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  • 1
    ISSN: 1573-8248
    Keywords: Aphides ; Entomophthorales ; caractérisation enzymatique ; application (de mycélium) ; serre ; laitue ; Aphids ; Entomophthorales ; isoenzyme profiles ; mycelium application ; glasshouses ; lettuce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary The efficiency of a biopreparation of one strain ofErynia neoaphidis Remaudière & Hennebert against lettuce aphids was tested in an untreated glasshouse, in Rennes during the spring 1983. The development of the strain was studied by periodic isolation of fungi from killed aphids and determination of their enzyme profile. The artificially established aphid populations showed a very low percentage of mortality (5 %). Izoenzyme profiles of the strains isolated during the experiment showed that the introduced strain ofE neoaphidis was established in the populations after spraying but was subsequently replaced by local strains of the same species. From the beginning of the experiment, the development of a local inoculum ofConidiobolus obscurus was observed, which was different from a strain introduced in the glasshouse two years before.
    Notes: Résumé Au cours d'une expérimentation réalisée en serre à Rennes, en 1983, on a éprouvé l'efficacité contre les pucerons de la laitueAulacorthum solani (Kaltenbach) etMacrosiphum euphorbiae (Thomas) d'une biopréparation d'Entomophthorale constituée de mycélium d'une souche deErynia neoaphidis Remaudière & Hennebert. L'étude de l'implantation de cette souche a été entreprise grâce à une technique de caractérisation enzymatique. Les populations de pucerons implantées expérimentalement en début d'essai sont faiblement attaquées par des mycoses (5 % de mortalité). La caractérisation enzymatique des souches d'Entomophthorales isolées de pucerons trouvés morts au cours de l'expérimentation montre que la souche deE. neoaphidis introduite s'est implantée dans les populations aphidiennes, mais qu'elle est par la suite remplacée par un inoculum autochtone de la même espèce. On observe également le développement dès le début de l'expérimentation d'un inoculum deC. obscurus qui ne correspond pas à la souche introduite 2 ans auparavant lors d'une précédente expérimentation.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2014-04-17
    Description: In aphids, clonal individuals can show distinct morphologic traits in response to environmental cues. Such phenotypic plasticity cannot be studied with classical genetic model organisms such as Caenorhabditis elegans or Drosophila melanogaster . The genetic basis of this biological process remain unknown, as mutations affecting this process are not available in aphids. Here, we describe a protocol to treat third-stage larvae with an alkylating mutagen, ethyl methanesulfonate (EMS), to generate random mutations within the Acyrthosiphon pisum genome. We found that even low concentrations of EMS were toxic for two genotypes of A. pisum . Mutagenesis efficiency was nevertheless assessed by estimating the occurrence of mutational events on the X chromosome. Indeed, any lethal mutation on the X-chromosome would kill males that are haploid on the X so that we used the proportion of males as an estimation of mutagenesis efficacy. We could assess a putative mutation rate of 0.4 per X-chromosome at 10 mM of EMS. We then applied this protocol to perform a small-scale mutagenesis on parthenogenetic individuals, which were screened for defects in their ability to produce sexual individuals in response to photoperiod shortening. We found one mutant line showing a reproducible altered photoperiodic response with a reduced production of males and the appearance of aberrant winged males (wing atrophy, alteration of legs morphology). This mutation appeared to be stable because it could be transmitted over several generations of parthenogenetic individuals. To our knowledge, this study represents the first example of an EMS-generated aphid mutant.
    Electronic ISSN: 2160-1836
    Topics: Biology
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  • 3
    Publication Date: 2018-06-21
    Description: We present, in this paper, numerical simulations of bubble sloshing in a spherical tank, resulting from a tank rotation around a fixed axis in microgravity conditions. This configuration is of great interest in space applications where sloshing can have harmful effects on the stability of satellites. Depending on the dimensionless numbers characterising this phenomenon, our study is focused on the motion and the deformation of a bubble, initially at rest, which is set in motion when the manoeuvre is starting until it reaches a constant rotation speed around the axis. It is shown in this article that, during the first stage of the manoeuvre, the motion of the bubble is essentially driven by the inertial force that depends on the angular acceleration. Next, when the angular velocity is increasing, the centrifugal force being dominant, the trajectory of the bubble is pushed towards the direction between the centre of the tank and the axis of rotation. Finally, when the angular velocity becomes constant, the bubble, reaching a quasi-steady position, is deformed and pressed against the solid boundary of the tank. A quantified description of these phenomena is proposed through a parametric study varying the essential dimensionless numbers, i.e.i the Bond number based on the angular velocity, and another Bond number based on the angular acceleration. As the temporal evolution of the forces acting on the satellite wall is of utmost importance for designing satellites and manoeuvres, we also present an analysis characterising the latter. We also detail the first comparisons between the numerical simulations and the Fluidics experiment performed in the International Space Station (ISS) in microgravity conditions. Thanks to these comparisons, we can validate the simulations in configurations of interest. © 2018 Cambridge University Press.
    Print ISSN: 0022-1120
    Electronic ISSN: 1469-7645
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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