Authors:H. Coutinho, J. Costa, V. Falcão-Silva, J. Siqueira-Júnior, and E. Lima
Some Staphylococcus species are frequently recognized as etiological agents of many animal and human opportunistic infections. This is the first report testing the antibiotic resistance-modifying activity of Eugenia jambolanum and Eugenia uniflora against methicillin-resistant Staphylococcus aureus — MRSA strain. In this study, the ethanol extracts of Eugenia jambolanum L., Eugenia uniflora L. and chlorpromazine were tested for their antimicrobial activity alone or in combination with aminoglycosides against an MRSA strain using microdilution method. Synergism between both extracts and all aminoglycosides assayed was demonstrated, except E. jambolanum and tobramycin. In the same form, synergism was observed between chlorpromazine and kanamicin, neomycin and tobramicin, indicating the involvement of an efflux system in the resistance to these aminoglycosides. It is therefore suggested that extracts from E. uniflora L. and E. jambolanum L. could be used as a source of plant derived natural products to modify antibiotic activity of aminoglycosides.
Authors:C. Galinha, M. Freitas, A. Pacheco, J. Coutinho, B. Maçãs, and A. Almeida
Selenium is an essential micronutrient for humans and animals, yet it is deficient in at least one billion people worldwide.
Plants and plant-derived products transfer the soil-uptaken selenium to humans; therefore, the cultivation of plants enriched
in selenium can be an effective way to improve the selenium status on humankind. This paper focuses on determining the ability
of bread wheat to accumulate selenium after supplementation. One of the methods for supplementing this element in plants is
foliar application with selenium solutions. These supplemented crop of wheat samples—bread wheat; Triticum aestivum L.—were used to determine if there is an increase of selenium content in cereal grains by comparing them with cereals cultivated
in 2009 and harvested in 2010 with no supplementation. The experiments were done using sodium selenate and sodium selenite
at three different selenium concentrations: 4, 20 and 100 g per hectare. Total Se is assessed by cyclic neutron activation
analysis (CNAA), through short irradiations on the fast pneumatic system (SIPRA) of the Portuguese Research Reactor (RPI-ITN).
The short-lived nuclide 77mSe, that features a half-lifetime of 17.5 s, was used to determine the Se content in SIPRA. The experiment was successful,
since the selenium concentration increased in the cropped grains and reached values up to 35 times the non-supplemented ones.
Authors:C. Galinha, M. Freitas, A. Pacheco, J. Coutinho, B. Maçãs, and A. Almeida
Selenium (Se) is an essential micronutrient for human health, but its deficiency may affect at least one billion people worldwide.
Plants and plant-derived products transfer the soil-uptaken Se to humans through the food chain, which is hardly enough when
soils have been always poor or already exhausted in bioavailable Se species. Other than agronomic approaches for enhancing
Se levels in cereals, such as soil and foliar supplements, seed enrichment may be viewed as an alternative Se-biofortification
technique. This study addresses the protocol for preparing Se-enriched wheat seeds, with the specific purpose of optimizing
the administration of Se to the seeds prior to sowing. The first step was to soak an amount of bread-wheat seeds in an active
Se solution, made with irradiated [Na2O4Se], and then monitoring 75Se in periodically-retrieved samples from that original amount. To avoid losing Se to soil (after sowing), and, especially,
to ensure that Se gets really absorbed into the seeds—and not just adsorbed onto them—the washing time of the seeds should
be optimized as well. This was carried out by washing Se-treated seeds several times, until no significant amount of the radiotracer
could be detected in the washing water. In what concerns the full optimization procedure, the overall results of the present
study point to an optimum time of 48 h for soaking and 24 h for washing.
Authors:C. Galinha, M. Freitas, A. Pacheco, J. Kameník, J. Kučera, H. Anawar, J. Coutinho, B. Maçãs, and A. Almeida
Selenium (Se) is an essential micronutrient for human health but it is deficient in at least 1 billion people around the globe.
