397 research outputs found

    Results of the MWPC gas gain uniformity tests performed at CERN

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    We present the results of the gas gain uniformity tests performed as part of the quality control of the multiwire proportional chambers produced at CERN for the LHCb Muon system, along with a description of the last hardware and software upgrades. The test provides a relative gas gain measurement over the whole chamber sensitive area. It is based on the analysis of the spectrum obtained when the chamber is exposed to a 241 ^{241}Am radioactive source. Since the measurement is normalized to the peak of a precise pulse generator, the gain uniformity can also be evaluated among different gas gaps and different chambers

    The genome structure of Arachis hypogaea (Linnaeus, 1753) and an induced Arachis allotetraploid revealed by molecular cytogenetics.

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    Peanut, Arachis hypogaea (Linnaeus, 1753) is an allotetraploid cultivated plant with two subgenomes derived from the hybridization between two diploid wild species, A. duranensis (Krapovickas & W. C. Gregory, 1994) and A. ipaensis (Krapovickas & W. C. Gregory, 1994), followed by spontaneous chromosomal duplication. To understand genome changes following polyploidy, the chromosomes of A. hypogaea, IpaDur1, an induced allotetraploid (A. ipaensis × A. duranensis)4x and the diploid progenitor species were cytogenetically compared. The karyotypes of the allotetraploids share the number and general morphology of chromosomes; DAPI+ bands pattern and number of 5S rDNA loci. However, one 5S rDNA locus presents a heteromorphic FISH signal in both allotetraploids, relative to corresponding progenitor. Whilst for A. hypogaea the number of 45S rDNA loci was equivalent to the sum of those present in the diploid species, in IpaDur1, two loci have not been detected. Overall distribution of repetitive DNA sequences was similar in both allotetraploids, although A. hypogaea had additional CMA3+ bands and few slight differences in the LTR-retrotransposons distribution compared to IpaDur1. GISH showed that the chromosomes of both allotetraploids had preferential hybridization to their corresponding diploid genomes. Nevertheless, at least one pair of IpaDur1 chromosomes had a clear mosaic hybridization pattern indicating recombination between the subgenomes, clear evidence that the genome of IpaDur1 shows some instability comparing to the genome of A. hypogaea that shows no mosaic of subgenomes, although both allotetraploids derive from the same progenitor species. For some reasons, the chromosome structure of A. hypogaea is inherently more stable, or, it has been at least, partially stabilized through genetic changes and selection

    Plant-pathogen interactions: what is proteomics telling us?

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    Review article - In this review, we highlight the proteins expressed during plant-virus, plant-bacterium, plant-fungus and plant-nematode interactions reported in proteomic studies, and discuss these findings considering the advantages and limitations of current proteomic tools

    Morpho-agronomic characterization and genetic divergence in lentil genotypes.

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    The aim of this study was to evaluate 48 lentil inbred lines and one commercial cultivar (Silvina), based on morpho-agronomic traits and to identify genotypes which can be used in a plant breeding program

    Construção e validação de membranas de macroarranjo de DNA para o estudo da interação planta-nematóide.

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