Effects of environmental factors on the toxicity of pesticides to zebrafish embryos

During the last century mean global temperatures have been increasing. According to the predictions, the temperature change is expected to exceed 1.5ºC in this century and the warming is likely to continue. Freshwater ecosystems are among the most sensitive mainly due to changes in the hydrologic cycle and consequently changes in several physico-chemical parameters (e.g. pH, dissolved oxygen). Alterations in environmental parameters of freshwater systems are likely to affect distribution, morphology, physiology and richness of a wide range of species leading to important changes in ecosystem biodiversity and function. Moreover, they can also work as co-stressors in environments where organisms have already to cope with chemical contamination (such as pesticides), increasing the environmental risk due to potential interactions. Therefore, the objective of this work was to evaluate the effects of climate change related environmental parameters on the toxicity of pesticides to zebrafish embryos. The following environmental factors were studied: pH (3.0-12.0), dissolved oxygen level (0-8 mg/L) and UV radiation (0-500 mW/m2). The pesticides studied were the carbamate insecticide carbaryl and the benzimidazole fungicide carbendazim. Stressors were firstly tested separately in order to derive concentration- or intensity-response curves to further study the effects of binary combinations (environmental factors x pesticides) by applying mixture models. Characterization of zebrafish embryos response to environmental stress revealed that pH effects were fully established after 24 h of exposure and survival was only affected at pH values below 5 and above 10. Low oxygen levels also affected embryos development at concentrations below 4 mg/L (delay, heart rate decrease and edema), and at concentrations below 0.5 mg/L the survival was drastically reduced. Continuous exposure to UV radiation showed a strong time-dependent impact on embryos survival leading to 100% of mortality after 72 hours of exposure. The toxicity of pesticides carbaryl and carbendazim was characterized at several levels of biological organization including developmental, biochemical and behavioural allowing a mechanistic understanding of the effects and highlighting the usefulness of behavioural responses (locomotion) as a sensitive endpoint in ecotoxicology. Once the individual concentration response relationship of each stressor was established, a combined toxicity study was conducted to evaluate the effects of pH on the toxicity of carbaryl. We have shown that pH can modify the toxicity of the pesticide carbaryl. The conceptual model concentration addition allowed a precise prediction of the toxicity of the jointeffects of acid pH and carbaryl. Nevertheless, for alkaline condition both concepts failed in predicting the effects. Deviations to the model were however easy to explain as high pH values favour the hydrolysis of carbaryl with the consequent formation of the more toxic degradation product 1- naphtol. Although in the present study such explanatory process was easy to establish, for many other combinations the “interactive” nature is not so evident. In the context of the climate change few scenarios predict such increase in the pH of aquatic systems, however this was a first approach focused in the lethal effects only. In a second tier assessment effects at sublethal level would be sought and it is expectable that more subtle pH changes (more realistic in terms of climate changes scenarios) may have an effect at physiological and biochemical levels with possible long term consequences for the population fitness.

Nutritional modulation of innate immune parameters in the epidermal mucus of Senegalese sole (Solea senegalensis)=Influência da dieta nos parâmetros da resposta imunitária inata do muco de linguado (Solea senegalensis)

Dissertação mest., Biologia Marinha, Universidade do Algarve, 2008

Role of insulin and insulin-like peptides in bone formation: identification of bone-specific target genes and regulatory mechanisms, and characterization of the insulin-mimetic effect of vanadium

Tese de Doutoramento em Biologia, Especialidade em Biologia Molecular, Universidade do Algarve, 2008

DNA damage in two bivalve species: Mytilus galloprovincialis and Ruditapes decussatus from the South coast of Portugal

Dissertação de mest., Estudos Marinhos e Costeiros, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2009

Optimisation of an aptamer-biosensor to detect C-reactive protein

Dissertação de Mestrado, Engenharia Biológica, Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, 2009

Mechanical cell lysis technique for plasmid recovery

Dissertação de Mestrado, Engenharia Biológica, Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, 2008

Improved extraction of arabinoxylans from rye bran and production of health beneficial oligosaccharides

Dissertação de mest., Engenharia Biológica, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011

Evolution of the extracellular matrix in deuterostomes and the influence of calcitropic hormones

Tese de dout., Biologia (Biologia Molecular), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2010

Electro-olfactograms in response to chromatographic fractions of food-related odorants in the Senegalese sole, Solea senegalensis

The Bohr effect, which can be most generally defined as the influence of pH on the oxygen binding affinity of proteins, is a common feature of respiratory pigments, ranging from the haemocyanins of molluscs and crustaceans to the haemoglobins of vertebrates. Its physiological role is generally seen in the facilitation of oxygen release from respiratory pigments during tissue acidosis. The magnitude of the effect can be influenced by a multitude of factors such as temperature, carbon dioxide, chloride ions, organic phosphates and the investigated pH range. Here we present data on the maximal alkaline Bohr effect in haemoglobins from a large number of species covering all vertebrate classes, obtained at physiological temperatures in the presence of 100 mM chloride ions and the absence of carbon dioxide and organic phosphates.