Cereals are by far the most significant agricultural crops, not only on a gross tonnage basis, but also by what they represent
in terms of energy supply and dietary intake for human nutrition worldwide. Portugal is no exception to such pattern. The
Portuguese situation is difficult to assess though, due to scarce information and lack of consistent studies on the subject.
In these terms, the Se status of major cereals and their cultivation soils are dealt with herein. Two species of wheat–bread
and durum wheat–were sown at the end of November 2009, and then sampled in different growth stages. Rye was collected during
harvest season, and cultivation soils were analyzed as well. Se results were within the range of: 100–225 ng g−1 for soils; 3–55 ng g−1 for durum wheat; 6–80 ng g−1 for bread wheat; and 4–30 ng g−1 for rye. Accuracy of the RNAA procedure was proved by analysis of reference materials NIST-SRM 1515 and NIST-SRM 8433.
Authors:P. Almeida, L. Dinis, J. Coutinho, T. Pinto, R. Anjos, J. Ferreira-Cardoso, M. Pimentel-Pereira, F. Peixoto, and J. Gomes-Laranjo
Studies on gas exchange parameters were made at different temperatures and radiation levels in seven seedling populations of chestnut cultivar Judia from different parts of the Trás-os-Montes region, Portugal. Differences were found for the optimal temperature, which was 31°C for JD7, 31.5°C for JD5, 32°C for JD2, 32.5°C for JD4, 33°C for JD3 and JD6, and 33.5°C for JD1 and the ink-resistant hybrid BRO310. At these values, rates of photosynthesis ranged between 8.7 and 13.4 mmol CO
for JD6 and JD7, while the light conditions allowing 90% of maximal photosynthesis varied between 650 (JD6) and 1385 (JD4) μmol m
. JD1 showed the highest value of leaf water potential, −0.35 Mpa, and JD6, JD7 and BRO310 the lowest, −0.65 Mpa. JD1 also showed the second lowest stomatal conductance (93 mmol m
) and transpiration rate (3.0 mmol H
).In relation to the photosynthetic pigments, JD3 and JD7 were the most sun-loving clones having the highest values for the Chl
ratio (3.2 and 3.3, respectively), while JD1 had the lowest Chl/Car ratio (3.9). The overall results suggested that the JD3, JD1 and JD5 populations might increase heat stress tolerance in Judia.
Authors:Ana Carla S. L. S. Coutinho, Solange A. Quintella, A. S. Araujo, Joana M. F. Barros, Anne M. G. Pedrosa, V. J. Fernandes Jr., and M. J. B. Souza
Nanoporous silica with narrow pore size distribution has attracted increasing attention as a novel material for separations and reactions involving large molecules. SBA-15 has been synthesized in an acidic medium using a triblock copolymer as template. In this work, the SBA-15 was synthesized by the hydrothermal treatment at 373 K for 48 h, of a gel with the following overall molar composition: 1.0TEOS:0.017P123:5.7HCl:193H2O, where TEOS is tetraethyl orthosilicate and P123 is poly(ethylene oxide, propylene oxide and 1,4-dioxane). The obtained material was characterized by thermogravimetry, X-ray diffraction, infrared spectroscopy and BET surface area. A kinetic study using the model free model was accomplished in the stage of decomposition of the template (P123). The obtained value of the apparent activation energy was ca. 131 kJ mol−1.
Authors:Ana P. Rodrigues, A. R. M. Holanda, G. P. Lustosa, S. M. B. Nóbrega, Willma J. Santana, Luciana B. S. Souza, and H. D. M. Coutinho
Serratia marcescens, a Gram-negative bacillus that belongs to the family Enterobacteriaceae, is a human opportunistic pathogen bacterium that causes many diseases, such as urinary tract infections, respiratory tract infections, bacteremia, conjunctivitis, endocarditis, meningitis and wound infections. Many plasmides that confers multi-drug resistance were discovered, such as virulence factors, like cytotoxins that damage epithelial cells. The main topic of this paper presents a review about the molecular traits evolved in the pathogenic processes mediated by Serratia and its mechanism of resistance to drugs.