The Plasmid Mobilome of the Model Plant-Symbiont Sinorhizobium meliloti: Coming up with New Questions and Answers

Rhizobia are Gram-negative Alpha- andBetaproteobacteria living in the underground that have theability to associate with legumes for the establishment ofnitrogen-fixing symbioses.Sinorhizobium melilotiinparticular—the symbiont ofMedicago,Melilotus, andTrigonellaspp.—has for the past decades served as a model organism forinvestigating, at the molecular level, the biology, biochemistry,and genetics of a free-living and symbiotic soil bacterium ofagricultural relevance. To date, the genomes of seven differentS. melilotistrains have been fully sequenced and annotated,and several other draft genomic sequences are also available(http://www.ncbi.nlm.nih.gov/genome/genomes/1004).The vast amount of plasmid DNA thatS. melilotifrequently bears(up to 45% of its total genome), the conjugative ability of some ofthose plasmids, and the extent of the plasmid diversity hasprovided researchers with an extraordinary system to investigatefunctional and structural plasmid molecular biology within theevolutionary context surrounding a plant-associated modelbacterium. Current evidence indicates that the plasmidmobilome inS. melilotiis composed of replicons varying greatlyin size and having diverse conjugative systems and propertiesalong with different evolutionary stabilities and biological roles.While plasmids carrying symbiotic functions (pSyms) are knownto have high structural stability (approaching that ofchromosomes), the remaining plasmid mobilome (referred to asthe non-pSym,functionally cryptic,oraccessorycompartment)has been shown to possess remarkable diversity and to be highlyactive in conjugation. In light of the modern genomic andcurrent biochemical data on the plasmids ofS. meliloti,the current article revises their main structural components,their transfer and regulatory mechanisms, and their potentialas vehicles in shaping the evolution of the rhizobial genome.Fil: Lagares, Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Sanjuán Pinilla, Juan. Consejo Superior de Investigaciones Científicas. Estación Experimental del Zaidín; EspañaFil: Pistorio, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentin

Development of an HPLC-based oligosaccharide synthesizer

Carbohydrates are the most abundant molecules on Earth. They are involved in a wide range of fundamental biological processes: anti-inflammation, immune response, joint lubrication, cell growth, antigenic determination. Carbohydrates are also held responsible for many damaging cellular processes, such as bacterial and viral infections, development of tumors, etc.. Therefore, the development of effective methods for the synthesis of complex carbohydrates has become a critical area of glycosciences. One challenge that stands out is the stereocontrol in the synthesis of glycosidic bonds, the linkage that serves as the only means to connect simple monosaccharides into complex oligomeric networks. Beyond this, the lack of a simple automated platform, similar to that utilized in the preparation of oligonucleotides and oligopeptides, significantly hampers access to oligosaccharides. The work presented herein addresses both of these limitations of oligosaccharides synthesis: stereocontrol and the lack of automation. The stereocontrolled formation of very challenging betamannosidic linkages has been achieved using a new reaction called Hydrogen-bondmediated Aglycone Delivery (HAD). Automation in Oligosaccharide solid phase synthesis has been accomplished using an AgilentTM HPLC, model 1260 Infinity, that was adapted to the polymer supported synthesis of oligosaccharides. The utility of the HAD reaction and the HPLC-based automated technology has been demonstrated by the synthesis of different oligosaccharide sequences in high stereoselectivities and yields

Patterns of listening comprehension strategies used by upper secondary school students

Maestría en Inglés Orientación Linguística AplicadaThis work investigated the listening comprehension patterns of memory, cognitive, compensation, metacognitive, and social affective strategies used by a group of upper secondary school students of English in a coeducational confessional private school from Córdoba, Argentina. The range and the types of strategies used by the participants were examined, and differences in strategy use between males and females were compared according to the task that they performed.Pistorio, María Inés. Universidad Nacional de Córdoba. Facultad de Lenguas; Argentin

Comparative genomic analysis of Acinetobacter spp. plasmids originating from clinical settings and environmental habitats

Bacteria belonging to the genus Acinetobacter have become of clinical importance over the last decade due to the development of a multi-resistant phenotype and their ability to survive under multiple environmental conditions. The development of these traits among Acinetobacter strains occurs frequently as a result of plasmid-mediated horizontal gene transfer. In this work, plasmids from nosocomial and environmental Acinetobacter spp. collections were separately sequenced and characterized. Assembly of the sequenced data resulted in 19 complete replicons in the nosocomial collection and 77 plasmid contigs in the environmental collection. Comparative genomic analysis showed that many of them had conserved backbones. Plasmid coding sequences corresponding to plasmid specific functions were bioinformatically and functionally analyzed. Replication initiation protein analysis revealed the predominance of the Rep_3 superfamily. The phylogenetic tree constructed from all Acinetobacter Rep_3 superfamily plasmids showed 16 intermingled clades originating from nosocomial and environmental habitats. Phylogenetic analysis of relaxase proteins revealed the presence of a new sub-clade named MOBQAci, composed exclusively of Acinetobacter relaxases. Functional analysis of proteins belonging to this group showed that they behaved differently when mobilized using helper plasmids belonging to different incompatibility groups.Fil: Salto, Ileana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Torres Tejerizo, Gonzalo Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentina. Universitat Bielefeld. Center For Biotechnology; AlemaniaFil: Wibberg, Daniel. Universitat Bielefeld. Center For Biotechnology; AlemaniaFil: Pühler, Alfred. Universitat Bielefeld. Center For Biotechnology; AlemaniaFil: Schlüter, Andreas. Universitat Bielefeld. Center For Biotechnology; AlemaniaFil: Pistorio, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentin

Analysis of fracture behaviour in active materials for lithium ion batteries

Abstract Several strong points make lithium ion battery one of the most widespread energy storage system. Nevertheless, one of the biggest drawbacks is the progressive damage which affects active materials, and influences cycle life as well. The hosting process of lithium ions causes the rise of mechanical stress in active material, which ultimately leads to the propagation of micro-flaws already present in fresh material. Finally, the damage of active material and solid-electrolyte interphase growth caused by cracks propagation result in capacity drop. The distribution of Mode I stress intensity factor is calculated along the semi-elliptical crack front on the outer surface and in the core of a three-dimensional spherical active material particle. A 3D and 2D finite element method analysis is performed in ANSYS Mechanical APDL starting from the mechanical stress state in active material computed with the electrochemical-mechanical model presented in previous works. The model is built using collapsed singular elements along the crack front, the not-singular version of these elements is used to model the outlying region of the crack area. The dependence of stress intensity factor on geometry size is deepened to evaluate the most critical condition. Moreover, the influence of current rate on stress intensity factor is investigated, in order to identify a current threshold beyond stress intensity factor is greater than the toughness of active material, and cracks start to propagate

A Low Cost Multi-sensor Strategy for Early Warning in Structural Monitoring Exploiting a Wavelet Multiresolution Paradigm

AbstractThis paper deals with a novel approach to validate alerts provided by an early warning system (EWS) for structural monitoring implemented through low cost multi-sensor nodes. In particular, a dedicated wavelet multiresolution methodology is presented to implement a reliable assessment of the structural behavior. Such strategy allows to discriminate the structural response to seismic sources from other exogenous inertial components. Results obtained demonstrate the suitability of the proposed solution in the framework of the development of low cost multi-sensor strategies for the early warning of anomalous structural behaviors

The Plasmid Mobilome of the Model Plant-Symbiont Sinorhizobium meliloti: Coming up with New Questions and Answers

Rhizobia are Gram-negative Alpha- and Betaproteobacteria living in the underground that have the ability to associate with legumes for the establishment of nitrogen-fixing symbioses. Sinorhizobium meliloti in particular—the symbiont of Medicago, Melilotus, and Trigonella spp.—has for the past decades served as a model organism for investigating, at the molecular level, the biology, biochemistry, and genetics of a free-living and symbiotic soil bacterium of agricultural relevance. To date, the genomes of seven different S. meliloti strains have been fully sequenced and annotated, and several other draft genomic sequences are also available (http://www.ncbi.nlm.nih.gov/genome/genomes/1004). The vast amount of plasmid DNA that S. meliloti frequently bears (up to 45% of its total genome), the conjugative ability of some of those plasmids, and the extent of the plasmid diversity has provided researchers with an extraordinary system to investigate functional and structural plasmid molecular biology within the evolutionary context surrounding a plant-associated model bacterium. Current evidence indicates that the plasmid mobilome in S. meliloti is composed of replicons varying greatly in size and having diverse conjugative systems and properties along with different evolutionary stabilities and biological roles. While plasmids carrying symbiotic functions (pSyms) are known to have high structural stability (approaching that of chromosomes), the remaining plasmid mobilome (referred to as the non-pSym, functionally cryptic, or accessory compartment) has been shown to possess remarkable diversity and to be highly active in conjugation. In light of the modern genomic and current biochemical data on the plasmids of S. meliloti, the current article revises their main structural components, their transfer and regulatory mechanisms, and their potential as vehicles in shaping the evolution of the rhizobial genome.Instituto de Biotecnologia y Biologia Molecula

A dual-mass resonant mems gyroscope design with electrostatic tuning for frequency mismatch compensation

The micro-electro-mechanical systems (MEMS)-based sensor technologies are considered to be the enabling factor for the future development of smart sensing applications, mainly due to their small size, low power consumption and relatively low cost. This paper presents a new structurally and thermally stable design of a resonant mode-matched electrostatic z-axis MEMS gyroscope considering the foundry constraints of relatively low cost and commercially available silicon-on-insulator multi-user MEMS processes (SOIMUMPs) microfabrication process. The novelty of the proposed MEMS gyroscope design lies in the implementation of two separate masses for the drive and sense axis using a unique mechanical spring configuration that allows minimizing the cross-axis coupling between the drive and sense modes. For frequency mismatch compensation between the drive and sense modes due to foundry process uncertainties and gyroscope operating temperature variations, a comb-drive-based electrostatic tuning is implemented in the proposed design. The performance of the MEMS gyroscope design is verified through a detailed coupled-field electric-structural-thermal finite element method (FEM)-based analysis

Relationship between rhinitis duration and worsening of nasal function

While it is well known that asthma is characterized by airway remodeling, few studies instead have investigated this issue in patients with allergic rhinitis (AR)