Horizontal compressive stress regime on the northern Cascadia margin inferred from borehole breakouts

During Integrated Ocean Drilling Program Expedition 311 five boreholes were drilled across the accretionary prism of the northern Cascadia subduction zone. Logging-while-drilling borehole images are utilized to determine breakout orientations to define maximum horizontal compressive stress orientations. Additionally, wireline logging data at two of these sites and from Site 889 of Ocean Drilling Program Leg 146 are used to define breakouts from differences in the aperture of caliper arms. At most sites, the maximum horizontal compressive stress SHmax is margin-normal, consistent with plate convergence. Deviations from this trend reflect local structural perturbations. Our results do not constrain stress magnitudes. If the margin-normal compressional stress is greater than the vertical stress, the margin-normal SHmax direction we observe may reflect current locking of a velocity-weakening shallow megathrust and thus potential for trench-breaching, tsunamigenic rupture in a future megathrust earthquake

The oxidation status of Mic19 regulates MICOS assembly.

The function of mitochondria depends on the proper organization of mitochondrial membranes. The morphology of the inner membrane is regulated by the recently identified mitochondrial contact site and cristae organizing system (MICOS) complex. MICOS mutants exhibit alterations in crista formation, leading to mitochondrial dysfunction. However, the mechanisms that underlie MICOS regulation remain poorly understood. MIC19, a peripheral protein of the inner membrane and component of the MICOS complex, was previously reported to be required for the proper function of MICOS in maintaining the architecture of the inner membrane. Here, we show that human and yeast MIC19 proteins undergo oxidation in mitochondria and require the mitochondrial intermembrane space assembly (MIA) pathway, which couples the oxidation and import of mitochondrial intermembrane space proteins for mitochondrial localization. Detailed analyses identified yeast Mic19 in two different redox forms. The form that contains an intramolecular disulfide bond is bound to Mic60 of the MICOS complex. Mic19 oxidation is not essential for its integration into the MICOS complex but plays a role in MICOS assembly and the maintenance of proper inner membrane morphology. These findings suggest that Mic19 is a redox-dependent regulator of MICOS function

High and low molecular weight crossovers in the longest relaxation time dependence of linear cis-1,4 polyisoprene by dielectric relaxations

The dielectric relaxation of cis-1,4 Polyisoprene [PI] is sensitive not only to the local and segmental dynamics but also to the larger scale chain (end-to-end) fluctuations. We have performed a careful dielectric investigation on linear PI with various molecular weights in the range of 1 to 320 kg/mol. The broadband dielectric spectra of all samples were measured isothermally at the same temperature to avoid utilizing shift factors. For the low and medium molecular weight range, the comparisons were performed at 250 K to access both the segmental relaxation and normal mode peaks inside the available frequency window (1 mHz–10 MHz). In this way, we were able to observe simultaneously the effect of molecular mass on the segmental dynamics—related with the glass transition process—and on the end-to-end relaxation time of PI and thus decouple the direct effect of molecular weight on the normal mode from that due to the effect on the monomeric friction coefficient. The latter effect is significant for low molecular weight (M w < 33 kg/mol), i.e., in the range where the crossover from Rouse dynamics to entanglement limited flow occurs. Despite the conductivity contribution at low frequency, careful experiments allowed us to access to the normal mode signal for molecular weights as high as M w = 320 kg/mol, i.e., into the range of high molecular weights where the pure reptation behavior could be valid, at least for the description of the slowest chain modes. The comparison between the dielectric relaxations of PI samples with medium and high molecular weight was performed at 320 K. We found two crossovers in the molecular weight dependence of the longest relaxation time, the first around a molecular weight of 6.5 ± 0.5 kg/mol corresponding to the end of the Rouse regime and the second around 75 ± 10 kg/mol. Above this latter value, we find a power law compatible with exponent 3 as predicted by the De Gennes theory

An optimized metaproteomics protocol for a holistic taxonomic and functional characterization of microbial communities from marine particles

This study aimed to establish a robust and reliable metaproteomics protocol for an in-depth characterization of marine particle-associated (PA) bacteria. To this end, we compared six well-established protein extraction protocols together with different MS-sample preparation techniques using particles sampled during a North Sea spring algae bloom in 2009. In the final optimized workflow, proteins are extracted using a combination of SDS-containing lysis buffer and cell disruption by bead-beating, separated by SDS-PAGE, in-gel digested and analysed by LC-MS/MS, before MASCOT search against a metagenome-based database and data processing/visualization with the in-house-developed bioinformatics tools Prophane and Paver. As an application example, free-living (FL) and particulate communities sampled in April 2009 were analysed, resulting in an as yet unprecedented number of 9354 and 5034 identified protein groups for FL and PA bacteria, respectively. Our data suggest that FL and PA communities appeared similar in their taxonomic distribution, with notable exceptions: eukaryotic proteins and proteins assigned to Flavobacteriia, Cyanobacteria, and some proteobacterial genera were found more abundant on particles, whilst overall proteins belonging to Proteobacteria were more dominant in the FL fraction. Furthermore, our data points to functional differences including proteins involved in polysaccharide degradation, sugar- and phosphorus uptake, adhesion, motility, and stress response

