CCM1-Teses
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- Searching for biocompounds in algae and seagrasses with potential use in thetreatment of Alzheimer’s diseasePublication . Silvestre, Águeda Laura dos Santos; Varela, J.; Custódio, Luísa Margarida BatistaThe number of older people at risk of developing dementia is growing rapidly worldwide, and Alzheimer’s disease (AD) represents the most common cause of dementia in the elderly. The principal characteristics of AD include the presence of amyloid plaques, neurofibrillary tangles, brain atrophy in specific brain areas and loss of the neurotransmitter acetylcholine (ACh), which is hydrolysed by the cholinesterases (ChE) acetylcholinesterase (AChE) and secondly by butyrilcholinesterase (BChE). Pharmacological treatments currently used to alleviate AD symptoms include ChE inhibitors, but they exhibit bioavailability problems and side effects like hepatotoxicity and gastrointestinal disorders. Thus, there is a high interest in finding better ChE inhibitors from natural sources. Due to the high oxygen consumption and lipid content, the central nervous system (CNS) is more sensitive to oxidative stress compared to other parts of our body. Thus, special interest has been assigned in nutritional antioxidants and metal chelation therapy as viable neuroprotective approaches for neurodegenerative disorders. Marine organisms are recognized as rich sources of novel biologically active compounds. However, its application in the treatment of neurological disorders is still scarcely explored. In this context, the main goal of this study was to evaluate the AChE and BChE inhibitory activity of methanol extracts made from different species of macro- and microalgae, seagrasses and halophytes, as well as evaluate their chelating activity on iron (Fe2+) and copper (Cu2+) ions. The most active species against both enzymes were the brown macroalgae Cystoseira compressa, C. nodicaulis and C. tamariscifolia and the halophytes Carpobrotus edulis and Frankenia laevis. The chelating activity was higher for Cu2+ than for Fe2+ in the majority of the species tested, being the most active the red macroalgae Plocamium cartilageneum. These species are thus promising candidates for more detailed in vitro and in vivo studies aiming their use as sources of innovative products with neuroprotective aplications.
- By-catch species susceptibilities and potential for survival in Algarve (South Portugal) deep-water crustacean trawl fisheryPublication . Adão, Ana Catarina Vasconcelos; Borges, Teresa C.; Breen, MikeBottom trawling for crustaceans in Portuguese coastal waters constitutes a rather important fishery in revenue terms, despite its clear negative impacts on deep-sea communities and marine ecosystems. This poorly selective harvest strategy catches large amounts of unwanted species that are thrown overboard for various reasons. However, survival of discards is not yet properly assessed and constitutes an essential parameter for the upcoming landing obligation, with an exemption for species with “high survival”. In this work, time-to-mortality and a vitality assessment were used to estimate immediate mortality and identify important biological characteristics on the susceptibility of a group of 14 by-catch species, most with commercial interest (Conger conger, Galeus melastomus, Helicolenus dactylopterus, Lepidorhombus boscii, Lophius budegassa, Lophius piscatorius, Merluccius merluccius, Micromesistius poutassou, Mullus surmuletus, Phycis blennoides, Scyliorhinus canicula, Trigla lyra, Trachurus trachurus and Trachurus picturatus). Only S. canicula and C. conger were identified as species with potential to survive after the discarding process. Present results on time-to-mortality show significant differences when comparing individual sizes for some species, with smaller individuals dying faster than larger ones. Furthermore, species with scales, gas bladder and high metabolic rates are more vulnerable to die after being discarded. A short captive observation experiment with C. conger was conducted, with 84% survival after 65 hours of monitoring. However, this survival rate is likely to be overestimated due to two facts: 1) the mortality rate did not stabilize at the end of the experiment; and 2) the majority of individuals showed severe injuries (scratches, bruises and deep wounds). These outcomes can help to identify species that will likely survive the discarding process, factors influencing its survival and provide reliable estimates of unaccounted fishing mortality, essential for stock management and conservation.
