Streptomyces‐derived quorum‐sensing systems engineered for adjustable transgene expression in mammalian cells and mice

Prokaryotic transcriptional regulatory elements have been adopted for controlled expression of cloned genes in mammalian cells and animals, the cornerstone for gene‐function correlations, drug discovery, biopharmaceutical manufacturing as well as advanced gene therapy and tissue engineering. Many prokaryotes have evolved specific molecular communication systems known as quorum‐sensing to coordinate population‐wide responses to physiological and/or physicochemical signals. A generic bacterial quorum‐sensing system is based on a diffusible signal molecule that prevents binding of a repressor to corresponding operator sites thus resulting in derepression of a target regulon. In Streptomyces, a family of butyrolactones and their corresponding receptor proteins, serve as quorum‐sensing systems that control morphological development and antibiotic biosynthesis. Fusion of the Streptomyces coelicolor quorum‐sensing receptor (ScbR) to a eukaryotic transactivation domain (VP16) created a mammalian transactivator (SCA) which binds and adjusts transcription from chimeric promoters containing an SCA‐specific operator module (PSPA). Expression of erythropoietin or the human secreted alkaline phosphatase (SEAP) by this quorum‐sensor‐regulated gene expression system (QuoRex) could be fine‐tuned by non‐toxic butyrolactones in a variety of mammalian cells including human primary and mouse embryonic stem cells. Following intraperitoneal implantation of microencapsulated Chinese hamster ovary cells transgenic for QuoRex‐controlled SEAP expression into mice, the serum levels of this model glycoprotein could be adjusted to desired concentrations using different butyrolactone dosing regime

Synthesis of some furanone derivatives : putative quorum sensing or chitinase inhibitors

Bacteria are able to communicate through chemical signals. They can for instance estimate their population by the use of signalling compounds: this phenomenon is called quorum sensing. Some of these signalling compounds are derivatives of homoserine lactones. When their concentration reaches a certain level, bacterial genes are triggered, which leads to virulence, bacterial film formation, and so on. Natural halogenated furanones 22 and 23 extracted from the marine alga Delisea pulchra proved to inhibit the quorum sensing. Other natural furanones 24a-27a extracted from Streptomyces antibioticus TÜ 99 were also quorum sensing inhibitors. As the structures of these natural compounds were similar to the homoserine lactones, additional furanones were synthesized in order to investigate their properties towards the quorum sensing. Following the synthetic route published by Grossmann [11], the compounds 56a, 56b, and 58 were prepared. The key step of the synthesis, which is a condensation of the menthylated furanone 38b and an aldehyde with LDA under kinetic conditions, was optimized. The biological activity of these three compounds, as well as of all intermediates, was investigated. The tests were carried out with a mutant strain of Chromobacterium violaceum, called CV026. Some of the synthetic furanones proved indeed to be weak quorum sensing inhibitors, however none of them was more active than the natural compound 22 [22]. In addition, some of these compounds were toxic for Chromobacterium violaceum. The Grossmann method, followed by a reduction of the side chain, was also used for the preparation of the flavour furanone 64, which had previously shown a weak inhibition of the pristinamycin production by Streptomyces pristinaespiralis. Further tests were carried out with mammalian cells, but the compound 64 proved to be toxic [21]. Other biological tests showed that some menthylated furanones were weak chitinase inhibitors. Starting from the assumption that menthylated furanones could have structure analogy with the most potent chitinase inhibitor allosamidin (75), the synthesis of glycosylated furanones was attempted. The main purpose was to replace the menthyl group by a monosaccharide or a disaccharide in a very short and very cheap process. The starting furanone 37 was treated with trichloroacetonitrile to give the trichloroacetimidate 93, which was submitted to glycosylation following a “reversed type Schmidt glycosylation” procedure using TMSOTf as Lewis acid. The obtained acetylated compounds 92, 96, and 97 were treated with guanidine. The deacetylated monosaccharides 101 and 102 were obtained in low yields whereas 97 was not completely deacetylated. The glycosylation afforded for each compounds 92, 96, and 97 a mixture of four diastereomers. Only the diastereomers of 96 could be partially separated by chromatography on silica gel. The structures of the a-anomers could not be completely elucidated, whereas the structures of the b-anomers could be obtained from an X-ray structure determination of 96d. The starting furanone 37 was also treated with (+)-isomenthol and (+)-menthol to give the compounds 104 and 105 respectively. These compounds, as well as the glycosylated furanones 92, 96a, 96b, 96c, 96d, 102, 104, and 105, were tested but none of these synthetic furanones were active as chitinase inhibitors

