957 resultados para Estrutura genética - peixes
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Dissertação de mest., Gestão Empresarial, Faculdade de Economia, Univ. do Algarve, 2001
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Dissertação de mest., Biologia Marinha, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2009
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Tese de dout., Ciências Biotecnológicas (Biotecnologia Vegetal), Univ. do Algarve, 2009
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Dissertação de mest., Geomática (Ciências da Informação Geográfica), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011
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Tese de dout., Ciências do Mar, da Terra e do Ambiente (Ecologia Marinha), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2012
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Dissertação de mest., Arquitectura Paisagista, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011
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The aquaculture industry aims at replacing significant amounts of marine fish oil by vegetable oils in fish diet. Dietary lipids have been shown to alter the fatty acid composition of bone compartments, which would impact the local production of factors controlling bone formation. Knowledge on the mechanisms underlying the nutritional regulation of bone metabolism is however scarce in fish. Two in vitro bone-derived cell systems developed from seabream (an important species for aquaculture in the Mediterranean region) vertebra, capable of in vitro mineralization and exhibiting prechondrocyte (VSa13) and pre-osteoblast (VSa16) phenotype, were used to assess the effect of certain polyunsaturated fatty acids (PUFAs; arachidonic (AA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids) on cell proliferation, extracellular matrix (ECM) mineralization and gene expression. While all PUFAs promoted morphological changes in both cell lines, VSa16 cell proliferation appeared to be stimulated by PUFAs in a dose dependent manner until 100M, whereas proliferation of VSa13 cells was impaired at concentrations above 10M. AA, EPA and DHA inhibited VSa13 ECM mineralization, alone and in combination, while VSa16 ECM mineralization was only inhibited by AA and EPA. DHA had the opposite effect, increasing mineralization almost by 2 fold. When EFAs were combined, DHA apparently compensated for the inhibitory effect of AA and EPA. Expression of marker genes for bone and lipid metabolisms has been investigated by qPCR and shown to be regulated in pre-osteoblasts exposed to individual PUFAs. Our results show that PUFAs are effectors of fish bone cell lines, altering cell morphology, proliferation and mineralization when added to culture medium. This work also demonstrates the suitability of our in vitro cell systems to get insights into mineralization-related effects of PUFAs in vivo and to evaluate the replacement of fish oils by vegetable oil sources in fish feeds.
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In aquaculture, application of fish hybrids has increased. This technique permits improvement of the fish production by providing specimens showing better growth rate when compared to the parental species. Indeed, sterile individuals are highly demanded because quite frequently parental fish mature before they reach the market size, which impairs their growth and decrease their economic value. Throughout the last years, the commercial and scientific interest in salmonids has increased rapidly, among them, the brook trout (Salvelinus fontinalis), Arctic charr (Salvelinus alpinus) are species that can be crossed to produce hybrids that might by cultured in the fish farms. In the present thesis, we have assessed chromosome numbers and evaluate gonadal sex in the brook trout X Arctic charr hybrid progenies. In our populations, the karyotype of the brook trout comprises 84 chromosomes: 16 bi-armed chromosomes (meta-submetacentric) and 68 one-armed chromosomes (telo-acrocentrics) and the chromosome arm number, NF= 100. Arctic charr karyotype shows variation related to the chromosome number (2n= 81-82) and stable chromosome arm number (NF= 100). 2n= 81 chromosomes consisted of 19 bi-armed and 62 one-armed chromosomes, while 2n= 82 karyotype was organized into 18 meta-submetacentric and 64 acrocentrics. The cytogenetic and histological analysis of the brook trout X Arctic charr hybrids (sparctics) was carried out to asses chromosome and chromosome arm number and gonadal sex of the studied specimens. Diploid chromosome number in the hybrids varied from 81 to 84 and individuals with 83 and 84 chromosomes were predominant. Most of the fish had chromosome arm number equal to 100. Robertsonian fusion in the Arctic charr and chromosome behaviour in the hybrid fish cells might lead to the observed variation in chromosome numbers in the hybrids. Among studied fish, 12 were males, 3 were females and 9 had intersex gonads. No correlation between chromosome number and disturbances in the gonadal development was found. This might suggest that intersex gonads might have been developed as a consequence of disturbances in the genetic sex determination process. Genetic sex determination acts properly in the parental species but in the hybrids this may not be as efficient.
