Browsing by Issue Date, starting with "2016-06"
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- Metabolic rate and rates of protein turnover in food-deprived cuttlefish, Sepia officinalis (Linnaeus 1758)Publication . Lamarre, Simon G.; MacCormack, Tyson J.; Sykes, António; Hall, Jennifer R.; Speers-Roesch, Ben; Callaghan, Neal I.; Driedzic, William R.To determine the metabolic response to food deprivation, cuttlefish (Sepia officinalis) juveniles were either fed, fasted (3 to 5 days food deprivation), or starved (12 days food deprivation). Fasting resulted in a decrease in triglyceride levels in the digestive gland, and after 12 days, these lipid reserves were essentially depleted. Oxygen consumption was decreased to 53% and NH4 excretion to 36% of the fed group following 3-5 days of food deprivation. Oxygen consumption remained low in the starved group, but NH4 excretion returned to the level recorded for fed animals during starvation. The fractional rate of protein synthesis of fasting animals decreased to 25% in both mantle and gill compared with fed animals and remained low in the mantle with the onset of starvation. In gill, however, protein synthesis rate increased to a level that was 45% of the fed group during starvation. In mantle, starvation led to an increase in cathepsin A-, B-, H-, and L-like enzyme activity and a 2.3-fold increase in polyubiquitin mRNA that suggested an increase in ubiquitin-proteasome activity. In gill, there was a transient increase in the polyubiquitin transcript levels in the transition from fed through fasted to the starved state and cathepsin A-, B-, H-, and L-like activity was lower in starved compared with fed animals. The response in gill appears more complex, as they better maintain rates of protein synthesis and show no evidence of enhanced protein breakdown through recognized catabolic processes.
- N-dimensional switch function for energy conservation in multiprocess reaction dynamicsPublication . Mogo, César; Brandão, J.The MReaDy program was designed for studying Multiprocess Reactive Dynamic systems, that is, complex chemical systems involving different and concurrent reactions. It builds a global potential energy surface integrating a variety of potential energy surfaces, each one of them representing an elementary reaction expected to play a role in the chemical process. For each elementary reaction, energy continuity problems may happen in the transition between potential energy surfaces due to differences in the functional form for each of the fragments, especially if built by different authors. A N-dimensional switch function is introduced in MReaDy in order to overcome such a problem. As an example, results of a collision trajectory calculation for H-2 + OH -> H3O are presented, showing smooth transition in the potential energy, leading to conservation in the total energy. Calculations for a hydrogen combustion system from 1000 K up to 4000 K shows a variation of 0.012% when compared to the total energy of the system. VC 2016 Wiley Periodicals, Inc.
- Extracellular proteins: Novel Key components of metal resistance in cyanobacteria?Publication . Joaquín, Giner-Lamia; Pereira, Sara B.; Bovea-Marco, Miquel; Futschik, Matthias E.; Tamagnini, Paula; Oliveira, PauloMetals are essential for all living organisms and required for fundamental biochemical processes. However, when in excess, metals can turn into highly-toxic agents able to disrupt cell membranes, alter enzymatic activities, and damage DNA. Metal concentrations are therefore tightly controlled inside cells, particularly in cyanobacteria. Cyanobacteria are ecologically relevant prokaryotes that perform oxygenic photosynthesis and can be found in many different marine and freshwater ecosystems, including environments contaminated with heavy metals. As their photosynthetic machinery imposes high demands for metals, homeostasis of these micronutrients has been widely studied in cyanobacteria. So far, most studies have focused on how cells are capable of controlling their internal metal pools, with a strong bias toward the analysis of intracellular processes. Ultrastructure, modulation of physiology, dynamic changes in transcription and protein levels have been studied, but what takes place in the extracellular environment when cells are exposed to an unbalanced metal availability remains largely unknown. The interest in studying the subset of proteins present in the extracellular space has only recently begun and the identification and functional analysis of the cyanobacterial exoproteomes are just emerging. Remarkably, metal-related proteins such as the copper-chaperone CopM or the iron-binding protein FutA2 have already been identified outside the cell. With this perspective, we aim to raise the awareness that metal-resistance mechanisms are not yet fully known and hope to motivate future studies assessing the role of extracellular proteins on bacterial metal homeostasis, with a special focus on cyanobacteria.
