Browsing by Issue Date, starting with "2015-05"
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- Acidification effects on biofouling communities: winners and losersPublication . Peck, Lloyd S.; Clark, Melody S.; Power, Deborah; Reis, Joao; Batista, Frederico; Harper, Elizabeth M.How ocean acidification affects marine life is a major concern for science and society. However, its impacts on encrusting biofouling communities, that are both the initial colonizers of hard substrata and of great economic importance, are almost unknown. We showed that community composition changed significantly, from 92% spirorbids, 3% ascidians and 4% sponges initially to 47% spirorbids, 23% ascidians and 29% sponges after 100days in acidified conditions (pH 7.7). In low pH, numbers of the spirorbid Neodexiospira pseudocorrugata were reduced x5 compared to controls. The two ascidians present behaved differently with Aplidium sp. decreasing x10 in pH 7.7, whereas Molgula sp. numbers were x4 higher in low pH than controls. Calcareous sponge (Leucosolenia sp.) numbers increased x2.5 in pH 7.7 over controls. The diatom and filamentous algal community was also more poorly developed in the low pH treatments compared to controls. Colonization of new surfaces likewise showed large decreases in spirorbid numbers, but numbers of sponges and Molgula sp. increased. Spirorbid losses appeared due to both recruitment failure and loss of existing tubes. Spirorbid tubes are comprised of a loose prismatic fabric of calcite crystals. Loss of tube materials appeared due to changes in the binding matrix and not crystal dissolution, as SEM analyses showed crystal surfaces were not pitted or dissolved in low pH conditions. Biofouling communities face dramatic future changes with reductions in groups with hard exposed exoskeletons and domination by soft-bodied ascidians and sponges.
- Using biological variables and reproductive strategy of the undulate ray Raja undulata to evaluate productivity and susceptibility to exploitationPublication . Serra-Pereira, Bárbara; Erzini, Karim; Figueiredo, IvoneThe present work provides a detailed analysis of the reproductive strategy of the undulate ray Raja undulata in Portuguese mainland waters. The species was found mostly between 30 and 40 m deep on sandy bottoms. Egg-laying sites were observed in the north, centre and south-west regions, mainly at depths below 30 m. The peak of the reproductive season occurred from December to May. Asynchrony between reproductively active females and males appeared to occur, although most adult males were capable of reproducing throughout the year. The estimated length at 50% maturity was 862 cm (87 years) and 768 cm (76 years) total length for females and males, respectively. The maximum potential fecundity was estimated to be 698 follicles per female per reproductive season, which are released in 47 batches of 15 follicles. The life-history and demographic parameters of R. undulata are similar to those of other skate species, while the potential rate of population increase (049) is above the published values for other elasmobranch species. With these new findings, this study makes an important contribution to the understanding of the life history of R. undulata, and provides a first evaluation of the productivity and susceptibility of the species to exploitation.
- Biomass-density data analysis: a comment on Cabaco et al. (2013)Publication . Vieira, Vasco M. N. C. S.; Miguel de Sousa Leitão, Francisco; Mateus, MarcosAppropriate use of mathematics and statistics is fundamental for sound interpretations of ecological results and to prevent inaccurate conclusions. Throughout the article by Cabaco etal. (2013) emerge cases of biased data analyses including absence of statistical tests, application of unsuited tests, inconsistent geometrical interpretation of xy data scatter, among others. These biases congregated into incorrect conclusions including (i) reporting a generalized nutrient limitation of seagrass meadows, (ii) proposing the intraspecific biomass-density relation of seaweeds as an ecological indicator, when results report little more than randomness, thus suggesting this relation is unsuited as an ecological indicator; (iii) contradicting general ecological theory without any statistical evidence; and (iv) misassociating their results to the ones by other authors.Synthesis. In order to help ecological researchers pinpoint sources of bias, we point out mistakes related to xy data analysis in Cabaco et al. (2013) that can occur in any subject area and flag others specific to biomass-density relations.
- Systematic interaction network filtering identifies CRMP1 as a novel suppressor of huntingtin misfolding and neurotoxicityPublication . Stroedicke, Martin; Bounab, Yacine; Strempel, Nadine; Klockmeier, Konrad; Yigit, Sargon; Friedrich, Ralf P.; Chaurasia, Gautam; Li, Shuang; Hesse, Franziska; Riechers, Sean-Patrick; Russ, Jenny; Nicoletti, Cecilia; Boeddrich, Annett; Wiglenda, Thomas; Haenig, Christian; Schnoegl, Sigrid; Fournier, David; Graham, Rona K.; Hayden, Michael R.; Sigrist, Stephan; Bates, Gillian P.; Priller, Josef; Andrade-Navarro, Miguel A.; Futschik, Matthias E.; Wanker, Erich E.Assemblies of huntingtin (HTT) fragments with expanded polyglutamine (polyQ) tracts are a pathological hallmark of Huntington's disease (HD). The molecular mechanisms by which these structures are formed and cause neuronal dysfunction and toxicity are poorly understood. Here, we utilized available gene expression data sets of selected brain regions of HD patients and controls for systematic interaction network filtering in order to predict disease-relevant, brain region-specific HTT interaction partners. Starting from a large protein-protein interaction (PPI) data set, a step-by-step computational filtering strategy facilitated the generation of a focused PPI network that directly or indirectly connects 13 proteins potentially dysregulated in HD with the disease protein HTT. This network enabled the discovery of the neuron-specific protein CRMP1 that targets aggregation-prone, N-terminal HTT fragments and suppresses their spontaneous self-assembly into proteotoxic structures in various models of HD. Experimental validation indicates that our network filtering procedure provides a simple but powerful strategy to identify disease-relevant proteins that influence misfolding and aggregation of polyQ disease proteins.