Dietary biodiesel-derived crude glycerol in gilthead seabream juveniles (Sparus aurata): effects on growth performance and metabolism

In the European Union the turn towards renewable energy sources has increased the production of biodiesel from rapeseed oil, leaving glycerol (also known as glycerin) as a valuable by-product. For every litre of biodiesel produced, approximately 79 g of crude glycerol are generated. As the biodiesel production grows, the quantity of crude glycerol generated will be considerable and its utilization will become an urgent topic. One possibility is the use of crude glycerol on animal feeds. Glycerol has been evaluated as a dietary energy source for several farm animals, including fish. A study was undertaken to assess the effect of dietary biodiesel-derived glycerol (from rapeseed oil) on the overall growth performance, digestive capacity and metabolic nutrient utilization in juvenile gilthead seabream fed a low fishmeal level diet. Two practical diets were formulated to be isonitrogenous (crude protein, 45.4% DM), isolipidic (18.5% DM) and isoenergetic (gross energy, 21.3 kJ/g DM). The control diet (CTRL) was formulated with intermediate levels of marine-derived proteins (19%). In the same basal formulation, 5% glycerol (GLY) was incorporated at the expenses of wheat. Each dietary treatment was tested in triplicate tanks over 63 days, with 20 gilthead seabream (Sparus aurata), with a mean initial body weight (IBW) of 27.9  0.12 g. At the end of the trial, fish fed the CTRL diet reached a final body weight of 84.3  2.2 g (more than 3-fold increase of initial body weight). Fish fed the GLY diet showed a significantly higher (P<0.05) growth, expressed in terms of final body weight and specific growth rate. Voluntary feed intake was similar between the two treatments, but both feed efficiency and protein efficiency ratio were significantly improved (P<0.05) in fish fed the GLY diet. Dietary glycerol had no effect (P>0.05) on the apparent digestibility of protein. In comparison to the control treatment, dietary glycerol significantly improved (P<0.05) protein and fat retention. Activities of digestive enzymes were significantly affected by the various dietary treatments. Fish fed the GLY diet showed an enhanced activity of alkaline phosphatase (ALP) and pepsin, while activities of lipase and leucine-alanine peptidase (LAP) were little affected by dietary glycerol. Fish show the ability to use crude glycerol as a dietary energy substrate.

Plume-lithosphere interaction at Santiago Island (Cape Verde) : implications for ocean island magma genesis models

Tese de doutoramento, Geologia (Geoquímica), Universidade de Lisboa, Faculdade de Ciências, 2014

Efeito da combinação de antibióticos e sinvastatina sobre microrganismos de interesse endodôntico e na expressão de marcadores odontoblásticos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Celiac disease detection using a transglutaminase electrochemical immunosensor fabricated on nanohybrid screen-printed carbon electrodes

Celiac disease is a gluten-induced autoimmune enteropathy characterized by the presence of tissue tranglutaminase (tTG) autoantibodies. A disposable electrochemical immunosensor (EI) for the detection of IgA and IgG type anti-tTG autoantibodies in real patient’s samples is presented. Screen-printed carbon electrodes (SPCE) nanostructurized with carbon nanotubes and gold nanoparticles were used as the transducer surface. This transducer exhibits the excellent characteristics of carbon–metal nanoparticle hybrid conjugation and led to the amplification of the immunological interaction. The immunosensing strategy consisted of the immobilization of tTG on the nanostructured electrode surface followed by the electrochemical detection of the autoantibodies present in the samples using an alkaline phosphatase (AP) labelled anti-human IgA or IgG antibody. The analytical signal was based on the anodic redissolution of enzymatically generated silver by cyclic voltammetry. The results obtained were corroborated with a commercial ELISA kit indicating that the electrochemical immunosensor is a trustful analytical screening tool.

O impacto do excesso de gordura corporal sobre a remodelação óssea de adolescentes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Contribuição para o conhecimento das propriedades pozolânicas da fracção fina resultante da produção de areia de origem granítica

O presente estudo diz respeito a um trabalho de pesquisa no âmbito de uma Tese de Mestrado incluída no segundo ciclo de estudos do curso de Engenharia Geotécnica e Geoambiente, realizado sobre as condições de desidroxilação para a obtenção de metacaulino com propriedades cimentíceas, a partir da fracção argilosa proveniente dos finos residuais da produção de areias de natureza granítica. O produto resultante da alteração e desintegração dos feldspatos constituintes dos granitos são ricos em caulinite. Na natureza e em particular no Norte de Portugal, existem significativos depósitos cauliníticos com características potenciadoras para a produção de metacaulino. O metacaulino utilizado neste estudo foi obtido de uma amostra de argila submetida a 750oC, por um período de tempo de 30 minutos, processo que permitiu a desidroxilação quase total da matéria-prima, transformando esta numa fase amorfa e irreversível, com propriedades pozolânicas. Os metacaulinos, também conhecidos por geopolímeros, são produtos de fácil produção utilizando uma matéria-prima abundante e proporcionam a obtenção de novos produtos que permitem a substituição parcial do cimento Portland normal na composição das pastas de betão, com vantagens significativas no comportamento mecânico e na resistência aos agentes atmosféricos. Neste estudo são apresentados os resultados dos ensaios de caracterização da matéria-prima, das condições de calcinação e do produto resultante da desidroxilação, nomeadamente a determinação da pozolanicidade e das características fundamentais para a aplicabilidade do produto. No âmbito da especialidade de Georrecursos, consideramos que este trabalho está perfeitamente adequado, já que, para além do estudo para o conhecimento das propriedades da matéria-prima, foi possível, através das alterações introduzidas com o tratamento térmico, obter um novo produto, cuja utilização terá importantes reflexos na sustentabilidade dos recursos naturais e sua utilização.