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O Amyloodinium ocellatum é um parasita dinoflagelado que aparece em aquaculturas por todo o mundo, infectando as brânquias e o tegumento dos peixes. Esta parasita é particularmente relevante na aquacultura mediterrânica onde os surtos causam perdas consideráveis. Apesar de já terem sido experimentados vários tratamentos, nenhum deles se revelou efectivo na erradicação do parasita e ainda alguns dos químicos utilizados podem ter importantes efeitos nocivos sobre o ambiente. Deste modo, o objectivo deste estudo foi testar novos fármacos para impedir o desenvolvimento e/ou eliminar o parasita em peixes já infectados. Os fármacos utilizados neste estudo foram endoperóxidos, uma recente classe de antimaláricos. Na primeira parte deste estudo realizaram-se ensaios in vitro onde se testaram os efeitos de diferentes concentrações (0,1mM; 1 mM; 2mM e 2,5mM) dos fármacos NAD17, NAD19, LCD93 e LCD67A sobre a divisão dos tomontes. Às 24 e 48 horas de exposição a 0,1mM NAD19 e 1mM LCD93, os tomontes observados não tinham entrado em divisão. Na segunda parte realizou-se um ensaio in vivo no qual os fármacos foram administrados a juvenis de dourada (Sparus aurata) a uma concentração de 10μmol/kg através de tratamento oral. No ensaio in vivo avaliou-se o possível efeito profiláctico dos fármacos na infecção através da análise da abundância e prevalência do parasita, da eficácia dos fármacos e dos efeitos do parasita e do tratamento na fisiologia e no eixo do stress dos animais infectados através de análises enzimáticas e de parâmetros bioquímicos do sangue. As medições realizadas ao plasma sanguíneo e às brânquias de douradas com diferentes níveis de infecção de A. ocellatum revelaram que não existe diferença significativa entre os controlos e os endoperóxidos para a dose testada. Será necessário realizar mais ensaios para obter conclusões sobre o efeito dos endoperóxidos no controlo do parasita de peixes A. ocellatum.
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The European sea bass, Dicentrarchus labrax, is one of the most important marine species cultivated in Southern Europe and has not benefited from selective breeding. One of the major goals in the sea bass (D. labrax) aquaculture industry is to understand and control the complexity of growth associated traits. The aim of the methodology developed for the studies reported in the thesis was not only to establish genetic and genomic resources for sea bass, but to also develop a conceptual strategy to efficiently create knowledge in a research environment that can easily be transferred to the aquaculture industry. The strategy involved; i) establishing an annotated sea bass transcriptome and then using it to, ii) identify new genetic markers for target QTL regions so that, iii) new QTL analysis could be performed and marker based resolution of the DNA regions of interest increased, and then iv) to merge the linkage map and the physical map in order to map the QTL confidence intervals to the sea bass genome and identify genes underlying the targeted traits. Finally to test if genes in the QTL regions that are candidates for divergent growth phenotypes have modified patterns of transcription that reflects the modified whole organism physiology SuperSAGE-SOLiD4 gene expression was used with sea bass with high growth heterogeneity. The SuperSAGE contributed to significantly increase the transcriptome information for sea bass muscle, brain and liver and also led to the identification of putative candidate genes lying in the genomic region of growth related QTL. Lastly all differentially expressed transcripts in brain, liver and muscle of the European sea bass with divergent specific growth rates were mapped to gene pathways and networks and the regulatory pathways most affected identified and established the tissue specific changes underlying the divergent SGR. Owing to the importance of European sea bass to Mediterranean aquaculture and the developed genomics resources from the present thesis and from other studies it should be possible to implement genetic selection programs using marker assisted selection.