- The impact of the Arrábida Marine Park (Portugal) on the decapod crustacean Eualus cranchii: a case studyPublication . Reis, Joana Rita Rebelo dos; Castro, Margarida; Bartilotti, CátiaMarine protected areas (MPAs) have been widely suggested as a tool for fisheries management, conservation goals and mitigation of other negative impacts of humans on the oceans. Within MPAs, sub-areas can be considered including Fully Protected Areas (FPA) and Partially Protected Areas (PPA), each one with different restrictions regarding anthropogenic activities. They can contribute to the increase of abundance and biodiversity of marine species and habitat improvement. This study aims to observe the abundance of the decapod crustacean Eualus cranchii at two different depths (surface and bottom) within fully- and partially- protected areas of the Arrábida Marine Park on the west coast of Portugal, in order to understand the effect of a protected area on the abundance of this species. Samples were collected every two weeks, from April to September 2013 at a fixed location in the FPA and PPA using Standard Monitoring Units for Recruitment of Fish (SMURFs), a tool that measures recruitment and settlement patterns in a repeatable way, helping to determine fish larval sources and sinks. A Three-Way ANOVA was performed to observe the existence of differences in abundance of E. cranchii as a function of protection type (FPA and PPA), depth (surface and bottom) and time (April, July and September). All level interactions were considered. The results showed that all three main factors were significant. Higher abundances are associated with FPA with about 77 % of the total number of individuals of E. cranchii present. With respect to depth 88 % of the individuals were found on the bottom. The highest larval abundance was recorded in July, representing 77 % of the total individuals analyzed in this study. Additionally, there was a significant interaction of time with protection level indicating that there were different trends along time in each area. Overall, MPAs can be viewed as a valuable tool to protect species abundance and diversity, yet they should not be considered as a final solution as other large-scale effects and subsequent community changes in coastal areas may also influence the abundance and distribution of marine species.
- Comparing Zostera and Spartina environments in relation to carbon burial: a sedimentary and geochemical approach from Ria FormosaPublication . Duque Núñez, Natalia; Veiga-Pires, C.; Santos, RuiCarbon sinks are natural or artificial reservoirs in which carbon can be accumulated for a certain length of time. Mangroves, salt marshes and seagrasses beds are habitats that have an important role on the carbon budget of the oceans and thus influence the oceanic cycle. In this study we aimed is to evaluate C storage capacity of two different intertidal environments, Zostera noltii vs Spartina maritima from Ria Formosa, as well as to evaluate the influence of hydrodynamics and sediment grain size in the C storage. This multidisciplinary and integrated approach includes biological, geological and chemical analyses in order to better understand the processes leading to Carbon accumulation in sediments. For such a purpose, we analyzed and measured the granulometry, color and mineral composition of the sediment, as well as the organic matter, calcium carbonate contents and the elemental composition. The results obtained reflect that the carbon sequestration (organic carbon content), is related to practically all the studied variables, Furthermore, there are significant differences between both biological communities. Spartina maritima shows nearly twice the organic carbon content than Zostera noltii. On the other hand, the distance to the main navigation channel, a proxy to hydrodynamics, affected all parameters, strongly affected C accumulation, with higher variability in Zostera than Spartina. C accumulation and sediment grain size were related to this gradient, as expected, where both parameters increased from the first station, close to the main channel, to last station the most remote. The carbon accumulation rate for Spartina environment was twice as high as those for Zostera environment, 131.8 g OC.m-2.year-1, 83.9 g OC.m-2.year-1, respectively, these differences were related to the influence to all the parameters analyzed in this study.
- Aspectos da variabilidade na abundância de juvenis de Mero (Epinephelus marginatus) (Lowe, 1834) (Pisces, Serranidae) na Costa Sul da Ilha Terceira, AçoresPublication . Sousa, Inês IsabelOs juvenis de Epinephelus marginatus são considerados como muito associados às zonas costeiras, o que lhes confere vulnerabilidade. Os objectivos do presente estudo são, nomeadamente, a obtenção de dados preliminares sobre o estado da população de juvenis da espécie na costa sul da Ilha Terceira nos Açores e o estudo paralelo da variabilidade da abundância associada a diferentes condições ambientais, em termos abióticos e em termos de composição específica da comunidade. O procedimento adoptado envolveu a aplicação do método de censos visuais em transectos. Na zona de costa exposta, não se verificou a presença dos juvenis da espécie. Nas baías, a densidade de meros juvenis estimada leva a considerar que há ocorrência de um saudável recrutamento para o manancial da área. As variações de abundância mostraram-se associadas ao grau de protecção das forças hidrodinâmicas proporcionado em cada local. Revelou-se também a preferência dos indivíduos por substratos complexos com disponibilidade de abrigos de tamanho adequado, com presença de pedregulhos irregulares médios e pequenos. A degradação do estado do mar parece levar os indivíduos ao abandono das zonas de baixa profundidade amostradas. As similaridades de Bray-Curtis da espécie com as restantes observadas revelaram-se baixas. Um dos aspectos comportamentais observados nos juvenis foi a tolerância da espécie na compartilha do abrigo com outros predadores crípticos e com conspecíficos.