55 Investigation of the RetS–GacAS regulatory network in clinical Pseudomonas aeruginosa isolates reveals evolutionary adaptation

Digitalitzat per Artypla

High Frequencies of Theropod Bite Marks Provide Evidence for Feeding, Scavenging, and Possible Cannibalism in a Stressed Late Jurassic Ecosystem

Bite marks provide direct evidence for trophic interactions and competition in the fossil record. However, variations in paleoecological dynamics, such as trophic relationships, feeding behavior, and food availability, govern the frequency of these traces. Theropod bite marks are particularly rare, suggesting that members of this clade might not often focus on bone as a resource, instead preferentially targeting softer tissues. Here, we present an unusually large sample of theropod bite marks from the Upper Jurassic Mygatt-Moore Quarry (MMQ). We surveyed 2,368 vertebrate fossils from MMQ in this analysis, with 684 specimens (28.885% of the sample) preserving at least one theropod bite mark. This is substantially higher than in other dinosaur-dominated assemblages, including contemporaneous localities from the Morrison Formation. Observed bite marks include punctures, scores, furrows, pits, and striations. Striated marks are particularly useful, diagnostic traces generated by the denticles of ziphodont teeth, because the spacing of these features can be used to provide minimum estimates of trace maker size. In the MMQ assemblage, most of the striations are consistent with denticles of the two largest predators known from the site: Allosaurus and Ceratosaurus. One of the bite marks suggests that a substantially larger theropod was possibly present at the site and are consistent with large theropods known from other Morrison Formation assemblages (either an unusually large Allosaurus or a separate, large-bodied taxon such as Saurophaganax or Torvosaurus). The distribution of the bite marks on skeletal elements, particularly those found on other theropods, suggest that they potentially preserve evidence of scavenging, rather than active predation. Given the relative abundances of the MMQ carnivores, partnered with the size-estimates based on the striated bite marks, the feeding trace assemblage likely preserves the first evidence of cannibalism in Allosaurus

Dynamical Probability Distribution Function of the SK Model at High Temperatures

The microscopic probability distribution function of the Sherrington-Kirkpatrick (SK) model of spin glasses is calculated explicitly as a function of time by a high-temperature expansion. The resulting formula to the third order of the inverse temperature shows that an assumption made by Coolen, Laughton and Sherrington in their recent theory of dynamics is violated. Deviations of their theory from exact results are estimated quantitatively. Our formula also yields explicit expressions of the time dependence of various macroscopic physical quantities when the temperature is suddenly changed within the high-temperature region.Comment: LaTeX, 6 pages, Figures upon request (here revised), To be published in J. Phys. Soc. Jpn. 65 (1996) No.

Spontaneous aggregation of the insulin-derived steric zipper peptide VEALYL results in different aggregation forms with common features.

Recently, several short peptides have been shown to self-assemble into amyloid fibrils with generic cross-beta spines, so-called steric zippers, suggesting common underlying structural features and aggregation mechanisms. Understanding these mechanisms is a prerequisite,for designing fibril-binding compounds and inhibitors of fibril formation. The hexapeptide VEALYL, corresponding to the residues B12-17 of full-length insulin, has been identified as one of these short segments. Here, we analyzed the structures of multiple, morphologically different (fibrillar, microcrystal-like, oligomeric) [C-13,N-15]VEALYL samples by solid-state nuclear magnetic resonance complemented with results from molecular dynamics simulations. By performing NHHC/CHHC experiments, we could determine that the beta-strands within a given sheet of the amyloid-like fibrils formed by the insulin hexapeptide VEALYL are stacked in an antiparallel manner, whereas the sheet-to-sheet packing arrangement was found to be parallel. Experimentally observed secondary chemical shifts for all aggregate forms, as well as empty set and Psi backbone torsion angles calculated with TALOS, are indicative of beta-strand conformation, consistent with the published crystal structure (PDB ID: 2OMQ). Thus, we could demonstrate that the structural features of all the observed VEALYL aggregates are in agreement with the previously observed homosteric zipper spine packing in the crystalline state, suggesting that several distinct aggregate morphologies share the same molecular architecture. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved