Structure-function dissection of Myxococcus xanthus CarD N-terminal domain, a defining member of the CarD-CdnL-TRCF family of RNA polymerase interacting proteins

© 2015 Bernal-Bernal et al. Two prototypes of the large CarD-CdnL-TRCF family of bacterial RNA polymerase (RNAP)-binding proteins, Myxococcus xanthus CarD and CdnL, have distinct functions whose molecular basis remain elusive. CarD, a global regulator linked to the action of several extracytoplasmic function (ECF) σ-factors, binds to the RNAP β subunit (RNAP-β) and to protein CarG via an N-terminal domain, CarDNt, and to DNA via an intrinsically unfolded C-terminal domain resembling eukaryotic high-mobility-group A (HMGA) proteins. CdnL, a CarDNt-like protein that is essential for cell viability, is implicated in σA-dependent rRNA promoter activation and interacts with RNAP-β but not with CarG. While the HMGA-like domain of CarD by itself is inactive, we find that CarDNt has low but observable ability to activate ECF σ-dependent promoters in vivo, indicating that the C-terminal DNA-binding domain is required to maximize activity. Our structure-function dissection of CarDNt reveals an N-terminal, five-stranded β-sheet Tudor-like domain, CarD1-72, whose structure and contacts with RNAP-β mimic those of CdnL. Intriguingly, and in marked contrast to CdnL, CarD mutations that disrupt its interaction with RNAP-β did not annul activity. Our data suggest that the CarDNt C-terminal segment, CarD61-179, may be structurally distinct from its CdnL counterpart, and that it houses at least two distinct and crucial function determinants: (a) CarG-binding, which is specific to CarD; and (b) a basic residue stretch, which is also conserved and functionally required in CdnL. This study highlights the evolution of shared and divergent interactions in similar protein modules that enable the distinct activities of two related members of a functionally important and widespread bacterial protein family.Peer Reviewe

A Note on Non-compact Cauchy surface

It is shown that if a space-time has non-compact Cauchy surface, then its topological, differentiable, and causal structure are completely determined by a class of compact subsets of its Cauchy surface. Since causal structure determines its topological, differentiable, and conformal structure of space-time, this gives a natural way to encode the corresponding structures into its Cauchy surface

Genotypic variability in radial resistance to water flow in olive roots and its response to temperature variations

As radial root resistance (Rp) represents one of the key components of the soil–plant–atmosphere continuum resistance catena modulating water transport, understanding its control is essential for physiologists, modelers and breeders. Reports of Rp, however, are still scarce and scattered in the scientific literature. In this study, we assessed genetic variability in Rp and its dependence on temperature in five widely used olive cultivars. In a first experiment, cultivar differences in Rp at 25 °C were evaluated from flow–pressure measurements in excised roots and subsequent analysis of root traits. In a second experiment, similar determinations were performed continually over a 5-h period in which temperature was gradually increased from 12 to 32 °C, enabling the assessment of Rp response to changing temperature. Despite some variability, our results did not show statistical differences in Rp among cultivars in the first experiment. In the second, cultivar differences in Rp were not significant at 12 °C, but they became so as temperature increased. Furthermore, the changes in Rp between 12 and 32 °C were higher than those expected by the temperature-driven decrease in water viscosity, with the degree of that change differing among cultivars. Also, Rp at 25 °C reached momentarily in the second experiment was consistently higher than in the first at that same, but fixed, temperature. Overall, our results suggest that there is limited variability in Rp among the studied cultivars when plants have been exposed to a given temperature for sufficient time. Temperature-induced variation in Rp might thus be partly explained by changes in membrane permeability that occur slowly, which explains why our values at 25 °C differed between experiments. The observed cultivar differences in Rp with warming also indicate faster acclimation of Rp to temperature changes in some cultivars than others.info:eu-repo/semantics/acceptedVersio

On the causal properties of warped product spacetimes

It is shown that the warped product spacetime P=M *_f H, where H is a complete Riemannian manifold, and the original spacetime M share necessarily the same causality properties, the only exceptions being the properties of causal continuity and causal simplicity which present some subtleties. For instance, it is shown that if diamH=+\infty, the direct product spacetime P=M*H is causally simple if and only if (M,g) is causally simple, the Lorentzian distance on M is continuous and any two causally related events at finite distance are connected by a maximizing geodesic. Similar conditions are found for the causal continuity property. Some new results concerning the behavior of the Lorentzian distance on distinguishing, causally continuous, and causally simple spacetimes are obtained. Finally, a formula which gives the Lorentzian distance on the direct product in terms of the distances on the two factors (M,g) and (H,h) is obtained.Comment: 22 pages, 2 figures, uses the package psfra

El mundo funerario Tardorromano en Baelo Claudia. Novedades de las intervenciones arqueológicas del 2005 en la muralla oriental

