Recordings of earthquakes by a temporary deployment of 84 short period seismometers in northern Chile were used to derive regional 3D seismic velocity models for the Taltal segment. We used the ...Regressive ESTimator (REST) package for event detection and automatic onset estimation of P‐ and S‐wave arrival times to create an earthquake catalog with 23,985 hypocenters. We followed standard acceptability criteria (i.e., azimuthal gap and residual cutoff) to create a high‐quality data set and inverted for 3D Vp, Vs and Vp/Vs models using local earthquake tomography. Plots of hypocenters from the catalog, comprising 16,349 earthquakes, reveal active structures in the upper crust, dip changes along the slab and fracturing within the oceanic crust. Moreover, the wavespeed models illuminate anomalies in both the Nazca and South American plates that correlate with the observed seismicity distribution, including variations from low (1.75) to high (>1.80) Vp/Vs near the Atacama fault system on the coastline and the Domeyko Fault System in the forearc. The seismic velocity models also provide evidence for fluid circulation caused by the subducting Taltal ridge on the coast and partial melting feeding a volcanic complex close to the Andes. Finally, the observed low Vp/Vs ratios (∼1.75) are associated with copper mining operations in the area, suggesting that this kind of imaging can be used to characterize the distribution of potential ore deposits in the area.
Plain Language Summary
We recorded earthquakes in northern Chile with a network of 84 seismometers and used the arrival times of P and S waves to generate 3D wavespeed models of the region. These models reveal several structures in the area, including changes in the angle of the subducting Nazca plate and fractures in the oceanic crust. Among features observed in both the Nazca and South American plates are the Atacama and Domeyko fault systems. We also infer fluid circulation caused by the subducting Taltal ridge and partial melting that feeds a volcanic complex near the Andes. Low values of the Vp/Vs ratio are associated with copper mining operations in the area and could be used to identify new ore deposits.
Key Points
Seismic catalog reveals forearc activity and slab dip variations. Vp anomalies in the oceanic plate are related to mid‐depth seismic events
Velocity models uncover anomalies in Salar de Atacama and Taltal ridge that might influence seismicity distribution and hydration changes
Shallow low Vp/Vs (<1.75) correlate with ore deposits; deep high Vp/Vs (>1.80) suggest fluids and melting for the Lastarria volcanic complex
The subduction zone of central Chile (36°S) has produced some of the world's largest earthquakes and significant volcanic eruptions. Understanding the fluid fluxes and structure of the subducting ...slab and overriding plate can provide insight into the tectonic processes responsible for both seismicity and magmatism. Broadband and long‐period magnetotelluric data were collected along a 350‐km profile in central Chile and Argentina and show a regional geoelectric strike of 15 ± 19° east of north. The preferred two‐dimensional inversion model included the geometry of the subducting Nazca plate as a constraint. On the upper surface of the Nazca plate, conductors were interpreted as fluids expelled from the downgoing slab via compaction at shallow depth (C1) and metamorphic reactions at depths of 40–90 km (C2 and C3). At greater depths (130 km), a conductor (C7) is interpreted as a region of partial melt related to deserpentinization in the backarc. A resistor on the slab interface (R1) is coincident with a high‐velocity anomaly which was interpreted as a strong asperity which may affect the coseismic slip behavior of large megathrust earthquakes at this latitude. Correlations with seismicity suggest slab fluids alter the forearc mantle and define the downdip limit of the seismogenic zone. Beneath the volcanic arc, several upper crustal conductors (C4 and C5) represent partial melt beneath the Tatara‐San Pedro Volcano and the Laguna del Maule Volcanic Field. A deeper lower crustal conductor (C6) underlies both volcanoes and suggests a connected network of melt in a thermally mature lower crust.
Plain Language Summary
Central Chile has experienced some of the world's largest earthquakes and many large volcanic eruptions. These disasters are caused by the tectonic processes in this region as the oceanic Nazca plate subducts beneath the South American plate. As the oceanic plate subducts, water is released, which can increase pressure, lubricate the plates, and lower rock melting points to produce magma. As such, fluids are an important control on where earthquakes and volcanoes occur. We image the electrical conductivity of this region using the magnetotelluric method since saline water and/or partial melt both have a high conductivity. Several conductors are imaged near the plate interface that can be related to presence of water or partial melt. Correlations between the locations of conductors and zones of low seismic velocity reported in previous seismic studies support the idea that there is an anomalous block of rock at 30‐km depth, which increases friction along the subducting plate interface. This could explain why the 2010 Maule earthquake did not rupture far inland. A conductor at 40‐km depth correlates with a gap between two clusters of earthquakes, which suggests that fluids may chemically alter the continental plate and reduce friction in this gap.