Synthesis and biological evaluation of some furanones as putative chitinase Inhibitors

Analogs of naturally occurring furanones that were reported to be weak inhibitors of Serratia marcescens chitinases were prepared and tested towards various chitinases. Some of these compounds - but not the natural products - were found to be weak but selective inhibitors; all glycosylated analogs tested were inactive. Activation of the plant enzyme hevamine was observed in one case, which is unusual

High-speed Private Information Retrieval Computation on GPU

International audienc

Thou Shall Not Shadow Thy Neighbour: Developing an Urban Planning Tool for the H2020 E-Shape Project

International audienceNowadays, urban areas are seeing growing trends both in urban development and photovoltaics (PV) deployment, with clear changes in their orography and aesthetics. However, these two movements do not necessarily share a coordinated strategy. There are guiding regulations which aim, in part, to ensure the exposure to sunlight. While this is traditionally seen from the perspective of human health impacts and the right to natural lighting [1], there have also been regulatory initiatives and proposals aiming to protect solar energy projects [2,3]. However, the lack of adequate assessment tools limits the definition of such policies. This work presents an urban planning tool developed in the scope of the e-shape H2020 project [4] which evaluates the impact of new urban projects in terms of the PV potential of surrounding areas. To achieve this, two main technical challenges were addressed: i) the development of an on-the-fly, As a Service (AaS), urban PV modelling framework; and ii) the implementation of an editable Digital Surface Model (DSM) which does not compromise the original data. It is also of interest to note that this tool is aligned with the FAIR data principles (findability, accessibility, interoperability, and reusability). In terms of functionality, end-users can add or remove existing infrastructures, modifying the existing urban orography, and obtain a spatio-temporal analysis, with both numerical and visual representations. With the expected growth of PV in urban environments and the fact that urban development outpaces the decades-long period needed to optimally exploit this technology, being able to model this impact will become more and more crucial in guiding future urban development regulations

Metamorphic reactions in deformed mafic rocks: timing, fluid percolation and equilibrium scales from undeformed gabbros to mylonites

International audienceWithin the Earth crust metamorphic reactions strongly participate to strain partitioning and localization. However, the timing of metamorphism relative to viscous deformation, the spatial scale of metamorphic processes and mineral re-equilibration remain elusive, with metamorphic reactions and associated fluid percolation generally considered as syn-kinematic. We investigate how, where and when (relative to viscous deformation) metamorphic reactions occurred in deformed gabbros of the Poroshiri Ophiolite of Hokkaido (Japan), in the core of a plate-boundary dextral shear zone. In these rocks, low and high strain areas preserve evidences of amphibolitization that occurred at 850-950°C (~5 kbar), triggered by fluid influx during fracturing (active in supra solidus conditions) and predating the viscous deformation. The abundance, composition heterogeneity of amphibole and the location of amphibole nucleation sites were regulated by water availability and by different reaction mechanisms as epitaxial growth or dissolution-reprecipitation observed at the nanoscale which controlled the magnitude and pathways of element supply (especially Fe and Mg). Pre-shearing metamorphism was accompanied by the local partial melting at grain boundaries and along crystallographic discontinuities of igneous clinopyroxene and resulted in grain size reduction of two orders of magnitude and formation of a patchwork of domains with different composition, where local chemical equilibria prevailed at the scale of 100-500 µm. Shearing occurred along the retrograde path, at 650-750°C and was coeval with amphibole and plagioclase recrystallization in high strain areas and in late fractures. Although fluid influx and amphibolitization reactions continued during shearing as attested by variations in major element content between high and low strain areas, mineral composition heterogeneities inherited from the pre-shearing metamorphic stage were largely preserved despite high strain and temperature, indicating in mylonites equilibrium scales shorter than 500 µm. Minor variations in amphibole modal abundance between inside and outside shear zones indicate that amphibolitization largely predated shearing and was controlled by fluid availability (through fracturing) rather than being strain-driven, with shearing mainly reworking the size and chemistry of amphibole grains. While throughout tectonic evolution, fluid infiltration primarily resulted from brittle fracturing active before and during viscous deformation, areas of pre-shearing amphibolitization appeared as preferential loci for strain localization and mineral re-equilibration during shearing. Pre-shearing metamorphism influenced strain localization and mineral re-equilibration during shearing also by controlling (i) the grain size reduction, (ii) the degree of phase mixing, (iii) the distribution of hydrated phases (and therefore of stored fluid) and (iv) the strain partitioning among the inherited metastable mineralogical domains

Distribution des bactéries pathogènes dans les sols évaluée par PCR quantitative en temps réel

National audienc