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- Fluoxetine induces photochemistry-derived oxidative stress on Ulva lactucaPublication . Feijão, Eduardo; Carvalho, Ricardo Cruz de; Duarte, Irina A.; Matos, Ana Rita; Cabrita, Maria Teresa; Utkin, Andrei B.; Caçador, Isabel; Marques, João Carlos; Novais, Sara C.; Lemos, Marco F.L.; Reis-Santos, Patrick; Fonseca, Vanessa; Duarte, BernardoEmerging pollutants impose a high degree of stress on marine ecosystems, compromising valuable resources, the planet and human health. Pharmaceutical residues often reachmarine ecosystems, and their input is directly related to human activities. Fluoxetine is an antidepressant, and one of the most prescribed selective serotonin reuptake inhibitors globally and has been detected in aquatic ecosystems in concentrations up to 40 μg L−1. The present study aims to evaluate the impact of fluoxetine ecotoxicity on the photochemistry, energy metabolism and enzyme activity of Ulva lactuca exposed to environmentally relevant concentrations (0.3, 0.6, 20, 40, and 80 μg L−1). Exogenous fluoxetine exposure induced negative impacts on U. lactuca photochemistry, namely on photosystem II antennae grouping and energy fluxes. These impacts included increased oxidative stress and elevated enzymatic activity of ascorbate peroxidase and glutathione reductase. Lipid content increased and the altered levels of key fatty acids such as hexadecadienoic (C16:2) and linoleic (C18:2) acids revealed strong correlations with fluoxetine concentrations tested. Multivariate analyses reinforced the oxidative stress and chlorophyll a fluorescence-derived traits as efficient biomarkers for future toxicology studies.
- Glyphosate-based herbicide toxicophenomics in marine diatoms: impacts on primary production and physiological fitnessPublication . Carvalho, Ricardo Cruz de; Feijão, Eduardo; Matos, Ana Rita; Cabrita, Maria Teresa; Novais, Sara C.; Lemos, Marco F.L.; Caçador, Isabel; Marques, João Carlos; Reis-Santos, Patrick; Fonseca, Vanessa F.; Duarte, BernardoGlyphosate is the main active component of the commercial formulation Roundup®, the most widely used chemical herbicide worldwide. However, its potential high toxicity to the environment and throughout trophic webs has come under increasing scrutiny. The present study aims to investigate the application of bio-optical techniques and their correlation to physiological and biochemical processes, including primary productivity, oxidative stress, energy balance, and alterations in pigment and lipid composition in Phaeodactylum tricornutum, a representative species of marine diatoms, using the case study of its response to the herbicide glyphosate-based Roundup® formulation, at environmentally relevant concentrations. Cultures were exposed to the herbicide formulation representing effective glyphosate concentrations of 0, 10, 50, 100, 250, and 500 ug L-1. Results showed that high concentrations decreased cell density; furthermore, the inhibition of photosynthetic activity was not only caused by the impairment of electron transport in the thylakoids, but also by a decrease of antioxidant capacity and increased lipid peroxidation. Nevertheless, concentrations of one of the plastidial marker fatty acids had a positive correlation with the highest concentration as well as an increase in total protein. Cell energy allocation also increased with concentration, relative to control and the lowest concentration, although culture growth was inhibited. Pigment composition and fatty acid profiles proved to be efficient biomarkers for the highest glyphosate-based herbicide concentrations, while bio-optical data separated controls from intermediate concentrations and high concentrations.
