The role of interleukin 1 receptor-associated kinase-4 (IRAK-4) kinase activity in IRAK-4-mediated signaling

Interleukin 1 receptor (IL-1R)-associated kinase-4 (IRAK-4) is required for various responses induced by IL-1R and Toll-like receptor signals. However, the molecular mechanism of IRAK-4 signaling and the role of its kinase activity have remained elusive. In this report, we demonstrate that IRAK-4 is recruited to the IL-1R complex upon IL-1 stimulation and is required for the recruitment of IRAK-1 and its subsequent activation/degradation. By reconstituting IRAK-4-deficient cells with wild type or kinase-inactive IRAK-4, we show that the kinase activity of IRAK-4 is required for the optimal transduction of IL-1-induced signals, including the activation of IRAK-1, NF-kappaB, and JNK, and the maximal induction of inflammatory cytokines. Interestingly, we also discover that the IRAK-4 kinase-inactive mutant is still capable of mediating some signals. These results suggest that IRAK-4 is an integral part of the IL-1R signaling cascade and is capable of transmitting signals both dependent on and independent of its kinase activity.     

Patterns of urine flow and electrolyte excretion in healthy elderly people.

Twenty four young (mean age 29.2 years, range 25-35) and 21 elderly (mean age 66.5, range 60-80) healthy subjects collected their urine in timed aliquots over 24 hours. The elderly subjects had been selected for their fitness by clinical and laboratory examinations and all lived independently at home. Sodium and potassium excretions were reduced in the elderly subjects compared with the young subjects, potassium excretion considerably so. This was despite similar 24 hour urine volumes and total solute excretion by both groups. The ratios of rates of excretion of water, electrolytes, and solutes during the night to the rates of excretion during the day were found to be higher in the elderly than the young subjects. Reduced day to night ratios of urinary excretion may be partly responsible for complaints of nocturia and sleep disturbance in elderly people.     

Studies in African Cyperaceae 28. New taxa and combinations in Abildgaardia Vahl IV

Eight new species of Abildgaardia subgen. Bulbostylis are described from tropical Africa, viz. Abildgaardia squarrosa, A. densiflora, A. acutespicata, A. angustespicata, A. lacunosa, A. microcephala, A. microrotundata and A. pluricephala .     

The bioreduction of a β-tetralone to its corresponding alcohol by the yeast Trichosporon capitatum MY1890 and bacterium Rhodococcus erythropolis MA7213 in a range of ionic liquids

The stereospecific reduction of 6-Br-β-tetralone to its corresponding alcohol (S)-6-Br-β-tetralol was carried out by the yeast Trichosporon capitatum MY1890 and by the bacterium Rhodococcus erythropolis MA7213, using a range of ionic liquids chosen for the diversity of their composition. The decrease in cell viability of both types of cell upon exposure to ionic liquids was found to be between that determined for cells residing purely in fermentation media, and cells residing in a two-phase mixture of media and organic solvent (toluene). For T. capitatum MY1890 bioconversions, the water miscible hydrophilic ionic liquid [Emim][TOS] gave a reaction profile comparable to that observed in the previously studied water-ethanol (10% v/v) system, in terms of overall rate of reaction (0.2 g (prod) L^-1 h^-1) and conversion (100%). Of the hydrophobic ionic liquids evaluated, [Oc₃MeN][BTA] gave the best conversion of 60%, but at a much reduced rate, suggesting solute mass transfer from the ionic liquid phase was rate limiting. For bioconversions carried out with R. erythropolis MA7213 employing 20% v/v [Emim][TOS] as a co-solvent, the conversion yield doubled, and a four-fold increase in initial rate was found compared to the standard ethanol co-solvent. This was attributed to improved cell viability and reduced aggregation of the R. erythropolis MA7213 compared to T. capitatum MY1890. Overall, this study demonstrates the feasibility of using ionic liquids for whole cell biocatalysis, however, no obvious link is apparent between the physico-chemical properties of ionic liquids, their influence on cell viability, and their efficacy as media for bioconversions.     

