Modeling Lewis catalyzed reactions in Metal Organic Frameworks

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Genetic and functional investigation of inherited neuropathies

With the discovery of next generation sequencing techniques the landscape of pathogenic gene discovery has shifted drastically over the last ten years. For the purpose of this thesis, focus was applied on finding genetic causes of inherited neuropathies, mainly Charcot-Marie-Tooth disease, by using both old and new genetic techniques and the accompanying functional investigations to prove the pathogenicity of these variants. Mutations in ATPase 6, the first mitochondrially encoded gene responsible for an isolated neuropathy, were found in five families with CMT2 by a traditional Sanger sequencing approach. The same approach was used to expand the phenotype associated with FIG4 mutations, known as CMT4J. Compound heterozygous mutations were found in a patient with a proximal and asymmetric weakness and rapid deterioration of strength in a single limb, mimicking CIDP. Several appropriate cohorts were screened for mutations in candidate genes with the traditional Sanger sequencing approach; however, no new pathogenic genes were found. In the case of the HINT1 gene, the originally stated frequency of 11% could not be replicated and a founder effect was suggested, underlying the importance of considering the ethnic background of a patient when screening for mutations in neuropathy-related genes. After the incorporation of exome sequencing, five CMT families were provided with a genetic diagnosis due to mutations in three novel genes and two previously known pathogenic genes. Many more families are currently under investigation and candidate genes have been found in some. Lastly, a series of divergent functional techniques was used to investigate the pathogenicity of IGHMBP2 mutations in 11 families with CMT2. IGHMBP2 mutations normally lead to SMARD1 and fibroblast and lymphoblast studies indicate that the IGHMBP2 protein levels are significantly higher in CMT2 than SMARD1, but lower than controls, suggesting that the clinical phenotype differences correlate to the IGHMBP2 protein levels

Plant and fungal identity determines pathogen protection of plant roots by arbuscular mycorrhizas

This is the peer reviewed version of the following article: BA Sikes, K Cottenie and JN Klironomos. (2009) Plant and fungal identity determines pathogen protection of plant roots by arbuscular mycorrhizas. Journal of Ecology 97: 1274-1280. http://dx.doi.org/10.1111/j.1365-2745.2009.01557.x, which has been published in final form at http://doi.org/10.1111/j.1365-2745.2009.01557.x This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.1. A major benefit of the mycorrhizal symbiosis is that it can protect plants from below-ground enemies, such as pathogens. Previous studies have indicated that plant identity (particularly plants that differ in root system architecture) or fungal identity (fungi from different families within the Glomeromycota) can determine the degree of protection from infection by pathogens. Here, we test the combined effects of plant and fungal identity to assess if there is a strong interaction between these two factors. 2. We paired one of two plants (Setaria glauca, a plant with a finely branched root system and Allium cepa, which has a simple root system) with one of six different fungal species from two families within the Glomeromycota. We assessed the degree to which plant identity, fungal identity and their interaction determined infection by Fusarium oxysporum, a common plant pathogen. 3. Our results show that the interaction between plant and fungal identity can be an important determinant of root infection by the pathogen. Infection by Fusarium was less severe in Allium (simple root system) or when Setaria (complex root system) was associated with a fungus from the family Glomeraceae. We also detected significant plant growth responses to the treatments; the fine-rooted Setaria benefited more from associating with a member of the family Glomeraceae, while Allium benefited more from associating with a member of the family Gigasporaceae. 4. Synthesis. This study supports previous claims that plants with complex root systems are more susceptible to infection by pathogens, and that the arbuscular mycorrhizal symbiosis can reduce infection in such plants – provided that the plant is colonized by a mycorrhizal fungus that can offer protection, such as the isolates of Glomus used here

Accessible health care for Roma: a gypsy's tale a qualitative in-depth study of access to health care for Roma in Ghent

