Time filter

Source Type

Rosa A.M.M.,IBB Institute for Biotechnology And Bioengineering | Louro A.F.,IBB Institute for Biotechnology And Bioengineering | Martins S.A.M.,IBB Institute for Biotechnology And Bioengineering | Inacio J.,Instituto Nacional Of Investigacao Agraria E Veterinaria | And 2 more authors.
Analytical Chemistry

Microfluidic paper-based analytical devices (μPADs) fabricated by wax-printing are suitable platforms for the development of simple and affordable molecular diagnostic assays for infectious diseases, especially in resource-limited settings. Paper devices can be modified for biological assays by adding appropriate reagents to the test areas. For this purpose, the use of affinity immobilization strategies can be a good solution for bioactive paper fabrication. This paper describes a methodology to capture labeled-DNA strands and hybrids on paper via the anchoring of antibodies with a fusion protein that combines a family 3 carbohydrate binding module (CBM) from Clostridium thermocellum, with high affinity to cellulose, and the ZZ fragment of the staphyloccocal protein A, which recognizes IgG antibodies via their Fc portion. Antibodies immobilized via CBM-ZZ were able to capture appropriately labeled (biotin, fluorescein) DNA strands and DNA hybrids. The ability of an antibody specific to biotin to discriminate complementary from noncomplementary, biotin-labeled targets was demonstrated in both spot and microchannel assays. Hybridization was detected by fluorescence emission of the fluorescein-labeled DNA probe. The efficiency of the capture of labeled-DNA by antibodies immobilized on paper via the CBM-ZZ construct was significantly higher when compared with a physical adsorption method where antibodies were simply spotted on paper without the intermediation of other molecules. The experimental proof of concept of wax-printed μPADs functionalized with CBM-ZZ for DNA detection at room temperature presented in this study constitutes an important step toward the development of easy to use and affordable molecular diagnostic tests. © 2014 American Chemical Society. Source

Correa M.J.,CONICET | Ferrero C.,CONICET | Puppo C.,CONICET | Puppo C.,National University of La Plata | Brites C.,Instituto Nacional Of Investigacao Agraria E Veterinaria
Food Hydrocolloids

Pasting and gelatinization behavior of rice gels from Japonica (Ariete, Euro), Indica (Gladio, Suriname) and waxy (Glutinous) varieties were analyzed. These varieties differ widely in amylose contents and differential scanning calorimetry (DSC) gelatinization temperatures. Besides, the effect of locust bean gum (LBG) addition and the impact of successive viscoanalyser multiple-heating-cooling and freezing-thawing cycles on the gels pasting viscosities (peak-ηpeak, trough-ηmin, final-ηfinal), viscoelasticity by oscillatory rheometry and syneresis were evaluated.Flours from different rice varieties exhibited distinct viscoanalyser curves and viscoelastic behaviors as well as different degree of syneresis. Euro and Ariete showed lower setback from peak (ηfinal-ηpeak) and syneresis, whereas Waxy had ηpeak superior to ηfinal (negative setback) and did not exhibit syneresis.The addition of LBG (0.5%, 1%, 2% w/w) significantly modified the pasting viscosities in single and multiple profiles, viscoelastic and syneresis properties of rice gels and the extent of the effect was dependent of rice varieties. In general, the addition of LBG caused an increase in peak, final and minimum viscosities but only rice gel from Ariete variety exhibited reduction of setback. Reduction of syneresis seems evident for 0.5% LBG addition on rice gels from Suriname and Ariete varieties, but 1% was needed for Gladio variety.Successive multiple-heating-cooling cycles led to a progressive decrease on viscosity after a second cycle for Japonica and Waxy varieties, in Indica varieties these peak viscosities were maintained or decreased in a lesser degree, syneresis was higher than in single cycles and is largely reduced in the presence of LBG.This study provides knowledge of different rheological behavior of rice varieties that would be relevant for utilization of rice gels on food applications. © 2012 Elsevier Ltd. Source

Resende A.,University of Lisbon | Catarino S.,Instituto Nacional Of Investigacao Agraria E Veterinaria | Geraldes V.,University of Lisbon | De Pinho M.,University of Lisbon
Industrial and Engineering Chemistry Research

