22 research outputs found

    A genome-wide comparison between selected and unselected Valle del Belice sheep reveals differences in population structure and footprints of recent selection

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    About three decades of breeding and selection in the Valle del Belìce sheep are expected to have left several genomic footprints related to milk production traits. In this study, we have assembled a dataset with 451 individuals of the Valle del Belìce sheep breed: 184 animals that underwent directional selection for milk production and 267 unselected animals, genotyped for 40,660 single-nucleotide polymorphisms (SNPs). Three different statistical approaches, both within (iHS and ROH) and between (Rsb) groups, were used to identify genomic regions potentially under selection. Population structure analyses separated all individuals according to their belonging to the two groups. A total of four genomic regions on two chromosomes were jointly identified by at least two statistical approaches. Several candidate genes for milk production were identified, corroborating the polygenic nature of this trait and which may provide clues to potential new selection targets. We also found candidate genes for growth and reproductive traits. Overall, the identified genes may explain the effect of selection to improve the performances related to milk production traits in the breed. Further studies using high-density array data, would be particularly relevant to refine and validate these results

    Chemical Composition, Antibacterial and Antifungal Activities of Four Essential Oils Collected in the North-East of Tunisia

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    This work aimed to determine the essential oil composition and their biological activities of four local medicinal plant species (Pinus halepensis, Tetraclinis articulata, Juniperus phoenicea and Juniperus oxycedrus) widely planted in the same geographical site. Essential oil isolation was isolated using hydrodistillation and the chemical composition was based on GC/MS analysis. The antibacterial and antifungal activities of essential oils were assessed against 8 pathogenic bacteria and 4 yeast, and 3 different tests were used. GC/MS results showed that essential oil chemical composition is highly affected by plant species (P<0.001). GC/MS identification revealed that β-phellandrene (21.8%), β-caryophyllene (37.2%), α-pinene (24.7%) and camphor (22.4%) were identified as the major compounds of J. phoenicea, P. halepensis, J. oxycedrus and T. articulata essential oils, respectively. Interestingly, two volatile compounds: β-pinene and p-cymen-8-ol were present in all isolated essential oils with similar concentrations: 0.8 and 0.5% of the total identified componenents. Antibacterial results suggested that essential oils were efficient in arresting the growth of most tested bacteria with different extent depending on the studied plant and bacterial strains. Interestingly, Pseudomonas aeruginosa was the most resistant bacterium and Shigella sonnei was the most sensible to tested essential oils. Indeed, the lowest and the highest inhibition diameters were recorded for latter bacterial strains, respectively. Concerning the antifungal activity, results showed interesting efficiency against tested Candida strains. The most susceptible yeast was Candida glabrata, and the most resistant strain was Candida krusei, as the inhibition zone diameter generated by tested essential oils were the lowest and were limited to 13 mm (J. oxycedrus

    2D and 3D Non-planar Dynamic Rupture by a Finite Volume Method

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    Understanding the physics of the rupture process requires very sophisticated and accurate tools in which both the geometry of the fault surface and realistic frictional behaviours could interact during rupture propagation. New formulations have been recently proposed for modelling the dynamic shear rupture of non-planar faults (Ando et al., 2004; Cruz-Atienza &Virieux, 2004; Huang &Costanzo, 2004) providing highly accurate field estimates nearby the crack edges at the expanse of a simple medium description or high computational cost. We propose a new method based on the finite volume formulation to model the dynamic rupture propagation of non-planar faults. After proper transformations of the velocity-stress elastodynamic system of partial differential equations following an explicit conservative law, we construct an unstructured time-domain numerical formulation of the crack problem. As a result, arbitrary non-planar faults can be explicitly represented without extra computational cost. The analysis of the total discrete energy through the fault surface leads us to the specification of dynamic rupture boundary conditions which insure the correct discrete energy time variation and, therefore, the system stability. These boundary conditions are set on stress fluxes and not on stress values, which makes the fracture to have no thickness. Different shapes of cracks are analysed. We present an example of a bidimensional non-planar spontaneous fault growth in heterogeneous media as well as preliminary results of a highly efficient extension to the three dimensional rupture model based on the standard MPI

    Dynamic non-planar crack rupture by a finite volume method

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    International audienceModelling dynamic rupture for complex geometrical fault structures is performed through a finite volume method. After transformations for building up the partial differential system following explicit conservative law, we design an unstructured bi-dimensional time-domain numerical formulation of the crack problem. As a result, arbitrary non-planar faults can be explicitly represented without extra computational cost. On these complex surfaces, boundary conditions are set on stress fluxes and not on stress values. Prescribed rupture velocity gives accurate solutions with respect to analytical ones depending on the mesh refinement, while solutions for spontaneous propagation are analysed through numerical means. An example of non-planar spontaneous fault growth in heterogeneous media demonstrates the good behaviour of the proposed algorithm as well as specific difficulties of such numerical modelling
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