Comparison of traditional field retting and Phlebia radiata Cel 26 retting of hemp fibres for fibre-reinforced composites

Classical field retting and controlled fungal retting of hemp using Phlebia radiata Cel 26 (a mutant with low cellulose degrading ability) were compared with pure pectinase reatment with regard to mechanical properties of the produced fibre/epoxy composites. For field retting a classification of the microbial evolution (by gene sequencing) and enzyme profiles were conducted. By phylogenetic frequency mapping, different types of fungi, many belonging to the Ascomycota phylum were found on the fibres during the first 2 weeks of field retting, and thereafter, different types of bacteria, notably Proteobacteria, also proliferated on the field retted fibres. Extracts from field retted fibres exhibited high glucanase activities, while extracts from P. radiata Cel 26 retted fibres showed high polygalacturonase and laccase activities. As a result, fungal retting gave a significantly higher glucan content in the fibres than field retting (77 vs. 67%) and caused a higher removal of pectin as indicated by lower galacturonan content of fibres (1.6%) after fibres were retted for 20 days with P. radiata Cel 26 compared to a galacturonan content of 3.6% for field retted fibres. Effective fibre stiffness increased slightly after retting with P. radiata Cel 26 from 65 to 67 GPa, while it decreased after field retting to 52 GPa. Effective fibre strength could not be determined similarly due to variations in fibre fracture strain and fibre-matrix adhesion. A maximum composite strength with 50 vol% fibres of 307 MPa was obtained using P. radiata Cel 26 compared to 248 MPa with field retting

Modulation of the MOP receptor (μ opioid receptor) by imidazo[1,2-a]imidazole-5,6-diones : in search of the elucidation of the mechanism of action

The μ-opioid receptors belong to the family of G protein-coupled receptors (GPCRs), and their activation triggers a cascade of intracellular relays with the final effect of analgesia. Classical agonists of this receptor, such as morphine, are the main targets in the treatment of both acute and chronic pain. However, the dangerous side effects, such as respiratory depression or addiction, significantly limit their widespread use. The allosteric centers of the receptors exhibit large structural diversity within particular types and even subtypes. Currently, a considerable interest is aroused by the modulation of μ-opioid receptors. The application of such a technique may result in a reduction in the dose or even discontinuation of classical opiates, thus eliminating the side effects typical of this class of drugs. Our aim is to obtain a series of 1-aryl-5,6(1H)dioxo-2,3-dihydroimidazo[1,2-a]imidazole derivatives and provide more information about their activity and selectivity on OP3 (MOP, human mu opioid receptor). The study was based on an observation that some carbonyl derivatives of 1-aryl-2-aminoimidazoline cooperate strongly with morphine or DAMGO in sub-threshold doses, producing similar results to those of normal active doses. To elucidate the possible mechanism of such enhancement, we performed a few in vitro functional tests (involving cAMP and β-arrestin recruitment) and a radioligand binding assay on CHO-K1 cells with the expression of the OP3 receptor. One of the compounds had no orthosteric affinity or intrinsic activity, but inhibited the efficiency of DAMGO. These results allow to conclude that this compound is a negative allosteric modulator (NAM) of the human μ-opioid receptor

Structural and biochemical characterization of a family 7 highly thermostable endoglucanase from the fungus Rasamsonia emersonii

Thermostable cellulases from glycoside hydrolase family 7 (GH7) are themain components of enzymatic mixtures for industrial saccharification oflignocellulose. Activity improvement of these enzymes via rational design isa promising strategy to alleviate the industrial costs, but it requires detailedstructural knowledge. While substantial biochemical and structural dataare available for GH7 cellobiohydrolases, endoglucanases are more elusiveand only few structures have been solved so far. Here, we report a newcrystal structure and biochemical characterization of a thermostableendoglucanase from the thermophilic ascomycete Rasamsonia emersonii,ReCel7B. The enzyme was compared with the homologous endoglucanasefrom the mesophilic model ascomycete Trichoderma reesei (TrCel7B),which unlike ReCel7B possesses an additional carbohydrate-binding module(CBM). With a temperature optimum of 80 °C, ReCel7B displayed anumber of differences in activity and ability to synergize with cellobiohydrolasescompared to TrCel7B. We improved both binding and kinetics ina chimeric variant of ReCel7B and a CBM, while we observe the oppositeeffect when the CBM was removed in TrCel7B. The crystal structure ofReCel7B was determined at 2.48 A resolution, with Rwork and Rfree factorsof 0.182 and 0.206, respectively. Structural analyses revealed that ReCel7Bhas increased rigidity in a number of peripheral loops compared toTrCel7B and fewer aromatics in the substrate-binding cleft. An increasednumber of glycosylations were identified in ReCel7B, and we propose a stabilizingmechanism for one of the glycans. Global structure–function interpretationsof ReCel7B highlight the differences in temperature stability,turnover, binding, and cellulose accessibility in GH7 endoglucanases

Testing Systematics of Gaia DR2 Parallaxes with Empirical Surface Brightness: Color Relations Applied to Eclipsing Binaries

International audienc

The Late-type Eclipsing Binaries in the Large Magellanic Cloud: Catalog of Fundamental Physical Parameters

International audienc