Modelling of methane partial oxidation in an asymmetric multilayered membrane reactor

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Natural and amyloid self-assembly of S100 proteins: structural basis of functional diversity

The S100 proteins are 10-12 kDa EF-hand proteins that act as central regulators in a multitude of cellular processes including cell survival, proliferation, differentiation and motility. Consequently, many S100 proteins are implicated and display marked changes in their expression levels in many types of cancer, neurodegenerative disorders, inflammatory and autoimmune diseases. The structure and function of S100 proteins are modulated by metal ions via Ca2+ binding through EF-hand motifs and binding of Zn2+ and Cu2+ at additional sites, usually at the homodimer interfaces. Ca2+ binding modulates S100 conformational opening and thus promotes and affects the interaction with p53, the receptor for advanced glycation endproducts and Toll-like receptor 4, among many others. Structural plasticity also occurs at the quaternary level, where several S100 proteins self-assemble into multiple oligomeric states, many being functionally relevant. Recently, we have found that the S100A8/A9 proteins are involved in amyloidogenic processes in corpora amylacea of prostate cancer patients, and undergo metal-mediated amyloid oligomerization and fibrillation in vitro. Here we review the unique chemical and structural properties of S100 proteins that underlie the conformational changes resulting in their oligomerization upon metal ion binding and ultimately in functional control. The possibility that S100 proteins have intrinsic amyloid-forming capacity is also addressed, as well as the hypothesis that amyloid self-assemblies may, under particular physiological conditions, affect the S100 functions within the cellular milieu

Flux Connections Between Gluconate Pathway, Glycolysis, and Pentose–Phosphate Pathway During Carbohydrate Metabolism in Bacillus megaterium QM B1551

Bacillus megaterium is a bacterium of great importance as a plant-beneficial bacterium in agricultural applications and in industrial bioproduction of proteins. Understanding intracellular processing of carbohydrates in this species is crucial to predicting natural carbon utilization as well as informing strategies in metabolic engineering. Here, we applied stable isotope-assisted metabolomics profiling and metabolic flux analysis to elucidate, at high resolution, the connections of the different catabolic routes for carbohydrate metabolism immediately following substrate uptake in B. megaterium QM B1551. We performed multiple 13C tracer experiments to obtain both kinetic and long-term 13C profiling of intracellular metabolites. In addition to the direct phosphorylation of glucose to glucose-6-phosphate (G6P) prior to oxidation to 6-phosphogluconate (6P-gluconate), the labeling data also captured glucose catabolism through the gluconate pathway involving glucose oxidation to gluconate followed by phosphorylation to 6P-gluconate. Our data further confirmed the absence of the Entner–Doudoroff pathway in B. megaterium and showed that subsequent catabolism of 6P-gluconate was instead through the oxidative pentose–phosphate (PP) pathway. Quantitative flux analysis of glucose-grown cells showed equal partition of consumed glucose from G6P to the Embden–Meyerhof–Parnas (EMP) pathway and from G6P to the PP pathway through 6P-gluconate. Growth on fructose alone or xylose alone was consistent with the ability of B. megaterium to use each substrate as a sole source of carbon. However, a detailed 13C mapping during simultaneous feeding of B. megaterium on glucose, fructose, and xylose indicated non-uniform intracellular investment of the different carbohydrate substrates. Flux of glucose-derived carbons dominated the gluconate pathway and the PP pathway, whereas carbon flux from both glucose and fructose populated the EMP pathway; there was no assimilatory flux of xylose-derived carbons. Collectively, our findings provide new quantitative insights on the contribution of the different catabolic routes involved in initiating carbohydrate catabolism in B. megaterium and related Bacillus species

Los papeles y funciones del enfermero de salud laboral en Brasil y en los Estados Unidos de America

