The submerged forearcs of Pacific subduction zones of North and South America are underlain by a coastally exposed basement of late Palaeozoic to early Tertiary age. Basement is either an igneous ...massif of an accreted intra-oceanic arc or oceanic plateau (e.g. Cascadia(?), Colombia), an in situ formed arc massif (e.g. Aleutian Arc) or an exhumed accretionary complex of low and high P/T metamorphic facies of late Palaeozoic (e.g. southern Chile, Patagonia) and Mesozoic age (e.g. Alaska). Seismic studies at Pacific forearcs image frontal prisms of trench sediment accreted to the seaward edge of forearc basement. Frontal prisms tend to be narrow (10–40 km), weakly consolidated and volumetrically small (∼35–40 km3/km of trench). In contrast, deep seismic imaging of submerged forearcs commonly reveals large volumes (∼2000 km3/km of trench) of underplated material accreted at subsurface depths of ∼10–30 km to the base of forearc basement. Underplates have been imaged below the southern Chile, Ecuador–Colombia, north Cascade, Alaska, and possibly the eastern Aleutian forearcs. Deep underplates have also been observed below the Japan and New Zealand forearcs. Seismic imaging of northern and eastern Pacific forearcs supports the conclusion drawn from field and laboratory studies that exposed low and high P/T accretionary complexes accumulated in the subsurface at depths of 10–30 km. It seems significant that imaged underplated bodies are characteristic of modern well-sedimented subduction zones. It also seems likely that large Pacific-rim underplates store a significant fraction of sediment subducted in Cenozoic time.
Earth's continental crust today is both created and destroyed by plate tectonic processes, a balance that is encapsulated by the traditional Chinese concept of yin-yang, whereby dualities act in ...concert as well as in opposition. Yin-yang conceptualizations of crustal growth and destruction are mostly related to plate tectonics; both occur mostly at subduction zones, by arc magmatic creation and by subduction removal. Crust is also created and destroyed by processes unrelated to plate tectonics, including losses by lower crust foundering and additions at hotspots. At present, creation and destruction of continental crust is either in balance (∼3.2 km
3
/year, or 3.2 AU) or more crust is being destroyed than created; the uncertainty comes from unknown deep losses of continental crust at collision zones and due to lower crustal foundering. The yin-yang creation-destruction balance changes over a supercontinent cycle, with crustal growth being greatest during supercontinent break-up due to high magmatic flux at new arcs and crustal destruction being greatest during supercontinent amalgamation due to subduction of continental material and increased sediment flux due to orogenic uplift. These conclusions challenge the widely held view that continental crust volume has increased over time due to plate tectonic activity; it is just as likely that this volume has decreased.
Establishment of telomere maintenance mechanisms is a universal step in tumor development to achieve replicative immortality. These processes leave molecular footprints in cancer genomes in the form ...of altered telomere content and aberrations in telomere composition. To retrieve these telomere characteristics from high-throughput sequencing data the available computational approaches need to be extended and optimized to fully exploit the information provided by large scale cancer genome data sets.
We here present TelomereHunter, a software for the detailed characterization of telomere maintenance mechanism footprints in the genome. The tool is implemented for the analysis of large cancer genome cohorts and provides a variety of diagnostic diagrams as well as machine-readable output for subsequent analysis. A novel key feature is the extraction of singleton telomere variant repeats, which improves the identification and subclassification of the alternative lengthening of telomeres phenotype. We find that whole genome sequencing-derived telomere content estimates strongly correlate with telomere qPCR measurements (r = 0.94). For the first time, we determine the correlation of in silico telomere content quantification from whole genome sequencing and whole genome bisulfite sequencing data derived from the same tumor sample (r = 0.78). An analogous comparison of whole exome sequencing data and whole genome sequencing data measured slightly lower correlation (r = 0.79). However, this is considerably improved by normalization with matched controls (r = 0.91).
TelomereHunter provides new functionality for the analysis of the footprints of telomere maintenance mechanisms in cancer genomes. Besides whole genome sequencing, whole exome sequencing and whole genome bisulfite sequencing are suited for in silico telomere content quantification, especially if matched control samples are available. The software runs under a GPL license and is available at https://www.dkfz.de/en/applied-bioinformatics/telomerehunter/telomerehunter.html .
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Hawaiian-Emperor hotspot track has a prominent bend, which has served as the basis for the theory that the Hawaiian hotspot, fixed in the deep mantle, traced a change in plate motion. However, ...paleomagnetic and radiometric age data from samples recovered by ocean drilling define an age-progressive paleolatitude history, indicating that the Emperor Sea-mount trend was principally formed by the rapid motion (over 40 millimeters per year) of the Hawaiian hotspot plume during Late Cretaceous to early-Tertiary times (81 to 47 million years ago). Evidence for motion of the Hawaiian plume affects models of mantle convection and plate tectonics, changing our understanding of terrestrial dynamics.