Background: In general, vulnerable populations experience more problems in accessing health care. This also applies to the Roma-population. In the City of Ghent, Belgium, a relativly large group of Roma resides more or less permanently. The aim of this study is to explore the barriers this population encounters in their search for care. Methods: In this qualitative study using in-depth interviews the barriers to health care for the Roma in Ghent are explored. We interviewed 12 Roma and 13 professionals (volunteers, health care providers,.) who had regular contact with the Roma-population in Ghent. For both groups purposive sampling was used to achieve maximal variation regarding gender, age, nationality and legal status. Results: The Roma-population in Ghent encounters various barriers in their search for care. Financial constraints, not being able to reach health care and having problems to get through the complexity of the system are some of the most critical problems. Another important finding is the crucial role of trust between patient and care provider in the care-giving process. Conclusion: Roma share several barriers with other minority groups, such as: financial constraints, mobility issues and not knowing the language. However, more distinctive for this group is the lack of trust in care providers and health care in general. As a result, restraint and lack of communication form serious barriers for both patient and provider in their interaction. In order to ensure equitable access for Roma, more emphasis should be on establishing a relationship of mutual respect and understanding

Seasonal patterns in the fish and crustacean community of a turbid temperate estuary (Zeeschelde Estuary, Belgium)

Fish and crustaceans were sampled for 1 year in the upper reaches of a temperate estuary characterized by high turbidity and a tidal range of up to 5 m. Samples were taken in the cooling-water circuit of the Doel Nuclear Power station (Zeeschelde, Belgium). Between July 1994 and June 1995, 55 fish species, two shrimp species and four crab species were recorded. The fish community was composed of 36 marine species, 16 freshwater species and three diadromous species. Shrimps, Gobiidae and Clupeidae dominated the samples both in numbers and biomass. An exceptionally clear seasonal succession was observed in the species composition. It is argued that young fish and crustaceans use the highly turbid Zeeschelde Estuary as a refuge from predators

Dispersal-mediated trophic interactions can generate apparent patterns of dispersal limitation in aquatic metacommunities

Dispersal is a major organising force in metacommunities, which may facilitate compositional responses of local communities to environmental change and affect ecosystem function. Organism groups differ widely in their dispersal abilities and their communities are therefore expected to have different adaptive abilities. In mesocosms, we studied the simultaneous compositional response of three plankton communities (zoo-, phyto- and bacterioplankton) to a primary productivity gradient and evaluated how this response was mediated by dispersal intensity. Dispersal enhanced responses in all three planktonic groups, which also affected ecosystem functioning. Yet, variation partitioning analyses indicated that responses in phytoplankton and bacterial communities were not only controlled by dispersal directly but also indirectly through complex trophic interactions. Our results indicate that metacommunity patterns emerging from dispersal can cascade through the food web and generate patterns of apparent dispersal limitation in organisms at other trophic levels.

Modeling citronellal cyclization in Cu3BTC2 and UiO-66

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Distinguishing ecological from evolutionary approaches to transposable elements

Considerable variation exists not only in the kinds of transposable elements (TEs) occurring within the genomes of different species, but also in their abundance and distribution. Noting a similarity to the assortment of organisms among ecosystems, some researchers have called for an ecological approach to the study of transposon dynamics. However, there are several ways to adopt such an approach, and it is sometimes unclear what an ecological perspective will add to the existing co-evolutionary framework for explaining transposon-host interactions. This review aims to clarify the conceptual foundations of transposon ecology in order to evaluate its explanatory prospects. We begin by identifying three unanswered questions regarding the abundance and distribution of TEs that potentially call for an ecological explanation. We then offer an operational distinction between evolutionary and ecological approaches to these questions. By determining the amount of variance in transposon abundance and distribution that is explained by ecological and evolutionary factors, respectively, it is possible empirically to assess the prospects for each of these explanatory frameworks. To illustrate how this methodology applies to a concrete example, we analyzed whole-genome data for one set of distantly related mammals and another more closely related group of arthropods. Our expectation was that ecological factors are most informative for explaining differences among individual TE lineages, rather than TE families, and for explaining their distribution among closely related as opposed to distantly related host genomes. We found that, in these data sets, ecological factors do in fact explain most of the variation in TE abundance and distribution among TE lineages across less distantly related host organisms. Evolutionary factors were not significant at these levels. However, the explanatory roles of evolution and ecology become inverted at the level of TE families or among more distantly related genomes. Not only does this example demonstrate the utility of our distinction between ecological and evolutionary perspectives, it further suggests an appropriate explanatory domain for the burgeoning discipline of transposon ecology. The fact that ecological processes appear to be impacting TE lineages over relatively short time scales further raises the possibility that transposons might serve as useful model systems for testing more general hypotheses in ecology