274 research outputs found

    Development of functional markers specific for seven Pm3 resistance alleles and their validation in the bread wheat gene pool

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    In the ideal case, molecular markers used for marker-assisted selection are allele-specific even if the alleles differ only by a few nucleotide polymorphisms within the coding sequence of target genes. Such ‘perfect' markers are completely correlated with the trait of interest. In hexaploid wheat (Triticum aestivum L.) the Pm3 locus encodes seven alleles (Pm3a-Pm3g) conferring resistance to different races of Blumeria graminis f.sp. tritici, the agent of powdery mildew, a major disease of bread wheat. All Pm3 alleles are known at the molecular level. Here, we generated specific markers for the Pm3 alleles based on nucleotide polymorphisms of coding and adjacent non-coding regions. The specificity of these markers was validated in a collection of 93 modern or historically important cultivars and breeding lines of wheat and spelt (Triticum spelta L.). These markers confirmed the presence of the predicted Pm3 alleles in 31 varieties and lines known to carry Pm3 resistance alleles. In a few varieties, Pm3 alleles different from alleles previously described based on pathogenicity tests or tightly linked markers were observed. In all these cases, the identity of the marker-detected Pm3 alleles was confirmed by DNA sequence analysis. Pm3 markers confirmed the absence of known Pm3 resistance alleles in 54 European wheat and spelt varieties in which Pm3 alleles had not been previously identified. These results indicate that the developed markers are highly diagnostic for specific Pm3 resistance alleles in a wide range of varieties and breeding lines, and will be useful (1) for identifying Pm3 alleles in the wheat gene pool, (2) for efficient marker-assisted selection of these genes, and (3) for combining multiple Pm3 alleles within a single cultivar through transgenic approache

    Study of domestic wastewater treatment bymacrophyte plant in Arid Region of South-east Algeria (case of el oued region)

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    Removal of wastewater pollution by natural treatment systems such as wetlands is achieved using filter media and macrophytes plants. The functioning of constructed wetlands relies on physical, chemical and biological processes. The aim of the present study is to evaluate the performance of the Phragmites australis for domestic wastewater  treatment under an arid climate. Experiments were conducted during three months (February, March and April). Results indicate that the variation of pH values of raw and treated wastewater is not significant. The electrical conductivity increases strongly during March and April. It was also found that dissolved oxygen in planted filter exceeds that of the unplanted one. Also, the higher performance in BOD and Ntot removal by the planted filter confirms the important role of this plant in the treatment process.Keywords: Pollution; wetlands; filter media; performance; Phragmites australis

    A MEMS-based solid propellant microthruster array for space and military applications

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    Since combustion is an easy way to achieve large quantities of energy from a small volume, we developed a MEMS based solid propellant microthruster array for small spacecraft and micro-air-vehicle applications. A thruster is composed of a fuel chamber layer, a top-side igniter with a micromachined nozzle in the same silicon layer. Layers are assembled by adhesive bonding to give final MEMS array. The thrust force is generated by the combustion of propellant stored in a few millimeter cube chamber. The micro-igniter is a polysilicon resistor deposited on a low stress SiO2/SiNx thin membrane to ensure a good heat transfer to the propellant and thus a low electric power consumption. A large range of thrust force is obtained simply by varying chamber and nozzle geometry parameters in one step of Deep Reactive Ion Etching (DRIE). Experimental tests of ignition and combustion employing home made (DB+x% BP) propellant composed of a Double-Base and Black-Powder. A temperature of 250 therefore degrees C, enough to propellant initiation, is reached for 40 mW of electric power. A combustion rate of about 3.4 mm/s is measured for DB+20% BP propellant and thrust ranges between 0.1 and 3,5 mN are obtained for BP ratio between 10% and 30% using a microthruster of 100 mu m of throat wide

    LifeTime-aware Backpressure - a new delay-enhanced Backpressure-based routing protocol

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    Dynamic Backpressure is a highly desirable family of routing protocols known for their attractive mathematical proprieties. However, these protocols suffer from a high end-to-end delay making them inefficient for real-time traffic with strict endto-end delay requirements. In this paper, we address this issue by proposing a new adjustable and fully distributed Backpressurebased scheme with low queue management complexity, named LifeTime-Aware BackPressure (LTA-BP). The novelty in the proposed scheme consists in introducing the urgency level as a new metric for service differentiation among the competing traffic flows in the network. Our scheme not just significantly improves the quality of service provided for real-time traffic with stringent end-to-end delay constraints, but interestingly protects also the flows with softer delay requirements from being totally starved. The proposed scheme has been evaluated and compared against other state of the art routing protocol, using computer simulation, and the obtained results show its superiority in terms of the achieved end-to-end delay and throughput

    Molecular analysis of fungal disease resistance in wheat

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    La influencia de las Tecnologías de la Información y Comunicación (TIC) en el sector turístico y en especial en la comunicación de los productos y en la gestión de las relaciones con los públicos es ampliamente conocida. Las aplicaciones Web 2.0 basadas en comentarios y valoraciones de usuarios a escala mundial, en concreto TripAdvisor, influencian las prácticas en relaciones públicas y comunicación turísticas obligando a una cuidada gestión de la reputación online. Si por un lado las nuevas herramientas 2.0 están à disposición de las organizaciones para comunicar con sus públicos, por otro lado son también fuente de comentários y valoraciones directas que pueden reforzar positivamente la imagen de una organización o contribuir con opiniones negativas que desafian nuevas práticas en relaciones públicas. A fin de determinar si estas aplicaciones están afectando el comportamiento de planificación y reservas de productos y servicios turísticos, hicimos un estudio basado en el análisis de Burguess y Kerr (2012) dirigida a turistas portugueses

    Comparative gene expression analysis of susceptible and resistant near-isogenic lines in common wheat infected by Puccinia triticina

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    Gene expression after leaf rust infection was compared in near-isogenic wheat lines differing in the Lr10 leaf rust resistance gene. RNA from susceptible and resistant plants was used for cDNA library construction. In total, 55 008 ESTs were sequenced from the two libraries, then combined and assembled into 14 268 unigenes for further analysis. Of these ESTs, 89% encoded proteins similar to (E value of < or =10(-5)) characterized or annotated proteins from the NCBI non-redundant database representing diverse molecular functions, cellular localization and biological processes based on gene ontology classification. Further, the unigenes were classified into susceptible and resistant classes based on the EST members assembled from the respective libraries. Several genes from the resistant sample (14-3-3 protein, wali5 protein, actin-depolymerization factor and ADP-ribosylation factor) and the susceptible sample (brown plant hopper resistance protein, caffeic acid O-methyltransferase, pathogenesis-related protein and senescence-associated protein) were selected and their differential expression in the resistant and susceptible samples collected at different time points after leaf rust infection was confirmed by RT-PCR analysis. The molecular pathogenicity of leaf rust in wheat was studied and the EST data generated made a foundation for future studies
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