A New Land Surface Hydrology within the Noah-WRF Land-Atmosphere Mesoscale Model Applied to Semiarid Environment: Evaluation over the Dantiandou Kori (Niger)

Land-atmosphere feedbacks, which are particularly important over the Sahel during the West African Monsoon (WAM), partly depend on a large range of processes linked to the land surface hydrology and the vegetation heterogeneities. This study focuses on the evaluation of a new land surface hydrology within the Noah-WRF land-atmosphere-coupled mesoscale model over the Sahel. This new hydrology explicitly takes account for the Dunne runoff using topographic information, the Horton runoff using a Green-Ampt approximation, and land surface heterogeneities. The previous and new versions of Noah-WRF are compared against a unique observation dataset located over the Dantiandou Kori (Niger). This dataset includes dense rain gauge network, surfaces temperatures estimated from MSG/SEVIRI data, surface soil moisture mapping based on ASAR/ENVISAT C-band radar data and in situ observations of surface atmospheric and land surface energy budget variables. Generally, the WAM is reasonably reproduced by Noah-WRF even if some limitations appear throughout the comparison between simulations and observations. An appreciable improvement of the model results is also found when the new hydrology is used. This fact seems to emphasize the relative importance of the representation of the land surface hydrological processes on the WAM simulated by Noah-WRF over the Sahel

Targeting of MuLV Gag to the plasma membrane is mediated by PI(4,5)P2 and PhosphatidylSerine

Oral presentationInternational audienceMembrane targeting by the modern human immunodeficiency viruses is dependent on the plasma membrane-located phospholipid PI(4,5)P2. In order to determine if evolutionarily distant retroviruses are targeted by a similar mechanism, we generated mutant Gag constructs in the matrix (MA) domain of the Murine Leukemia Virus (MuLV) and examined their binding to membrane models and phenotypes in cell culture. Mutations in the MA polybasic region altered Gag localization, membrane binding and virion production. In addition, we show that MA binds with good affinity to all the phosphatidylinositol phosphates but displays a strong specificity for PI(4,5)P2 only if enhanced by phophatidylserine. Virus production was strongly impaired by PI(4,5)P2 depletion under 5ptaseIV overexpression. Our results suggest that the N-terminal polybasic region of MA is essential for Gag targeting to the plasma membrane and Gag cellular trafficking. The binding of the MA domain to PI(4,5)P2 appears to be a conserved feature among retroviruses, despite the fact that the MuLV-MA domain is structurally different from that of HIV-1 and -2 and lacks a readily identifiable PI(4,5)P2 binding cleft

Multi-Layered Films Containing a Biomimetic Stimuli-Responsive Recombinant Protein

Electrostatic self-assembly was used to fabricate new smart multi-layer coatings, using a recombinant elastin-like polymer (ELP) and chitosan as the counterion macromolecule. The ELP was bioproduced, purified and its purity and expected molecular weight were assessed. Aggregate size measurements, obtained by light scattering of dissolved ELP, were performed as a function of temperature and pH to assess the smart properties of the polymer. The build-up of multi-layered films containing ELP and chitosan, using a layer-by-layer methodology, was followed by quartz-crystal microbalance with dissipation monitoring. Atomic force microscopy analysis permitted to demonstrate that the topography of the multi-layered films could respond to temperature. This work opens new possibilities for the use of ELPs in the fabrication of biodegradable smart coatings and films, offering new platforms in biotechnology and in the biomedical area

The social nature of serial murder: The intersection of gender and modernity

The literature on the aetiology of serial killing has benefited from analyses which offer an alternative perspective to individual/psychological approaches and consider serial murder as a sociological phenomenon. The main argument brought to bear within this body of work identifies the socio-economic and cultural conditions of modernity as enabling and legitimating the motivations and actions of the serial killer. This article interrogates this work from the standpoint of a gendered reading of modernity. Using the Yorkshire Ripper case, it emphasizes how in addition to the political economy, gender relations and masculinity shape the dynamics of serial murder and its representation

Ni-, Pt- and (Ni/Pt)-doped TiO₂ nanophotocatalysts : a smart approach for sustainable degradation of Rhodamine B dye

