Somatic embryogenesis, organogenesis and callus growth kinetics of flax (Linum usitatissimum L.)

The effects of plant growth regulators (PGR) on calli induction, morphogenesis and somatic embryogenesis of flax were studied. The organogenic and callus formation capacity were assessed for different types of source explants. Root and shoot explants were equally good material for calli production but the former produced calli without shoot regeneration capacity. Under the experimental conditions tested, 2,4-dichlorophenoxyacetic acid (2,4-D) + zeatin (ZEA) was the most efficient PGR combination on calli induction and biomass production. The calli were green but with no rhizogenic capacity. On the contrary, and at similar concentrations, indole-3-butyric acid (IBA) + kinetin (KIN) induced white or pale green friable calli with a good root regeneration capacity (60%). A factorial experiment with different combinations of 2,4-D + ZEA + gibberellic acid (GA3) levels revealed that the direction of explant differentiation was determined by specific PGR interactions and concentrations. The results from these experiments revealed that the morphogenetic pathway (shoot versus root differentiation) can be manipulated on flax explants by raising the 2,4-D level from 0.05 to 3.2 mg l-1 in the induction medium. The induction and development of somatic embryos from flax explants was possible in a range of 2,4-D+ZEA concentrations surrounding 0.4 mg l-1 2,4-D and 1.6 mg l-1 ZEA, the most efficient phytohormonal combination.Junta Nacional de Investigação Científica e Tecnológia (JNICT) - BD/2771/93

Influence of medium parameters on somatic embryogenesis from hypocotyl explants of flax (Linum usitatissimum L.) : effect of carbon source, total inorganic nitrogen and balance between ionic forms and interaction between calcium and zeatin

The effects of different carbon sources, total inorganic nitrogen concentration, nitrate to ammonium ratio and the interaction between calcium and zeatin (ZEA) levels on somatic embryogenesis from flax hypocotyl explants were studied in three independent factorial experiments. MS medium supplemented with the monosaccharides glucose or fructose at high concentrations (4%) gave consistently highly embryogenic cultures, with higher somatic embryos frequencies and higher growth rates when compared with media supplemented with sucrose or maltose. Although media with maltose had performed well in a 1 to 4% concentration range, media supplemented with sucrose at 4% appeared to inhibit the induction and development of somatic embryos. Independently of the effect of the nitrogen content, the balance between both ionic forms (NO3- and NH4+) played a dramatic role on the induction of somatic embryogenesis and somatic embryos growth. Nitrate is important to calli differentiation and growth and a high ammonium content increased somatic embryo frequency. The embryogenic vs. undifferentiated cell growth commitment of flax explants was determined by an interaction between calcium and ZEA levels, a high calcium/low ZEA affording very low embryogenic potencial and high calli biomass. A high ZEA concentration was essential for the normal development of somatic embryos.Junta Nacional de Investigação Científica e Tecnológica (JNICT) - BD/2771/93

Ontogenic variations in free and esterified fatty acids during somatic embryogenesis of flax (Linum usitatissimum L.)

In vitro cultures of flax (Linum usitatissimum L.) were established on MS medium and four samplings were made during the 7 weeks of culture. The samples varied from the original hypocotyl segments (HS) at t0 and segments with incipient calli formation (HSC) after 2 weeks (t2), to embryogenic calli (EC), non-embryogenic calli (NEC) and somatic embryos (SE) collected after 5 (t5) and 7 weeks (t7). The respective free fatty acids (FFA) and esterified fatty acids (EFA) were extracted and analyzed, as methyl esters, by GC and GC-MS, and the data were submitted to ANOVA and PCA statistical analysis. The main FFA in all samples was 16:0, 18:0, 18:1, 18:2 and 18:3. EFA fractions were more diverse containing some less common FA. The development of SE was associated with a decrease in neutral lipids. Both the total FFA and the total EFA, as fractions of total lipids, increased with the dedifferentiation and the early calli formation leveling off thereafter (t5 to t7). FA variations related to dedifferentiation of hypocotyl tissues and growth of non-embryogenic calli, somatic embryogenesis, and development of somatic embryos were observed. Predominant or tissue-specific FA was also found. The value of 18:3/18:2 and 18:0/18:3 ratios as potential indicators of SE autotrophy and calli embryogenic capacity is discussed

Ontogenic variations in n-alkanes during somatic embryogenesis of flax (Linum usitatissimum L.)

