Browsing by Author "Reis-Santos, Patrick"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
- 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.
- Fluoxetine arrests growth of the model diatom Phaeodactylum tricornutum by increasing oxidative stress and altering energetic and lipid metabolismPublication . Feijão, Eduardo; Carvalho, Ricardo Cruz de; Duarte, Irina A.; 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, BernardoPharmaceutical residues impose a new and emerging threat to aquatic environments and its biota. One of the most commonly prescribed pharmaceuticals is the antidepressant fluoxetine, a selective serotonin re-uptake inhibitor that has been frequently detected, in concentrations up to 40 ug L-1, in aquatic ecosystems. The present study aims to investigate the ecotoxicity of fluoxetine at environmentally relevant concentrations (0.3, 0.6, 20, 40, and 80 ug L-1) on cell energy and lipid metabolism, as well as oxidative stress biomarkers in the model diatom Phaeodactylum tricornutum. Exposure to higher concentrations of fluoxetine negatively affected cell density and photosynthesis through a decrease in the active PSII reaction centers. Stress response mechanisms, like b-carotene (b-car) production and antioxidant enzymes [superoxide dismutase (SOD) and ascorbate peroxidase (APX)] up-regulation were triggered, likely as a positive feedback mechanism toward formation of fluoxetine-induced reactive oxygen species. Lipid peroxidation products increased greatly at the highest fluoxetine concentration whereas no variation in the relative amounts of long chain polyunsaturated fatty acids (LC-PUFAs) was observed. However, monogalactosyldiacylglycerol-characteristic fatty acids such as C16:2 and C16:3 increased, suggesting an interaction between light harvesting pigments, lipid environment, and photosynthesis stabilization. Using a canonical multivariate analysis, it was possible to evaluate the efficiency of the application of bio-optical and biochemical techniques as potential fluoxetine exposure biomarkers in P. tricornutum. An overall classification efficiency to the different levels of fluoxetine exposure of 61.1 and 88.9% were obtained for bio-optical and fatty acids profiles, respectively, with different resolution degrees highlighting these parameters as potential efficient biomarkers. Additionally, the negative impact of this pharmaceutical molecule on the primary productivity is also evident alongside with an increase in respiratory oxygen consumption. From the ecological point of view, reduction in diatom biomass due to continued exposure to fluoxetine may severely impact estuarine and coastal trophic webs, by both a reduction in oxygen primary productivity and reduced availability of key fatty acids to the dependent heterotrophic upper levels.
- 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.
- Water and otolith chemistry: implications for discerning estuarine nursery habitat use of a juvenile flatfishPublication . Martinho, Filipe; Pina, Beatriz; Nunes, Margarida; Vasconcelos, Rita P.; Fonseca, Vanessa F.; Crespo, Daniel; Primo, Ana Lígia; Vaz, Ana; Pardal, Miguel A.; Gillanders, Bronwyn M.; Tanner, Susanne E.; Reis-Santos, PatrickVariations in otolith elemental composition are widely used to reconstruct fish movements. However, reconstructing habitat use and environmental histories of fishes within estuaries is still a major challenge due to the dynamic nature of these coastal environments. In this study, we performed a laboratory experiment to investigate the effects of variations in salinity (three levels; 5, 18, 30) and temperature (two levels; 16, 21 C) on the otolith elemental composition (Mg:Ca, Mn:Ca, Sr:Ca, Ba:Ca) of juvenile Senegalese sole Solea senegalensis. Temperature and salinity treatments mirrored the natural conditions of the estuarine habitats occupied by juvenile Senegalese sole, thereby providing information on the applicability of otolith microchemistry to reconstruct habitat use patterns within estuarine nurseries, where individual fish move across complex salinity and temperature gradients. While Sr:Ca and Ba:Ca in otoliths were both positively related to salinity, no temperature effect was observed. Partition coefficients, proxies for element incorporation rates increased with increasing salinity for Sr (DSr) and Ba (DBa). In contrast, salinity and temperature had little influence on otolith Mn:Ca and Mg:Ca, supporting physiological control on the incorporation of these elements. Our results are a stepping stone for the interpretation of otolith chemical profiles for fish collected in their natural habitats and contribute to better understanding the processes involved in otolith element incorporation.