Ni (1 wt%)-, Pt (1 wt%)- and [Ni (0.5 wt%)/Pt (0.5 wt%)]-doped TiO₂ nanoporous catalysts have been successfully obtained through a facile two-step hydrothermal route. TiO₂ crystallizes mostly in the anatase phase and acts as a mesoporous matrix. Meanwhile, Ni, Pt and Ni/Pt dopants form small nanoparticles (NPs) (3-95 nm in diameter) which are hosted by the TiO₂ framework. The resulting composites exhibit a rather large surface area, in the range of 186-200 m2/g. The band gap energy reduces from 3.03 eV for the undoped TiO₂ to 2.15 eV for the Pt-loaded TiO₂. As a consequence, absorption expands toward the visible light range. The photodegradation of Rhodamine B dye in aqueous medium has been investigated under UV-vis light irradiation. The presence of Ni, Pt and Ni/Pt NPs significantly enhances the photocatalytic activity of the material. Furthermore, the Ni-doped TiO₂ shows ferromagnetic behavior at room temperature, which makes its recovery and subsequent fast reutilization possible. Interestingly, this sample also exhibits the best stability upon recycling. Considering all the current challenges in sustainable water remediation, these new photocatalysts could find applications in real environmental contexts in the near future

Free-standing polyelectrolyte membranes made of chitosan and alginate

Free-standing films have increasing applications in the biomedical field as drug delivery systems for wound healing and tissue engineering. Here, we prepared free-standing membranes by the layer-by-layer assembly of chitosan and alginate, two widely used biomaterials. Our aim was to produce a thick membrane and to study the permeation of model drugs and the adhesion of muscle cells. We first defined the optimal growth conditions in terms of pH and alginate concentration. The membranes could be easily detached from polystyrene or polypropylene substrate without any postprocessing step. The dry thickness was varied over a large range from 4 to 35 μm. A 2-fold swelling was observed by confocal microscopy when they were immersed in PBS. In addition, we quantified the permeation of model drugs (fluorescent dextrans) through the free-standing membrane, which depended on the dextran molecular weight. Finally, we showed that myoblast cells exhibited a preferential adhesion on the alginate-ending membrane as compared to the chitosan-ending membrane or to the substrate side.This work was financially supported by Foundation for Science and Technology (FCT) through the Scholarship SFRH/BD/64601/2009 granted to S.G.C. C.M. is indebted to Grenoble INP for financial support via a postdoctoral fellowship. This work was supported by the European Commission (FP7 Program) via a European Research Council starting grant (BIOMIM, GA 259370 to C.P.). C.P. is also grateful to Institut Universitaire de France and to Grenoble Institute of Technology for financial support. We thank Isabelle Paintrand for her technical help with the confocal apparatus and Patrick Chaudouet for his help with SEM imaging

Secondary structure of rhBMP-2 in a protective biopolymeric carrier material

Efficient delivery of growth factors is one of the great challenges of tissue engineering. Polyelectrolyte multilayer films (PEM) made of biopolymers have recently emerged as an interesting carrier for delivering recombinant human bone morphogenetic protein 2 (rhBMP-2 noted here BMP-2) to cells in a matrix-bound manner. We recently showed that PEM made of poly(l-lysine) and hyaluronan (PLL/HA) can retain high and tunable quantities of BMP-2 and can deliver it to cells to induce their differentiation in osteoblasts. Here, we investigate quantitatively by Fourier transform infrared spectroscopy (FTIR) the secondary structure of BMP-2 in solution as well as trapped in a biopolymeric thin film. We reveal that the major structural elements of BMP-2 in solution are intramolecular β-sheets and unordered structures as well as α-helices. Furthermore, we studied the secondary structure of rhBMP-2 trapped in hydrated films and in dry films since drying is an important step for future applications of these bioactive films onto orthopedic biomaterials. We demonstrate that the structural elements were preserved when BMP-2 was trapped in the biopolymeric film in hydrated conditions and, to a lesser extent, in dry state. Importantly, its bioactivity was maintained after drying of the film. Our results appear highly promising for future applications of these films as coatings of biomedical materials, to deliver bioactive proteins while preserving their bioactivity upon storage in dry state.This work was supported by the French Ministry of Research through an ANR-EmergenceBIO grant (ANR-09-EBIO-012-01), by the European Commission (FP7 program) via a European Research Council starting grant (BIOMIM, GA 259370), and by GRAVIT (081012_FIBIOS). C.P. is grafetul to IUF for financial support