Hypocotyl segments of flax seedlings germinated in vitro, were used to induce indirect somatic embryogenesis on solid medium. The composition and distribution of n-alkanes in flax tissues collected at different developmental stages were studied by GC and GC-MS. During induction and development of callus from hypocotyl tissues a decrease in the percentage of total lipids was observed. In all types of tissue sampled - hypocotyl segments used as primary explants, hypocotyl segments with differentiating calli at the cut ends, embryogenic and non-embryogenic calli and somatic embryos - a skewed-normal distribution of n-alkanes with a low mass range (C13-C21) were found. The highest content of n-alkanes occurred in the primary hypocotyl explants and in the early stages of callus development. Longer carbon chain n-alkanes were observed only in the mature or differentiated tissues of hypocotyls and somatic embryos. Although the n-alkane contents decreased with time, in somatic embryos and calli, a significantly lower n-alkane content was observed in embryogenic calli when compared to non-embryogenic calli independent of the time in culture. These results suggest the utilisation of n-alkanes for heterotrophic cellular growth as well as its mobilisation from embryogenic calli to developing somatic embryosJunta Nacional de Investigação Científica e Tecnológica (JNICT) - BD/2771/93

Atitudes do consumidor em relação às práticas do marketing em Portugal

Com o presente trabalho de investigação pretendeu-se medir e conhecer a atitude do consumidor português face às políticas do Marketing-Mix, nas diferentes regiões de Portugal Continental através da aplicação de um inquérito. A dimensão da amostra para aferir sobre a população foi de 600 indivíduos selecionados proporcionalmente à população existente com mais de 15 anos, de acordo com os dados da mesma fonte. De referir que para tal assumiuse um erro de precisão de 4% e um nível de significância de 5%. Os principais resultados permitiram observar que os consumidores manifestaram uma atitude positiva relativamente as atividades de Marketing-Mix qualidade do produto e distribuição e vendas, pois a satisfação nos respetivos parâmetros corresponde às expectativas dos mesmos. Por outro lado, revelaram uma atitude negativa quanto à política de preço dos produtos e à política de comunicação, pois os consumidores revelaram uma insatisfação para estas atividades

Drinking of Salvia officinalis tea increases CCl4-induced hepatotoxicity in mice

In a previous study, the drinking of a Salvia officinalis tea (prepared as an infusion) for 14 days improved liver antioxidant status in mice and rats where, among other factors, an enhancement of glutathione-S-transferase (GST) activity was observed. Taking in consideration these effects, in the present study the potential protective effects of sage tea drinking against a situation of hepatotoxicity due to free radical formation, such as that caused by carbon tetrachloride (CCl4), were evaluated in mice of both genders. Contrary to what was expected, sage tea drinking significantly increased the CCl4-induced liver injury, as seen by increased plasma transaminase levels and histology liver damage. In accordance with the previous study, sage tea drinking enhanced significantly GST activity. Additionally, glutathione peroxidase was also significantly increased by sage tea drinking. Since CCl4 toxicity results from its bioactivation mainly by cytochrome P450 (CYP) 2E1, the expression level of this protein was measured by Western Blot. An increase in CYP 2E1 protein was observed which may explain, at least in part, the potentiation of CCl4-induced hepatotoxicity conferred by sage tea drinking. The CCl4-induced hepatotoxicity was higher in females than males. In conclusion, our results indicate that, although sage tea did not have toxic effects of its own, herb–drug interactions are possible and may affect the efficacy and safety of concurrent medical therapy with drugs that are metabolized by phase I enzymes.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/6942/2001, POCI/AGR/62040/200

