El sistema turbidítico conglomerático de Andatza (Pirineos occidentales): Estratigrafía, sedimentología y control estructural

This is a field-based work that describes the stratigraphy and sedimentology of the Andatza Conglomerate Formation. Based on facies analysis three facies associations of a coarse-grained turbidite system and the related slope have been identified: (1) an inner fan of a turbidite system (or canyon) and (2) a low- and (3) a high-gradient muddy slope respectively. The spatial distribution of the facies associations and the palaeocurrent analysis allow to interpret a depositional model for the Andatza Conglomerates consisting of an L-shaped, coarse-grained turbidite system, whose morphology was structurally controlled by synsedimentary basement-involved normal faults. The coarse-grained character of the turbidite system indicates the proximity of the source area, with the presence of a narrow shelf that fed the turbidite canyon from the north.En este trabajo se describe la estratigrafía y sedimentología de la Formación Conglomerados de Andatza. Mediante el análisis de facies se han interpretado tres asociaciones de facies principales correspondientes a un sistema turbidítico (de grano grueso) y al talud: un sistema turbidítico interno (o cañón), un talud fangoso de alto gradiente y otro de bajo gradiente. La distribución cartográfica de las asociaciones de facies junto con el análisis de paleocorrientes describen un modelo sedimentario de sistema turbidítico de grano grueso en forma de “L” para los Conglomerados de Andatza, cuya morfología fue controlada por fallas normales sinsedimentarias de basamento. El carácter grosero del tamaño de grano de este sistema turbidítico indica la proximidad del área fuente de los conglomerados, que alimentaría el cañón turbidítico desde el norte a través de una estrecha plataforma marina

Fauna de Ammonites del tránsito complejo Urgoniano-Flysch negro entre Germka y Deba (Albiense medio y superior, region Vascocantábrica Septentrional)

En este trabajo se describe la fauna de ammonites de los complejos Urgoniano y Supraurgoniano (Flysch Negro), entre Gernika y Deba (Bizkaia y Gipuzkoa). El Complejo Urgoniano está formado por altos carbonatados y surcos lutíticos separados por fallas activas. Las calizas son fundamentalmente micríticas con corales y rudistas, y las lutitas adyacentes presentan megabrechas calizas y conglomerados silíceos resedimentados. El Flysch Negro está constituido por capas métricas de areniscas turbidIticas que pasan lateralmente a lutitas y areniscas turbiditicas delgadas y a areniscas bioturbadas. Los ammonites encontrados en estas dos unidades se agrupan en dos asociaciones principales, que corresponden al Albiense medio (Complejo Urgoniano) y a la parte inferior del Albiense superior (Flysch Negro). Dentro de la primera asociación se incluyen especies de los siguientes géneros: Phylloceras, Anagaudryceras, Kossmatella, Tetragonites, Puzosia, Desmoceras, Lyelliceras, Tegoceras, Neophlycticeras, Metahamites y Hamites. La segunda asociación se caracteriza por la presencia de especies de: Kossmatella, Puzosia, Hysteroceras y Morton iceras. La fauna descrita es cosmopolita y presenta caracteres tanto atlánticos como del Tethys.The fauna of ammonites from the Urgonian and Supraurgonian (Black Flysch) complexes, between Gemika and Deba (Bizkaia and Gipuzkoa), is described. The Urgonian consist of limestone horsts and lutite troughs separated by active faults. Limestones are mainly rudist and coral micrites and the adjacent lutites enclose resedimented limestone megabreccias and quartz conglomerates. The Black Flysch is made up of thick sandy turbidites passing laterally to lutites and thin sandy turbidites and to thoroughly bioturbated sandstones. Two ammonite associations are distinguished from these units, corresponding to the Middle Albian (Urgoman complex) and to the early Upper Albian (Black Flysch complex). Species of the following genera are described within the first association (Middle Albian): Phylloceras, Anagaudryceras, Kossmatella, Tetragonites, Puzosia, Desmoceras, Lyeiiceras, Tegoceros, Neophlycticeras, Metahamites and Hamites. The second association (early Upper Albian) includes species of: Kossmatella, Puzosia, Hysteroceras and Mortoniceras. The fauna described is cosmopolitan and its constituent taxa show atlantic as well as tethyan characteristics

Recognition of aminoacyl-tRNA: a common molecular mechanism revealed by cryo-EM

The accuracy of ribosomal translation is achieved by an initial selection and a proofreading step, mediated by EF-Tu, which forms a ternary complex with aminoacyl(aa)-tRNA. To study the binding modes of different aa-tRNAs, we compared cryo-EM maps of the kirromycin-stalled ribosome bound with ternary complexes containing Phe-tRNAPhe, Trp-tRNATrp, or Leu-tRNALeuI. The three maps suggest a common binding manner of cognate aa-tRNAs in their specific binding with both the ribosome and EF-Tu. All three aa-tRNAs have the same ‘loaded spring' conformation with a kink and twist between the D-stem and anticodon stem. The three complexes are similarly integrated in an interaction network, extending from the anticodon loop through h44 and protein S12 to the EF-Tu-binding CCA end of aa-tRNA, proposed to signal cognate codon–anticodon interaction to the GTPase centre and tune the accuracy of aa-tRNA selection

