57 resultados para Trindade and Martin Vaz Islands
Resumo:
Although genome sequencing of microbial pathogens has shed light on the evolution of virulence, the drivers of the gain and loss of genes and of pathogenicity islands (gene clusters), which contribute to the emergence of new disease outbreaks, are unclear. Recent experiments with the bean pathogen Pseudomonas syringae pv. phaseolicola illustrate how exposure to resistance mechanisms acts as the driving force for genome reorganization. Here we argue that the antimicrobial conditions generated by host defences can accelerate the generation of genome rearrangements that provide selective advantages to the invading microbe. Similar exposure to environmental stress outside the host could also drive the horizontal gene transfer that has led to the evolution of pathogenicity towards both animals and plants.
Resumo:
Motivation: Hydrogen bonds are one of the most important inter-atomic interactions in biology. Previous experimental, theoretical and bioinformatics analyses have shown that the hydrogen bonding potential of amino acids is generally satisfied and that buried unsatisfied hydrogen-bond-capable residues are destabilizing. When studying mutant proteins, or introducing mutations to residues involved in hydrogen bonding, one needs to know whether a hydrogen bond can be maintained. Our aim, therefore, was to develop a rapid method to evaluate whether a sidechain can form a hydrogen-bond. Results: A novel knowledge-based approach was developed in which the conformations accessible to the residues involved are taken into account. Residues involved in hydrogen bonds in a set of high resolution crystal structures were analyzed and this analysis is then applied to a given protein. The program was applied to assess mutations in the tumour-suppressor protein, p53. This raised the number of distinct mutations identified as disrupting sidechain-sidechain hydrogen bonding from 181 in our previous analysis to 202 in this analysis.
Resumo:
The formation and composition of secondary organic aerosol (SOA) from the photooxidation of benzene, p-xylene, and 1,3,5-trimethylbenzene has been simulated using the Master Chemical Mechanism version 3.1 (MCM v3.1) coupled to a representation of the transfer of organic material from the gas to particle phase. The combined mechanism was tested against data obtained from a series of experiments conducted at the European Photoreactor (EUPHORE) outdoor smog chamber in Valencia, Spain. Simulated aerosol mass concentrations compared reasonably well with the measured SOA data only after absorptive partitioning coefficients were increased by a factor of between 5 and 30. The requirement of such scaling was interpreted in terms of the occurrence of unaccounted-for association reactions in the condensed organic phase leading to the production of relatively more nonvolatile species. Comparisons were made between the relative aerosol forming efficiencies of benzene, toluene, p-xylene, and 1,3,5-trimethylbenzene, and differences in the OH-initiated degradation mechanisms of these aromatic hydrocarbons. A strong, nonlinear relationship was observed between measured (reference) yields of SOA and (proportional) yields of unsaturated dicarbonyl aldehyde species resulting from ring-fragmenting pathways. This observation, and the results of the simulations, is strongly suggestive of the involvement of reactive aldehyde species in association reactions occurring in the aerosol phase, thus promoting SOA formation and growth. The effect of NO, concentrations on SOA formation efficiencies (and formation mechanisms) is discussed.
Resumo:
Europe's commitment to language learning has resulted in higher percentages of pupils studying foreign languages during primary education. In England, recent policy decisions to expand foreign language learning at primary level by 2010 create major implications for transition to secondary. This paper presents findings on transition issues from case studies of a DfES-funded project evaluating 19 local authority Pathfinders piloting the introduction of foreign language learning at primary level. Research on transition in other countries sets these findings in context. Finally, it investigates the challenges England faces for transition in the light of this expansion and discusses future implications.
Resumo:
Background: Parkinson's disease is a common neurodegenerative disorder that affects an increasing number of older people every year. Dysphagia is not only a common feature, but one that results in poor nutrition and an increased risk of bronchopneumonia. Previous work has suggested that the oral flora is altered in patients with oral pathology. Methods: Fifty patients were assessed to quantify the incidence of oral Gram-negative bacteria. Results: Sixteen of the patients with Parkinson's disease were found to have six different Gram-negative bacilli in their oral cavities. The 20 different Gram-negative bacteria present were Escherichia coli (n=7), Klebsiella spp. (n=3), Kluyvera spp. (n=3), Serratia spp. (n=3), Proteus spp. (n=2) and Enterobacter spp. (n=2). We found that the oral cavity of 16 (32%) of the patients with Parkinson's disease was abnormally colonised with Gram-negative bacteria and that Gram-negative bacteria were more likely to occur in those patients in whom oromuscular dysfunction was present (88% vs. 21%; p<0.05). Conclusion: Further work is required to determine the association between oral flora and the pathogenic organisms found in aspiration pneumonia as well as work on innovative treatments to reduce oral Gram-negative bacteria in those patients at particular risk of aspiration pneumonia.
