A chromosome-scale assembly reveals chromosomal aberrations and exchanges generating genetic diversity in Coffea arabica germplasm

In order to better understand the mechanisms generating genetic diversity in the recent allotetraploid species Coffea arabica, here we present a chromosome-level assembly obtained with long read technology. Two genomic compartments with different structural and functional properties are identified in the two homoeologous genomes. The resequencing data from a large set of accessions reveals low intraspecific diversity in the center of origin of the species. Across a limited number of genomic regions, diversity increases in some cultivated genotypes to levels similar to those observed within one of the progenitor species, Coffea canephora, presumably as a consequence of introgressions deriving from the so-called Timor hybrid. It also reveals that, in addition to few, early-occurring exchanges between homoeologous chromosomes, there are numerous recent chromosomal aberrations including aneuploidies, deletions, duplications and exchanges. These events are still polymorphic in the germplasm and could represent a fundamental source of genetic variation in such a lowly variable species

Pheno-genotypic and symbiotic characterization of isolated rhizobia of Desmanthus Virgatus (l.) Willd. In soils of the province of Jujuy (Argentina)

Las leguminosas forrajeras nativas presentan un gran potencial productivo y un ejemplo de ellas es Desmanthus virgatus de amplia distribución en el centro norte de Argentina. El objetivo del trabajo fue realizar una caracterización feno-genotípica y simbiótica de rizobios que forman nódulos en D. virgatus con vista hacia el uso sustentable integral de dicha leguminosa. Para ello, se estableció una colección de 17 aislamientos recuperados de suelos de Jujuy. La caracterización fenotípica permitió reconocer rizobios de crecimiento rápido que mostraron un desarrollo óptimo entre pH 5 y 8, temperaturas de 28 a 35°C, y en concentraciones de 1% (p/v) de NaCl. Se hallaron rizobios con capacidad de crecimiento en condiciones extremas de pH 9 y a 40°C. Los aislamientos se identificaron como pertenecientes a Ensifer spp. y los perfiles de amplificación de ADN genómico mostraron escasa diversidad genética. La inoculación de D. virgatus con la cepa 8L12.1 (Ensifer sp.) produjo incrementos de biomasa seca aérea de 73% en cámara de cultivo y 124% a campo respecto a las plantas sin inocular y sin fertilizar.Native forage legumes have great productive potential and an example of which is Desmanthus virgatus with a wide distribution in central and northern Argentina. The objective of the work was to carry out a pheno-genotypic and symbiotic characterization of rhizobia that form nodules in D. virgatus with a view to the integral sustainable use of said legume. For this, a collection of 17 isolates recovered from Jujuy soils was established. Phenotypic characterization allowed to recognize fast-growing rhizobia that showed an optimal development between pH 5 y 8, temperatures to 28 a 35°C, and in concentrations of 1% (w/v) of NaCl. Rhizobia with growth capacity were found under extreme conditions of pH 9 and at 40°C. The isolates were identified as belonging to Ensifer spp. and the genomic DNA amplification profiles showed little genetic diversity. The inoculation of D. virgatus with the strain 8L12.1 (Ensifer sp.) produced increases of 73% aerial dry biomass in the cultivation chamber and 124% in the field with respect to the uninoculated and unfertilized plants.Instituto de Biotecnologia y Biologia Molecula

Revised analysis of the mobility and ION degradation in high-k gate stacks: surface optical phonons vs. remote Coulomb scattering

We use Multi-Subband Monte Carlo simulations to understand which mechanism is mainly responsible for the mobility degradation observed in nMOSFETs featuring high-k dielectrics. Direct comparison with the experimental data of Cass\ue9 et al. points out that for realistic interfacial layer thicknesses the effect of surface optical phonons on the mobility is very modest, and that the measured mobility reduction can be attributed to remote Coulomb scattering of charge in the gate-stack with concentrations in the order of 10^14 cm-2. We found that the drain current reduction in short channel devices is, instead, not as strong as the mobility reduction

Simulation study of the on-current improvements in Ge and sGe versus Si and sSi nano-MOSFETs

This paper employs a state-of-the-art semi-classical transport model for inversion layers to analyze the Ion in Si, sSi, Ge and sGe n- and p-MOSFETs by accounting for all the relevant scattering mechanisms (including the remote surface-optical phonons (SOph) and remote Coulomb scattering (remQ) related to high-\u3ba dielectrics), in which strain is implicitly introduced by a modification of the band structure. Our models are first validated against experiments for both mobility and IDS in nanoscale transistors. Then the Ion in Ge and Si MOSFETs is compared for different crystal orientations and strain conditions