Inhibitors of retrograde trafficking active against ricin and Shiga toxins also protect cells from several viruses, Chlamydiales and Leishmania

Medical countermeasures to treat biothreat agent infections require broad-spectrum therapeutics that do not induce agent resistance. A cell-based high-throughput screen (HTS) against ricin toxin combined with hit optimization allowed selection of a family of compounds that meet these requirements. The hit compound Retro-2 and its derivatives have been demonstrated to be safe in vivo in mice even at high doses. Moreover, Retro-2 is an inhibitor of retrograde transport that affects syntaxin-5- dependent toxins and pathogens. As a consequence, it has a broad-spectrum activity that has been demonstrated both in vitro and in vivo against ricin, Shiga toxin-producing O104:H4 enterohemorrhagic E. coli and Leishmania sp. and in vitro against Ebola, Marburg and poxviruses and Chlamydiales. An effect is anticipated on other toxins or pathogens that use retrograde trafficking and syntaxin-5. Since Retro-2 targets cell components of the host and not directly the pathogen, no selection of resistant pathogens is expected. These lead compounds need now to be developed as drugs for human use

Comparison of airborne and spaceborne 95-GHz radar reflectivity and evaluation of multiple scattering effects in spaceborne Measurements

International audienc

Chemical evolution of organic molecules under Mars-like UV radiation conditions simulated in the laboratory with the "Mars organic molecule irradiation and evolution" (MOMIE) setup

International audienceUnderstanding the evolution of organic matter on Mars is a major goal to drive and discuss past, present and future in situ analyses. Here we demonstrate the ability of the MOMIE (for Mars Organic Molecules Irradiation and Evolution) laboratory device in giving both in situ qualitative and quantitative data on the evolution of organic molecules under simulated Martian surface ultraviolet light (190-400 nm), mean temperature (218±2 K) and pressure (6±1 mbar). We describe the chemical evolution of glycine, an amino acid, which is very rapidly processed when exposed to direct ultraviolet radiations, with a molecular half-life of 231±110 hours on Mars consistent with existing results. Moreover we report the first tentative detection of peptide bond formation activated by UV radiation reaching the Mars surface. We show that organics as simple as glycine could experience multiple chemical pathways at Mars, both in the solid and gaseous phase. Finally, we derive the quantum efficiency for the photodestruction of glycine of 2.18±1.45×10−3 molecule photon−1 in the 200-250 nm wavelength range. This value is significantly higher than previous estimates done by methane evolved measurements. Current and future studies performed with this simulation setup could produce kinetic and chemical insights into the evolution of organics on Mars

Soil erosion by wind over tilled surfaces in South Tunisia

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Enantiomeric derivatization on the Mars Organic Molecule Analyzer (MOMA) experiment aboard ExoMars 2018: how to unravel martian chirality

International audienceWe present the results of laboratory experiments which display the feasability and limitations of the detection of an enantiomeric excess of complex organic molecules in various analog samples, depending on the mineralogy of the Mars analog solid sample

Le projet RALI : Combinaison d'un radar nuage et d'un lidar pour l'étude des nuages faiblement précipitants.

The Rali (radar-lidar) project is a new tool which combines a radar and a lidar for observing weakly- precipitating clouds. This paper des- cribes the instruments used or improved for Rali, together with the algorithms for reproducing cloud parameters and shows some of the first scientific results. Around March 2005, the Rali instrument will be installed in the new French research aircraft and will allow the scientific community to get coupled observa- tions of dynamical, microphysical and radiative properties of aerosols and weakly-precipitating clouds.Le projet Rali (radar-lidar) développe un nouveau moyen d’observation des nuages faiblement précipitants, qui repose sur la combinaison d’un radar et d’un lidar. On décrit ici les instru- ments utilisés ou mis au point dans le cadre de Rali et les algorithmes de res- titution des paramètres des nuages, puis on présente quelques exemples des premiers résultats scientifiques obtenus. À l’horizon mars 2005, l’ins- trument Rali sera intégré dans les nouveaux avions de recherche fran- çais et permettra à la communauté scientifique d’accéder à des observa- tions couplées de la dynamique, de la microphysique et des propriétés radia- tives des nuages faiblement précipi- tants et des aérosols

In situ sample treatment on Titan, aboard the DraMS experiment

International audienceIn 2027 NASA will launch a new exobiological mission to Titan: Dragonfly [1,2]. Onboard the DraMS instrument will aim to map the organic compounds present on the surface of the satellite and to study the fate of this organic matter towards a potential prebiotic chemistry [3,4]. To do so, DraMS is equipped with a gas chromatography instrument coupled to a mass spectrometer (GC-MS). In order to be analyzed, the samples taken by the DrACO module will be placed in an oven which will allow the sample treatment. Different techniques of sample treatment can be used: pyrolysis, derivatization and thermochemolysis. Pyrolysis allows to volatilize efficiently the organic content of the sample but has the disadvantage of degrading the original content. The derivatization allows to avoid the degradation of the labile molecules while allowing their volatilization. This derivatization will be realized thanks to the use of DMF-DMA (dimethylformamide dimethylacetal) [5]. This reagent allows to keep the asymmetry centers of the labile molecules while volatilizing them and thus allowing the separation of their enantiomers on a chiral column of Chirasil-Dex type. The last technique, thermochemolysis, is dedicated to more refractory compounds. It combines both pyrolysis and derivatization techniques by using TMAH (tetramethylammonium hydroxide) or TMSH (trimethylsulfonium hydroxide) and temperatures of about 500°C [6].In order to optimize the treatment of DraMS samples, we studied the impact of each derivatization and thermochemolysis reagent on the identified organic targets (amino acids, nucleic bases, fatty acids, etc.) as well as using Titan analogues synthesized at LATMOS (UVSQ, France): Tholins [7]

In situ sample treatment on Titan, aboard the DraMS experiment

International audienceIn 2027 NASA will launch a new exobiological mission to Titan: Dragonfly [1,2]. Onboard the DraMS instrument will aim to map the organic compounds present on the surface of the satellite and to study the fate of this organic matter towards a potential prebiotic chemistry [3,4]. To do so, DraMS is equipped with a gas chromatography instrument coupled to a mass spectrometer (GC-MS). In order to be analyzed, the samples taken by the DrACO module will be placed in an oven which will allow the sample treatment. Different techniques of sample treatment can be used: pyrolysis, derivatization and thermochemolysis. Pyrolysis allows to volatilize efficiently the organic content of the sample but has the disadvantage of degrading the original content. The derivatization allows to avoid the degradation of the labile molecules while allowing their volatilization. This derivatization will be realized thanks to the use of DMF-DMA (dimethylformamide dimethylacetal) [5]. This reagent allows to keep the asymmetry centers of the labile molecules while volatilizing them and thus allowing the separation of their enantiomers on a chiral column of Chirasil-Dex type. The last technique, thermochemolysis, is dedicated to more refractory compounds. It combines both pyrolysis and derivatization techniques by using TMAH (tetramethylammonium hydroxide) or TMSH (trimethylsulfonium hydroxide) and temperatures of about 500°C [6].In order to optimize the treatment of DraMS samples, we studied the impact of each derivatization and thermochemolysis reagent on the identified organic targets (amino acids, nucleic bases, fatty acids, etc.) as well as using Titan analogues synthesized at LATMOS (UVSQ, France): Tholins [7]