Paleostrain stratigraphic analysis of calcite twins across the Cambrian-Ordovician unconformity in the Tethyan Himalaya, Spiti and Zanskar valley regions, India

Abstract Calcite strain analyses were conducted on low-grade Cambrian and Carboniferous limestone samples collected above and below the Cambrian-Ordovician unconformity in the Spiti and Zanskar valley regions of the NW Himalaya in order to compare strain patterns in rocks that bracket an enigmatic early Paleozoic tectonic episode. All samples record a layer-parallel shortening strain at a high angle to folds and faults in the Tethyan Himalayan fold-thrust belt. In the Carboniferous samples, we relate these layer-parallel strains to the onset of Cenozoic deformation within the Tethyan Himalayan fold-thrust belt. The Cambrian sample from the Spiti area contains a layer-parallel shortening strain even though the Cambrian-Ordovician unconformity is angular. This suggests that the twinning strains in the Cambrian sample may have formed at the onset of early Paleozoic folding and subsequent erosion, and that early phases of Cenozoic shortening were coaxial to early Paleozoic shortening. The maximum shortening axis in the Carboniferous samples, which is probably parallel to the early thrust transport direction in the Tethyan Himalayan fold-thrust belt, is parallel to the NE movement of India with respect to Eurasia in the Middle Eocene, suggesting that it might closely correspond to the India/Eurasian slip direction during this time period

Gaussian Quantum Information

The science of quantum information has arisen over the last two decades centered on the manipulation of individual quanta of information, known as quantum bits or qubits. Quantum computers, quantum cryptography and quantum teleportation are among the most celebrated ideas that have emerged from this new field. It was realized later on that using continuous-variable quantum information carriers, instead of qubits, constitutes an extremely powerful alternative approach to quantum information processing. This review focuses on continuous-variable quantum information processes that rely on any combination of Gaussian states, Gaussian operations, and Gaussian measurements. Interestingly, such a restriction to the Gaussian realm comes with various benefits, since on the theoretical side, simple analytical tools are available and, on the experimental side, optical components effecting Gaussian processes are readily available in the laboratory. Yet, Gaussian quantum information processing opens the way to a wide variety of tasks and applications, including quantum communication, quantum cryptography, quantum computation, quantum teleportation, and quantum state and channel discrimination. This review reports on the state of the art in this field, ranging from the basic theoretical tools and landmark experimental realizations to the most recent successful developments.Comment: 51 pages, 7 figures, submitted to Reviews of Modern Physic

Human oxygen sensing may have origins in prokaryotic elongation factor Tu prolyl-hydroxylation

Significance The Fe(II)- and 2-oxoglutarate (2OG)-dependent hypoxia-inducible transcription factor prolyl-hydroxylases play a central role in human oxygen sensing and are related to other prolyl-hydroxylases involved in eukaryotic collagen biosynthesis and ribosomal modification. The finding that a PHD-related prolyl-hydroxylase in Pseudomonas spp. regulates pyocyanin biosynthesis supports prokaryotic origins for the eukaryotic prolyl-hydroxylases. The identification of the switch I loop of elongation factor Tu (EF-Tu) as a Pseudomonas prolyl-hydroxylase domain containing protein (PPHD) substrate provides evidence of roles for 2OG oxygenases in both translational and transcriptional regulation. A structure of the PPHD:EF-Tu complex, the first to the authors' knowledge of a 2OG oxygenase with its intact protein substrate, reveals that major conformational changes occur in both PPHD and EF-Tu and will be useful in the design of new prolyl-hydroxylase inhibitors. </jats:p

Parallel laboratory evolution and rational debugging reveal genomic plasticity to S. cerevisiae synthetic chromosome XIV defects

Synthetic chromosome engineering is a complex process due to the need to identify and repair growth defects and deal with combinatorial gene essentiality when rearranging chromosomes. To alleviate these issues, we have demonstrated novel approaches for repairing and rearranging synthetic Saccharomyces cerevisiae genomes. We have designed, constructed, and restored wild-type fitness to a synthetic 753,096-bp version of S. cerevisiae chromosome XIV as part of the Synthetic Yeast Genome project. In parallel to the use of rational engineering approaches to restore wild-type fitness, we used adaptive laboratory evolution to generate a general growth-defect-suppressor rearrangement in the form of increased TAR1 copy number. We also extended the utility of the synthetic chromosome recombination and modification by loxPsym-mediated evolution (SCRaMbLE) system by engineering synthetic-wild-type tetraploid hybrid strains that buffer against essential gene loss, highlighting the plasticity of the S. cerevisiae genome in the presence of rational and non-rational modifications. </p

