Metais em plantas e algas : acumulação e potencial aplicação em processos de remediação

The present work reports the study of the bioaccumulation of potentially toxic elements (cadmium, lead and mercury) by marine macroalgae (Ulva lactuca, Fucus vesiculosus and Gracilaria gracilis), abundant in the coast and estuarine systems worldwide. These organisms proved to be capable of withstanding moderate multi-metallic contamination (environmentally relevant concentrations), incorporating high amounts of metal in their tissues. The high removal percentages achieved, in particular for mercury (99%), demonstrate the potential of these algae as a basis for a new biotechnological treatment of saline waters contaminated with metals (more efficient, cost-effective and environmentally friendly than conventional methods). U. lactuca was considered the most promising due to the better performance presented. The comparison between the bioaccumulation and biosorption processes suggested that in some cases the use of the living organism will have advantages over the application of biomass, due to the simplicity of the overall process, and the lower residual concentration of metal achieved in the solution (especially for Cd). The transfer and accumulation of Hg by terrestrial plants (Brassica juncea and Lolium perenne) in agricultural fields near a contaminated industrial area was also studied. Despite the low bioaccumulation factors found (<1), there were high Hg content in plants (up to 84 mg kg-1 in roots and up 6.9 mg kg-1 in shoots, dry weight). Daily intake estimates for grazing animals (cows and sheep) pointed to the potential risk to human health derived from consumption of their meat. The results highlighted the important role that plants and algae may have in protection, risk assessment and remediation of environmental systems contaminated with metals.

Structural analysis of glycans and development of microarrays from Helcobacter pylori cell surface glycome

