Browsing by Issue Date, starting with "2013-05"
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- Coordinated regulation of chromatophore differentiation and melanogenesis during the ontogeny of skin pigmentation of Solea senegalensis (Kaup, 1858)Publication . Darias, Maria J.; Andree, Karl B.; Boglino, Anais; Fernandez, Ignacio; Estevez, Alicia; Gisbert, EnricAbnormal pigmentation of Senegalese sole has been described as one problem facing the full exploitation of its commercial production. To improve our understanding of flatfish pigmentation of this commercially important species we have evaluated eleven genes related to two different processes of pigmentation: melanophore differentiation, and melanin production. The temporal distribution of gene expression peaks corresponds well with changes in pigmentation patterns and the intensity of skin melanization. Several gene ratios were also examined to put in perspective possible genetic markers for the different stages of normal pigmentation development. Further, the phenotypic changes that occur during morphogenesis correspond well with the main transitions in gene expression that occur. Given the dramatic phenotypic alterations which flatfish undergo, including the asymmetric coloration that occurs between the ocular and the blind side, and the synchrony of the two processes of morphogenesis and pigmentation ontogenesis, these species constitute an interesting model for the study of pigmentation. In this study we present a first approximation towards explaining the genetic mechanisms for regulating pigmentation ontogeny in Senegalese sole, Solea senegalensis.
- Skeletal anomalies in reared European fish larvae and juveniles. Part 1: normal and anomalous skeletogenic processesPublication . Boglione, Clara; Gavaia, Paulo; Koumoundouros, Giorgos; Gisbert, Enric; Moren, Mari; Fontagne, Stephanie; Witten, Paul EckhardThis critical review summarizes the knowledge about fish skeletal tissues and inherent normal and anomalous development. Particular emphasis is given to existing literature on reared European fishes. The aim was to identify the main gaps of knowledge that require to be filled, in order to precociously identify anomalous developmental patterns that lead to skeletal anomalies in reared finfish larvae and juveniles. The review also aims to extend our knowledge about the factors that are possibly involved in the onset of skeletal anomalies. The final goal is the optimization of the morphological quality of farmed juvenile fish.
- Modeling biomass particle drying, devolatilization and combustion in a grate fired combustorPublication . Sousa, Nelson; Azevedo, João L.T.The paper presents the application of a numerical model to describe the evolution of a particle in a grate fired combustion system. Due to the particle dimensions, important temperature gradients exist inside the particles and reactions occur within the particles. A model using layers is used to describe the processes inside the particles. The biomass composition is expressed as fractions of moisture, unreacted biomass, char and ash. Biomass conversion is described by a competitive reaction model leading to the formation of light volatiles, tars and char. Tar is subject of secondary reactions inside the particles forming either light gases or char. Transport equations are solved for the gases within the particle including oxygen from the environment that reacts with gases or char. The model is applied to different heating rates leading to different amounts of tars and char in accordance with data from the literature. The model is also applied to simulate the combustion of a single trunk standing in a heated gas stream and comparisons are done for the temperature and mass loss.
- A metamorfose em Claude CrébillonPublication . Carvalho, Ana Alexandra Mendonça Seabra da Silva Andrade deNeste artigo, estudaremos os sentidos da metamorfose em quatro narrativas de Claude Crébillon: Le Sylphe, ou Songe de Madame de R*** écrit par elle-même à Madame de S*** (1730); L’Écumoire ou Tanzaï et Néadarné. Histoire japonoise (1734); Le Sopha. Conte moral (1742); e Ah Quel Conte! Conte politique et astronomique (1754). Enquanto contista, o autor recupera e transforma um vasto fundo cultural onde se cruzam as diferentes tradições associadas ao maravilhoso. Os vários sentidos da metamorfose serão aqui considerados quer enquanto processo estético-literário problematizador do exotismo maravilhoso na literatura coeva, quer como um meio lúdico e transgressor de criticar tanto a moral e os costumes excessivamente hedonistas, como as manobras do poder político. Assim, nestas obras, o processo da metamorfose está ao serviço da visão crítica sobre a literatura e a sociedade que caracteriza a poética de Crébillon.
- Maximal, potential and singular operators in the local "complementary" variable exponent Morrey type spacesPublication . Guliyev, Vagif S.; Hasanov, Javanshir J.; Samko, StefanWe consider local "complementary" generalized Morrey spaces M-c({x0})p(.).omega (Omega) in which the p-means of function are controlled over Omega \ B(x(0), r) instead of B(x(0), r), where Omega subset of R-n is a bounded open set, p(x) is a variable exponent, and no monotonicity type condition is imposed onto the function omega(r) defining the "complementary" Morrey-type norm. In the case where omega is a power function, we reveal the relation of these spaces to weighted Lebesgue spaces. In the general case we prove the boundedness of the Hardy-Littlewood maximal operator and Calderon-Zygmund singular operators with standard kernel, in such spaces. We also prove a Sobolev type M-c({x0})p(.).omega (Omega) -> M-c({x0})p(.).omega (Omega)-theorem for the potential operators I-alpha(.), also of variable order. In all the cases the conditions for the boundedness are given it terms of Zygmund-type integral inequalities-on omega(r), which do not assume any assumption on monotonicity of omega(r).
