212 research outputs found

    Constraints on upper crustal fluid circulation and seismogenesis from in-situ outcrop quantification of complex fault zone permeability

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    : The permeability of fault zones plays a significant role on the distribution of georesources and on seismogenesis in the brittle upper crust, where both natural and induced seismicity are often associated with fluid migration and overpressure. Detailed models of the permeability structure of fault zones are thus necessary to refine our understanding of natural fluid pathways and of the mechanisms leading to fluid compartmentalization and possible overpressure in the crust. Fault zones commonly contain complex internal architectures defined by the spatial juxtaposition of "brittle structural facies" (BSF), which progressively and continuously form and evolve during faulting and deformation. We present the first systematic in-situ outcrop permeability measurements from a range of BSFs from two architecturally complex fault zones in the Northern Apennines (Italy). A stark spatial heterogeneity of the present-day permeability (up to four orders of magnitude) even for tightly juxtaposed BSFs belonging to the same fault emerges as a key structural and hydraulic feature. Insights from this study allow us to better understand how complex fault architectures steer the 3D hydraulic structure of the brittle upper crust. Fault hydraulic properties, which may change through space but also in time during an orogenesis and/or individual seismic cycles, in turn steer the development of overpressured volumes, where fluid-induced seismogenesis may localize

    Constraints on upper crustal fluid circulation and seismogenesis from in-situ outcrop quantification of complex fault zone permeability

    Get PDF
    The permeability of fault zones plays a significant role on the distribution of georesources and on seismogenesis in the brittle upper crust, where both natural and induced seismicity are often associated with fluid migration and overpressure. Detailed models of the permeability structure of fault zones are thus necessary to refine our understanding of natural fluid pathways and of the mechanisms leading to fluid compartmentalization and possible overpressure in the crust. Fault zones commonly contain complex internal architectures defined by the spatial juxtaposition of "brittle structural facies" (BSF), which progressively and continuously form and evolve during faulting and deformation. We present the first systematic in-situ outcrop permeability measurements from a range of BSFs from two architecturally complex fault zones in the Northern Apennines (Italy). A stark spatial heterogeneity of the present-day permeability (up to four orders of magnitude) even for tightly juxtaposed BSFs belonging to the same fault emerges as a key structural and hydraulic feature. Insights from this study allow us to better understand how complex fault architectures steer the 3D hydraulic structure of the brittle upper crust. Fault hydraulic properties, which may change through space but also in time during an orogenesis and/or individual seismic cycles, in turn steer the development of overpressured volumes, where fluid-induced seismogenesis may localize

    Gut bacteria facilitate adaptation to crop rotation in the western corn rootworm

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    11917-11922Insects are constantly adapting to human-driven landscape changes; however, the roles of their gut microbiota in these processes remain largely unknown. The western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) (Coleoptera: Chrysomelidae) is amajor corn pest that has been controlled via annual rotation between corn (Zea mays) and nonhost soybean (Glycine max) in the United States. This practice selected for a 'rotation-resistant' variant (RR-WCR) with reduced ovipositional fidelity to cornfields.When in soybean fields, RRWCRs also exhibit an elevated tolerance of antiherbivory defenses (i.e., cysteine protease inhibitors) expressed in soybean foliage. Here we show that gut bacterial microbiota is an important factor facilitating this corn specialist's (WCR's) physiological adaptation to brief soybean herbivory. Comparisons of gut microbiota between RR- and wild-type WCR (WT-WCR) revealed concomitant shifts in bacterial community structure with host adaptation to soybean diets. Antibiotic suppression of gut bacteria significantly reduced RR-WCR tolerance of soybean herbivory to the level of WT-WCR, whereas WTWCR were unaffected. Our findings demonstrate that gut bacteria help to facilitate rapid adaptation of insects inmanaged ecosystems

