Recursos de colección

Repositório do ISPA Instituto Superior de Psicologia Aplicada (11.029 recursos)

No Repositório do ISPA pode encontrar diversos tipos de documentos, em formato digital, resultantes da produção científica do ISPA designadamente: teses de doutoramento, teses de mestrado, artigos em publicações periódicas nacionais e internacionais, relatórios técnicos, artigos em actas de conferências nacionais e internacionais e capítulos de livros.

BIOL - Artigos em revistas internacionais

Mostrando recursos 1 - 20 de 31

  1. Accounting for animal density gradients using independent information in distance sampling surveys

    Marques, Tiago A.; Buckland, Stephen T.; Bispo, Regina; Howland, Brett
    Distance sampling is extensively used for estimating animal density or abundance. Conventional methods assume that location of line or point transects is random with respect to the animal population, yet transects are often placed along linear features such as roads, rivers or shorelines that do not randomly sample the study region, resulting in biased estimates of abundance. If it is possible to collect additional data that allow an animal density gradient with respect to the transects to be modelled, we show how to extend the conventional distance sampling likelihood to give asymptotically unbiased estimates of density for the covered area. We illustrate the proposed methods using data for...

  2. New allelic variants found in key rice salt-tolerance genes an association study

    Negrão, Sónia; Almadanim, M. Cecília; Pires, Inês S.; Abreu, Isabel A.; Maroco, João; Courtois, Brigitte; Gregorio, Glenn B.; McNally, Kenneth L.; Oliveira, Maria Margarida
    Salt stress is a complex physiological trait affecting plants by limiting growth and productivity. Rice, one of the most important food crops, is rated as salt-sensitive. High-throughput screening methods are required to exploit novel sources of genetic variation in rice and further improve salinity tolerance in breeding programmes. To search for genotypic differences related to salt stress, we genotyped 392 rice accessions by EcoTILLING. We targeted five key salt-related genes involved in mechanisms such as Na+/K+ ratio equilibrium, signalling cascade and stress protection, and we found 40 new allelic variants in coding sequences. By performing association analyses using both general and mixed linear...

  3. Drought stress response in Jatropha curcas: Growth and physiology

    Sapeta, Helena; Costa, J. Miguel; Lourenço, Tiago; Maroco, João; Van der Linde, Piet; Oliveira, Maria Margarida
    Tolerance to drought remains poorly described for Jatropha curcas accessions from different geographical and climatic origins. To address this issue we studied the response of two J. curcas accessions, one from Indonesia (wet tropical climate) and the other from Cape Verde islands (semi-arid climate). Potted seedlings (with 71 days) of both accessions were subjected to continuous well watered conditions (control) or to a drought stress period followed by re-watering. To mimic natural conditions in which drought stress develops gradually, stress was imposed progressively by reducing irrigation (10% reduction every 2 days, on a weight base), for a period of 28 days, until a...

  4. Modeling carcass removal time for avian mortality assessment in wind farms using survival analysis

    Bispo, Regina; Bernardino, Joana; Marques, Tiago A.; Pestana, Dinis
    In monitoring studies at wind farms, the estimation of bird and bat mortality caused by collision must take into account carcass removal by scavengers or decomposition. In this paper we propose the use of survival analysis techniques to model the time of carcass removal. The proposed method is applied to data collected in ten Portuguesewind farms.We present and compare results obtained from semiparametric and parametric models assuming four main competing lifetime distributions (exponential, Weibull, log-logistic and log-normal). Both homogeneous parametric models and accelerated failure time models were used. The fitted models enabled the estimation of the carcass persistence rates and the calculation of a scavenging correction factor for...

  5. Effects of partial root-zone drying irrigation on cluster microclimate and fruit composition of field-grown Castelão grapevines

    Santos, Tiago P.; Lopes, Carlos Manuel Antunes; Rodrigues, M. Lucília; Souza, Cláudia R. de; Silva, Jorge R.; Maroco, João; Pereira, João Santos; Chaves, Maria Manuela
    The partial root-zone drying (PRD) irrigation technique has been proposed for viticulture as a possible way to save water without compromising yield. Half of the plant root system is slowly dehydrating whereas the other half is irrigated; after about two weeks the opposite side of vines is irrigated. A PRD irrigation system (50 % of the crop evapotranspiration - ETc) was installed in a vineyard (Vitis vinifera L. cv. Castelão) in Southern Portugal and compared with two other irrigation systems, deficit irrigation, DI (50 % ETc) and full irrigation, FI (100 % ETc), as well as with non-irrigated vines (NI). Water was applied twice a week, from fruit set (mid-June) until...