Cross-sectional exploratory research developed to outline the roles and functions of occupational health nurses (OHNs) in Brazil and compare them with those in the United States. The sample consisted of 154 Brazilian occupational health nurses. First, the instrument Job Analysis Survey of Occupational Health Nursing Practice was translated into Portuguese, followed by data collection and data analysis, comparing the results of the proposed study in Brazil with the findings of a job delineation study conducted in the United States. It was found that most were women, white, between 41 and 50 years of age and working primarily at hospitals or medical centers as clinicians and managers/administrators. Besides, it was found that most Brazilian OHNs spend more time in managerial roles, followed by consultant and educator responsibilities while, in the United States, OHNs spend significantly more time in education/advisory roles.Investigación transversal realizada con el objetivo de definir los papeles y funciones de los enfermeros de salud laboral (ESLs) en Brasil y compararles con los de los Estados Unidos de América (EUA). La muestra fue compuesta por ciento cincuenta y cuatro enfermeros de salud laboral brasileños. Primero, fue realizada la traducción de lo instrumento Job Analysis Survey of Occupational Health Nursing Practice para el Portugués, seguido de la recolecta y análisis de los datos, comparándolos con los hallazgos de un estudio conducido en los EUA. Se encontró que la mayoría eran mujeres, blancas, entre 41 y 50 años e trabajan en hospitales y centros médicos como enfermeros clínicos y administradores. También se encontró que ESLs brasileños dedican más tiempo en funciones administrativas, seguidas de responsabilidades de consultoría y educador, mientras en los EUA los ESLs dedican significativamente más tiempo en funciones educativas y de asesoría.Estudo transversal desenvolvido com o objetivo de delinear as responsabilidades e funções das enfermeiras do trabalho no Brasil e compará-las às atribuições das enfermeiras de saúde ocupacional nos Estados Unidos. A amostra foi composta por 154 enfermeiras do trabalho. Inicialmente, foi realizada a tradução para a língua portuguesa do instrumento de coleta de dados Job Analysis Survey of Occupational Health Nursing Practice, seguido da coleta e análise dos resultados, comparando-os aos dados obtidos num estudo realizado nos EUA. Foi constatado que a maioria das enfermeiras eram mulheres, brancas, com faixa etária entre 41 e 50 anos e trabalhavam em hospitais e centros médicos como enfermeiras clínicas ou administradoras. Além disso, observou-se que as enfermeiras brasileiras despendem maior tempo em funções administrativas, atividades de consultoria e ações educativas, enquanto que as enfermeiras norte-americanas gastam um tempo significativamente maior desenvolvendo papéis educativos e de consultoria

S100A6 Amyloid Fibril Formation Is Calcium-modulated and Enhances Superoxide Dismutase-1 (SOD1) Aggregation

S100A6 is a small EF-hand calcium- and zinc-binding protein involved in the regulation of cell proliferation and cytoskeletal dynamics. It is overexpressed in neurodegenerative disorders and a proposed marker for Amyotrophic Lateral Sclerosis (ALS). Following recent reports of amyloid formation by S100 proteins, we investigated the aggregation properties of S100A6. Computational analysis using aggregation predictors Waltz and Zyggregator revealed increased propensity within S100A6 helices HI and HIV. Subsequent analysis of Thioflavin-T binding kinetics under acidic conditions elicited a very fast process with no lag phase and extensive formation of aggregates and stacked fibrils as observed by electron microscopy. Ca2+ exerted an inhibitory effect on the aggregation kinetics, which could be reverted upon chelation. An FT-IR investigation of the early conformational changes occurring under these conditions showed that Ca2+ promotes anti-parallel β-sheet conformations that repress fibrillation. At pH 7, Ca2+ rendered the fibril formation kinetics slower: time-resolved imaging showed that fibril formation is highly suppressed, with aggregates forming instead. In the absence of metals an extensive network of fibrils is formed. S100A6 oligomers, but not fibrils, were found to be cytotoxic, decreasing cell viability by up to 40%. This effect was not observed when the aggregates were formed in the presence of Ca2+. Interestingly, native S1006 seeds SOD1 aggregation, shortening its nucleation process. This suggests a cross-talk between these two proteins involved in ALS. Overall, these results put forward novel roles for S100 proteins, whose metal-modulated aggregation propensity may be a key aspect in their physiology and function

Cytotoxicity of albebetin oligomers depends on cross-β-sheet formation

AbstractPrefibrillar cytotoxicity was suggested as a common amyloid characteristic. We showed two types of albebetin prefibrillar oligomers are formed during incubation at pH 7.3. Initial round-shaped oligomers consist of 10–15 molecules determined by atomic force microscopy, do not bind thioflavin-T and do not affect viability of granular neurons and SH-SY5Y cells. They are converted into ca. 30–40-mers possessing cross-β-sheet and reducing viability of neuronal cells. Neither monomers nor fibrils possess cytotoxicity. We suggest that oligomeric size is important for stabilising cross-β-sheet core critical for cytotoxicity. As albebetin was used as a carrier-protein for drug delivery, examination of amyloidogenicity is required prior polypeptide biomedical applications

Remote Sensing of Chiral Signatures on Mars

We describe circular polarization as a remote sensing diagnostic of chiral signatures which may be applied to Mars. The remarkable phenomenon of homochirality provides a unique biosignature which can be amenable to remote sensing through circular polarization spectroscopy. The natural tendency of microbes to congregate in close knit communities would be beneficial for such a survey. Observations of selected areas of the Mars surface could reveal chiral signatures and hence explore the possibility of extant or preserved biological material. We describe a new instrumental technique that may enable observations of this form.Comment: 14 pages, 3 figures; to be published in Planetary and Space Scienc