ESS - CIIMAR@E2S - Comunicações em eventos científicos
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- Contributions of TOXICROP project for the assessment of the impacts of toxic cyanobacteria in agriculture †Publication . Campos, Alexandre; Freitas, Marisa; Oudra, Brahim; Vasconcelos, VítorWater contaminated with microcystins (MCs) or other cyanotoxins is recurrently used in agriculture and for crop irrigation. Several deleterious effects of MCs in plants that may impair crop productivity, including a decrease in growth and tissue necrosis, as well as an inhibition of photosynthesis and metabolic changes, have been reported. Studies also revealed a significant accumulation of MCs in edible tissues and plant organs, which raise concerns related to food safety. The European project TOXICROP precisely tackles this environmental problem. The main aims of the project are to map agricultural risk areas of cyanotoxin occurrence, to assess the fate of cyanotoxins in crops, and evaluate the impacts of using low-quality water for crop irrigation. The project also develops research on water remediation, exploring nature-based technologies. Here, we review part of the research carried out in the project, concerning the toxicity of cyanotoxins in crops. The research from TOXICROP Consortium has revealed for instance that adult strawberry or faba bean plants are susceptible to moderate concentrations of MCs (10 to 20 µg MCs/L). Furthermore, experiments with faba bean and common wheat grown in sterile (microorganism-free) and non-sterile (microorganism-rich) soil, watered with 100 μg MCs/L, revealed that native rhizospheric microbiota play an important role in the mitigation of the phytotoxic impact of MCs on plant growth, reducing toxin accumulation in both soils and plant tissues. Our studies also revealed that leaf vegetables, such as lettuce and spinach, growing in hydroponics are more susceptible to MCs than to the toxin, cylindrospermopsin (CYN). The lowest toxin concentrations affecting spinach and lettuce growth were 5 + 5 and 25 + 25 µg/L CYN/MC mixtures, respectively. The results also reveal that the accumulation of MCs and CYN in plants depends on the conditions in which plants grow and concentrations of toxins in the irrigation water. In some cases, MCs are accumulated in plant tissues and exceed the tolerable daily intake proposed by the World Health Organization. We highlight the importance and contributions of this research to the definition and implementation of regulatory limits for cyanotoxins in irrigation waters.
- 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.
- Impact of microcystin contaminated water on quality of carrots (Daucuscarota)Publication . Machado, J.; Azevedo, J.; Freitas, Marisa; Pinto, Edgar; Vasconcelos, Vitor; Campos, AlexandreCyanobacteria blooms are often found in freshwaters and may reflect the increased eutrophication of these environments and because of this many water resources worldwide may have a limited utilization. The presence of these microorganisms may pose a serious threat to water quality because many of them produce a large diversity of toxins that can be harmful to human health (Figueiredo et a l., 2004). On the other hand contaminated waters used to agricultural purposes may pose additional concerns to food safety. The absorption of toxins by plants may induce morphological and physiological changes that can lead to a loss of productivity as well as toxin bioaccumulation in edible tissues. However, the impact of cyanotoxins on plants and its ability to enter the food chain via this pathway is not fully understood (Kitleret al ., 2012). Microcystin (MC) is the cyanotoxin most frequently present in eutrophic freshwaters causing serious problems to human health, being the liver the main target. These toxins are potent and specific inhibitors of protein phosphatases PP1 and PP2Ain both animals and higher plants (Figueiredo et al., 2004). It is known that MC affect a number of physiological processes in plants (Corbel et al ., 2013). The plant root system is usually more exposed, via soil irrigation, and therefore root-vegetables more prone to contamination. Carrots (Daucuscarota) are root-vegetables with great importance for human nourishment and economy, with extensive use all over the world (Singh et al ., 2012).