  6. Grape berry metabolism in field-grown grapevines exposed to different irrigation strategies

    Souza, Cláudia R. de; Maroco, João; Santos, Tiago P.; Rodrigues, M. Lucília; Lopes, Carlos Manuel Antunes; Pereira, João Santos; Chaves, Maria Manuela
    The response of grape berry metabolism to vine water status was investigated in field grown grapevines (Vitis vinifera cv. Castelão) in southern Portugal. Water was supplied as: full irrigation (FI), to minimum water deficit corresponding to 100 % of crop evapotranspiration (Etc), partial rootzone drying (PRD) and deficit irrigation (DI), both corresponding to an irrigation amount of 50 % Etc, and a rainfed, i.e. no irrigation treatment (NI). In PRD, water was supplied to one side of the root system during each irrigation period, alternating sides every 15 d approximately. During the growing period, PRD and DI vines showed intermediate pre-dawn leaf water potential (Ψpd) values (around -0.4 MPa) by the end...

  7. Responses to water stress in two Eucalyptus globulus clones differing in drought tolerance

    Silva, Filipe Costa e; Shvaleva, Alla L.; Maroco, João; Chaves, Maria Manuela; Pereira, João Santos
    We evaluated drought resistance mechanisms in a drought-tolerant clone (CN5) and a drought-sensitive clone (ST51) of Eucalyptus globulus Labill. based on the responses to drought of some physiological, biophysical and morphological characteristics of container-grown plants, with particular emphasis on root growth and hydraulic properties. Water loss in excess of that supplied to the containers led to a general decrease in growth and significant reductions in leaf area ratio, specific leaf area and leaf-to-root area ratio. Root hydraulic conductance and leaf-specific hydraulic conductance decreased aswater stress became more severe. During the experiment, the drought-resistant CN5 clone maintained higher leaf water status (higher predawn and midday leaf water potentials), sustained a higher growth rate (new...

  8. Drought-induced photosynthetic inhibition and autumn recovery in two Mediterranean oak species (Quercus ilex and Quercus suber)

    Vaz, Margarida Maria de Almeida; Pereira, João Santos; Gazarini, Luís Carlos; David, Teresa Soares; David, Jorge Soares; Rodrigues, A.; Maroco, João; Chaves, Maria Manuela
    Responses of leaf water relations and photosynthesis to summer drought and autumn rewetting were studied in two evergreen Mediterranean oak species, Quercus ilex spp. rotundifolia and Quercus suber. The predawn leaf water potential (ΨlPD), stomatal conductance (gs) and photosynthetic rate (A) at ambient conditions were measured seasonally over a 3-year period. We also measured the photosynthetic response to light and to intercellular CO2 (A/PPFD and A/ Ci response curves) under water stress (summer) and after recovery due to autumn rainfall. Photosynthetic parameters, Vcmax, Jmax and triose phosphate utilization (TPU) rate, were estimated using the Farquhar model. RuBisCo activity, leaf chlorophyll, leaf nitrogen concentration and leaf carbohydrate concentration were also measured. All measurements were performed...

  9. Metabolic responses to water deficit in two Eucalyptus globulus clones with contrasting drought sensitivity

    Shvaleva, Alla L.; Silva, Filipe Costa e; Breia, Elsa; Jouve, Laurent; Hausman, Jean-François; Almeida, Maria Helena; Maroco, João; Rodrigues, M. Lucília; Pereira, João Santos; Chaves, Maria Margarida
    We compared the metabolic responses of leaves and roots of two Eucalyptus globulus Labill. clones differing in drought sensitivity to a slowly imposed water deficit. Responses measured included changes in concentrations of soluble and insoluble sugars, proline, total protein and several antioxidant enzymes. In addition to the general decrease in growth caused by water deficit, we observed a decrease in osmotic potential when drought stress became severe. In both clones, the decrease was greater in roots than in leaves, consistent with the observed increases in concentrations of soluble sugars and proline in these organs. In roots of both clones, glutathione reductase activity increased significantly in response towater deficit, suggesting that this enzyme...

  10. Evaluation of control transcripts in real-time RT-PCR expression analysis during maritime pine embryogenesis

    Gonçalves, Sónia; Cairney, John; Maroco, João; Oliveira, Maria Margarida; Miguel, Célia M.
    In order to determine the suitability of reference or housekeeping genes as internal controls in real-time reverse transcriptase PCR (RT-PCR) assays for quantification of target mRNAs, we studied the levels of expression of four candidate reference genes in maritime pine by real-time RT-PCR. The expression levels obtained for glyceraldehyde-3-phosphate-dehydrogenase, 18S ribosomal RNA, eukaryotic translation initiation factor eIF4AII and ubiquitin in nine stages of embryo development revealed that none of the genes tested proved to be suitable as an internal control. Copy number quantification of the four transcripts showed an average relative variation of seven fold. We propose that the combination of a precise method for RNA quantification, internal controls for monitoring RT reaction and PCR...

