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Using biomarkers to address the impacts of pollution on limpets ( Patella depressa ) and their mechanisms to cope with stress

Publication . Silva, Cátia S. E.; Novais, Sara C.; Simões, Tiago; Caramalho, Márcia; Gravato, Carlos; Rodrigues, Maria J.; Maranhão, Paulo; Lemos, Marco F. L.

Contaminant discharges, derived from human activities, are major concerns as they exert a continuous ecological pressure on aquatic systems, causing in fact cascading community effects. Although with associated ecological and fitness costs, physiological and biochemical defense mechanisms may restore the organism’s internal balance. Several studies have pointed biomarkers as tools to assess contamination levels, and also to understand potential mechanisms to cope with stress. In the present study, the fitness costs of limpets Patella depressa located in two different contaminated sites and when transplanted into a different common environment – with no known historical contamination – were assessed through the measurement of oxidative stress, energy metabolism responses, and fatty acid profile changes. Integrated biomarker response index (IBR) revealed differences in responses between organisms of the different origin sites, with greater antioxidant and detoxification activities in the site with the higher contamination life-history (higher IBR index). Moreover, different abilities of this species to deal with the new environmental condition were also observed. After the transplant, and despite the differences in the initial profiles, response patterns became similar between both populations (similar IBR index), with organisms from the less contaminated site suffering a higher impact with a demarked increase in their detoxification and antioxidant defenses, as well as higher changes on fatty acid abundance/composition. Through an integrated biomarker profile analysis in a transplant context, this work provides a distinct insight on the mechanisms of response and tolerance to environmental stress, and fitness costs of this potential sentinel marine species in the context of environmental contamination changes.

2018Journal article

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Changes in fatty acid profile and chemical composition of meagre (Argyrosomus regius) fed with different lipid and selenium levels

Publication . Simões, Tiago; Fonseca, Sthelio B.; Augusto, Ana; Granada, Luana; Ozório, Rodrigo O. A.; Gonçalves, Jose F. M.; Pascoal, Leonardo A. F.; Silva, José H. V.; Lemos, Marco F. L.

This studyaimed to evaluatechangesin body composition, speciallymuscleandliver fatty acid profileinmeagre (Argyrosomus regius) fed with different dietary lipid sources and levels, with or without selenium supplementation. Six hundred meagre were fed twice a day, 6 days per week, with eight experimental diets for 60 days. Diets were a combination of fish oil or a vegetable blend (45% linseedþ 35% rapeseedþ 20% soybean oil), at 12 or 17% of oil and 0 or 1 mg/kg of organic selenium, in a 2 2 2 factorial design. The whole body protein and lipid content were affected by the dietary oil source. Fish oil diets increased long-chain (LC) PUFAs content in the edible tissues, while vegetable oil-based diets increased short-chain (SC) PUFAs. Vegetable oil diet tended to decrease thefish proteincontent.A higherlipidlivercontentwas observedinmeagre fed the vegetable oil blend. The results also suggested the ability of meagre to convert SC-PUFA to LC-PUFA when the vegetable oilisincludedin their diet. The possibility for partial substitution offish oil by vegetable oilin meagre diets, resulting in lower dependence of fish oil in meagre farming, is also demonstrated here

2017Journal article

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From laboratory to the field: Validating molecular markers of effect in Folsomia candida exposed to a fungicide-based formulation

Publication . Simões, Tiago; Novais, Sara C.; Natal-da-Luz, Tiago; Renaud, Mathieu; Leston, Sara; Ramos, Fernando; Römbke, Jörg; Dick, Roelofs; Van Straalen, Nico M.; Sousa, José P.; Lemos, Marco F. L.

Under controlled laboratory conditions, toxicity data tend to be less variable than in more realistic in-field studies and responses may thus differ from those in the natural environment, creating uncertainty. The validation of data under environmental conditions is therefore a major asset in environmental risk assessment of chemicals. The present study aimed to validate the mode of action of a commercial fungicide formulation in the soil invertebrate F. candida, under more realistic exposure scenarios (in-field bioassay), by targeting specific molecular biomarkers retrieved from laboratory experiments. Organisms were exposed in soil cores under minimally controlled field conditions for 4 days to a chlorothalonil fungicide dosage causing 75% reduction of reproduction in a previous laboratory experiment (127 mg a.i. kg−1 ) and half this concentration (60 mg a.i. kg−1 ). After exposure, organisms were retrieved and RNA was extracted from each pool of organisms. According to previous laboratorial omics results with the same formulation, ten genes were selected for gene expression analysis by qRT-PCR, corresponding to key genes of affected biological pathways including glutathione metabolism, oxidation-reduction, body morphogenesis, and reproduction. Six of these genes presented a dose-response trend with higher up- or down-regulation with increasing pesticide concentrations. Highly significant correlations between their expression patterns in laboratory and in-field experiments were observed. This work shows that effects of toxicants can be clearly demonstrated in more realistic conditions using validated biomarkers. Our work outlines a set of genes that can be used to assess the early effects of pesticides in a realistic agricultural scenario.

2019-06Journal article

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