Biosynthesis of Phenylnannolone A, a MDR Reversal Agent from <em>Nannocystis pusilla</em>

Myxobacteria are gliding bacteria known to produce an immense diverse spectrum of natural products with unique modes of action. Nannocystis pusilla B150 is a myxobacterial representative, which is able to synthesize polyketides, named phenylnannolones. Phenylnannolone A showed inhibitory activity towards the ABCB1 gene product p-glycoprotein and reverses daunorubicin resistance in cultured cancer cells. Feeding studies with labeled precursors revealed, besides three acetates, a butyrate and a phenylalanine-derived starter unit, also the unprecedented incorporation of a C-2 carbon atom derived from acetate. This labeling pattern suggested novel biochemical reactions. To decipher the biochemical reactions leading to the formation of phenylnannolone A, the biosynthetic gene cluster for phenylnannolone A was identified and sequenced; this revealed a gene encoding for a Polyketide Synthase (PKS), whose domain order is consistent with the putative biosynthesis that we postulated for phenylnannolone A. However, the putative loading module comprises an NRPS-like loading module that activates the aromatic starter unit. Investigations on the functionality and substrate selectivity of the loading module were tested in a γ-18O4-ATP pyrophosphate exchange assay and showed the significant and specific activation of cinnamic acid by the AMP-ligase

Implementation of a Wireless Mesh Network of Ultra Light MAVs with Dynamic Routing

This paper describes the implementation and characterisation of a mobile ad-hoc network (MANET) of ultra-light intelligent flying robots. The flying nature of the network makes it suitable to collect or disseminate content in urban areas or challenging terrain, where line-of-sight connection between the Micro Air Vehicles (MAVs) allows for more efficient communication. Dynamic routing in the network enables the nodes to intelligently establish multi-hop routes to extend the communication range or to overcome obstacles. The presented MANET relies on the IEEE 802.11n WiFi standard for data communications and uses the OLSR routing protocol. Routing decisions based on dynamic link quality measurements allow the network to cope with the fast variability of the wireless channel and the high mobility of the MAVs. The implementation of such a system calls for the integration of advanced communication and control technologies in a very restrictive platform, be it in terms of weight, power consumption or availability of suitable off-the-shelf hardware. A detailed description of the system design is presented, and its performance is characterised based on in-flight network measurements. To the best of our knowledge, this is the first report of OLSR successfully tested in a MANET with such fast dynamics. We verify the trade-off between achievable throughput and the number of hops, and we report on the sensitivity of communication performance and routing behaviour to MAV orientation and flight path. Mitigation of such dependencies and improvements to the routing algorithm are discussed along with future research directions

Genomic Analysis of the Hydrocarbon-Producing, Cellulolytic, Endophytic Fungus Ascocoryne sarcoides

The microbial conversion of solid cellulosic biomass to liquid biofuels may provide a renewable energy source for transportation fuels. Endophytes represent a promising group of organisms, as they are a mostly untapped reservoir of metabolic diversity. They are often able to degrade cellulose, and they can produce an extraordinary diversity of metabolites. The filamentous fungal endophyte Ascocoryne sarcoides was shown to produce potential-biofuel metabolites when grown on a cellulose-based medium; however, the genetic pathways needed for this production are unknown and the lack of genetic tools makes traditional reverse genetics difficult. We present the genomic characterization of A. sarcoides and use transcriptomic and metabolomic data to describe the genes involved in cellulose degradation and to provide hypotheses for the biofuel production pathways. In total, almost 80 biosynthetic clusters were identified, including several previously found only in plants. Additionally, many transcriptionally active regions outside of genes showed condition-specific expression, offering more evidence for the role of long non-coding RNA in gene regulation. This is one of the highest quality fungal genomes and, to our knowledge, the only thoroughly annotated and transcriptionally profiled fungal endophyte genome currently available. The analyses and datasets contribute to the study of cellulose degradation and biofuel production and provide the genomic foundation for the study of a model endophyte system

Commande et contrôle d'une installation solaire thermique

91 p. : ill. ; 30 cmThe productions of hot water with solar energy allow the best use of available energy resources and contribute to reduce emission of greenhouse gas effect. The purpose of this work is to study the energy performances of solar water heater installations through the use of dvanced technology by using the remote control to monitor the energy efficiency and ensure the good working of installation at all moments so we guaranteed the results. The set of experimental measurement has been undertaken by the use of different instruments of measurement temperature transmitter, pulse meter, electrical counter…etc). The temperature transmitter measure and transmit the information to control station, here the necessary control has been transmit to pumps, electrical contribution, valves etc). A good dimensioning or calculation of the installation, to ensure an optimal productivities, is required, in this way a new software is used which is developed in CSTB FRANCE called "SIMSOL" based on dynamic simulation ( measure with a step of a hour), the result of the simulation is compared to the measured ones, and we can deduce that the employed process is quite reliable and profitable for the tested installatio