Identification of Genetic Factors that Modify Clinical Onset of Huntington’s Disease

SummaryAs a Mendelian neurodegenerative disorder, the genetic risk of Huntington’s disease (HD) is conferred entirely by an HTT CAG repeat expansion whose length is the primary determinant of the rate of pathogenesis leading to disease onset. To investigate the pathogenic process that precedes disease, we used genome-wide association (GWA) analysis to identify loci harboring genetic variations that alter the age at neurological onset of HD. A chromosome 15 locus displays two independent effects that accelerate or delay onset by 6.1 years and 1.4 years, respectively, whereas a chromosome 8 locus hastens onset by 1.6 years. Association at MLH1 and pathway analysis of the full GWA results support a role for DNA handling and repair mechanisms in altering the course of HD. Our findings demonstrate that HD disease modification in humans occurs in nature and offer a genetic route to identifying in-human validated therapeutic targets in this and other Mendelian disorders.PaperCli

CAG repeat not polyglutamine length determines timing of Huntington’s disease onset

Variable, glutamine-encoding, CAA interruptions indicate that a property of the uninterrupted HTT CAG repeat sequence, distinct from the length of huntingtin’s polyglutamine segment, dictates the rate at which Huntington’s disease (HD) develops. The timing of onset shows no significant association with HTT cis-eQTLs but is influenced, sometimes in a sex-specific manner, by polymorphic variation at multiple DNA maintenance genes, suggesting that the special onset-determining property of the uninterrupted CAG repeat is a propensity for length instability that leads to its somatic expansion. Additional naturally occurring genetic modifier loci, defined by GWAS, may influence HD pathogenesis through other mechanisms. These findings have profound implications for the pathogenesis of HD and other repeat diseases and question the fundamental premise that polyglutamine length determines the rate of pathogenesis in the “polyglutamine disorders.

Characterisation of breccias in sediment core CRP-1 (Table 1)

CoreScan images were examined to determine the origin of breccias in the CRP-1 core. Breccias occur throughout the core. but are dominant deformation features in the upper 85 m. Breccia textures, boundaries and texture arrangements suggest that in situ fracturing and horizontal planar shearing are important deformation mechanisms in the upper part of the Miocene section. Forceful injections of silt and clay into fractures point to dewatering of overpressurised sediment. Breccias located below 55 metres below the sea floor (mbsf) occur associated with soft-sediment deformation, which is absent in younger intervals of the core. Deformation styles interpreted from the breccia textures, their downcore distribution, and the relations of breccias with sequence boundaries and lithologies, such as diamictites and graded beds, suggest brecciation occurred as a result of subglacial shearing and mass-movement processes. These mechanisms were also proposed for breccias and soft sediment deformation features observed in other McMurdo Sound cores. Subglacial shearing was a possible cause for the development of two thick brecciated intervals at ~44 and at ~79 mbsf, whereas slope failure and redeposition was probably the cause of brecciation below ~85 mbsf

(Table 1) Core intervals of sediment core CRP-3 that have been stitched and reorientated to North

CRP-3 cores were not orientated with respect to North during coring operations. However, borehole televiewer (BHTV) logging did obtain azimuthally orientated images of the borehole wall, and core processing included digital imaging of the outer surface of 85% of the cores. Images of many individual core segments can be digitally joined, or stitched, by rotating them to match the shapes of their adjoining surfaces and then closing the gap. By aligning features (fractures, bedding, and clasts) on stitched-core images with correlative features on orientated BHTV images, we reorientated 231 m of core, or 25% of the cored interval. We estimate that the orientation uncertainty is ±10° for entire stitched-core intervals, and ±15° for individual features such as a single fracture or palaeomagnetic sample. Reliability of core orientations was confirmed by comparing azimuths of bedding and fractures measured directly within these reorientated cores to those measured within orientated borehole televiewer images