Similarities in Restriction Fragment Patterns of Mitochondrial DNAs of PhytophthoraSpecies Strongly Depend on the Restriction Enzyme Used Due to Heterogeneous Base Distribution and Sequence Conservation

Mitochondrial DNAs of six morphologically different Phytophthora species were digested with 15 restriction enzymes. The numbers of restriction fragments obtained differed considerably from those theoretically expected for random base distribution. Enzymes with relatively many G and C in their recognition sequences produced significantly larger numbers of fragments. Moreover, fragments generated by most of these enzymes were more often shared by two or more species than those from enzymes with more A and T in their recognition sequence. It is concluded that base distribution in mitochondrial DNA of Phytophthora is heterogeneous,AT-rich stretches occurring scattered over the mitochondrial genome and GC-rich regions present in conserved sequences, presumably genes. A practical consequence for taxonomic RFLP studies is that optimal enzymes can be selected, depending on the desired level of resolution.     

Directed evolution of biocatalytic processes

The benefits of applying biocatalysts to organic synthesis, such as their high chemo-, regio-, and enantio-specificity and selectivity, must be seriously considered, especially where chemical routes are unavailable, complex or prohibitively expensive. In cases where a potential biocatalytic route is not yet efficient enough to compete with chemical synthesis, directed evolution, and/or process engineering could be implemented for improvements. While directed evolution has demonstrated great potential to enhance enzyme properties, there will always be some aspects of biocatalytic processes that it does not address. Even where it can be successfully applied, the resources required for its implementation must currently be weighed against the feasibility of, and resources available for developing a chemical synthesis route. Here, we review the potential of combining directed evolution with process engineering, and recent developments to improve their implementation. Favourable targets for the directed evolution of new biocatalysts are the syntheses of highly complex molecules, especially where chemistry, metabolic engineering or recombineering provide a partial solution. We also review some of the recent advances in the application of these approaches alongside the directed evolution of biocatalysts.     

Mechanical Coupling between Endoderm Invagination and Axis Extension in Drosophila

How genetic programs generate cell-intrinsic forces to shape embryos is actively studied, but less so how tissue-scale physical forces impact morphogenesis. Here we address the role of the latter during axis extension, using Drosophila germband extension (GBE) as a model. We found previously that cells elongate in the anteroposterior (AP) axis in the extending germband, suggesting that an extrinsic tensile force contributed to body axis extension. Here we further characterized the AP cell elongation patterns during GBE, by tracking cells and quantifying their apical cell deformation over time. AP cell elongation forms a gradient culminating at the posterior of the embryo, consistent with an AP-oriented tensile force propagating from there. To identify the morphogenetic movements that could be the source of this extrinsic force, we mapped gastrulation movements temporally using light sheet microscopy to image whole Drosophila embryos. We found that both mesoderm and endoderm invaginations are synchronous with the onset of GBE. The AP cell elongation gradient remains when mesoderm invagination is blocked but is abolished in the absence of endoderm invagination. This suggested that endoderm invagination is the source of the tensile force. We next looked for evidence of this force in a simplified system without polarized cell intercalation, in acellular embryos. Using Particle Image Velocimetry, we identify posteriorwards Myosin II flows towards the presumptive posterior endoderm, which still undergoes apical constriction in acellular embryos as in wildtype. We probed this posterior region using laser ablation and showed that tension is increased in the AP orientation, compared to dorsoventral orientation or to either orientations more anteriorly in the embryo. We propose that apical constriction leading to endoderm invagination is the source of the extrinsic force contributing to germband extension. This highlights the importance of physical interactions between tissues during morphogenesis.     

Genome Sequence of Ralstonia sp. Strain PBA, a Bacterium Involved in the Biodegradation of 4-Aminobenzenesulfonate

Ralstonia sp. strain PBA was isolated from textile wastewater in a coculture with Hydrogenophaga sp. strain PBC. Here we present the assembly and annotation of its genome, which may provide further insights into the mechanism of its interaction with strain PBC during 4-aminobenzenesulfonate degradation.     

Small molecule modulators of aggregation in synthetic melanin polymerizations

There are numerous potential applications for melanin-binding compounds, and new methods are of interest to identify melanin-binding agents. A portion of the polymerization to eumelanin, the black to brown pigment in humans, is thought to be supramolecular aggregation of nanoparticles derived from dihydroxyindoles. Starting with chloroquine, a known eumelanin-binding compound, the ability of small molecules to influence aggregation in synthetic eumelanin polymerizations was investigated. Twenty-eight compounds were tested, including pharmaceuticals, dyes, aromatics, and amines. Compounds that either accelerate or delay the appearance of macroscopic particles in synthetic eumelanin polymerizations were uncovered.