cyanotoxins, inclusively mixtures. Proteomic technologies seem to be suitable to investigate the effects of MC-LR and CYN and may allow the identification of early stress responses, which are not perceptible by traditional endpoints. Proteomics may also provide new insights of protein biomarkers of exposure and the identification of allergenic proteins, which may be of interest for human health risk assessment. However, human health problems due to MC-LR and CYN are most likely associated to its chronic exposure by drinking water and contaminated food. Previous studies have shown that aquatic organisms, especially bivalves (filter-feeding organisms), can accumulate high levels of cyanotoxins without lethal effect. Based on the potential for human health risks, a provisional tolerable daily intake (TDI) of 0.04 and 0.03μg/kg-body weight, has been established for MC-LR and CYN, respectively. However, the risks associated to the consumption of contaminated food may increase if the consumers use storage and processing practices that enhance the concentration of cyanotoxins and their bioaccessibility. It has been reported that MCs are stable at high concentration of cyanotoxins and their bioaccessibility. It has been reported that MCs are stable at high temperatures (above 300 °C) and they can with stand several hours boiling. Likewise, CYN is highly watersoluble and stable to extreme temperatures and pHs, thus the knowledge of the influence of storage and cooking practices as well as human digestion on MC-LR and CYN concentration in food is required to a more accurate human risk assessment.
- Exploring bioactive properties of marine cyanobacteria Isolated from the Portuguese coast: high potential as a source of anticancer compoundsPublication . Costa, Margarida; Garcia, Mónica; Costa-Rodrigues, Joao; Costa, Maria Sofia; Ribeiro, Maria João; Fernandes, Maria Helena; Barros, Piedade; Barreiro, Aldo; Vasconcelos, Vítor; Martins, RosarioThe oceans remain a major source of natural compounds with potential in pharmacology. In particular, during the last few decades, marine cyanobacteria have been in focus as producers of interesting bioactive compounds, especially for the treatment of cancer. In this study, the anticancer potential of extracts from twenty eight marine cyanobacteria strains, belonging to the underexplored picoplanktonic genera, Cyanobium, Synechocystis and Synechococcus, and the filamentous genera, Nodosilinea, Leptolyngbya, Pseudanabaena and Romeria, were assessed in eight human tumor cell lines. First, a crude extract was obtained by dichloromethane:methanol extraction, and from it, three fractions were separated in a Si column chromatography. The crude extract and fractions were tested in eight human cancer cell lines for cell viability/toxicity, accessed with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactic dehydrogenase release (LDH) assays. Eight point nine percent of the strains revealed strong cytotoxicity; 17.8% showed moderate cytotoxicity, and 14.3% assays showed low toxicity. The results obtained revealed that the studied genera of marine cyanobacteria are a promising source of novel compounds with potential anticancer activity and highlight the interest in also exploring the smaller filamentous and picoplanktonic genera of cyanobacteria.
- Lettuce (Lactuca sativa L.) leaf-proteome profiles after exposure to cylindrospermopsin and a microcystin-LR/cylindrospermopsin mixture: A concentration-dependent responsePublication . Freitas, Marisa; Campos, Alexandre; Azevedo, Joana; Barreiro, Aldo; Planchon, Sébastien; Renaut, Jenny; Vasconcelos, VítorThe intensification of agricultural productivity is an important challenge worldwide. However, environmental stressors can provide challenges to this intensification. The progressive occurrence of the cyanotoxins cylindrospermopsin (CYN) and microcystin-LR (MC-LR) as a potential consequence of eutrophication and climate change is of increasing concern in the agricultural sector because it has been reported that these cyanotoxins exert harmful effects in crop plants. A proteomic-based approach has been shown to be a suitable tool for the detection and identification of the primary responses of organisms exposed to cyanotoxins. The aim of this study was to compare the leaf-proteome profiles of lettuce plants exposed to environmentally relevant concentrations of CYN and a MC-LR/CYN mixture. Lettuce plants were exposed to 1, 10, and 100 lg/l CYN and a MC-LR/CYN mixture for five days. The proteins of lettuce leaves were separated by twodimensional electrophoresis (2-DE), and those that were differentially abundant were then identified by matrix-assisted laser desorption/ionization time of flight-mass spectrometry (MALDI-TOF/TOF MS). The biological functions of the proteins that were most represented in both experiments were photosynthesis and carbon metabolism and stress/defense response. Proteins involved in protein synthesis and signal transduction were also highly observed in the MC-LR/CYN experiment. Although distinct protein abundance patterns were observed in both experiments, the effects appear to be concentration-dependent, and the effects of the mixture were clearly stronger than those of CYN alone. The obtained results highlight the putative tolerance of lettuce to CYN at concentrations up to 100 lg/l. Furthermore, the combination of CYN with MC-LR at low concentrations (1 lg/l) stimulated a significant increase in the fresh weight (fr. wt) of lettuce leaves and at the proteomic level resulted in the increase in abundance of a high number of proteins. In contrast, many proteins exhibited a decrease in abundance or were absent in the gels of the simultaneous exposure to 10 and 100 lg/l MC-LR/CYN. In the latter, also a significant decrease in the fr. wt of lettuce leaves was obtained. These findings provide important insights into the molecular mechanisms of the lettuce response to CYN and MC-LR/CYN and may contribute to the identification of potential protein markers of exposure and proteins that may confer tolerance to CYN and MC-LR/CYN. Furthermore, because lettuce is an important crop worldwide, this study may improve our understanding of the potential impact of these cyanotoxins on its quality traits (e.g., presence of allergenic proteins).