This work aims to develop a process of ultrafiltration in diafiltration mode to concentrate the fraction of white wine polysaccharides of high molecular weight (arabinogalactan-proteins and mannoproteins) and to purify this fraction in terms of polyphenols, organic acids, and minerals removal. The membrane ETNA 10PP from AlfaLaval was characterized by an hydraulic permeability, Lp, of 105 L/(h·m2·bar) and a molecular weight cutoff, MWCO, of 17 kDa. A membrane surface area of 0.036 m2 was installed in a Lab-Unit M20 from Alva Laval. The permeation operating conditions, in total recirculation mode, were a temperature of 25 C, pressures ranging from 0.5 to 5 bar, and an average velocity of 0.94 m/s. The ultrafiltration in concentration mode was run up to concentration factors of 4.25, and when diafiltration was introduced the concentration factors went up to 6.3. The permeate fluxes were maintained at an average value of 58 L/(h·m2). © 2013 American Chemical Society. Source

Mateus C.,Instituto Nacional Of Investigacao Agraria E Veterinaria
Bulletin of Insectology

Spatial distribution and flight and predation activities of Coenosia attenuata Stein (Diptera Muscidae) adults were studied in greenhouse vegetable crops in the Oeste region, Portugal. During spring and summer, fewer flies were seen in the crops in the middle of the day in relation to the morning and afternoon periods. Males/ females ratio was 1:4, independently of the season. Flies were significantly more abundant in the sunny areas of crops in relation to the shadowed ones, and were found landed on cucumber and sweet pepper plants (especially on leaves), in opposition to tomato plants; in this crop, flies preferred the tutors and other greenhouse structures. Adults were also abundant next to the soil, on the plastic covering it and on irrigation pipes. Outside greenhouses, adults were landed everywhere. Most flies, when landed in the pending cucumber leaves, were next to their borders and oriented downwards. Some flights were trigged by insects flying inside a range of about 30 cm distance (here called "provoked flights"), and also by other movements made by the observer nearby. Insects landed on the same leaf as the predator, moving closely (but not flying), were not attacked. The majority of flights registered had no visible cause ("non-provoked flights"), some of them looking more like jumps. In 72% of provoked flights, flies returned to the leaf they had just left, and in almost half of them, they adopted both the location and the orientation they had before in the leaf. The percentage of preys captured was very low: many flights were probably the result of a territorial behaviour and not of a predation activity. Cannibalism was not detected in the field. Predation in the field occurred on whiteflies, small hymenopterans, leafhoppers, leafminers, sciarids, psocopterans, and also on thrips. Most preys were attacked in the cervix area. Source

Costa A.,New University of Lisbon | Costa A.,Instituto Nacional Of Investigacao Agraria E Veterinaria | Madeira M.,University of Lisbon | Plieninger T.,Copenhagen University
Applied Geography

The cork oak (Quercus suber L.) woodlands of the agroforestry landscapes of Southwestern Iberia are undergoing drastic change due to severe natural and anthropogenic disturbances. These may eventually result in woodland loss or deforestation, the final step of an ongoing process of woodland degradation. Monitoring changes in the spatial patterns of woodlands - especially fractional canopy cover of woodlands and/or their patchiness in the landscape mosaic - potentially enables forecasting of loss and responding to it at an early stage. We examine the degradation process in two cork oak woodlands, resulting from distinct disturbances, wildfire and oak mortality, aimed at evaluating the changes, trends and deviations of the spatial attributes of these woodlands as they move from an initial (less disturbed ecosystem) to a final state (more disturbed ecosystem). While undergoing disturbances, both woodlands exhibited similar trends of decreasing fractional canopy cover and decreasing number of larger patches. Patchiness rather than fractional canopy cover seems, however, to be potentially more useful as a signature of imminent oak woodlands deforestation, given that its contrast before and after disturbance was much higher. The structural dynamics of oak woodlands is a crucial but neglected issue that needs greater attention from policy forums working toward their conservation and restoration as well as from stakeholders and society as a whole. © 2014 Elsevier Ltd. Source

Discover hidden collaborations