- Diversity, expression and mechanism of action of estrogen receptors in sea bream, Sparus auratusPublication . Pinto, Patricia IS; Canario, Adelino V. M.; Sweeney, G. E.Two estrogen receptor subtypes (ERα and ERβ) mediate most estrogen actions in vertebrates, including fishes. Furthermore in teleost fishes two ERβ genes are differentially expressed. In this thesis, an ERβ (sbERβb) was cloned from the hermaphrodite teleost fish sea bream (Sparus auratus) which added to the previously cloned sbERα and sbERβa. sbERβb specifically binds estrogen agonists and antagonists with high affinity. The three sbER genes (α, βa, βb) have a partially overlapping but differential distribution in male and female sea bream tissues and produce multiple transcripts. Two exon2 deleted sbERα variants were also identified with different tissue distribution and hormonal regulation. Estradiol-17β up-regulated the expression of sbERα and down-regulated both sbERβs in liver, suggesting a major role for ERα in vitellogenesis. Agonistic effects were identified for the “pure antiestrogen” ICI 182,780 in several estrogenic responses, probably mediated by sbERα up regulation in liver. The immunolocalization of sbER proteins in sea bream scales suggested that the calcium mobilising actions of E2 in scales are via a direct action on osteoclasts. Subtractive hybridization followed by RT-PCR demonstrated for the first time in fish testis the E2 up regulation of some typical liver E2-induced genes (e.g. vitellogenins and choriogenins).
- Thyroid axis disruption by goitrogens: a molecular and functional approachPublication . Guerreiro, Eduarda Mazagão; Power, Deborah; Pinto, PatriciaThe number of chemicals to which organisms are exposed as a consequence of environmental contamination by Industry and Agriculture is increasing. However, there is a severe lack of information about the biological effects of many frequently occurring chemicals. The present thesis is focused on the effects on the thyroid tissue of adult zebra fish of the antimicrobial agent Triclosan (TCS) which is frequently found in personnel hygiene products and foodstuff. After 21 days exposure of adult zebrafish to TCS (100 mg/kg/day) and the thyroid disruptor, Propylthiouracil (PTU, positive control) (5 mg/kg/day), histological observation of thyroid tissue in sections of the pharynx was performed. These observations indicated significant (p<0.05) increase in follicle areas coupled with the decrease of thyrocyte height (thyrocyte inactivation) in TCS treated zebrafish. In the PTU treated zebrafish only a reduction in thyrocyte activity was observed. In order to understand how the test chemical TCS might bring about its effect, the gene expression of Thyroglobulin (Tg), Thyroid Peroxidase (TPO), Sodium-Iodine Symporter (NIS) and Cathepsin B (CtsB) together with Thyroid Stimulating Hormone (TSH) in whole zebrafish head was determined using quantitative real-time Polymerase Chain Reaction (qRT-PCR). After sample normalization against the zebrafish spermatogenic glyceraldehyde-3-phosphate dehydrogenases (GAPDH-2), validated as reference gene for this study, a significant increase (p<0.05) in expression of TSH and NIS were detected. The expression of pituitary TSH increased in the PTU and TCS groups compared to the control group, while NIS expression only increased in the TCS treated zebrafish. For the remaining genes, no significant changes in gene expression were detected, maybe as a consequence of high individual variation. In summary, the results of the study indicate that the drug TCS at a concentration of 100 mg/kg/day for 21 days appears to influence TH synthesis. The increase in TSH and NIS transcription coupled to the inactivation of the thyroid tissue observed in this work, are indicative of effects caused by a reduction in circulating THs. It remains to be established the mechanism by which TCS reduces thyroid tissue activity in adult zebra fish.