- Monitoring of physico-chemical parameters and their influence on the cyanobacteria occurrence: a case study in Alqueva reservoirs.Publication . Silva, Inês; Barreiro, Aldo; Vasconcelos, Vitor; Campos, Alexandre; Freitas, MarisaAlqueva complex is constituted by 17 reservoirs/dams interconnected by waterways, being built to provide water for agricultural irrigation, as well as for human consumption and recreational activities in Alentejo region.
- New Invertebrate Vectors for PST, Spirolides and Okadaic Acid in the North AtlanticPublication . Silva, Marisa; Barreiro, Aldo; Rodriguez, Paula; Otero, Paz; Azevedo, Joana; Alfonso, Amparo; Botana, Luis; Vasconcelos, VitorThe prevalence of poisoning events due to harmful algal blooms (HABs) has declined during the last two decades through monitoring programs and legislation, implemented mainly for bivalves. However, new toxin vectors and emergent toxins pose a challenge to public health. Several locations on the Portuguese coast were surveyed between 2009 and 2010 for three distinct biotoxin groups [saxitoxin (PST), spirolide (SPX) and okadaic acid (OA)], in 14 benthic species of mollusks and echinoderms. Our main goals were to detect new vectors and unravel the seasonal and geographical patterns of these toxins. PSTs were analyzed by the Lawrence method, SPXs by LC-MS/MS, and OA by LC-MS/MS and UPLC-MS/MS. We report 16 new vectors for these toxins in the North Atlantic. There were differences in toxin contents among species, but no significant geographical or seasonal patterns were found. Our results suggest that legislation should be adjusted to extend the monitoring of marine toxins to a wider range of species besides edible bivalves.
- Picocyanobacteria from a clade of marine cyanobium revealed bioactive potential against microalgae, bacteria, and marinePublication . Costa, Maria Sofia; Costa, Margarida; Ramos, Vitor; Leão, Pedro N.; Barreiro, Aldo; Vasconcelos, Vítor; Martins, RosarioThe production of bioactive compounds either toxic or with pharmacological applications by cyanobacteria is well established. However, picoplanktonic forms within this group of organisms have rarely been studied in this context. In this study, the toxicological potential of picocyanobacteria from a clade of marine Cyanobium strains isolated from the Portuguese coast was examined using different biological models. First, strains were identified by applying morphological and molecular approaches and cultured under lab conditions. A crude extract and three fractions reflecting a preliminary segregation of lipophilic metabolites were tested for toxicity with the marine microalga Nannochloropsis sp., the bacteria Pseudomonas sp., the brine shrimp Artemia salina, and fertilized eggs of the sea urchin Paracentrotus lividus. No significant apparent adverse effects were noted against Artemia salina. However, significant adverse effects were found in all other assays, with an inhibition of Nannochloropsis sp. and Pseudomonas sp. growth and marked reduction in Paracentrotus lividus larvae length. The results obtained indicated that Cyanobium genus may serve as a potential source of interesting bioactive compounds and emphasize the importance of also studying smaller picoplanktonic fractions of marine cyanobacteria.