The first results of an archaeological excavation carried out in the Baelo Claudia city wall are shown. The area is the one between the so called “Puerta de Carteia” ant the 4th tower . Six stratigraphic soundings have been developed, fi ve of them outside the wall and only one inside. A late roman cementery has been discovered in the upper part of the sequence, dating back to the V-VII c. AD. An archaeological, paleoanthropologic, paleopathologic study of the skeletals, and the funeral ritual has been carried out. Eight tombs have been digged up, three double and four single, containing seven adults and four children. Two tombs show an interesting disposition of skeletal remains, some of them reusing the graves, and a newly born with an anomalous position. Also, animals phalanges could have been placed in the children tombs as amulets, as well as a marine shell probably as a symbol of a fi sherman. All of adults present skeletal stress work and nutritional indicators.Se presentan los primeros resultados de una actuación arqueológica realizada en la muralla oriental de Baelo Claudia, comprendida entre la denominada Puerta de Carteia y la torre 4. Se han realizado seis sondeos estratigráfi cos, cinco extramuros y uno al interior de la cinta muraria, en los cuales se ha documentado una necrópolis tardorromana (ss. V-VII d.C.) en la parte superior de la secuencia estratigráfi ca. Se exponen los resultados preliminares del estudio arqueológico, paleoantropológico y paleopatológico, y del ritual funerario, de los individuos hallados en las ocho tumbas excavadas. El total de individuos exhumados fue de once (siete adultos y cuatro infantiles), hallándose unos interesantes rituales de reutilización de las tumbas, un recién nacido en una posición “anómala” y falanges de animales depositadas, quizás como amuletos, así como una caracola como ajuar de un posible almadrabero. Tanto en hombres como en mujeres se advierten marcadores paleoocupacionales que muestran que realizaban una actividad laboral intensa

Killing spinor initial data sets

A 3+1 decomposition of the twistor and valence-2 Killing spinor equation is made using the space spinor formalism. Conditions on initial data sets for the Einstein vacuum equations are given so that their developments contain solutions to the twistor and/or Killing equations. These lead to the notions of twistor and Killing spinor initial data. These notions are used to obtain a characterisation of initial data sets whose development are of Petrov type N or D.Comment: 31 pages, submitted to J. Geom. Phy

The Multimode Resource Constrained Project Scheduling Problem for Repetitive Activities in Construction Projects

[EN] In construction projects, resource availability might limit the implementation of ideal schedules. Especially, when repetitive activities are involved, traditional resource¿constrained project scheduling problem (RCPSP) models fail to allocate the resource consumption in an efficient manner. Besides, actual models only provide local optimal solutions and do not incorporate activity acceleration routines. To fulfill this gap, partially, a mathematical optimization model, the multimode RCPSP for repetitive activities in construction projects, is proposed and solved to optimality; it takes into account acceleration routines under real construction scenarios using spreadsheets. The article shows a complete computational experimentation over a real construction project, considering several scenarios of resource availabilities and continuity conditions. The model allows analyzing the resources efficiency indexes comparing them to resource consumptions, continuity of activities, and objective functions that reveal that fragmented activities do not provide better resource efficiency outcomes.This research was partially supported by the FAPA program of Universidad de Los Andes, Colombia (code P14.246922.005/01). The authors would also like to thank the research group of Construction Engineering and Management (INgeco) at Universidad de los Andes.García-Nieves, J.; Ponz-Tienda, JL.; Salcedo-Bernal, A.; Pellicer Armiñana, E. (2018). The Multimode Resource Constrained Project Scheduling Problem for Repetitive Activities in Construction Projects. Computer-Aided Civil and Infrastructure Engineering. 33(8):655-671. https://doi.org/10.1111/mice.12356S65567133

Gamma Irradiation of Aqueos Solution of L-Aspartic Acid, L-Aspartic Acid in Solid State, and L-Aspartic Acid Adsorbed into Na-Montmorillonite: Its Relevance in Chemistry Prebiotic

Aspartic acid is an amino acid present in the modern proteins, however, is considered a primitive amino acid hence its importance in prebiotic chemistry experiments studies. In some works of prebiotic chemistry have been studied the synthesis and the stability of organic matter under high energy sources, and the role of clays has been highlighted due to clays that can affect the reaction mechanisms in the radiolytic processes. The present work is focused on the study of the role of Namontmorillonite in the gamma radiolysis processes of L-aspartic acid. Gamma radiolysis processes were carried out in three different systems a) L-aspartic acid in aqueous solution; b) L-aspartic acid in solid-state; and c) L-aspartic acid adsorbed into Na-montmorillonite. L-aspartic acid was analyzed by high-performance liquid chromatography−electrospray ionization−mass spectrometry (HPLCESI-MS). The results showed that the decomposition of L-aspartic acid considerably decreased in the presence of clay thus highlighting the protector role of clays and favors the stability of organic matter even under the possible high energy conditions of primitive environments. The principal product ofgamma radiolysis of L-aspartic acid was succinic acid produced by deamination reaction. On the other hand, when aspartic acid was irradiated in solid-state the main product was the L-aspartic acid dimer. Both radiolysis products are important for chemical evolution processes for L-aspartic acid in primitive environments