- Demography of a deep-sea lantern shark (Etmopterus spinax) caught in trawl fisheries of the northeastern Atlantic: Application of Leslie matrices with incorporated uncertaintiesPublication . Coelho, Rui; Alpizar-Jara, Russell; Erzini, KarimThe deep-sea lantern shark Etmopterus spinax occurs in the northeast Atlantic on or near the bottoms of the outer continental shelves and slopes, and is regularly captured as bycatch in deep-water commercial fisheries. Given the lack of knowledge on the impacts of fisheries on this species, a demographic analysis using age-based Leslie matrices was carried out. Given the uncertainties in the mortality estimates and in the available life history parameters, several different scenarios, some incorporating stochasticity in the life history parameters (using Monte Carlo simulation), were analyzed. If only natural mortality were considered, even after introducing uncertainties in all parameters, the estimated population growth rate (A) suggested an increasing population. However, if fishing mortality from trawl fisheries is considered, the estimates of A either indicated increasing or declining populations. In these latter cases, the uncertainties in the species reproductive cycle seemed to be particularly relevant, as a 2-year reproductive cycle indicated a stable population, while a longer (3-year cycle) indicated a declining population. The estimated matrix elasticities were in general higher for the survivorship parameters of the younger age classes and tended to decrease for the older ages. This highlights the susceptibility of this deep-sea squaloid to increasing fishing mortality, emphasizing that even though this is a small-sized species, it shows population dynamics patterns more typical of the larger-sized and in general more vulnerable species. (C) 2014 Elsevier Ltd. All rights reserved.
- Assessment of trace element pollution and its environmental risk to freshwater sediments influenced by anthropogenic contributions: The case study of Alqueva reservoir (Guadiana Basin)Publication . Palma, Patricia; Ledo, Lidia; Alvarenga, PaulaThe Guadiana Basin.(SW Iberian Peninsula) is affected by acid mine drainage (AMD), a consequence of ancient mining activities in the Iberian Pyrite Belt (IPB). Consequently, the sedimerits at the Alqueva reservoir (SE Portugal) in the Guadiana Basin are potentially contaminated by trace elements, which make important: (i) to characterize the status of trace element pollution of the sediments; (ii) to evaluate the mobility and the bioavailability of As, Cd, Cu, Cr, Pb and Zn; and (iii) to assess the environmental risk associated with the total and bioavailable concentrations of trace elements, using the sediment quality guidelines (SQGs) and the risk assessment code (RAC). Metal enrichment factors (EF) and geoaccumulation indexes (I-geo), determined taking into account the regional background levels, revealed that, among the metals analyzed, Cd contributed the highest to pollution levels followed by Pb and As. Despite the trace element contamination of the Alqueva sediments, the sequential extraction showed that Most of them are found in the oxidizable and residual fractions, which indicates that they are sparingly bioavailable, with exception of Cd (acid-labile fraction) and Pb (reducible fraction). Based on the RAC, Cd was the only metal that presented a high risk, while Pb, As and Zn showed a medium risk. Moreover, the SQGs revealed the existence of certain areas of extremely high risk, particularly related to high concentrations of total As and, in less extent, of Pb and Cd, associated with AMD, wastewater discharges and runoff of plant protection products from agricultural fields located near the reservoir. (C) 2015 Elsevier By. All rights reserved.
- MF Calculator: A Web-Based Application for Analyzing SimilarityPublication . Sales, Celia M. D.; Wakker, Peter P.; Alves, Paula C. G.; Faisca, LuisThis paper presents the metric-frequency calculator (MF Calculator), an online application to analyze similarity. The MF Calculator implements a metric-frequency similarity algorithm for the quantitative assessment of similarity in ill-structured data sets. It is widely applicable as it can be used with nominal, ordinal, or interval data when there is little prior control over the variables to be observed regarding number or content. The MF Calculator generates a proximity matrix in CSV, XML or DOC format that can be used as input to traditional statistical techniques such as hierarchical clustering, additive trees, or multidimensional scaling. The MF Calculator also displays a graphical representation of outputs using additive similarity trees. A simulated example illustrates the implementation of the MF calculator. An additional example with real data is presented, in order to illustrate the potential of combining the MF Calculator with cluster analysis. The MF Calculator is a user-friendly tool available free of charge. It can be accessed from http : //mfcalculator.celiasales.org/Calculator.aspx, and it can be used by non-experts from a wide range of social sciences.