- Development of an ecotoxicological protocol for the deep-sea fauna using the hydrothermal vent shrimp Rimicaris exoculataPublication . Auguste, M.; Mestre, N. C.; Rocha, T. L.; Cardoso, C.; Cueff-Gauchard, V.; Le Bloa, S.; Cambon-Bonavita, M. A.; Shillito, B.; Zbinden, M.; Ravaux, J.; Bebianno, Maria JoãoIn light of deep-sea mining industry development, particularly interested in massive-sulphide deposits enriched in metals with high commercial value, efforts are increasing to better understand potential environmental impacts to local fauna. The aim of this study was to assess the natural background levels of biomarkers in the hydrothermal vent shrimp Rimicaris exoculata and their responses to copper exposure at in situ pressure (30MPa) as well as the effects of depressurization and pressurization of the high-pressure aquarium IPOCAMP. R. exoculata were collected from the chimney walls of the hydrothermal vent site TAG (Mid Atlantic Ridge) at 3630m depth during the BICOSE cruise in 2014. Tissue metal accumulation was quantified in different tissues (gills, hepatopancreas and muscle) and a battery of biomarkers was measured: metal exposure (metallothioneins), oxidative stress (catalase, superoxide dismutase, glutathione-S-transferase and glutathione peroxidase) and oxidative damage (lipid peroxidation). Data show a higher concentration of Cu in the hepatopancreas and a slight increase in the gills after incubations (for both exposed groups). Significant induction of metallothioneins was observed in the gills of shrimps exposed to 4μM of Cu compared to the control group. Moreover, activities of enzymes were detected for the in situ group, showing a background protection against metal toxicity. Results suggest that the proposed method, including a physiologically critical step of pressurizing and depressurizing the test chamber to enable the seawater exchange during exposure to contaminants, is not affecting metal accumulation and biomarkers response and may prove a useful method to assess toxicity of contaminants in deep-sea species.
- Numismas da horta da misericórdia (Faro): catálogo geralPublication . Valente, Marco Paulo Gouveia FerreiraO presente catálogo surge por forma a colmatar algumas lacunas relativamente ao que os estudos da numismática têm sido votados nas últimas décadas – salvo algumas honrosas excepções ao nível das publicações, como o são o caso de certas revistas da especialidade, nomeadamente a NVMMVS e A Permuta (da Sociedade Portuguesa de Numismática), A Moeda (Revista Portuguesa de Numismática, Medalhística e Notafilia, editada pela Publinummus) e alguns estudos efectuados por colegas que a tal se dedicam (ou dedicavam) com afinco e abnegação, como os colegas Alberto Gomes†, M. Gomes Marques†, J. Rodrigues Marinho, Francisco Magro. Apesar de todas estas publicações, os hiatos cronológicos e os estudos quer de casos específicos, como de áreas mais abrangentes do ponto de vista espacial, estão em larga escala por ser efectuados. Esperamos, sinceramente, que este nosso estudo venha a contribuir para o avolumar de conhecimento, das várias épocas históricas, que estudos numismáticos desta espécie vêm assim colmatando.
- Cherenkov radiation with massive, CPT-violating photonsPublication . Colladay, Don; McDonald, Patrick; Potting, RobertusThe source of CPT violation in the photon sector of the Standard Model Extension arises from a Chern-Simons-like contribution that involves a coupling to a fixed background vector field k(AF)(mu). These Lorentz- and CPT-violating photons have well-known theoretical issues that arise from missing states at low momenta when k(AF)(mu) is timelike. In order to make the theory consistent, a tiny mass for the photon can be introduced, well below current experimental bounds. The implementation of canonical quantization can then be implemented as in the CPT-preserving case by using the Stuckelberg mechanism. We explicitly construct a covariant basis of properly normalized polarization vectors at fixed three-momentum satisfying the momentum space field equations, in terms of which the vector field can be expanded. As an application of the theory, we calculate the Cherenkov radiation rate for the case of purely timelike k(AF)(mu) and find a radiation rate at high energies that has a contribution that does not depend on the mass used to regulate the photons.
- Question of Lorentz violation in muon decayPublication . Noordmans, J. P.; Onderwater, C. J. G.; Wilschut, H. W.; Timmermans, R. G. E.Possibilities to test the Lorentz invariance of the weak interaction in muon decay are considered. We derive the direction-dependent muon-decay rate with a general Lorentz-violating addition to the W-boson propagator. We discuss measurements of the directional and boost dependence of the Michel parameters and of the muon lifetime as a function of absolute velocity. The total muon-decay rate in the Lorentz-violating standard model extension is addressed. Suggestions are made for dedicated (re) analyses of the pertinent data and for future experiments.