Helicobacter pylori is a bacterial pathogen that affects more than half of the world’s population with gastro-intestinal diseases and is associated with gastric cancer. The cell surface of H. pylori is decorated with lipopolysaccharides (LPSs) composed of three distinct regions: a variable polysaccharide moiety (O-chain), a structurally conserved core oligosaccharide, and a lipid A region that anchors the LPS to the cell membrane. The O-chain of H. pylori LPS, exhibits unique oligosaccharide structures, such as Lewis (Le) antigens, similar to those present in the gastric mucosa and are involved in interactions with the host. Glucan, heptoglycan, and riban domains are present in the outer core region of some H. pylori LPSs. Amylose-like glycans and mannans are also constituents of some H. pylori strains, possibly co-expressed with LPSs. The complexity of H. pylori LPSs has hampered the establishment of accurate structure-function relationships in interactions with the host, and the design of carbohydrate-based therapeutics, such as vaccines. Carbohydrate microarrays are recent powerful and sensitive tools for studying carbohydrate antigens and, since their emergence, are providing insights into the function of carbohydrates and their involvement in pathogen-host interactions. The major goals of this thesis were the structural analysis of LPSs from H. pylori strains isolated from gastric biopsies of symptomatic Portuguese patients and the construction of a novel pathogen carbohydrate microarray of these LPSs (H. pylori LPS microarray) for interaction studies with proteins. LPSs were extracted from the cell surface of five H. pylori clinical isolates and one NCTC strain (26695) by phenol/water method, fractionated by size exclusion chromatography and analysed by gas chromatography coupled to mass spectrometry. The oligosaccharides released after mild acid treatment of the LPS were analysed by electrospray mass spectrometry. In addition to the conserved core oligosaccharide moieties, structural analyses revealed the presence of type-2 Lex and Ley antigens and N-acetyllactosamine (LacNAc) sequences, typically found in H. pylori strains. Also, the presence of O-6 linked glucose residues, particularly in LPSs from strains 2191 and NCTC 26695, pointed out to the expression of a 6-glucan. Other structural domains, namely ribans, composed of O-2 linked ribofuranose residues were observed in the LPS of most of H. pylori clinical isolates. For the LPS from strain 14382, large amounts of O-3 linked galactose units, pointing to the occurrence of a galactan, a domain recently identified in the LPS of another H. pylori strain. A particular feature to the LPSs from strains 2191 and CI-117 was the detection of large amounts of O-4 linked N-acetylglucosamine (GlcNAc) residues, suggesting the presence of chitin-like glycans, which to our knowledge have not been described for H. pylori strains. For the construction of the H. pylori LPS microarray, the structurally analysed LPSs, as well as LPS-derived oligosaccharide fractions, prepared as neoglycolipid (NGL) probes were noncovalently immobilized onto nitrocellulosecoated glass slides. These were printed together with NGLs of selected sequence defined oligosaccharides, bacterial LPSs and polysaccharides. The H. pylori LPS microarray was probed for recognition with carbohydratebinding proteins (CBPs) of known specificity. These included Le and blood group-related monoclonal antibodies (mAbs), plant lectins, a carbohydratebinding module (CBM) and the mammalian immune receptors DC-SIGN and Dectin-1. The analysis of these CBPs provided new information that complemented the structural analyses and was valuable in the quality control of the constructed microarray. Microarray analysis revealed the occurrence of type-2 Lex and Ley, but not type-1 Lea or Leb antigens, supporting the results obtained in the structural analysis. Furthermore, the H. pylori LPSs were recognised by DC-SIGN, a mammalian lectin known to interact with this bacterium through fucosylated Le epitopes expressed in its LPSs. The -fucose-specific lectin UEA-I, showed restricted binding to probes containing type-2 blood group H sequence and to the LPSs from strains CI-117 and 14382. The presence of H-type-2, as well Htype- 1 in the LPSs from these strains, was confirmed using specific mAbs. Although H-type-1 determinant has been reported for H. pylori LPSs, this is the first report of the presence of H-type-2 determinant. Microarray analysis also revealed that plant lectins known to bind 4-linked GlcNAc chitin oligosaccharide sequences bound H. pylori LPSs. STL, which exhibited restricted and strong binding to 4GlcNAc tri- and pentasaccharides, differentially recognised the LPS from the strain CI-117. The chitin sequences recognised in the LPS could be internal, as no binding was detected to this LPS with WGA, known to be specific for nonreducing terminal of 4GlcNAc sequence. Analyses of the H. pylori LPSs by SDS-PAGE and Western blot with STL provided further evidence for the presence of these novel domains in the O-chain region of this LPS. H. pylori LPS microarray was also applied to analysis of two human sera. The first was from a case infected with H. pylori (H. pylori+ CI-5) and the second was from a non-infected control.The analysis revealed a higher IgG-reactivity towards H. pylori LPSs in the H. pylori+ serum, than the control serum. A specific IgG response was observed to the LPS isolated from the CI-5 strain, which caused the infection. The present thesis has contributed to extension of current knowledge on chemical structures of LPS from H. pylori clinical isolates. Furthermore, the H. pylori LPS microarray constructed enabled the study of interactions with host proteins and showed promise as a tool in serological studies of H. pyloriinfected individuals. Thus, it is anticipated that the use of these complementary approaches may contribute to a better understanding of the molecular complexity of the LPSs and their role in pathogenesis.