- Effects of propranolol on growth, lipids and energy metabolism and oxidative stress response of Phaeodactylum tricornutumPublication . Duarte, Bernardo; Feijão, Eduardo; Carvalho, Ricardo Cruz de; Duarte, Irina A.; Silva, Marisa; Matos, Ana Rita; Cabrita, Maria Teresa; Novais, Sara C.; Lemos, Marco F.L.; Marques, João Carlos; Caçador, Isabel; Reis-Santos, Pactick; Fonseca, Vanessa F.Present demographic trends suggest a rise in the contributions of human pharmaceuticals into coastal ecosystems, underpinning an increasing demand to evaluate the ecotoxicological effects and implications of drug residues in marine risk assessments. Propranolol, a non-selective B-adrenoceptor blocker, is used worldwide to treat high blood pressure conditions and other related cardiovascular conditions. Although diatoms lack B-adrenoceptors, this microalgal group presents receptor-like kinases and proteins with a functional analogy to the animal receptors and that can be targeted by propranolol. In the present work, the authors evaluated the effect of this non-selective B-adrenoceptor blocker in diatom cells using P. tricornutum as a model organism, to evaluate the potential effect of this compound in cell physiology (growth, lipids and energy metabolism and oxidative stress) and its potential relevance for marine ecosystems. Propranolol exposure leads to a significant reduction in diatom cell growth, more evident in the highest concentrations tested. This is likely due to the observed impairment of the main primary photochemistry processes and the enhancement of the mitochondrial respiratory activity. More specifically, propranolol decreased the energy transduction from photosystem II (PSII) to the electron transport chain, leading to an increase in oxidative stress levels. Cells exposed to propranolol also exhibited high-dissipated energy flux, indicating that this excessive energy is effciently diverted, to some extent, from the photosystems, acting to prevent irreversible photoinhibition. As energy production is impaired at the PSII donor side, preventing energy production through the electron transport chain, diatoms appear to be consuming storage lipids as an energy backup system, to maintain essential cellular functions. This consumption will be attained by an increase in respiratory activity. Considering the primary oxygen production and consumption pathways, propranolol showed a significant reduction of the autotrophic O2 production and an increase in the heterotrophic mitochondrial respiration. Both mechanisms can have negative effects on marine trophic webs, due to a decrease in the energetic input from marine primary producers and a simultaneous oxygen production decrease for heterotrophic species. In ecotoxicological terms, bio-optical and fatty acid data appear as highly effcient tools for ecotoxicity assessment, with an overall high degree of classification when these traits are used to build a toxicological profile, instead of individually assessed.
- Comfortably numb: Ecotoxicity of the non-steroidal anti-inflammatory drug ibuprofen on Phaeodactylum tricornutumPublication . Feijão, Eduardo; Carvalho, Ricardo da Cruz de; Duarte, Irina A.; Matos, Ana Rita; Cabrita, Maria Teresa; Barreiro, Aldo; Lemos, Marco F.L.; Novais, Sara C.; Marques, João Carlos; Caçador, Isabel; Reis-Santos, P.; Silva, Marisa; Fonseca, Vanessa; Duarte, BernardoEmerging pollutants such as pharmaceuticals are continuously released to aquatic environments posing a rising threat to marine ecosystems. Yet, monitoring routines and ecotoxicity data on biota worldwide for these substances are lacking. Non-steroidal anti-inflammatory drugs are among the most prescribed and found pharmaceuticals in aquatic environments. The toxicity effects of environmentally relevant concentrations of ibuprofen on primary productivity, oxidative stress and lipid metabolism of the diatom Phaeodactylum tricornutum were assessed. Diatom cultures were exposed to 0, 0.8, 3, 40, 100 and 300 μg L-1 ibuprofen concentrations, usually found in the vicinity of wastewater treatment plants and coastal environments. Higher concentrations (100 and 300 μg L-1) had a negative impact in P. triconutum growth, inhibiting the chloroplastic energy transduction in the electron transport chain resulting in lower energy reaching the PS I (r2 = - 0.55, p < 0.05). In contrast, the mitochondrial electron transport and available energy increased (r2 = 0.68 and r2 = 0.85, p < 0.05 respectively), mostly due to enhancements in lipid and protein contents as opposed to reduction of carbohydrates. A general up-regulation of the antioxidant enzymes could contributed to alleviate oxidative stress resulting in the decrease of lipid peroxidation products (r2 = 0.77, p < 0.05). Canonical analysis of principal components was performed and successfully discriminated exposure groups, with optical data excelling in classifying samples to different ibuprofen concentrations, being potentially used as environmental indicators. Finally, the identified mild to severe effects of ibuprofen on diatoms are likely to be exacerbated by the sustained use of this drug worldwide, underpinning the urgency of evaluating the impacts of this pharmaceutical on coastal and marine trophic webs.