Evolução da pesquisa brasileira em Resource-Based View (RBV): estudo das ENANPAD na área de estratégia entre 1997-2006

O objetivo do presente trabalho foi verificar a contribuição brasileira nos estudos de estratégia o enfoque na RESOURCE-BASED VIEW – RBV. O estudo visou expor e analisar a evolução da pesquisa em RBV no Brasil, a partir dos trabalhos selecionados e apresentados no ENANPAD. No levantamento preliminar para a análise dos artigos, considerando 10 anos de ENANPAD (1997 – 2006), foram selecionados 57 artigos. A identificação e seleção dos artigos envolveram os seguintes critérios: avaliação dos títulos e resumos dos artigos apresentados na área de estratégia entre 1997 e 2006; busca complementar por palavras-chave tais como RBV, VBR, recursos, capacidades, competências, visão baseada em recursos e resource-based view, core competence e de dynamic capabilitiess na base de dados do ENANPAD. Procedemos também à análise das referências utilizadas nos artigos. Na primeira parte revemos brevemente aspectos fundamentais da RBV. Na segunda parte apresentamos a metodologia seguida na coleta dos dados e fazemos à análise dos resultados. Concluímos com uma discussão geral, propondo a partir da evolução dos trabalhos nacionais uma agenda que possa orientar pesquisas futuras

Phenolic compounds protect HepG2 cells from oxidative damage : relevance of glutathione levels

Prova tipográfica (In Press)In the present work, the potential hepatoprotective effects of five phenolic compounds were evaluated against oxidative damages induced by tert-butyl hydroperoxide (t-BHP) in HepG2 cells in order to relate in vitro antioxidant activity with cytoprotective effects. t-BHP induced considerable cell damages to HepG2 cells as shown by significant LDH leakage, increased lipid peroxidation, DNA damage as well as decreased reduced glutathione (GSH) levels. All tested phenolic compounds significantly decreased cell death induced by t-BHP (when in co-incubation). If the effects of quercetin are given the reference value 1, the compounds rank in the following order according to inhibition of cell death: luteolin (4.0) > quercetin (1.0) > rosmarinic acid (0.34) > luteolin-7-glucoside (0.30) > caffeic acid (0.21). The results underscore the importance of the compound’s lipophilicity in addition to its antioxidant potential for its biological activity. All tested phenolic compounds were found to significantly decrease lipid peroxidation and prevent GSH depletion induced by t-BHP, but only luteolin and quercetin significantly decreased DNA damage. Therefore, the lipophilicity of the natural antioxidants tested appeared to be of even higher importance for DNA protection than for cell survival. The protective potential against cell death was probably achieved mainly by preventing intracellular GSH depletion. The phenolic compounds studied here showed protective potential against oxidative damages induced in HepG2 cells that could be beneficial against liver diseases where it is known that oxidative stress plays a crucial role.Fundação para a Ciência e Tecnologia -SFRH/BD/6942/2001; POCTI/AGR/62040/2004

O Exercício pode Prevenir ou Tratar a Toxicodependência

Disponível em suporte de papel na Biblioteca da FCDEF-UCNo final do século XX e no inicio do século XXI a actividade física tem vindo a demonstrar um papel muito importante no que diz respeito ao tratamento e prevenção de algumas doenças. Os benefícios de ter uma pratica regular ao longo de toda a vida são vastos e cada vez mais procuras ter uma vida activa. Vários estudos recentes apontam para novos campos de actuação da actividade física regular, como sendo a de dependência de substancias como a droga, o álcool, o tabaco e a Cannabis. O consumo destas substancia é praticada cada vez mais cedo resultando em problemas, muitas vezes graves para as pessoas que o fazem. Este estudo pretendeu rever a literatura sobre o tema da toxicodependência e a prevenção ou tratamento através da actividade física regular. Foram revistos 10 estudos que se relacionam com a droga, o álcool, o tabaco e a Cannabis e a influencia da actividade física no consumo destas substancias. Concluiu-se que no caso do tabaco e da Cannabis não existiu evidencias que a actividade física previna ou provoque a abstinência do consumo destas substancias. No álcool a actividade física parece ter um efeito protetivo do consumo de bebidas alcoólicas. Nas drogas como a heroína e cocaína a actividade física tem um papel protetivo do consumo destas substancias, e quem já a consome verifica-se uma redução desse consumo. Não existe consistência quanto à intensidade, duração, numero de sessões ou tipo de exercício mais eficaz para cada caso