Infection mechanism of Diplodia corticola

Diplodia corticola is regarded as the most virulent fungus involved in cork oak decline, being able to infect not only Quercus species (mainly Q. suber and Q. ilex), but also grapevines (Vitis vinifera) and eucalypts (Eucalyptus sp.). This endophytic fungus is also a pathogen whose virulence usually manifests with the onset of plant stress. Considering that the infection normally culminates in host death, there is a growing ecologic and socio-economic concern about D. corticola propagation. The molecular mechanisms of infection are hitherto largely unknown. Accordingly, the aim of this study was to unveil potential virulence effectors implicated in D. corticola infection. This knowledge is fundamental to outline the molecular framework that permits the fungal invasion and proliferation in plant hosts, causing disease. Since the effectors deployed are mostly proteins, we adopted a proteomic approach. We performed in planta pathogenicity tests to select two D. corticola strains with distinct virulence degrees for our studies. Like other filamentous fungi D. corticola secretes protein at low concentrations in vitro in the presence of high levels of polysaccharides, two characteristics that hamper the fungal secretome analysis. Therefore, we first compared several methods of extracellular protein extraction to assess their performance and compatibility with 1D and 2D electrophoretic separation. TCA-Acetone and TCA-phenol protein precipitation were the most efficient methods and the former was adopted for further studies. The proteins were extracted and separated by 2D-PAGE, proteins were digested with trypsin and the resulting peptides were further analysed by MS/MS. Their identification was performed by de novo sequencing and/or MASCOT search. We were able to identify 80 extracellular and 162 intracellular proteins, a milestone for the Botryosphaeriaceae family that contains only one member with the proteome characterized. We also performed an extensive comparative 2D gel analysis to highlight the differentially expressed proteins during the host mimicry. Moreover, we compared the protein profiles of the two strains with different degrees of virulence. In short, we characterized for the first time the secretome and proteome of D. corticola. The obtained results contribute to the elucidation of some aspects of the biology of the fungus. The avirulent strain contains an assortment of proteins that facilitate the adaptation to diverse substrates and the identified proteins suggest that the fungus degrades the host tissues through Fenton reactions. On the other hand, the virulent strain seems to have adapted its secretome to the host characteristics. Furthermore, the results indicate that this strain metabolizes aminobutyric acid, a molecule that might be the triggering factor of the transition from a latent to a pathogenic state. Lastly, the secretome includes potential pathogenicity effectors, such as deuterolysin (peptidase M35) and cerato-platanin, proteins that might play an active role in the phytopathogenic lifestyle of the fungus. Overall, our results suggest that D. corticola has a hemibiotrophic lifestyle, switching from a biotrophic to a necrotrophic interaction after plant physiologic disturbances.This understanding is essential for further development of effective plant protection measures.

Estudo da recuperação da deficiência de ferro em plantas de morangueiro (Fragaria x ananassa Duch.) numa perspectiva sustentável

Consulta interdita até nova indicação

Contributo das saídas de campo na Lagoa dos Salgados para a identificação de indicadores de sustentabilidade

Dissertação de mest., Biologia e Geologia, Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, 2008

Influência dos processos de identificação, motivação e estratégias de coping no comportamento aditivo

Dissertação de Mestrado, Psicologia, especialidade de Psicologia da Saúde, Faculdade de Ciências Humanas e Sociais, Universidade do Algarve, 2007

Identificação de indicadores moleculares de bem-estar durante o cultivo de dourada (Sparus aurata, Linnaeus 1758), utilizando técnicas de proteómica

Dissertação de Mestrado, Biologia Marinha, Especialização em Biotecnologia Marinha, Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, 2008

Identificação das características dos clientes associadas ao risco de crédito

O processo da tomada de decisão sobre a avaliação de uma solicitação de crédito comercial é por vezes difícil para o julgamento humano, devido à imensidão de variáveis que estão em jogo e das suas inter- relações. Neste artigo propomo-nos identificar as características dos clientes associadas a alto e a baixo risco, com recurso a um modelo aplicacional. A partir de uma base de dados de um cartão de crédito, formada por variáveis de natureza qualitativa e quantitativa, ajustámos um modelo logit binário, com o objectivo de tornar o processo de decisão mais objectivo e quantificável. Em seguida, identificámos oito classes de risco através da aplicação de um método de classificação não hierárquica (K-means) sobre o vector da pontuação do modelo logit. Aferimos temporalmente o comportamento de cada classe de risco ao longo de 70 meses, verificando-se que probabilidades baixas de default estão associadas a classes de risco baixo. As características dos clientes tipicamente associadas ao risco de crédito foram identificadas através de uma Análise Factorial das Correspondências.