Resumo:
We investigated the short-term (7 days) and long-term (60 days) metabolic effect of high fat diet induced obesity (DIO) and weight gain in isogenic C57BL/6 mice and examined the specific metabolic differentiation between mice that were either strong-responders (SR), or non-responders (NR) to weight gain. Mice (n = 80) were fed a standard chow diet for 7 days prior to randomization into a high-fat (HF) (n = 56) or a low-fat (LF) (n = 24) diet group. The (1)H NMR urinary metabolic profiles of LF and HF mice were recorded 7 and 60 days after the diet switch. On the basis of the body weight gain (BWG) distribution of HF group, we identified NR mice (n = 10) and SR mice (n = 14) to DIO. Compared with LF, HF feeding increased urinary excretion of glycine conjugates of β-oxidation intermediate (hexanoylglycine), branched chain amino acid (BCAA) catabolism intermediates (isovalerylglycine, α-keto-β-methylvalerate and α-ketoisovalerate) and end-products of nicotinamide adenine dinucleotide (NAD) metabolism (N1-methyl-2-pyridone-5-carboxamide, N1-methyl-4-pyridone-3-carboxamide) suggesting up-regulation of mitochondrial oxidative pathways. In the HF group, NR mice excreted relatively more hexanoylglycine, isovalerylglycine, and fewer tricarboxylic acid (TCA) cycle intermediate (succinate) in comparison to SR mice. Thus, subtle regulation of ketogenic pathways in DIO may alleviate the saturation of the TCA cycle and mitochondrial oxidative metabolism.
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A novel version of the classical surface pressure tendency equation (PTE) is applied to ERA-Interim reanalysis data to quantitatively assess the contribution of diabatic processes to the deepening of extratropical cyclones relative to effects of temperature advection and vertical motions. The five cyclone cases selected, Lothar and Martin in December 1999, Kyrill in January 2007, Klaus in January 2009, and Xynthia in February 2010, all showed explosive deepening and brought considerable damage to parts of Europe. For Xynthia, Klaus and Lothar diabatic processes contribute more to the observed surface pressure fall than horizontal temperature advection during their respective explosive deepening phases, while Kyrill and Martin appear to be more baroclinically driven storms. The powerful new diagnostic tool presented here can easily be applied to large numbers of cyclones and will help to better understand the role of diabatic processes in future changes in extratropical storminess.
Resumo:
Recognizing the importance of tourism's experiential aspects, this research examines how hedonic and utilitarian values relate to tourist's overall shopping experience satisfaction and destination loyalty. Study findings suggest both hedonic and utilitarian shopping values are strongly linked to overall shopping satisfaction. Overall shopping satisfaction fully mediates utilitarian shopping value's effect on destination repatronage intention (DRI), destination word-of-mouth (DWoM), and partially mediates hedonic shopping value's (HSV) effect on DRI and DWoM. Study results advance consumer behavior theory and offer managerial implications for retailers operating in a rapidly maturing tourism destination in Turkey's Mediterranean region.
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In this chapter, I will focus on the female participation in what became known as ‘The Retomada do Cinema Brasileiro’, or the Brazilian Film Revival, by thinking beyond differences of gender, class, age and ethnicity. I will first re-consider the Retomada phenomenon against the backdrop of its historical time, so as to evaluate whether the production boom of the period translated into a creative peak, and, if so, how much of this carried onto the present day. I will then look at the female participation in this phenomenon not just in terms of numerical growth of women film directors, admittedly impressive, but only partially reflective of the drastic changes in the modes of production and address effected by the neoliberal policies introduced in the country in the mid 1990s. I will argue that the most decisive contribution brought about by the rise of women in Brazilian filmmaking has been the spread of team work and shared authorship, as opposed to a mere aspiration to the auteur pantheon, as determined by a notoriously male-oriented tradition. Granted, films focusing on female victimisation were rife during the Retomada period and persist to this day, and they have been, and continue to be, invaluable for the understanding of women’s struggles in the country. However, rather than resorting to feminist readings of representational strategies in these films, I will draw attention to other, presentational aesthetic experiments, open to the documentary contingent and the unpredictable real, which, I argue, suspend the pedagogical character of representational narratives. In order to demonstrate that new theoretical tools are needed to understand the gender powers at play in contemporary world cinema, I will, to conclude, analyse an excerpt of the film, Delicate Crime (Crime delicado, Beto Brant, 2006), where team work comes out as a particularly effective female, and feminist, procedure.