Sistema de sensorização e controlo baseado em ZigBee para aplicação em bicicletas elétricas

Dissertação de mestrado integrado em Engenharia de ComunicaçõesEsta dissertação descreve uma solução para implementar a comunicação sem fios entre sensores indicadores de esforço físico, um smartphone e um sistema de controlo de uma bicicleta elétrica. Um dos objetivos deste trabalho consiste na especificação de alguns cenários para o controlo de esforço físico dos utilizadores, tirando partido do sistema de controlo dessa bicicleta, com a finalidade de proporcioná-los com a possibilidade de melhorar a sua aptidão física. Nesta dissertação é implementada uma infraestrutura de rede, baseada em ZigBee, para dar suporte à comunicação entre as diversas partes do sistema. Os testes efetuados visam aferir se a qualidade de serviço oferecida, mais especificamente no atraso fim a fim, é adequada para suportar os diversos cenários de controlo de esforço. O consumo de energia e o alcance também são considerados uma vez que são características fundamentais no contexto deste trabalho. A comunicação entre as diversas partes do sistema é assegurada através do módulo SDZ-539 da Spectec que desempenha o papel de gateway entre o smartphone e a rede ZigBee. A escolha deste módulo baseou-se no facto de permitir a comunicação entre sensores baseados em ZigBee/IEEE 802.15.4 com um smartphone Android. Durante a fase de implementação e testes verificou-se que este módulo tem algumas limitações, nomeadamente a necessidade de fazer polling, ao nível aplicacional, para receber os dados provenientes da rede ZigBee, e também pelo facto de ter um consumo de energia considerável mesmo em situações de baixa utilização. Com os resultados obtidos nos testes foi possível determinar o melhor compromisso entre o intervalo de polling, o atraso e o consumo energético de modo a responder às necessidades do sistema. Além disso foram obtidos resultados que mostram que o alcance das comunicações sem fios é aceitável tendo em conta o propósito para o qual o sistema foi projetado.This dissertation describes a solution for implementing the wireless communication between sensors that measure physical effort, a smartphone and an electric bicycle control system. One of the objectives of this work was to specify some scenarios to control users’ physical effort, by taking advantage of the bicycles control system, in order to provide them with the possibility of improving their fitness level. In this dissertation a network infrastructure, based on the ZigBee protocol, was implemented to support the communication between the different parts of the system. The tests performed aim to assess whether or not the quality of service, more specifically, the end to end delay, is adequate to support the different scenarios that were initially specified. The power consumption and range are also considered since they are key features in the context of this work. The communication between the different parts of the system is ensured by Spectec’s SDZ-539 module, which acts as a gateway between the smartphone and the ZigBee network. The choice of this module was due to the fact that it enabled the communication between ZigBee/IEEE 802.15.4 based sensors and an Android smartphone. During the implementation and testing phase it was verified that the module has some limitations, namely the need for polling at the Android application level to receive data from the ZigBee network, and also the fact that power consumption was considerably high even with low utilization. With the results obtained from the tests it was possible to determine a trade-off between the polling interval, the end to end delay and the power consumption in order to meet the systems requirements. Furthermore, the obtained results show that the wireless communication range is acceptable regarding the purpose for which the system was designed