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A incapacidade para reconhecer e expressar adequadamente emoções tem sido comumente verificada em grupos clínicos com perturbação do desenvolvimento (e.g. autismo). Alguns autores verificaram semelhanças no comportamento emocional entre sujeitos com perturbação do desenvolvimento e sujeitos com perturbações clinicas e da personalidade. Neste contexto, o estudo da personalidade patológica e normal passou a ser alvo de interesse por parte de autores dedicados ao estudo do processamento de emoções e da sua influência no comportamento social. Neste sentido, e à semelhança do que tem sido realizado em estudos recentes, foi nosso objetivo avaliar de que forma os diferentes traços de personalidade influenciam a capacidade para reconhecer emoções básicas através da face. Para tal, foram testados 72 participantes da população geral (42 mulheres e 30 homens) com uma média de idades de 23.29 (± 3.38) anos e uma média de escolaridade de 15.47 (± 2.13) anos. Todos os sujeitos responderam a um instrumento de personalidade e psicopatologia (Inventário Clínico Multiaxial de Millon- III) sendo posteriormente distribuídos por duas análises: Análise 1- Grupo sem sintomatologia composto pelos grupos: personalidade histriónica (N=18), personalidade compulsiva (N=18) e personalidade narcisista (N=13); e Análise 2- Grupo com sintomatologia que se subdivide em: grupo com ansiedade (N=13), grupo com hipomania (N=8) e grupo sem sintomas (N=13). Depois de avaliada a estrutura de personalidade e as funções executivas, os participantes responderam a uma tarefa visual para a avaliação do processamento de emoções básicas com recurso ao software Presentation. Os principais resultados revelam diferenças significativas para o processamento da emoção tristeza no grupo sem sintomatologia, com o grupo com características de personalidade narcisista a revelar uma menor acuidade que os restantes grupos. No grupo com sintomatologia, o grupo com ansiedade apresentou uma menor acuidade na emoção raiva, quando comparado com o grupo saudável. Estes resultados são discutidos tendo por base um quadro concetual que sugere que o processamento de emoções básicas varia de acordo com a estrutura de personalidade.
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Marine protected areas (MPAs) have been widely proposed for conservation purposes and as a tool for fisheries management. The Arrábida Marine Park is the first MPA in continental Portugal having a management plan, fully implemented since 2009. The main objective of this study was to evaluate the effect of protection measures on rocky reef fish assemblages and target invertebrates through before-after and control-effect (no-take vs. fished areas) underwater visual surveys and analysis of landings trends. Second, we used surveys before, during and after implementation of the management plan to understand fishers‟ preferences for fishing grounds and adaptation to the new rules, and evaluated the reserve effect through analysis of both ecological responses and fishing effort density. Third, we identified the main oceanographic drivers influencing the structure of reef fish assemblages and predicted the community structure for the last 50 years, in light of climatic change. Overall results suggest positive responses in biomass but not yet in numbers of some commercial species, with no effects on non-target species. The reserve effect is reinforced by the increase in landings of commercial species, despite increased fishing effort density in some areas, especially with octopus traps. Fishing grounds are mainly chosen based on the distribution of target species and associated habitats, but distance to port, weather conditions and safety also influence fishers‟ choices. Moreover, different fisheries respond differently to the protection measures, and within each fishery, individual fishers show distinct strategies, with some operating in a broader area whereas others keep preferred territories. Our results also show that wind stress and temperature are the main oceanographic drivers for rocky reef fish assemblages, with tropicalization of assemblages and polewards movements of species over the last 50 years consistent with temperature trends. We believe this study provides significant lessons for marine conservation and management of coastal systems.
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First described more that 150 years ago, the systematics of the genera Geomalacus and Letourneuxia (Arionidae, Gastropoda, Pulmonata) is still challenging. The taxonomic classification of arionid species is based on extremely labile characters such as body size or color that depends both on diet and environment, as well as age. Moreover, there is little information on the genetic diversity and population structure of the Iberian slugs that could provide extra clues to disentangle their problematic classification. The present work uses different analytical tools such as habitat suitability (Ecological Niche Modeling - ENM), cytogenetic analysis and phylogeography to establish the geographical distribution and evolutionary history of these pulmonate slugs. The potential distribution of the four Geomalacus species was modeled using ENM, which allowed the identification of new locations for G. malagensis, including a first report in Portugal. Also, it was predicted a much wider distribution for G. malagensis and G. oliveirae than previously known. Classical cytogenetic analyses were assayed with reproductive and a novel use of somatic tissues (mouth and tentacles) returning the number of chromosomes for the four Geomalacus species and L. numidica (n = 31, 2n = 62) and the respective karyotypes. G. malagensis and L. numidica present similar chromosome morphologies and karyotypic formulae, being more similar to each other than the Geomalacus among themselves. We further reconstructed the phylogeny of the genera Geomalacus and Letourneuxia using partial sequences of the mitochondrial cytochrome oxidase subunit I (COI) and the nuclear ribosomal small subunit (18S rRNA), and applied an independent evolutionary rate method, the indicator vectors correlation, to evaluate the existence of cryptic diversity within species. The five nominal species of Geomalacus and Letourneuxia comprise 14 well-supported cryptic lineages. Letourneuxia numidica was retrieved as a sister group of G. malagensis. G. oliveirae is paraphyletic with respect to G. anguiformis. According to our dating estimates, the most recent common ancestor of Geomalacus dates back to the Middle Miocene (end of the Serravallian stage). The major lineage splitting events within Geomalacus occurred during the dry periods of the Zanclean stage (5.3-3.6 million years) and some lineages were confined to more humid mountain areas of the Iberian Peninsula, which lead to a highly geographically structured mitochondrial genetic diversity. The major findings of this are the following: (1) provides updated species distribution maps for the Iberian Geomalacus expanding the known geographic distribution of the concerned species, (2) unravels the cryptic diversity within the genera Geomalacus and Letourneuxia, (3) Geomalacus oliveirae is paraphyletic with G. anguiformis and (4) Letourneuxia numidica is sister group of G. malagensis.