The Cryo-EM Structure of a Complete 30S Translation Initiation Complex from Escherichia coli

Formation of the 30S initiation complex (30S IC) is an important checkpoint in regulation of gene expression. The selection of mRNA, correct start codon, and the initiator fMet-tRNAfMet requires the presence of three initiation factors (IF1, IF2, IF3) of which IF3 and IF1 control the fidelity of the process, while IF2 recruits fMet-tRNAfMet. Here we present a cryo-EM reconstruction of the complete 30S IC, containing mRNA, fMet-tRNAfMet, IF1, IF2, and IF3. In the 30S IC, IF2 contacts IF1, the 30S subunit shoulder, and the CCA end of fMet-tRNAfMet, which occupies a novel P/I position (P/I1). The N-terminal domain of IF3 contacts the tRNA, whereas the C-terminal domain is bound to the platform of the 30S subunit. Binding of initiation factors and fMet-tRNAfMet induces a rotation of the head relative to the body of the 30S subunit, which is likely to prevail through 50S subunit joining until GTP hydrolysis and dissociation of IF2 take place. The structure provides insights into the mechanism of mRNA selection during translation initiation

SecM-Stalled Ribosomes Adopt an Altered Geometry at the Peptidyl Transferase Center

A structure of a ribosome stalled during translation of the SecM peptide provides insight into the mechanism by which the large subunit active site is inactivated

Molecular dynamics of ribosomal elongation factors G and Tu

Translation on the ribosome is controlled by external factors. During polypeptide lengthening, elongation factors EF-Tu and EF-G consecutively interact with the bacterial ribosome. EF-Tu binds and delivers an aminoacyl-tRNA to the ribosomal A site and EF-G helps translocate the tRNAs between their binding sites after the peptide bond is formed. These processes occur at the expense of GTP. EF-Tu:tRNA and EF-G are of similar shape, share a common binding site, and undergo large conformational changes on interaction with the ribosome. To characterize the internal motion of these two elongation factors, we used 25 ns long all-atom molecular dynamics simulations. We observed enhanced mobility of EF-G domains III, IV, and V and of tRNA in the EF-Tu:tRNA complex. EF-Tu:GDP complex acquired a configuration different from that found in the crystal structure of EF-Tu with a GTP analogue, showing conformational changes in the switch I and II regions. The calculated electrostatic properties of elongation factors showed no global similarity even though matching electrostatic surface patches were found around the domain I that contacts the ribosome, and in the GDP/GTP binding region

EMDataBank.org: unified data resource for CryoEM

Cryo-electron microscopy reconstruction methods are uniquely able to reveal structures of many important macromolecules and macromolecular complexes. EMDataBank.org, a joint effort of the Protein Data Bank in Europe (PDBe), the Research Collaboratory for Structural Bioinformatics (RCSB) and the National Center for Macromolecular Imaging (NCMI), is a global ‘one-stop shop’ resource for deposition and retrieval of cryoEM maps, models and associated metadata. The resource unifies public access to the two major archives containing EM-based structural data: EM Data Bank (EMDB) and Protein Data Bank (PDB), and facilitates use of EM structural data of macromolecules and macromolecular complexes by the wider scientific community

Paleomagnetic and paleocurrent preliminary data from the Mid-Cretaceous black flysh group, Western Pyrenees: Tectonic implications

Datos paleomagnéticos y de paleocorrientes preliminares correspondientes a depósitos turbidíticos en torno al monoclinal sinclinal de Aitzeta (margen norte de la Cuenca Vasco-Cantábrica) indican rotaciones de eje vertical de bloques de edad Albiense superior (Subzona C. auritus) y terciaria (?). Los datos, combinados con los rasgos estructurales del área, evidencian una rotación antihoraria de ~27º (bloque de Deba) durante la Subzona C. auritus, y rotaciones antihorarias de ~27º y ~55º (bloques de Galdonamendi y Mizkia, respectivamente) y horarias de ~40º (bloque de Andutz) de edad terciaria (?). Los resultados obtenidos son coherentes y permiten reconstruir la compleja historia estructural y deposicional del área.Published3-62.2. Laboratorio di paleomagnetismoN/A or not JCRreserve

Paleomagnetic and paleocurrent preliminary data from the Mid-Cretaceous black flysh group, Western Pyrenees: Tectonic implications

Datos paleomagnéticos y de paleocorrientes preliminares correspondientes a depósitos turbidíticos en torno al monoclinal sinclinal de Aitzeta (margen norte de la Cuenca Vasco-Cantábrica) indican rotaciones de eje vertical de bloques de edad Albiense superior (Subzona C. auritus) y terciaria (?). Los datos, combinados con los rasgos estructurales del área, evidencian una rotación antihoraria de ~27º (bloque de Deba) durante la Subzona C. auritus, y rotaciones antihorarias de ~27º y ~55º (bloques de Galdonamendi y Mizkia, respectivamente) y horarias de ~40º (bloque de Andutz) de edad terciaria (?). Los resultados obtenidos son coherentes y permiten reconstruir la compleja historia estructural y deposicional del área