Structure de l’industrie et l’avantage secteur de la téléphone mobile en Algérie 2003-2008.

For the company has a competitive position, it must recommend a strategy that takes into account competition, the industry structure, organizational aspects competitive forces within the meaning of M.PORTER, and the strategic groups in the said area . In Algeria, the mobile sector has experienced rapid growth, while incorporating the latest technologies in the future. Our study focuses on the structure of this sector which is both recent onset but which offers the structural featur

Social Constraints and the Quest for a Spiritual Identity: A Comparative Study between Theodore Dreiser’s An American Tragedy and Richard Wright’s Native Son

The present research delves into the social constraints, behind the tragedies of Clyde Griffiths and Bigger Thomas: protagonists of An American Tragedy and Native Son .The study equally endeavors at shedding light on the protagonist’s journey of quest for a religious identity. The dissertation therefore aims at (1) eliciting the various societal constraints (2) identifying the different aspects necessary to the establishment of a spiritual identity (3) disclosing the influence of the social constraints on the establishment of a spiritual identity within the materialistic confines of America’s twentieth century society. In their fictional renditions, Theodore Dreiser and Richard Wright denounce society for holding responsibility of the protagonists’ acts. For them, Griffiths and Thomas are not culprits, since they do not act out of their free will. Society imposes on them heavy restraints and compulsion. Accordingly, their criminality is the inevitable ramification of society’s restrictions. From a naturalistic perspective, societal constraints are to censure, not the weak Thomas and Griffiths, entirely ignorant to the law of social deterministic game. Dreiser and Wright, in other words, view them as blameless products of a disclosed environment, which predetermined their actions. In a sense, the two novels constitute an excruciating testimony to the consequences of the social constraints. On the other hand, Thomas and Griffiths make a spiritual journey towards a greater understanding of the Christian faith. Yet, attainting an inner spiritual meaning is once more inhibited by an outer struggle against societal strains. Thomas and Griffiths recognize that although belonging to a Christian nation, their spiritual selfhood is a matter of question. For them, religion is a source of pain and suffering as it makes them acknowledge the fact that they are killers without any considerations of their human condition. It is very appalling dilemma; the feeling of the spiritual unbelonging or the pain of assuming the other’s faults. In fact, the nature of this work - two long novels and writers coming from different backgrounds - entails recoursing to eclectic approach in which psychoanalysis and biographical criticism play a significant part. Besides, the research will equally employ some other theories such as Historicism, Marxist theory and Race Critical Theory

Escherichia coli TatA and TatB Proteins Have N-out, C-in Topology in Intact Cells

The twin arginine protein transport (Tat) system translocates folded proteins across the cytoplasmic membrane of prokaryotes and the thylakoid membrane of chloroplasts. In Escherichia coli, TatA, TatB, and TatC are essential components of the machinery. A complex of TatB and TatC acts as the substrate receptor, whereas TatA is proposed to form the Tat transport channel. TatA and TatB are related proteins that comprise an N-terminal transmembrane helix and an adjacent amphipathic helix. Previous studies addressing the topological organization of TatA have given conflicting results. In this study, we have addressed the topological arrangement of TatA and TatB in intact cells by labeling of engineered cysteine residues with the membrane-impermeable thiol reagent methoxypolyethylene glycol maleimide. Our results show that TatA and TatB share an N-out, C-in topology, with no evidence that the amphipathic helices of either protein are exposed at the periplasmic side of the membrane. We further show that the N-out, C-in topology of TatA is fixed and is not affected by the absence of other Tat components or by the overproduction of a Tat substrate. These data indicate that topological reorganization of TatA is unlikely to accompany Tat-dependent protein transport

Modification of 13-hydroperoxide lyase expression in olive affects plant growth and results in altered volatile profile

Este trabajo demostró el papel del gen 13-HPL en la ruta de síntesis de compuesto volátiles en plantas de olivo. Se obtuvieron plantas con la sobreexpresión o el silenciamiento del gen y se estudió el efecto resultante. El silenciamiento del gen por transformación genética con RNAi mediada por A. tumefaciens condujo a la disminución de compuestos volátiles de 6 carbonos y un fuerte incremento de los de 5 carbonos, modificando el perfil de volátiles producidos, además de conllevar un fenotipo de plantas débiles y de pequeño crecimiento.This work was supported by the OLEAGEN Project funded by the Fundaci´on Genoma Espa˜na, Junta de Andalucía through Instituto de Investigación y Formación Agraria y Pesquera (IFAPA) and Corporación Tecnológica de Andalucía (CTA)

Appearance of Membrane Compromised, Viable But Not Culturable and Culturable Rhizobial Cells as a Consequence of Desiccation

For agricultural purposes, drought related stresses negatively affect the Rhizobiaceae in at least three ways. Firstly, rhizobial populations are affected by desertification of agricultural soils. Secondly, the quality of dry-base inocula, also called formula, is negatively affected by a drying step, and thirdly, rhizosphere bacteria protect crop-plants against drought. Although survival of cultivatable bacteria has been studied intensively in dry-base seed inocula and in-vitro, thus far research has only marginally addressed the bacterial cell, its cellular structures and physiology. Many questions remain regarding the sensing of and physiological response of rhizobia to desiccation. This review will focus on the three different fractions of cells after desiccation, the membrane compromised cells, the viable but not culturable cells and the culturable cells