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All systems found in nature exhibit, with different degrees, a nonlinear behavior. To emulate this behavior, classical systems identification techniques use, typically, linear models, for mathematical simplicity. Models inspired by biological principles (artificial neural networks) and linguistically motivated (fuzzy systems), due to their universal approximation property, are becoming alternatives to classical mathematical models. In systems identification, the design of this type of models is an iterative process, requiring, among other steps, the need to identify the model structure, as well as the estimation of the model parameters. This thesis addresses the applicability of gradient-basis algorithms for the parameter estimation phase, and the use of evolutionary algorithms for model structure selection, for the design of neuro-fuzzy systems, i.e., models that offer the transparency property found in fuzzy systems, but use, for their design, algorithms introduced in the context of neural networks. A new methodology, based on the minimization of the integral of the error, and exploiting the parameter separability property typically found in neuro-fuzzy systems, is proposed for parameter estimation. A recent evolutionary technique (bacterial algorithms), based on the natural phenomenon of microbial evolution, is combined with genetic programming, and the resulting algorithm, bacterial programming, advocated for structure determination. Different versions of this evolutionary technique are combined with gradient-based algorithms, solving problems found in fuzzy and neuro-fuzzy design, namely incorporation of a-priori knowledge, gradient algorithms initialization and model complexity reduction.
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Bone morphogenetic proteins (BMPs) are multifunctional growth factors belonging to the transforming growth factor β (TGFβ) superfamily with a central role in bone formation and mineralization. BMP2, a founding member of this family, has demonstrated remarkable osteogenic properties and is clinically used to promote bone repair and fracture healing. Lack of basic data on factors regulating BMP2 expression and activity have hampered a better understanding of its role in bone formation and bone-related diseases. The objective of this work was to collect new functional data and determine spatiotemporal expression patterns in a fish system aiming towards a better understanding of BMP2 function and regulation. Transcriptional and post-transcriptional regulation of gilthead seabream BMP2 gene was inferred from luciferase reporter systems. Several bone- and cartilage-related transcription factors (e.g. RUNX3, MEF2c, SOX9 and ETS1) were found to regulate BMP2 transcription, while microRNA 20a was shown to affect stability of the BMP2 transcript and thus the mineralogenic capacity of fish bone-derived host cells. The regulation of BMP2 activity through an interaction with the matrix Gla protein (MGP) was investigated in vitro using BMP responsive elements (BRE) coupled to luciferase reporter gene. Although we demonstrated the functionality of the experimental system in a fish cell line and the activation of BMP signaling pathway by seabream BMP2, no conclusive evidence could be collected on a possible interaction beween MGP and BMP2. The evolutionary relationship among the members of BMP2/4/16 subfamily was inferred from taxonomic and phylogenetic analyses. BMP16 diverged prior to BMP2 and BMP4 and should be the result of an ancient genome duplication that occurred early in vertebrate evolution. Structural and functional data suggested that all three proteins are effectors of the BMP signaling pathway, but expression data revealed different spatiotemporal patterns in teleost fish suggesting distinct mechanisms of regulation. In this work, through the collection of novel data, we provide additional insight into the regulation, the structure and the phylogenetic relationship of BMP2 and its closely related family members.