  11. Susceptibility of embryogenic and organogenic tissues of maritime pine (Pinus pinaster) to antibiotics used in Agrobacterium-mediated genetic transformation

    Tereso, Susana; Miguel, Célia M.; Maroco, João; Oliveira, Maria Margarida
    The effects of antibiotics commonly used in Agrobacterium-mediated transformation were studied on Pinus pinaster tissues. Embryogenic tissue growth from three embryogenic lines and adventitious bud induction from cotyledons from three open-pollinated seed families were analysed. Cefotaxizme, carbenicillin and timentin commonly used for Agrobacterium elimination, at concentrations of 200–400 mg l –1 did not inhibit the embryogenic tissue growth on filter paper nor as clumps. Adventitious bud induction and bud number were significantly reduced for one of the tested families when using 400 mg l–1 cefotaxime or timentin. The selection agent kanamycin significantly inhibited growth of embryogenic tissue on filter paper in all the embryogenic lines and concentrations tested (20–50 mg l–1). Kanamycin also inhibited growth of embryogenic clumps...

  12. Analysis of genetic stability at SSR loci during somatic embryogenesis in maritime pine (Pinus pinaster)

    Marum, Liliana; Rocheta, Margarida; Maroco, João; Oliveira, Maria Margarida; Miguel, Célia M.
    Somatic embryogenesis (SE) is a propagation tool of particular interest for accelerating the deployment of new high-performance planting stock in multivarietal forestry. However, genetic conformity in in vitro propagated plants should be assessed as early as possible, especially in long-living trees such as conifers. The main objective of this work was to study such conformity based on genetic stability at simple sequence repeat (SSR) loci during somatic embryogenesis in maritime pine (Pinus pinaster Ait.). Embryogenic cell lines (ECLs) subjected to tissue proliferation during 6, 14 or 22 months, as well as emblings regenerated from several ECLs, were analyzed. Genetic variation at seven SSR loci was detected in ECLs under proliferation conditions for all...

  13. Effects of long-term exposure to elevated CO2 and N fertilization on the development of photosynthetic capacity and biomass accumulation in Quercus suber L.

    Maroco, João; Breia, Elsa; Faria, T.; Pereira, João Santos; Chaves, Maria Manuela
    The effects of long-term (4 year) CO2 enrichment (70Pa versus 35 Pa) and nitrogen nutrition (8mM versus 1mM NO3–) on biomass accumulation and the development of photosynthetic capacity in leaves of cork oak (Quercus suber L., a Mediterranean evergreen tree) were studied. The evolution of photosynthetic parameters with leaf development was estimated by fitting the biochemical model of Farquhar et al. (Planta 149, 78–90, 1980) with modifications by Sharkey (Botanical Review 78, 71–75, 1985) to A–Ci response curves. CO2 enrichment had a small reduction effect on the development of the maximum CO2 fixation capacity by Rubisco (VCmax), and no effect over maximum electron...

  14. Utilization of O2 in the metabolic optimization of C4 photosynthesis

    Maroco, João; Ku, Maurice S. B.; Edwards, Gerald E.
    The combined effects of O2 on net rates of photosynthesis, photosystem II activity, steady-state pool size of key metabolites of photosynthetic metabolism in the C4 pathway, C3 pathway and C2 photorespiratory cycle and on growth were evaluated in the C4 species Amaranthus edulis and the C3 species Flaveria pringlei. Increasing O2 reduced net CO2 assimilation in F. pringlei due to an increased flux of C through the photorespiratory pathway. However, in A. edulis increasing O2 up to 5–10% stimulated photosynthesis. Analysis of the pool size of key metabolites in A. edulis suggests that while there is some O2 dependent photorespiration,...

  15. Oxygen sensitivity of C4 photosynthesis: Evidence from gas exchange and chlorophyll fluorescence analyses with different C4 subtypes

    Maroco, João; Ku, Maurice S. B.; Edwards, Gerald E.
    Because photosynthetic rates in C4 plants are the same at normal levels of O2 (c. 20 kPa) and at c. 2 kPa O2 (a conventional test for evaluating photorespiration in C3 plants) it has been thought that C4 photosynthesis is O2 insensitive. However, we have found a dual effect of O2 on the net rate of CO2 assimilation among species representing all three C4 subtypes from both monocots and dicots. The optimum O2 partial pressure for C4 photosynthesis at 30 °C, atmospheric CO2 level, and half full sunlight (1000 μmol quanta m-2 s-1) was about 5-10 kPa. Photosynthesis was inhibited...