    Melatonin prevents chemical-induced Haemopoietic cell death

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    Melatonin (MEL), a methoxyindole synthesized by the pineal gland, is a powerful antioxidant in tissues as well as within cells, with a fundamental role in ameliorating homeostasis in a number of specific pathologies. It acts both as a direct radical scavenger and by stimulating production/activity of intracellular antioxidant enzymes. In this work, some chemical triggers, with different mechanisms of action, have been chosen to induce cell death in U937 hematopoietic cell line. Cells were pre-treated with 100 μM MEL and then exposed to hydrogen peroxide or staurosporine. Morphological analyses, TUNEL reaction and Orange/PI double staining have been used to recognize ultrastructural apoptotic patterns and to evaluate DNA behavior. Chemical damage and potential MEL anti-apoptotic effects were quantified by means of Tali® Image-Based Cytometer, able to monitor cell viability and apoptotic events. After trigger exposure, chromatin condensation, micronuclei formation and DNA fragmentation have been observed, all suggesting apoptotic cell death. These events underwent a statistically significant decrease in samples pre-treated with MEL. After caspase inhibition and subsequent assessment of cell viability, we demonstrated that apoptosis occurs, at least in part, through the mitochondrial pathway and that MEL interacts at this level to rescue U937 cells from death. © 2014 by the authors; licensee MDPI, Basel, Switzerland

    Architecture and permeability structure of the Sibillini Mts. Thrust and influence upon recent, extension-related seismicity in the central Apennines (Italy) through fault-valve behavior

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    The central Apennines are a fold-thrust belt currently affected by post-orogenic ex-tensional seismicity. To constrain the influ-ence that the inherited thrust-related struc-tures exert on the present seismic behavior of the belt, we provide the high-resolution structural and hydraulic characterization of one of the most external exposed thrust fault systems of the central Apennines, the Sibil-lini Mts. Thrust Front (STF). We integrate structural mapping, multiscale structural analysis, and in situ air permeability on the brittle structural facies of the thrust zone. We also performed K-Ar dating of selected fault rocks to better constrain structural in-heritance. The STF is defined by a complex, similar to 300-m-thick deformation zone involving Meso-Cenozoic marl and limestone that re-sults from the accommodation of both seis-mic and aseismic slip during shortening. Permeability measurements indicate that the low permeability (10-2 divided by 10-3 D) of the marly rich host rock diminishes within the thrust zone, where the principal slip surfaces and associated S-C structures represent efficient hydraulic barriers (permeability down to similar to 3 x 10-10 D) to sub-vertical fluid flow. Field data and K-Ar dating indicate that the STF began its evolution ca. 7 Ma (early Messin-ian). We suggest that the studied thrust zone may represent a barrier for the upward migration of deep fluids at the hypocentral depth of present-day extensional earth-quakes. We also speculate on the influence that similar deformation zones may have at depth on the overall regional seismotectonic pattern by causing transient fluid overpres-sures and, possibly, triggering cyclic exten-sional earthquakes on normal faults prone to slip while crosscutting the earlier thrust zones (as per a classic fault valve behavior). This mechanism may have controlled the ori-gin of the 2016-2017 central Apennines dev-astating earthquakes

    Patterns of differential gene expression in adult rotation - resistant and wild - type western corn rootworm digestive tracts

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    692-704The western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is an important pest of corn. Annual crop rotation between corn and soybean disrupts the corn-dependent WCR life cycle and is widely adopted to manage this pest. This strategy selected for rotation-resistant (RR) WCR with reduced ovipositional fidelity to corn. Previous studies revealed that RR-WCR adults exhibit greater tolerance of soybean diets, different gut physiology, and host-microbe interactions compared to rotation-susceptible wild types (WT). To identify the genetic mechanisms underlying these phenotypic changes, a de novo assembly of the WCR adult gut transcriptome was constructed and used for RNA-sequencing analyses of RNA libraries from different WCR phenotypes fed with corn or soybean diets. Global gene expression profiles of WT- and RR-WCR were similar when feeding on corn diets, but different when feeding on soybean. Using network- based methods, we identified gene modules transcriptionally correlated with the RR phenotype. Gene ontology enrichment analyses indicated that the functions of these modules were related to metabolic processes, immune responses, biological adhesion, and other functions/processes that appear to correlate to documented traits in RR populations. These results suggest that gut transcriptomic divergence correlated with brief soybean feeding and other physiological traits may exist between RR- and WT-WCR adults
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