- Catálogo do espólio documental de Joaquim Magalhães (1909-1999)Publication . Fidalgo, Andreia; Martins, Susana Calado; Mendes, António RosaUm acervo pessoal de natureza documental reflete sem qualquer sombra de dúvidas, a vivência e criatividade pessoais, profissionais e académicas do seu possuidor/autor. E um acervo pessoal com a dimensão e a diversidade do acervo do Dr. Joaquim Peixoto Magalhães é sem sombra de dúvida de uma riqueza intelectual assinalável
- Skeletal anomalies in reared European fish larvae and juveniles. Part 2: main typologies, occurrences and causative factorsPublication . Boglione, Clara; Gisbert, Enric; Gavaia, Paulo; Witten, Paul E.; Moren, Mori; Fontagne, Stephanie; Koumoundouros, GiorgosThe presence of skeletal anomalies in farmed teleost fish is currently a major problem in aquaculture, entailing economical, biological and ethical issues. The common occurrence of skeletal abnormalities in farmed fish and the absence of effective solutions for avoiding their onset or definitely culling out the affected individuals as early as possible from the productive cycle, highlight the need to improve our knowledge on the basic processes regulating fish skeletogenesis and skeletal tissues differentiation, modelling and remodelling. Severe skeletal anomalies may actually occur throughout the entire life cycle of fish, but their development often begins with slight aberrations of the internal elements. Comprehensive investigation efforts conducted on reared larvae and juveniles could provide a great contribution in filling the gap in knowledge, as skeletogenesis and skeletal tissue differentiation occur during these early life stages. The aim of this review is to provide a synthetic but comprehensive picture of the actual knowledge on the ontogeny, typologies and occurrence of skeletal anomalies, and on the proposed causative factors for their onset in larvae and juveniles of European farmed fish. The state-of-art of knowledge of these issues is analysed critically intending to individualize the main gaps of knowledge that require to be filled, in order to optimize the morphological quality of farmed juveniles.
- Fish larval nutrition and feed formulation: knowledge gaps and bottlenecks for advances in larval rearingPublication . Hamre, Kristin; Yufera, Manuel; Ronnestad, Ivar; Boglione, Clara; Conceicao, Luis E. C.; Izquierdo, MarisolDespite considerable progress in recent years, many questions regarding fish larval nutrition remain largely unanswered, and several research avenues remain open. A holistic understanding of the supply line of nutrients is important for developing diets for use in larval culture and for the adaptation of rearing conditions that meet the larval requirements for the optimal presentation of food organisms and/or microdiets. The aim of the present review is to revise the state of the art and to pinpoint the gaps in knowledge regarding larval nutritional requirements, the nutritional value of live feeds and challenges and opportunities in the development of formulated larval diets.
- Activation of Type 1 Cannabinoid Receptor (CB1R) promotes neurogenesis in murine subventricular zone cell culturesPublication . Xapelli, Sara; Agasse, Fabienne; Sarda-Arroyo, Laura; Bernardino, Liliana; Santos, Tiago; Ribeiro, Filipa F.; Valero, Jorge; Braganca, José; Schitine, Clarissa; de Melo Reis, Ricardo A.; Sebastiao, Ana M.; Malva, Joao O.The endocannabinoid system has been implicated in the modulation of adult neurogenesis. Here, we describe the effect of type 1 cannabinoid receptor (CB1R) activation on self-renewal, proliferation and neuronal differentiation in mouse neonatal subventricular zone (SVZ) stem/progenitor cell cultures. Expression of CB1R was detected in SVZ-derived immature cells (Nestin-positive), neurons and astrocytes. Stimulation of the CB1R by (R)-(+)-Methanandamide (R-m-AEA) increased self-renewal of SVZ cells, as assessed by counting the number of secondary neurospheres and the number of Sox2+/+ cell pairs, an effect blocked by Notch pathway inhibition. Moreover, R-m-AEA treatment for 48 h, increased proliferation as assessed by BrdU incorporation assay, an effect mediated by activation of MAPK-ERK and AKT pathways. Surprisingly, stimulation of CB1R by R-m-AEA also promoted neuronal differentiation (without affecting glial differentiation), at 7 days, as shown by counting the number of NeuN-positive neurons in the cultures. Moreover, by monitoring intracellular calcium concentrations ([Ca2+](i)) in single cells following KCl and histamine stimuli, a method that allows the functional evaluation of neuronal differentiation, we observed an increase in neuronal-like cells. This proneurogenic effect was blocked when SVZ cells were co-incubated with R-m-AEA and the CB1R antagonist AM 251, for 7 days, thus indicating that this effect involves CB1R activation. In accordance with an effect on neuronal differentiation and maturation, R-m-AEA also increased neurite growth, as evaluated by quantifying and measuring the number of MAP2-positive processes. Taken together, these results demonstrate that CB1R activation induces proliferation, self-renewal and neuronal differentiation from mouse neonatal SVZ cell cultures.
- Phenolics extraction from sweet potato peels: key factors screening through a placket-burman designPublication . Anastácio, Ana; Carvalho, Isabel Saraiva deSweet potato peels usually considered as waste in food service operations may be upgraded into value added functional foods with high phenolic content and antioxidant activity. The effect of nine extraction variables was identified as relevant in previous phenolics extraction studies, because solvent solid ratio, time, pH, peeling cut depth, particle size, temperature, solvent, sample amount and agitation were combined in a 12 run Placket–Burman design to screen for key factors. The extraction of phenolic compounds was only significantly (p < 0.05) affected by solvent:solid ratio (positively) and peel cut depth (negatively) with similar effect magnitude. These factors effects presented similar direction, size and significance on extracts antioxidant activity measured by FRAP. Regression models on FRAP transformed by squared root function revealed the two factor interaction peel cut depth and sample amount as the third most influencing factor. Beyond the usage of sweet potato peels as a new constituent for human food, it should also be tested for ingredient optimized in the production of functional foods.
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