  16. Shifts in plant respiration and carbon use efficiency at a large-scale drought experiment in the eastern Amazon

    Metcalfe, Daniel B.; Meir, Patrick; Aragão, Luiz E. O. C.; Lobo-do-Vale, Raquel; Galbraith, David; Fisher, Rosie; Chaves, Maria Manuela; Maroco, João; Costa, António L. da; Almeida, Samuel S.; Braga, Alan P.; Gonçalves, Paulo L.; Athaydes, João de; Costa, Mauricio da; Portela, T. T. B.; Oliveira, A. A. R. de; Malhi, Yadvinder; Williams, Mathew
    The effects of drought on the Amazon rainforest are potentially large but remain poorly understood. Here, carbon (C) cycling after 5 yr of a large-scale through-fall exclusion (TFE) experiment excluding about 50% of incident rainfall from an eastern Amazon rainforest was compared with a nearby control plot. • Principal C stocks and fluxes were intensively measured in 2005. Additional minor components were either quantified in later site measurements or derived from the available literature. • Total ecosystem respiration (Reco) and total plant C expenditure (PCE, the sum of net primary productivity (NPP) and autotrophic respiration (Rauto)), were elevated on the TFE plot relative to the control. The increase in...

  17. Impact of deficit irrigation on water use efficiency and carbon isotope composition (δ13C) of field-grown grapevines under Mediterranean climate

    Souza, Cláudia R. de; Maroco, João; Santos, Tiago P.; Rodrigues, M. Lucília; Lopes, Carlos Manuel Antunes; Pereira, João Santos; Chaves, Maria Manuela
    The objective of this study was to evaluate the effect of deficit irrigation on intrinsic water use efficiency (A/gs) and carbon isotope composition (δ 13C) of two grapevine cultivars (Moscatel and Castelão), growing in a commercial vineyard in SW Portugal. The study was done in two consecutive years (2001 and 2002). The treatments were full irrigation (FI), corresponding to 100% of crop evapotranspiration (ETc), rain-fed (no irrigation, NI), and two types of deficit irrigation (50% ETc): (i) by supplying the water either to one side of the root system or to the other, which is partial rootzone drying (PRD), or (ii) dividing the same amount of water by the two sides of...

  18. Partial rootzone drying: effects on growth and fruit quality of field-grown grapevines (Vitis vinifera)

    Santos, Tiago P.; Lopes, Carlos Manuel Antunes; Rodrigues, M. Lucília; Souza, Cláudia R. de; Maroco, João; Pereira, João Santos; Silva, Jorge R.; Chaves, Maria Manuela
    A study to assess the effects of the Partial Rootzone Drying (PRD) irrigation strategy in comparison to other irrigation systems was carried out in southern Portugal in two field-grown grapevines varieties, Moscatel and Castelão. We addressed the question of whether by regulating growth and plant water use, the PRD system would enable an equilibrated vegetative development, leading to a favourable capture of solar radiation for photoassimilate production and, at the same time to provide an optimum environment for fruit maturation. Three irrigation schemes were applied in addition to the non-irrigated (NI) vines: partial root drying (PRD), 50% of crop evapotranspiration...

  19. Partial rootzone drying: Regulation of stomatal aperture and carbon assimilation in field-grown grapevines (Vitis vinifera cv. Moscatel)

    Souza, Cláudia R. de; Maroco, João; Santos, Tiago P.; Rodrigues, M. Lucília; Lopes, Carlos Manuel Antunes; Pereira, João Santos; Chaves, Maria Manuela
    The effects of 'partial rootzone drying' (PRD) irrigation compared with other irrigation systems, namely non-irrigated (NI), full irrigation (FI) and deficit irrigation (DI), on stomatal conductance and carbon assimilation were evaluated in field-grown grapevines (Vitis vinifera L. cv. Moscatel). At the end of the growing season, pre-dawn leaf water potential was highest in FI (–0.18 ± 0.01 MPa; mean ± s.e.), intermediate in PRD (–0.30 ± 0.01 MPa) and DI (–0.36 ± 0.02 MPa), and lowest in NI vines (–0.64 ± 0.03 MPa). Stomatal conductance measured under controlled conditions of light and temperature was reduced in NI (ca 60%) and...

  20. Understanding plant responses to drought - from genes to the

    Chaves, Maria Manuela; Maroco, João; Pereira, João Santos
    In the last decade, our understanding of the processes underlying plant response to drought, at the molecular and whole-plant levels, has rapidly progressed. Here, we review that progress. We draw attention to the perception and signalling processes (chemical and hydraulic) of water deficits. Knowledge of these processes is essential for a holistic understanding of plant resistance to stress, which is needed to improve crop management and breeding techniques. Hundreds of genes that are induced under drought have been identified. A range of tools, from gene expression patterns to the use of transgenic plants, is being used to study the specific...

Aviso de cookies: Usamos cookies propias y de terceros para mejorar nuestros servicios, para análisis estadístico y para mostrarle publicidad. Si continua navegando consideramos que acepta su uso en los términos establecidos en la Política de cookies.