Nutrition and farming practices as modulators of quality in gilthead seabream (Sparus aurata)

Gilthead seabream is the most important farmed species in the Mediterranean, and knowledge on how common farming practices impact its quality is limited. As such, this Thesis aimed to evaluate how gilthead seabream flesh quality is affected by some of these practices. In Chapter 2, the influence of nutritional factors was evaluated, specifically the high replacement of traditional marine-derived ingredients, both fishmeal and fish oil, with vegetable sources. We have seen that the vegetable-based diets tested did not greatly impact seabream flesh quality, although some alterations were seen in the fatty acid profile of the muscle. However, and despite having caused no alterations in flesh texture, vegetable ingredients reduced the amount of sulphated glycosaminoglycans in the extracellular matrix, affected muscle pH and reduced the activity of proteolytic enzymes. Throughout this Thesis, we measured for the first time the activity of proteolytic enzymes in seabream muscle, and cathepsin B was found to play a pivotal role in post-mortem muscle degradation. In Chapter 3, we evaluated the effect of harvesting and slaughter stress on seabream quality, and contrary to what is seen in most farmed species, our results show that gilthead seabream muscle structure is highly resistant to changes caused by stressful events. Nonetheless, considering that welfare is an increasingly important quality criterion, the use of a zero-withdrawal anaesthetic as a rested harvest technique or even slaughter method could prove valuable to the industry. In Chapter 4, we used maslinic acid as a dietary supplement, to modulate the muscle’s energetic status pre-mortem. As a finishing strategy, maslinic acid failed to increase levels of glycogen and ATP in the muscle. However, supplementation resulted in higher muscle fibre diameter and lower cathepsin B activity, and maslinic acid is likely to be useful to promote growth in this species. In general our Thesis has generated new knowledge to a major challenge facing the aquaculture industry, which is to find a compromise between the trends towards intensive rearing and consumer demand for healthy, high quality seafood being ethically acceptable and having a low impact on the environment.

Instrumentação e controlo para regulação de pH em sistemas de cultivo de organismos aquáticos

A Ria Formosa é um tesouro ambiental sem paralelo, preservando uma fauna e flora únicas no mundo. A riqueza deste habitat é de enorme importância para a região, e extremamente apetecível para cientistas oriundos de todas as partes do globo, que aqui frequentemente se deslocam para conduzirem estudos científicos e experiências. O Centro de Ciências do Mar (CCMAR) da Universidade do Algarve (que inclui o Centro Experimental do Ramalhete) conduz estudos e experiências neste palco, estudos que são de inquestionável valor para o conhecimento e desenvolvimento científico. Um assunto que está a merecer a atenção da comunidade científica mundial nos últimos anos é a questão da acidificação dos oceanos. A diminuição gradual do pH das águas pode vir a ter graves repercussões nos ecossistemas marinhos, e o Centro Experimental do Ramalhete tem vindo a conduzir experiências com fauna e flora provenientes da Ria Formosa em águas com níveis de pH mais reduzido, condições que se prevê que os oceanos venham a ter no futuro. Os equipamentos de instrumentação e controlo a que o Centro tem acesso condicionam as experiências que ali são levadas a cabo pelos investigadores, pelo que o desenvolvimento de equipamentos adequados incorporando tecnologias apropriadas permitiria a realização de novas e melhores experiências no campo da biologia marinha. Ao nível do controlo existe uma lacuna no mercado, entre controladores para aquariofilia demasiado simples e controladores industriais demasiado dispendiosos e complexos. Esta dissertação pretende colmatar essa lacuna através do desenvolvimento de um protótipo de um sistema distribuído microcontrolado para aquisição de dados e controlo de pH que vá ao encontro das necessidades dos investigadores do Centro e que se pretende simples, modular, flexível, económico e expansível no futuro. O foco centra-se no desenvolvimento da instrumentação necessária para as medições de temperatura e pH, e depois no estudo de uma malha de controlo PID utilizando como base um modelo do sistema obtido através de resultados experimentais, para o controlo automático do pH.

Study of influence of regulatory polymorphisms of expression in development of breast cancer

The human genome has millions of genetics variants that can affect gene expression. These variants are known as cis-regulatory variants and are responsible for intra-species phenotypic differences and individual susceptibility to disease. One of the diseases affected by cis-regulatory variants is breast cancer. Breast cancer is one of the most common cancers, with approximately 4500 new cases each year in Portugal. Breast cancer has many genes mutated and TP53 has been shown to be relevant for this disease. TP53 is one of the most commonly mutated genes in human cancer and it is involved in cell cycle regulation and apoptosis. Previous work by Maia et al has shown that TP53 has differential allelic expression (DAE), which suggests that this gene may be under the influence of cis-regulatory variants. Also, its DAE pattern is totally altered in breast tumours with normal copy number. We hypothesized that cis-regulatory variants affecting TP53 may have a role in breast cancer development and treatment. The present work aims to identify the cis-regulatory variants playing a role in TP53 expression, using in silico, in vitro and in vivo approaches. By bioinformatic tools we have identified candidate cis-regulatory variants and predicted the possible transcription factor binding sites that they affect. By EMSA we studied DNA-protein interactions in this region of TP53. The in silico analysis allowed us to identified three candidate cis-regulatory SNPs which may affect the binding of seven transcription factors. However, the EMSA experiments have not been conclusive and we have not yet confirmed whether any of the identified SNPs are associated with gene expression control of TP53. We will carry out further experiments to validate our findings.

Bio-synthesis of nanosized semiconductors using mine wastes as material sources

This work describes the synthesis of nanosized metal sulfides and respective SiO2 and/or TiO2 composites in high yield via a straightforward process, under ambient conditions (temperature and pressure), by adding to aqueous metals a nutrient solution containing biologically generated sulfide from sulfate-reducing bacteria (SRB). The nanoparticles‘ (NPs) morphological properties were shown not to be markedly altered by the SRB growth media composition neither by the presence of bacterial cells. We further extended the work carried out, using the effluent of a bioremediation system previously established. The process results in the synthesis of added value products obtained from metal rich effluents, such as Acid Mine Drainage (AMD), when associated with the bioremediation process. Precipitation of metals using sulfide allows for the possibility of selective recovery, as different metal sulfides possess different solubilities. We have evaluated the selective precipitation of CuS, ZnS and FeS as nanosized metal sulfides. Again, we have also tested the precipitation of these metal sulfides in the presence of support structures, such as SiO2. Studies were carried out using both artificial and real solutions in a continuous bioremediation system. We found that this method allowed for a highly selective precipitation of copper and a lower selectivity in the precipitation of zinc and iron, though all metals were efficiently removed (>93% removal). This research has also demonstrated the potential of ZnS-TiO2 nanocomposites as catalysts in the photodegradation of organic pollutants using the cationic dye, Safranin-T, as a model contaminant. The influence of the catalyst amount, initial pH and dye concentration were also evaluated. Finally, the efficiency of the precipitates as catalysts in sunlight mediated photodegradation was investigated, using different volumes of dye-contaminated water (150 mL and 10 L). This work demonstrates that all tested composites have the potential to be used as photocatalysts for the degradation of Safranin-T.

Toxina botulínica para além da cosmética

Dissertação de mestrado, Ciências Farmacêuticas, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

Sistema remoto para monitorização de ambientes refrigerados em viaturas automóveis

Dissertação de mestrado, Engenharia Elétrica e Eletrónica (Tecnologias de Informação e Telecomunicações), Instituto Superior de Engenharia, Universidade do Algarve, 2015

Locust bean gum-based microparticles for pulmonary delivery of antibiotics

Dissertação de Mestrado, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2016