Combination of 13 C/ 113 Cd NMR, potentiometry, and voltammetry in characterizing the interactions between Cd and two models of the main components of soil organic matter

International audienceThis work allowed the characterization of the Cd-binding sites of two compounds taken as models for exudates, the main components of soil organic matter (SOM). The studied compounds were exopolysaccharides (EPS), specifically exudates of roots (polygalacturonic acid) and of soil bacteria (Phytagel). Potentiometric acid– base titrations were performed and fitting of the obtained results indicated the presence of two main classes of acidic sites, defined by their pK a values, for both EPS but of a different nature when comparing the two compounds. The two studied exopolysaccharides presented different acidic/ basic site ratios: 0.15 for Phytagel and 0.76 for polyga-lacturonic acid. Spectroscopic techniques (13 C/ 113 Cd NMR, FTIR) distinguished different Cd surroundings for each of the studied EPS, which is in agreement with the titration results. Furthermore, these analyses indicated the presence of –COOH and –OH groups in various proportions for each exopolysaccharide, which should be linked to their reactiv-ity towards cadmium. Cadmium titrations (voltammetric measurements) also differentiated different binding sites for each compound and allowed the determination of the strength of the Cd-binding site of the EPS. Fitting of the results of such voltammetric measurements was performed using PROSECE (Programme d'Optimisation et de Speci-ation Chimique dans l'Environnement), a software coupling chemical speciation calculation and binding parameter optimization. The fitting, taking into account the Cd 2+ /H

The V0-ATPase mediates apical secretion of exosomes containing Hedgehog-related proteins in Caenorhabditis elegans

Polarized intracellular trafficking in epithelia is critical in development, immunity, and physiology to deliver morphogens, defensins, or ion pumps to the appropriate membrane domain. The mechanisms that control apical trafficking remain poorly defined. Using Caenorhabditis elegans, we characterize a novel apical secretion pathway involving multivesicularbodies and the release of exosomes at the apical plasma membrane. By means of two different genetic approaches, we show that the membrane-bound V0 sector of the vacuolar H+-ATPase (V-ATPase) acts in this pathway, independent of its contribution to the V-ATPase proton pump activity. Specifically, we identified mutations in the V0 “a” subunit VHA-5 that affect either the V0-specific function or the V0+V1 function of the V-ATPase. These mutations allowed us to establish that the V0 sector mediates secretion of Hedgehog-related proteins. Our data raise the possibility that the V0 sector mediates exosome and morphogen release in mammals

2D Numerical Modeling of the Ultrasonic Wave Propagation in Concrete: a Parameterization Study in the Multiple Scattering Medium

Linear Ultrasonic Techniques play a major role in Non-Destructive Evaluation (NDE) for civil engineering structures in concrete since they can meet operational requirements. Interpretation of ultrasonic measurements could be improved by a better understanding of ultrasonic wave propagation in a multiple scattering medium. In this work, we aim to get a 2D numerical model of ultrasonic wave propagating in concrete integrating the multiple scattering phenomena. This model will be used to realize some parametric studies of different parameters (wave frequency, aggregate size…) in order to interpreter the measurements or to optimize the measurement parameters before an auscultation. To get our numerical model, we use a step-by-step methodology based on the comparison between numerical results from SPECFEM software and experimental data and analytical approach available in the literature. First, this methodology was applied to one scattering element (cylinder) in a homogenous medium. Then, we model a multiple scattering media composed of a set of cylinders of random sizes and positions. Finally, we used numerical descriptions adapted to the case of industrial concrete that takes into account aggregates with a special size distribution in a mortar matrix

Zn speciation in the organic horizon of a contaminated soil by micro X-ray fluorescence, micro and powder EXAFS spectroscopy and isotopic dilution.

Soils which have been acutely contaminated by heavy-metals show distinct characteristics, such as colonization by metal-tolerant plant species and topsoil enrichment in weakly degraded plant debris because biodegradation processes are strongly inhibited by contamination. Such an organic topsoil, located downwind of an active zinc smelter and extremely rich in Zn (~ 2%, dry weight), was investigated by X-ray diffraction (XRD), synchrotron-based X-ray microfluorescence (μSXRF), and powder and micro extended X-ray absorption fine structure (EXAFS) spectroscopy for Zn speciation, and by isotopic dilution for Zn lability. EXAFS spectra recorded on size fractions and on selected spots of thin sections were analyzed by principal component analysis (PCA) and linear combination fits (LCFs). Although Zn primary minerals (franklinite, sphalerite and willemite) are still present (~ 15% of total Zn) in the bulk soil, Zn was found to be predominantly speciated as Zn-organic matter complexes (~ 45%), outer-sphere complexes (~ 20%), Zn-sorbed phosphate (~ 10%) and Znsorbed iron oxyhydroxides (~ 10%). The bioaccumulated Zn fraction is likely complexed to soil organic matter after the plants' death. The proportion of labile Zn ranges from 54 to 92%, depending on the soil fraction, in agreement with the high proportion of organically-bound Zn. Despite its marked lability, Zn seems to be retained in the topsoil thanks to the huge content of organic matter, which confers to this horizon a high sorption capacity. The speciation of Zn in this organic soil horizon is compared with that found in other types of soils

Параметрична логістична модель планування роботи різних видів транспорту

Запропонована логістична модель планування роботи різних видів транспорту вантажної станції за умов ефективного використання вантажно-розвантажувальних механізмів, вантажних фронтів та складської обробки вантажів.Предложенная логистическая модель планирования работы различных видов транспорта грузовой станции в условиях эффективного использования погрузочно-разгрузочных механизмов, грузовых фронтов и складской обработки грузов.The proposed model of logistic planning of transport modes cargo station for the effective use of material handling equipment, commercial fronts and warehouse handling

The WHHERE coactivator complex is required for retinoic acid-dependent regulation of embryonic symmetry

Bilateral symmetry is a striking feature of the vertebrate body plan organization. Vertebral precursors, called somites, provide one of the best illustrations of embryonic symmetry. Maintenance of somitogenesis symmetry requires retinoic acid (RA) and its coactivator Rere/Atrophin2. Here, using a proteomic approach we identify a protein complex, containing Wdr5, Hdac1, Hdac2 and Rere (named WHHERE), which regulates RA signaling and controls embryonic symmetry. We demonstrate that Wdr5, Hdac1, and Hdac2 are required for RA signaling in vitro and in vivo. Mouse mutants for Wdr5 and Hdac1 exhibit asymmetrical somite formation characteristic of RA-deficiency. We also identify the Rere-binding histone methyltransferase Ehmt2/G9a, as a RA coactivator controlling somite symmetry. Upon RA treatment, WHHERE and Ehmt2 become enriched at RA target genes to promote RNA polymerase II recruitment. Our work identifies a protein complex linking key epigenetic regulators acting in the molecular control of embryonic bilateral symmetry