BIOCHEMICAL DIFFERENTIATION AMONG S. aureus, S. Intermedius AND S. hyicus ISOLATED FROM BOVINES WITH SUBCLINICAL MASTITIS

Staphylococcus aureus é, entre as espécies de estafilococos, a mais relacionada a infecções em animais e humanos, bem como a doenças de origem alimentar. Entretanto, S. intermedius e S. hyicus, duas espécies com características morfológicas muito similares a S. aureus, também podem causar doenças, bem como produzir enterotoxinas em alimentos, tornando importante a diferenciação entre essas três espécies de estafilococos. O objetivo deste trabalho foi avaliar a eficiência de oito técnicas bioquímicas com relação à sua capacidade para distinguir entre S. aureus, S. intermedius e S. hyicus. Para isso, 65 cepas, previamente identificadas em nível de espécie através de técnicas moleculares, foram submetidas aos testes de produção de pigmentos carotenóides, atividade hemolítica em ágar sangue, produção de b- galactosidase, produção de acetoína, atividade lipolítica em polisorbato, fermentação aeróbica da maltose, fermentação anaeróbica do manitol e crescimento em ágar Baird-Paker e ágar P suplementados com acriflavina. Verificou-se que os testes de sensibilidade a acriflavina e de produção de b- galactosidase apresentaram bom poder discriminatório, demonstrando serem os melhores testes bioquímicos para a diferenciação entre essas três espécies de estafilococos. Abstract Among staphylococcus species, Staphylococcus aureus is the one mostly related to animal and human infections, as well as food diseases. However, S. intermedius and S. hyicus, two species with very similar morphological characteristics to S. aureus, can also cause diseases as well as produce enterotoxins in food, what makes important the differentiation of these three species. The aim of this work was to study the efficiency of eight biochemical techniques regarding their capacity to distinguish among S. aureus, S. intermedius and S. hyicus. For that purpose, sixty five strains, previously identified at species level through molecular techniques, were submitted to the tests of carotenoid pigments production, hemolytic activity in blood agar, b- galactosidase production, acetoin production, lipolytic activity in polysorbate, maltose aerobic fermentation, manitol anaerobic fermentation and growth in Baird-Parker and P agar supplemented with acriflavine. It was verified that tests of sensitivity to acriflavine and b-galactosidase production display good distinguishing properties, constituting as a whole, the best biochemical tests for the identification of these three staphylococcus species

Radion Stabilization in Compact Hyperbolic Extra Dimensions

We consider radion stabilization in hyperbolic brane-world scenarios. We demonstrate that in the context of Einstein gravity, matter fields which stabilize the extra dimensions must violate the null energy condition. This result is shown to hold even allowing for FRW-like expansion on the brane. In particular, we explicitly demonstrate how one putative source of stabilizing matter fails to work, and how others violate the above condition. We speculate on a number of ways in which we may bypass this result, including the effect of Casimir energy in these spaces. A brief discussion of supersymmetry in these backgrounds is also given.Comment: 16 pages, 1 figur

Stellar evolution and modelling stars

In this chapter I give an overall description of the structure and evolution of stars of different masses, and review the main ingredients included in state-of-the-art calculations aiming at reproducing observational features. I give particular emphasis to processes where large uncertainties still exist as they have strong impact on stellar properties derived from large compilations of tracks and isochrones, and are therefore of fundamental importance in many fields of astrophysics.Comment: Lecture presented at the IVth Azores International Advanced School in Space Sciences on "Asteroseismology and Exoplanets: Listening to the Stars and Searching for New Worlds" (arXiv:1709.00645), which took place in Horta, Azores Islands, Portugal in July 201

Suboptimal acclimation of photosynthesis to light in wheat canopies

Photosynthetic acclimation (photoacclimation) is the process whereby leaves alter their morphology and/or biochemistry to optimise photosynthetic efficiency and productivity according to long-term changes in the light environment. Three-dimensional (3D) architecture of plant canopies impose complex light dynamics, but the drivers for photoacclimation in such fluctuating environments are poorly understood. A technique for high-resolution 3D reconstruction was combined with ray tracing to simulate a daily time course of radiation profiles for architecturally contrasting field- grown wheat canopies. An empirical model of photoacclimation was adapted to predict the optimal distribution of photosynthesis according to the fluctuating light patterns throughout the canopies. Whilst the photoacclimation model output showed good correlation with field-measured gas exchange data at the top of the canopy, it predicted a lower optimal light saturated rate of photosynthesis (Pmax) at the base. Leaf Rubisco and protein content were consistent with the measured Pmax. We conclude that although the photosynthetic capacity of leaves is high enough to exploit brief periods of high light within the canopy (particularly towards the base), the frequency and duration of such sunflecks are too small to make acclimation a viable strategy in terms of carbon gain. This suboptimal acclimation renders a large portion of residual photosynthetic capacity unused, and reduces photosynthetic nitrogen use efficiency (PNUE) at thecanopy level with further implications for photosynthetic productivity. It is argued that(a) this represents an untapped source of photosynthetic potential and (b) canopy nitrogen could be lowered with no detriment to carbon gain or grain protein content

Field-induced single-ion magnetic behaviour in a highly luminescent Er3+ complex

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