Obtención de plantas compuestas de olivo mediante transformación con Agrobacterium rhizogenes

La transformación con Agrobacterium rhizogenes ha sido utilizada como herramienta para estudios de genómica funcional en raíces (Collier et al. 2005 Plant Journal 43:449-457; Baranski et al. 2006 Plant Cell Reports 25:190-197). La obtención de plantas compuestas de olivo (sistema radicular transgénico y parte aérea no transgénica), mediante esta técnica, sería de gran ayuda para estudiar la interacción de esta especie con los patógenos de suelo Verticillium dahliae y Rosellinia necatrix. En este trabajo, se presentan las primeras aproximaciones para la transformación de brotes micropropagados de olivo mediante A. rhizogenes. Se han utilizado 2 genotipos procedentes de semilla del cv. Picual, uno con baja capacidad de enraizamiento, P1, y otro, con alta capacidad, P138, y dos cepas de A. rhizogenes: A4, que contiene el plásmido silvestre Ri, y K599, con el plásmido binario pKGWFS7.0-35SP, que incluye el gen marcador gfp. En el caso del genotipo P1, en la fase de co-cultivo con la bacteria, se añadieron al medio 3 mg/l AIB, para facilitar la formación de raíces. En el genotipo P138, se obtuvo un 100% de enraizamiento tanto en el tratamiento control como en el de brotes infectados con la cepa A4; sin embargo, aquéllos inoculados con la cepa K599 sólo alcanzaron un 70% de enraizamiento. Asimismo, se observó que el 61% de las raíces obtenidas tras la infección con K599 mostraron fluorescencia verde bajo el microscopio confocal. En el genotipo P1, el 60% de las plantas control formaron raíces, frente al 10% de plantas infectadas con A4 y ninguna con la cepa K599. La naturaleza transgénica de las raíces obtenidas tras la infección con A4, en ambos genotipos, se evaluará mediante amplificación por PCR del gen RolB.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Growth of Leuconostoc mesenteroides NRRL-B523 in an alkaline medium: Suboptimal pH growth inhibition of a lactic acid bacterium

Bacterial profile modification (BPM), a form of tertiary oil recovery, diverts water from the water-flooded high-permeability zone into the oil-bearing low-permeability zone. During field use, exopolymer-producing bacteria plug the high-permeability zone only in the immediate vicinity of the injection point (the near-well bore region). For effective BPM the plug must penetrate far into the formation. Slowing the specific growth rate, lengthening the lag phase, and slowing the polymerization rate are techniques that can prolong the onset of biopolymer gelation and extend the depth of the biological plug. In batch experiments, the growth of Leuconostoc mesenteroides NRRL-B523 was inhibited by the synergistic effects of high substrate loading and an alkaline pH. Exponential growth was delayed up to 190 h. It was observed that cell division was significantly retarded until the medium pH, reduced by the acid byproducts of fermentation, reached a critical value of 6.79 ± 0.06. A mathematical model was developed to describe the relationship between specific growth rate, lag time, and medium pH. © 2004 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34343/1/20315_ftp.pd

The Twin-Arginine Pathway for Protein Secretion

About 20 to 30% of proteins synthesized in the bacterial cytoplasm are destined for extracytoplasmic locations ( 1 ). They pass the cytoplasmic membrane using specialized transport systems, involving gated pores, energy, and signal peptides to direct protein export. Two major protein export systems are known, namely, the general secretory (Sec) pathway and the twin-arginine translocation (Tat) pathway ( Fig. 1 ). Most proteins use the Sec pathway, common to all domains of life. The Tat pathway, the focus of this review, is more exclusive. For example, it has only ∼30 native substrates in the Gram-negative bacterium Escherichia coli, and it is not universally conserved ( 2 )

Transport of Folded Proteins by the Tat System

The twin-arginine protein translocation (Tat) system has been characterized in bacteria, archaea and the chloroplast thylakoidal membrane. This system is distinct from other protein transport systems with respect to two key features. Firstly, it accepts cargo proteins with an N-terminal signal peptide that carries the canonical twin-arginine motif, which is essential for transport. Second, the Tat system only accepts and translocates fully folded cargo proteins across the respective membrane. Here, we review the core essential features of folded protein transport via the bacterial Tat system, using the three-component TatABC system of Escherichia coli and the two-component TatAC systems of Bacillus subtilis as the main examples. In particular, we address features of twin-arginine signal peptides, the essential Tat components and how they assemble into different complexes, mechanistic features and energetics of Tat-dependent protein translocation, cytoplasmic chaperoning of Tat cargo proteins, and the remarkable proofreading capabilities of the Tat system. In doing so, we present the current state of our understanding of Tat-dependent protein translocation across biological membranes, which may serve as a lead for future investigations