Key Points
A magnetotelluric survey was collected over the Chilean subduction zone at 36 degrees south in order to map geoelectric structure
Conductors show important dehydration reactions along plate interface as well as important zones of crustal melt beneath the volcanic arc
Correlations with previous seismic results show a possible asperity on plate interface, which may influence megathrust rupture
Herpesvirus infections are highly prevalent in the human population and persist for life. They are often acquired subclinically but potentially progress to life-threatening diseases in ...immunocompromised individuals. The interferon system is indispensable for the control of herpesviral replication. However, the responsible antiviral effector mechanisms are not well characterized. The type I interferon-induced, human myxovirus resistance 2 (
) gene product MxB, a dynamin-like large GTPase, has recently been identified as a potent inhibitor of HIV-1. We now show that MxB also interferes with an early step of herpesvirus replication, affecting alpha-, beta-, and gammaherpesviruses before or at the time of immediate early gene expression. Defined MxB mutants influencing GTP binding and hydrolysis revealed that the effector mechanism against herpesviruses is thoroughly different from that against HIV-1. Overall, our findings demonstrate that MxB serves as a broadly acting intracellular restriction factor that controls the establishment of not only retrovirus but also herpesvirus infection of all three subfamilies.
Human herpesviruses pose a constant threat to human health. Reactivation of persisting herpesvirus infections, particularly in immunocompromised individuals and the elderly, can cause severe diseases, such as zoster, pneumonia, encephalitis, or cancer. The interferon system is relevant for the control of herpesvirus replication as exemplified by fatal disease outcomes in patients with primary immunodeficiencies. Here, we describe the interferon-induced, human
gene product MxB as an efficient restriction factor of alpha-, beta-, and gammaherpesviruses. MxB has previously been described as an inhibitor of HIV-1. Importantly, our mutational analyses of MxB reveal an antiviral mechanism of herpesvirus restriction distinct from that against HIV-1. Thus, the dynamin-like MxB GTPase serves as a broadly acting intracellular restriction factor that controls retrovirus as well as herpesvirus infections.
Schmallenberg virus (SBV) is an insect-transmitted orthobunyavirus that can cause abortions and congenital malformations in the offspring of ruminants. Even though the two viral surface glycoproteins ...Gn and Gc are involved in host cell entry, the specific cellular receptors of SBV are currently unknown. Using genome-wide CRISPR-Cas9 forward screening, we identified 3'-phosphoadenosine 5'-phosphosulfate (PAPS) transporter 1 (PAPST1) as an essential factor for SBV infection. PAPST1 is a sulfotransferase involved in heparan sulfate proteoglycan synthesis encoded by the solute carrier family 35 member B2 gene (
). SBV cell surface attachment and entry were largely reduced upon the knockout of
, whereas the reconstitution of
in these cells fully restored their susceptibility to SBV infection. Furthermore, treatment of cells with heparinase diminished infection with SBV, confirming that heparan sulfate plays an important role in cell attachment and entry, although to various degrees, heparan sulfate was also found to be important to initiate infection by two other bunyaviruses, La Crosse virus and Rift Valley fever virus. Thus, PAPST1-triggered synthesis of cell surface heparan sulfate is required for the efficient replication of SBV and other bunyaviruses.
SBV is a newly emerging orthobunyavirus (family
) that has spread rapidly across Europe since 2011, resulting in substantial economic losses in livestock farming. In this study, we performed unbiased genome-wide CRISPR-Cas9 screening and identified PAPST1, a sulfotransferase encoded by
, as a host entry factor for SBV. Consistent with its role in the synthesis of heparan sulfate, we show that this activity is required for efficient infection by SBV. A comparable dependency on heparan sulfate was also observed for La Crosse virus and Rift Valley fever virus, highlighting the importance of heparan sulfate for host cell infection by bunyaviruses. Thus, the present work provides crucial insights into virus-host interactions of important animal and human pathogens.