- Field measurements of intertidal bar evolution on a high-energy beach systemPublication . Jackson, Derek W. T.; Cooper, J. Andrew G.; O'Connor, Marianne; Guisado-Pintado, Emilia; Loureiro, C.; Anfuso, GiorgioNearshore bars play a pivotal role in coastal behaviour, helping to protect and restore beach systems particularly in post-storm conditions. Examination of bar behaviour under various forcing conditions is important to help understand the short-to medium-term evolution of sandy beach systems. This study carried out over a nine-week period examines, the behaviour of three intertidal bars along a high energy sandy beach system in northwest Ireland using high-frequency topographic surveys and detailed nearshore hydrodynamic modelling.Results show that, in general, there was onshore migration for all the bars during the study period, despite the variability observed between bars, which was driven mostly by wave dominated processes. Under the prevailing conditions migration rates of up to 1.83 mday(-1) and as low as 0.07 mday(-1) were observed. During higher wave energy events the migration rates of the bars decelerated in their onshore route, however, under lower wave energy conditions, they quickly accelerated maintaining their shoreward migration direction. Tidal influence appears to be subordinate in these conditions, being restricted to moderating the localized wave energy at low tides and in maintaining runnel configurations providing accommodation space for advancing slip faces.The study highlights the intricate behavioural patterns of intertidal bar behaviour along a high energy sandy coastline and provides new insights into the relative importance of wave and tidal forcing on bar behaviour over a relatively short time period. Copyright (C) 2016 John Wiley & Sons, Ltd.
- Inhalable antitubercular therapy mediated by locust bean gum microparticlesPublication . Alves, Ana; Cavaco, Joana; Guerreiro, Filipa; Lourenço, J. P.; Costa, Ana M. Rosa da; Grenha, AnaTuberculosis remains a major global health problem and alternative therapeutic approaches are needed. Considering the high prevalence of lung tuberculosis (80% of cases), the pulmonary delivery of antitubercular drugs in a carrier system capable of reaching the alveoli, being recognised and phagocytosed by alveolar macrophages (mycobacterium hosts), would be a significant improvement to current oral drug regimens. Locust bean gum (LBG) is a polysaccharide composed of galactose and mannose residues, which may favour specific recognition by macrophages and potentiate phagocytosis. LBG microparticles produced by spray-drying are reported herein for the first time, incorporating either isoniazid or rifabutin, first-line antitubercular drugs (association efficiencies >82%). Microparticles have adequate theoretical properties for deep lung delivery (aerodynamic diameters between 1.15 and 1.67 μm). The cytotoxic evaluation in lung epithelial cells (A549 cells) and macrophages (THP-1 cells) revealed a toxic effect from rifabutin-loaded microparticles at the highest concentrations, but we may consider that these were very high comparing with in vivo conditions. LBG microparticles further evidenced strong ability to be captured by macrophages (percentage of phagocytosis >94%). Overall, the obtained data indicated the potential of the proposed system for tuberculosis therapy.
- Climatic and geologic controls on the piezometry of the Querença-Silves karst aquifer, Algarve (Portugal)Publication . Neves, Maria; Costa, Luis; Monteiro, José PauloKarst aquifers in semi-arid regions, like Queren double dagger a-Silves (Portugal), are particularly vulnerable to climate variability. For the first time in this region, the temporal structure of a groundwater-level time series (1985-2010) was explored using the continuous wavelet transform. The investigation focused on a set of four piezometers, two at each side of the S. Marcos-Quarteira fault, to demonstrate how each of the two sectors of the aquifer respond to climate-induced patterns. Singular spectral analysis applied to an extended set of piezometers enabled identification of several quasi-periodic modes of variability, with periods of 6.5, 4.3, 3.2 and 2.6 years, which can be explained by low-frequency climate patterns. The geologic forcing accounts for similar to 15 % of the differential variability between the eastern and western sectors of the aquifer. The western sector displays spatially homogenous piezometric variations, large memory effects and low-pass filtering characteristics, which are consistent with relatively large and uniform values of water storage capacity and transmissivity properties. In this sector, the 6.5-year mode of variability accounts for similar to 70 % of the total variance of the groundwater levels. The eastern sector shows larger spatial and temporal heterogeneity, is more reactive to short-term variations, and is less influenced by the low-frequency components related to climate patterns.