The role of extension in the Miocene denudation of the Nevado-Filábride Complex, Betic Cordillera (SE Spain)

The Internal Zone of the Betic Cordillera, SE Spain, consists of a nappe stack of three complexes, the deepest of which is the Nevado-Filábride Complex. The zone is separated from the overlying Alpujárride Complex by a crustal scale shear zone that has variously been interpreted as a thrust or an extensional detachment. A suite of 74 new apatite and zircon fission track results have been obtained from the Nevado-Filábride Complex and these have been used to define regional cooling patterns for the complex. Rapid cooling (105°C–200°C Ma−1) is spatially related to the tectonic contact with the overlying Alpujárride Complex-Cooling to near-surface temperatures occurred first in the east (Sierra de los Filabres) during the mid-Serravallian (12±1 Ma) and was completed by the early Tortonian (9–8 Ma) in the west (Sierra Nevada). There is no correlation between fission track age and sample elevation. These results are consistent with tectonic unroofing of this complex, a finding that favors extension as the mechanism by which the two complexes were brought into contact. Extension spans the middle and earliest upper Miocene (12–8 Ma) in the study area and therefore lasted much longer than previously documented. A hypothesis is advanced which links oblique convergence between the Iberian plate and the Betic Internal Zones, resulting in crustal contraction at depth, with orogen parallel extension in the middle and upper crust

Testing the Use of Anisotropy of Magnetic Susceptibility (AMS) in Determining Genetic Origins of Paleoproterozoic Diamictites

The Huronian Supergroup (2.4-2.1 Ga) in Ontario, Canada is widely accepted as an important stratigraphic interval for interpreting Paleoproterozoic climate. This is because it contains some of the oldest glaciogenic rocks on the planet. However, massive and poorly-stratified diamictites in the Gowganda Formation of the Huronian Supergroup have varying depositional interpretations among sedimentologists (subglacial, rainout, sediment gravity flow etc.). Diamictites can occur from a variety of processes and, therefore, proper depositional interpretation is essential for unraveling detailed environmental conditions at the time of deposition. Anisotropy of magnetic susceptibility (AMS) looks at the orientation of magnetic particles within a rock and coupled with sedimentary investigation, can help interpret depositional processes. Rock magnetic data show that magnetism is carried by multi-vortex (titano)magnetite in fine-grained facies and includes the addition of a higher- coercivity contribution (potentially diagenetic goethite) in some sandstone facies. Most magnetic fabrics iii are oblate in shape and oriented transverse to flow, although vertical fabrics were found in sites that exhibited substantial deformation or dewatering. Results and observations from this project suggest that Gowganda sedimentation was dominated by sediment gravity flows, deposited on a marine post-glacial slope with a southwestern transport direction. Interpretation of depositional processes through a combination of AMS and sedimentologic observation provide a more comprehensive understanding of the environmental conditions controlling deposition, and in this case, painting a more elaborate picture of Paleoproterozoic climate transitions. In contrast with subglacially derived diamictites, which are deposited directly under glacial ice, those produced by sediment gravity flows suggest a more glacially distal to non- glacial environment. The presence of bedded diamictites, water escape structures, quarter structures around clasts, a general lack of shear horizons and striated/faceted clasts as well as an abundance of flow-transvers magnetic fabrics observed in most Gowganda facies suggest this more distal environment. However, subglacial deformation and deposition cannot be entirely ruled out for one oriented and striated boulder bed horizon producing flow-aligned magnetic fabrics; both characteristics of subglacial processes

A nucleosome-free dG-dC-rich sequence element promotes constitutive transcription of the essential yeast RIO1 gene

RIO1 is an essential gene that encodes a protein serine kinase and is transcribed constitutively at a very low level. Transcriptional activation of RIO1 dispenses with a canonical TATA box as well as with classical transactivators or specific DNAbinding factors. Instead, a dGdCrich sequence element, that is located 40 to 48 bp upstream the single site of mRNA initiation, is essential and presumably constitutes the basal promoter. In addition, we demonstrate here that this promoter element comprises a nucleosomefree gap which is centered at the dGdC tract and flanked by two positioned nucleosomes. This element is both, necessary and sufficient, for basal transcription initiation at the RIO1 promoter and, thus, constitutes a novel type of core promoter element