- Some don't like it hot: microhabitat-dependent thermal and water stresses in a trailing edge populationPublication . Mota, Catarina F.; Engelen, Aschwin H.; Serrao, Ester A.; Pearson, Gareth A.The distributional limits of species in response to environmental change are usually studied at large temporal and/or geographical scales. However, organismal scale habitat variation can be overlooked when investigating large-scale averages of key factors such as temperature. We examine how microhabitat thermal conditions relate to physiological limits, which may contribute to recent range shifts in an intertidal alga. We defined the onset and maximum temperatures of the heat-shock response (HSR) for a southern edge population of Fucus vesiculosus, which has subsequently become extinct. The physiological threshold for resilience (assayed using chlorophyll fluorescence) coincided with declining HSR, determined from the temperature-dependent induction of seven heat-shock protein transcripts. In intertidal habitats, temperature affects physiology directly by controlling body temperature and indirectly through evaporative water loss. We investigated the relationship between the thermal environment and in situ molecular HSR at microhabitat scales. Over cm to m scales, four distinct microhabitats were defined in algal patches (canopy surface, patch edge, subcanopy, submerged channels), revealing distinct thermal and water stress environments during low-tide emersion. The in situ HSR agreed with estimated tissue temperatures in all but one microhabitat. Remarkably, in the most thermally extreme microhabitat (canopy surface), the HSR was essentially absent in desiccated tissue, providing a potential escape from the cellular metabolic costs of thermal stress. Meteorological records, microenvironmental thermal profiles and HSR data indicate that the maximum HSR is approached or exceeded in hydrated tissue during daytime low tides for much of the year. Furthermore, present-day summer seawater temperatures are sufficient to induce HSR during high-tide immersion, preventing recovery and resulting in continuous HSR during daytime low-tide cycles over the entire summer. HSR in the field matched microhabitat temperatures more closely than local seawater or atmospheric data, suggesting that the impacts of climatic change are best understood at the microhabitat scale, particularly in intertidal areas.
- A influência do estilo comunicacional do treinador de futebol sobre a expressão emocional do futebolistaPublication . Silva, José Eduardo Correia Quadros da; Vieira, Luís Sérgio; Gomes, Alexandra Isabel Cabral da SilvaOs comportamentos do treinador são determinantes para o bem-estar psicológico, aprendizagem e rendimento dos futebolistas. A compreensão sobre a relação entre comportamentos do treinador e o estado emocional dos futebolistas é por isso, um elemento chave para que a interação se torne satisfatória e produtiva para ambos. A partir de um desenho metodológico que conjugou métodos qualitativos e quantitativos e utilizando amostras de treinadores e futebolistas de diferentes níveis competitivos, recolhemos dados que permitiram perceber que no contexto de treino, o treinador profissional demonstra uma frequência comportamental mais reduzida que o treinador amador. O treinador profissional revelou uma tendência para o uso de comportamentos controladores e reativos, e o treinador amador para comportamentos mais técnicos, de reforço e espontâneos. A caracterização do padrão comportamental do treinador durante uma semana de treinos evidenciou um modo de atuação premeditado e rigído, dependente dos objetivos inerentes a cada tipo de treino e em concordância com os acontecimentos dos jogos. A valorização por parte dos treinadores, da dimensão psicológica-emocional como variável importante para o rendimento do futebolista, não se refletiu na capacidade para intervir a esse nível. O quadro emocional dos futebolistas mostrou uma sobreposição das emoções positivas sobre as emoções negativas e uma intensidade emocional mais intensa no jogo relativamente ao treino. Ficou demonstrada uma interferência de certas variáveis independentes sobre as emoções positivas, emoções negativas e habilidade física percebida. As emoções positivas e as emoções negativas não se relacionaram, e a habilidade física percebida e as emoções positivas mostraram um grau de dependência entre si. Na relação entre comportamentos do treinador e reação emocional do futebolista, parece existir uma causalidade entre comportamentos mais controladores e emoções negativas, e comportamentos promotores de autonomia e emoções positivas.
- Determinantes da estrutura de capital das PME do Distrito de FaroPublication . Delgado, Elisangela Vanusa dos Santos; Matias, FernandaO presente estudo pretende identificar os determinantes de estrutura de capital do Distrito de Faro e verificar a aderência dos resultados obtidos ao enquadramento teórico e empírico da estrutura de capital. Este estudo baseia-se em dados financeiros de uma amostra final composta por 520 PME do distrito de Faro do período compreendido entre 2008 e 2011. Foram ajustados modelos de regressão linear múltipla. Os resultados sugerem que o nível de endividamento de curto prazo e de médio e longo prazo das PME do distrito de Faro é afetado pela tangibilidade dos seus ativos, pelo seu nível de rendibilidade e pela sua idade. As empresas mais rendíveis e mais velhas tendem a apresentar menor nível de capital alheio e aquelas que dispõem de mais ativos tangíveis e são de maior dimensão tendem a exibir mais dívida de longo prazo nos seus balanços. Por sua vez, as oportunidades de crescimento tendem a ser financiadas com dívida de curto prazo. Estes resultados conferem suporte à teoria da pecking order.
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