A hipótese de progressão na aprendizagem do conteúdo "reprodução" nas plantas

Dissertação de mest., Dinamização das Ciências em Contexto Escolar, Escola Superior de Educação e Comunicação, Univ. do Algarve, 2010

Técnicas biomoleculares no diagnòstico e tipificação em virologia vegetal

Tese de dout., Ciências Agrárias (Protecção de Plantas), Unidade de Ciências e Tecnologias Agrárias, Univ. do Algarve, 1994

Identificação e caracterização de duas isoformas da Ferritina da amêijoa R. decussatus e avaliação de algumas das suas propriedades biológicas

Dissertação de mest., Biologia Molecular e Microbiana, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011

Foto-identificação de tartarugas marinhas (Chelonia mydas e Eretmochelys imbricata) na Reserva Biológica Marinha do Arvoredo (Santa Catarina, Brasil)

Dissertação de mest., Biologia Marinha (Ecologia e Conservação Marinha), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2012

Identificação e estudo dos sistemas tipo de produção de alfarroba. Influência das medidas da PAC nestes sistemas

O presente documento constitui o relatório final do projecto “Estudo dos Sistemas Agrários Tradicionais”, executado em parceria com a Consejería de Agricultura Y Pesca da Junta da Anadalucía, no âmbito da Iniciativa Comunitária Interreg II (Programa Operativo Interregional II).

Inteligência emocional, stress percecionado e sentimento de presença como preditores da identificação avatar em ambiente virtual

Este estudo procurou encontrar em primeiro qual o efeito da Inteligência emocional e do sentimento de presença sobre a identificação avatar em ambiente virtual, e em segundo se a identificação avatar estava associada a uma mudança de Self. O ambiente virtual foi simulado através de um jogo em 3ª pessoa (SOCOM4), onde os participantes tinham de jogar com um soldado de guerra americano. Os participantes (N = 82) preencheram uma escala de Inteligência emocional previamente à prova e posteriormente medidas de identificação, de stress e de atitudes face aos soldados. Os resultados demonstraram que o fator atenção e clareza (inteligência emocional) estão relacionados com a identificação. Foi encontrado também que a identificação ao avatar estava associada a uma mudança de Self. A identificação foi ainda associada a uma avaliação mais positiva dos soldados e da aceitação do uso dos mesmos. Foram ainda encontrados resultados para um possível modelo de mediação sobre os tipos de identificação com o prazer no jogo, dificuldades cognitivas e valoração de soldados pela variável traços estereotipicamente de soldados.

Avaliação da eficiência e identificação dos fatores determinantes da eficiência do setor bancário em Portugal

A participação na área Euro e a atual crise financeira têm condicionado substancialmente o setor bancário português, para o qual se prevê a continuação de quebras significativas nos rendimentos e uma crescente pressão competitiva, sendo a eficiência um fator imprescindível para a sobrevivência. Foram avaliados diversos indicadores de eficiência dos principais bancos a operar em Portugal, através da metodologia DEA. As principais contribuições deste estudo consistem (1) na incorporação de novas variáveis nos modelos DEA, que refletem, para além da rendibilidade, a criação de valor e o custo de oportunidade do capital; (2) na exploração de indicadores e modelos complementares de eficiência mais exigentes que os tradicionais e (3) na aplicação de regressões fracionais aos índices DEA complementares. Os principais resultados revelam que o modelo de rendibilidade apresenta os níveis de eficiência média padrão mais elevados e o modelo de intermediação os mais baixos. Registam-se muitas ineficiências de escala e de gestão de recursos na maioria dos bancos. A aplicação de modelos bietápicos permitiu contornar a habitual problemática inerente à coexistência das abordagens de produção e intermediação. A aplicação de modelos de eficiência composta permitiu a identificação dos bancos falso-eficientes nos modelos de eficiência padrão. A aplicação de regressões para proporções, mais apropriadas que as tradicionais regressões lineares ou que o modelo Tobit, para lidar com a natureza fracionaria dos índices DEA, permitiu a identificação dos fatores determinantes da eficiência dos principais bancos a operar em Portugal. Os modelos de regressão fracional mostram evidências de melhor especificação relativamente aos modelos de regressão tradicionais. As variáveis que parecem exercer maior influência sobre os níveis de eficiência bietápica global são as variáveis internacionalização, dimensão e tipo de propriedade do capital e sobre os níveis de eficiência composta de rendibilidade são as variáveis cost-to-income, número de empregados por balcão e rendibilidade do ativo.