Innate immunity is critically dependent on the rapid production of interferon in response to intruding viruses. The intracellular pathogen recognition receptors RIG-I and MDA5 are essential for ...interferon induction by viral RNAs containing 5' triphosphates or double-stranded structures, respectively. Viruses with a negative-stranded RNA genome are an important group of pathogens causing emerging and re-emerging diseases. We investigated the ability of genomic RNAs from substantial representatives of this virus group to induce interferon via RIG-I or MDA5. RNAs isolated from particles of Ebola virus, Nipah virus, Lassa virus, and Rift Valley fever virus strongly activated the interferon-beta promoter. Knockdown experiments demonstrated that interferon induction depended on RIG-I, but not MDA5, and phosphatase treatment revealed a requirement for the RNA 5' triphosphate group. In contrast, genomic RNAs of Hantaan virus, Crimean-Congo hemorrhagic fever virus and Borna disease virus did not trigger interferon induction. Sensitivity of these RNAs to a 5' monophosphate-specific exonuclease indicates that the RIG-I-activating 5' triphosphate group was removed post-transcriptionally by a viral function. Consequently, RIG-I is unable to bind the RNAs of Hantaan virus, Crimean-Congo hemorrhagic fever virus and Borna disease virus. These results establish RIG-I as a major intracellular recognition receptor for the genome of most negative-strand RNA viruses and define the cleavage of triphosphates at the RNA 5' end as a strategy of viruses to evade the innate immune response.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
La Crosse virus (LACV) is a major cause of pediatric encephalitis and aseptic meningitis in the Midwestern, Mid-Atlantic, and Southern United States, where it is an emerging pathogen. The LACV Gc ...glycoprotein plays a critical role in the neuropathogenesis of LACV encephalitis as the putative virus attachment protein. Previously, we identified and experimentally confirmed the location of the LACV fusion peptide within Gc and generated a panel of recombinant LACVs (rLACVs) containing mutations in the fusion peptide as well as the wild-type sequence. These rLACVs retained their ability to cause neuronal death in a primary embryonic rat neuronal culture system, despite decreased replication and fusion phenotypes. To test the role of the fusion peptide in vivo, we tested rLACVs in an age-dependent murine model of LACV encephalitis. When inoculated directly into the CNS of young adult mice (P28), the rLACV fusion peptide mutants were as neurovirulent as the rLACV engineered with a wild-type sequence, confirming the results obtained in tissue culture. In contrast, the fusion peptide mutant rLACVs were less neuroinvasive when suckling (P3) or weanling (P21) mice were inoculated peripherally, demonstrating that the LACV fusion peptide is a determinant of neuroinvasion, but not of neurovirulence. In a challenge experiment, we found that peripheral challenge of weanling (P21) mice with fusion peptide mutant rLACVs protected from a subsequent WT-LACV challenge, suggesting that mutations in the fusion peptide are an attractive target for generating live-attenuated virus vaccines. Importantly, the high degree of conservation of the fusion peptide amongst the
and, structurally, other arboviruses suggests that these findings are broadly applicable to viruses that use a class II fusion mechanism and cause neurologic disease.
A profile of broadband magnetotelluric stations was acquired between 2009 and 2016 at 35°–36°S in the Southern Volcanic Zone of the Chilean Andes to image the subduction zone and its relation with ...the volcanic arc at this latitude. This transect extends from the Coastal Cordillera across the Central Valley and the volcanic arc of the Principal Cordillera to the Argentine border. Two active volcanic complexes are found along this profile: Tatara-San Pedro is located on the modern volcanic front, and the Laguna del Maule volcanic field is found approximately 30 km to the east. The latter exhibits considerable signs of unrest, such as uplift rates of up to 25 cm/year, and has produced a high concentration of silicic eruptions in the last 25 ky. The data covered the period range from 0.001 to 1000 s. Robust processing techniques were used, including remote reference, and dimensionality was investigated by estimation of geoelectric strike, skew and analysis of the induction arrows. The data were modeled using a 2D inversion algorithm to produce a resistivity model which was consistent with surface geology and seismicity. The final resistivity model shows a generally resistive fore-arc structure, coincident with the tectonic environment, and a wide conductive region from the volcanic front to the east. This suggests a broad region of magmatism throughout the arc, related to three distinct magma bodies, associated with the Tatara-San Pedro and Laguna del Maule volcanic complexes and the Mariposa Geothermal System.
People in need of care, chronic or acute, often present problematic food intake and special nutritional needs. Integrated, person-centred and pro-active food and nutritional care delivery has been ...proven effective for people in health care. However, skills mismatches have been reported in different professions involved, which also applies to the role of chefs in healthcare. The EU funded project NECTAR aims at closing this gap by creating a new job profile, called Chef Gastro-Engineering (CGE). The current publication summarizes the status quo in hospitals and gives a perspective on the future role of chefs in integrated healthcare delivery.
Many viruses subvert the cellular interferon (IFN) system with so-called IFN antagonists. Bunyamwera virus (BUNV) belongs
to the family Bunyaviridae and is transmitted by arthropods. We have recently ...identified the nonstructural protein NSs of BUNV as a virulence factor
that inhibits IFN- β gene expression in the mammalian host. Here, we demonstrate that NSs targets the RNA polymerase II (RNAP II) complex. The
C-terminal domain (CTD) of RNAP II consists of 52 repeats of the consensus sequence YSPTSPS. Phosphorylation at serine 5 is
required for efficient initiation of transcription, and subsequent phosphorylation at serine 2 is required for mRNA elongation
and 3â²-end processing. In BUNV-infected mammalian cells, serine 5 phosphorylation occurred normally. Furthermore, RNAP II
was able to bind to the IFN- β gene promoter as revealed by chromatin immunoprecipitation analysis, indicating that the initiation of transcription was
not disturbed by NSs. However, NSs prevented CTD phosphorylation at serine 2, suggesting a block in transition from initiation
to elongation. Surprisingly, no interference with CTD phosphorylation was observed in insect cells. Our results indicate that
BUNV uses an unconventional mechanism to block IFN synthesis in the mammalian host by directly dysregulating RNAP II. Moreover,
by inducing a general transcriptional block, NSs may contribute to the lytic infection observed in mammalian cells as opposed
to persistent infection in the insect host.
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