DNA Display II. Genetic Manipulation of Combinatorial Chemistry Libraries for Small-Molecule Evolution

Biological in vitro selection techniques, such as RNA aptamer methods and mRNA display, have proven to be powerful approaches for engineering molecules with novel functions. These techniques are based on iterative amplification of biopolymer libraries, interposed by selection for a desired functional property. Rare, promising compounds are enriched over multiple generations of a constantly replicating molecular population, and subsequently identified. The restriction of such methods to DNA, RNA, and polypeptides precludes their use for small-molecule discovery. To overcome this limitation, we have directed the synthesis of combinatorial chemistry libraries with DNA “genes,” making possible iterative amplification of a nonbiological molecular species. By differential hybridization during the course of a traditional split-and-pool combinatorial synthesis, the DNA sequence of each gene is read out and translated into a unique small-molecule structure. This “chemical translation” provides practical access to synthetic compound populations 1 million-fold more complex than state-of-the-art combinatorial libraries. We carried out an in vitro selection experiment (iterated chemical translation, selection, and amplification) on a library of 10(6) nonnatural peptides. The library converged over three generations to a high-affinity protein ligand. The ability to genetically encode diverse classes of synthetic transformations enables the in vitro selection and potential evolution of an essentially limitless collection of compound families, opening new avenues to drug discovery, catalyst design, and the development of a materials science “biology.

Recent trends in the size and the distribution of inherited wealth in the UK

In this paper we use HMRC estate statistics and micro-data from four UK household surveys to examine changes in the size, the composition and the distribution of inherited wealth in the UK over the period 1985-2010. Our findings indicate that the period under examination is characterised by a substantial increase in the flow of inheritance. This increase, which was particularly marked in the early 2000s, was mainly driven by the rise in house prices and to a lesser extent by the increase in the proportion of inheritances which included housing assets. The distribution of inheritance amongst recipients became more unequal over this period. However, the inequality-increasing effect from the greater dispersion in the distribution of inheritance was counterbalanced by the increase in the percentage of the population who received an inheritance, resulting in a small decrease in the inequality of inheritance for the population overall. Analysis of the distribution of inheritance by socio-economic status suggests a positive association between inheritance and socio-economic status with some suggestive evidence that this association might have strengthened over time. Overall, however, the value of inheritance for most people is rather small and the differences across groups rather moderate

The solution structural ensembles of RNA kink-turn motifs and their protein complexes

With the growing number of crystal structures of RNA and RNA/protein complexes, a critical next step is understanding the dynamic behavior of these entities in solution in terms of conformational ensembles and energy landscapes. To this end, we have used X-ray scattering interferometry (XSI) to probe the widespread RNA kink-turn motif and its complexes with the canonical kink-turn binding protein L7Ae. XSI revealed that the folded kink-turn is best described as a restricted conformational ensemble. The ions present in solution alter the nature of this ensemble, and protein binding can perturb the kink-turn ensemble without collapsing it to a unique state. This study demonstrates how XSI can reveal structural and ensemble properties of RNAs and RNA/protein complexes in solution and uncovers the behavior of an important RNA/protein motif. This type of information will be necessary to understand, predict, and engineer the behavior and function of RNAs and their protein complexes

Numerical estimation of entropy loss on dimerization: improved prediction of the quaternary structure of the GCN4 leucine zipper

A lattice based model of a protein is used to study the dimerization equilibrium of the GCN4 leucine zipper. Replica exchange Monte Carlo is used to determine the free energy of both the monomeric and dimeric forms as a function of temperature. The method of coincidences is then introduced to explicitly calculate the entropy loss associated with dimerization, and from it the free energy difference between monomer and dimer, as well as the corresponding equilibrium reaction constant. We find that the entropy loss of dimerization is a strong function of energy (or temperature), and that it is much larger than previously estimated, especially for high energy states. The results confirm that it is possible to study the dimerization equilibrium of GCN4 at physiological concentrations within the reduced representation of the protein employed

Crystal structures of the HCl salts of pseudopeptidic macrocycles display ‘‘knobs into holes’’ hydrophobic interactions between aliphatic side chains

The crystal structures of three HCl salts of pseudopeptidic macrocycles show a H-bonding tubular stack of the rings, where the amino acidic side chains (Val, Leu, Ile) display an inter-columnar “knobs into holes” hydrophobic interaction patter