During the Integrated Ocean Drilling Program (IODP), a total of 41.54m of basement rock, consolidated volcaniclastic sediment, was recovered beneath a thin sediment cover. The drilled site is at the ...eastern end of the crestal area of Bowers Ridge, a north and westward sweeping offshoot of the Aleutian Arc into the Bering Sea. The volcanic sequence recovered from Holes U1342A and U1342D was divided into six major lithologic units. We used the single grain 40Ar–39Ar dating method performed by step-wise heated laser fusion technique to date andesites of Unit 1. Thereby two ages of Oligocene volcanism (34–32Ma, 28–26Ma) were distinguished each other according to our 40Ar–39Ar data. These ages refute a hypothesized Cretaceous origin in the North Pacific as an exotic arc massif or sector of the Hawaiian-Emperor chain and indicate that the Bowers Ridge is a Bering-Sea formed arc or remnant arc that ceased forming in the latest Oligocene to the earliest Miocene time.
R-type pyocins are high-molecular-weight bacteriocins that resemble bacteriophage tail structures and are produced by some Pseudomonas aeruginosa strains. R-type pyocins kill by dissipating the ...bacterial membrane potential after binding. The high-potency, single-hit bactericidal kinetics of R-type pyocins suggest that they could be effective antimicrobials. However, the limited antibacterial spectra of natural R-type pyocins would ultimately compromise their clinical utility. The spectra of these protein complexes are determined in large part by their tail fibers. By replacing the pyocin tail fibers with tail fibers of Pseudomonas phage PS17, we changed the bactericidal specificity of R2 pyocin particles to a different subset of P. aeruginosa strains, including some resistant to PS17 phage. We further extended this idea by fusing parts of R2 tail fibers with parts of tail fibers from phages that infect other bacteria, including Escherichia coli and Yersinia pestis, changing the killing spectrum of pyocins from P. aeruginosa to the bacterial genus, species, or strain that serves as a host for the donor phage. The assembly of active R-type pyocins requires chaperones specific for the C-terminal portion of the tail fiber. Natural and retargeted R-type pyocins exhibit narrow bactericidal spectra and thus can be expected to cause little collateral damage to the healthy microbiotae and not to promote the horizontal spread of multidrug resistance among bacteria. Engineered R-type pyocins may offer a novel alternative to traditional antibiotics in some infections.
Underlying the midslope Valparaiso Terrace, the Valparaiso Basin constitutes a unique and prominent deepwater forearc basin on the central Chile margin. The basin contains a 3–3.5 km thick sediment ...fill of late Cenozoic age. The seismic‐stratigraphic architecture of the Valparaiso Basin fill shows that margin‐wide subsidence above the underthrusting Juan Fernández Ridge, an aseismic volcanic swell crested with seamounts on the Nazca plate, characterized the basin evolution. Contemporaneously with margin subsidence and seaward rotation of the upper slope and shelf, the outer part of the forearc was deformed by thrust faulting above the leading flank of underthrusting seamounts that rotated the middle slope to a more horizontal attitude and formed seaward‐vergent outer forearc highs. Subsidence of the margin above the underthrusting Juan Fernández Ridge is ascribed to processes of subduction erosion, enhanced by factors related to subduction of the ridge, that caused dismemberment of upper plate material along the shallow aseismic part of the plate interface and transfer of material to the downgoing Nazca plate. Accelerated midslope subsidence, 55–75 km landward of the trench, coincides with the seaward limit of interplate seismicity, suggesting that enhanced basal erosion is related to the transition from aseismic to stick slip subduction behavior. Since subduction of the Juan Fernández Ridge began near 33°S ∼10 Ma ago, the Chile Trench north of 33°S is inferred to have retreated ∼3 km/Myr, and the midslope Valparaiso Basin subsided ∼0.3–0.5 km/Myr, approximating analogous Neogene rates for the Peruvian margin.
At least since the middle Miocene (∼16 Ma), subduction erosion has been the dominant process controlling the tectonic evolution of the Pacific margin of Costa Rica. Ocean Drilling Program Site 1042 ...recovered 16.5 Ma nearshore sediment at ∼3.9 km depth, ∼7 km landward of the trench axis. The overlying Miocene to Quaternary sediment contains benthic foraminifera documenting margin subsidence from upper bathyal (∼200 m) to abyssal (∼2000 m) depth. The rate of subsidence was low during the early to middle Miocene but increased sharply in the late Miocene‐early Pliocene (5–6.5 Ma) and at the Pliocene‐Pleistocene boundary (2.4 Ma). Foraminifera data, bedding dip, and the geometry of slope sediment indicate that tilting of the forearc occurred coincident with the onset of rapid late Miocene subsidence. Seismic images show that normal faulting is widespread across the continental slope; however, extension by faulting only accounts for a minor amount of the post‐6.5 Ma subsidence. Basal tectonic erosion is invoked to explain the subsidence. The short‐term rate of removal of rock from the forearc is about 107–123 km3 Myr−1 km−1. Mass removal is a nonsteady state process affecting the chemical balance of the arc: the ocean sediment input, with the short‐term erosion rate, is a factor of 10 smaller than the eroded mass input. The low 10Be concentration in the volcanic arc of Costa Rica could be explained by dilution with eroded material. The late Miocene onset of rapid subsidence is coeval with the arrival of the Cocos Ridge at the subduction zone. The underthrusting of thick and thermally younger ocean crust decreased the subduction angle of the slab along a large segment of the margin and changed the dynamic equilibrium of the margin taper. This process may have induced the increase in the rate of subduction erosion and thus the recycling of crustal material to the mantle.
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