- Potential of Asparagopsis armata as a biopesticide for weed control under an invasive seaweed circular-economy frameworkPublication . Duarte, Bernardo; Carreiras, João; Feijão, Eduardo; Carvalho, Ricardo Cruz de; Matos, Ana Rita; Fonseca, Vanessa F.; Novais, Sara C.; Lemos, Marco F. L.Marine macroalgae have been increasingly targeted as a source of bioactive compounds to be used in several areas, such as biopesticides. When harvesting invasive species, such as Asparagopsis armata, for this purpose, there is a two-folded opportunity: acquiring these biomolecules from a low-cost resource and controlling its spreading and impacts. The secondary metabolites in this seaweed’s exudate have been shown to significantly impact the physiology of species in the ecosystems where it invades, indicating a possible biocidal potential. Considering this in the present work, an A. armata exudate cocktail was applied in the model weed Thellungiella halophila to evaluate its physiological impact and mode of action, addressing its potential use as a natural biocide. A. armata greatly affected the test plants’ physiology, namely, their photochemical energy transduction pathway (impairing light-harvesting and chemical energy production throughout the chloroplast electron transport chain), carotenoid metabolism and oxidative stress. These mechanisms of action are similar to the ones triggered when using the common chemical pesticides, highlighting the potential of the A. armata exudate cocktail as an eco-friendly biopesticide.
- Effect biomarkers of the widespread antimicrobial triclosan in a marine model diatomPublication . Duarte, Bernardo; Feijão, Eduardo; Carvalho, Ricardo Cruz de; Matos, Ana Rita; Cabrita, Maria Teresa; Novais, Sara C.; Moutinho, Ariana; Lemos, Marco F.L.; Marques, João Carlos; Caçador, Isabel; Reis-Santos, Patrick; Fonseca, VanessaThe present-day COVID-19 pandemic has led to the increasing daily use of antimicrobials worldwide. Triclosan is a manmade disinfectant chemical used in several consumer healthcare products, and thus frequently detected in surface waters. In the present work, we aimed to evaluate the effect of triclosan on diatom cell photophysiology, fatty acid profiles, and oxidative stress biomarkers, using the diatom Phaeodactylum tricornutum as a model organism. Several photochemical effects were observed, such as the lower ability of the photosystems to efficiently trap light energy. A severe depletion of fucoxanthin under triclosan application was also evident, pointing to potential use of carotenoid as reactive oxygen species scavengers. It was also observed an evident favouring of the peroxidase activity to detriment of the SOD activity, indicating that superoxide anion is not efficiently metabolized. High triclosan exposure induced high cellular energy allocation, directly linked with an increase in the energy assigned to vital functions, enabling cells to maintain the growth rates upon triclosan exposure. Oxidative stress traits were found to be the most efficient biomarkers as promising tools for triclosan ecotoxicological assessments. Overall, the increasing use of triclosan will lead to significant effects on the diatom photochemical and oxidative stress levels, compromising key roles of diatoms in the marine system.
- Effects of glyphosate-based herbicide on primary production and physiological fitness of the macroalgae Ulva lactucaPublication . Carvalho, Ricardo Cruz de; Feijão, Eduardo; Matos, Ana Rita; Cabrita, Maria Teresa; Utkin, Andrei B.; Novais, Sara C.; Lemos, Marco F.L.; Caçador, Isabel; Marques, João Carlos; Reis-Santos, Patrick; Fonseca, Vanessa F.; Duarte, BernardoThe use of glyphosate-based herbicides (GBHs) worldwide has increased exponentially over the last two decades increasing the environmental risk to marine and coastal habitats. The present study investigated the effects of GBHs at environmentally relevant concentrations (0, 10, 50, 100, 250, and 500 ug.L-1) on the physiology and biochemistry (photosynthesis, pigment, and lipid composition, antioxidative systems and energy balance) of Ulva lactuca, a cosmopolitan marine macroalgae species. Although GBHs cause deleterious effects such as the inhibition of photosynthetic activity, particularly at 250 ug.L-1, due to the impairment of the electron transport in the chloroplasts, these changes are almost completely reverted at the highest concentration (500 ug.L-1). This could be related to the induction of tolerance mechanisms at a certain threshold or tipping point. While no changes occurred in the energy balance, an increase in the pigment antheraxanthin is observed jointly with an increase in ascorbate peroxidase activity. These mechanisms might have contributed to protecting thylakoids against excess radiation and the increase in reactive oxygen species, associated with stress conditions, as no increase in lipid peroxidation products was observed. Furthermore, changes in the fatty acids profile, usually attributed to the induction of plant stress response mechanisms, demonstrated the high resilience of this macroalgae. Notably, the application of bio-optical tools in ecotoxicology, such as pulse amplitude modulated (PAM) fluorometry and laser-induced fluorescence (LIF), allowed separation of the control samples and those treated by GBHs in different concentrations with a high degree of accuracy, with PAM more accurate in identifying the different treatments.