N$_{3}^{-}$ azide anion confined inside finite-size carbon nanotubes

In this work, the confinement of an N\(_{3}^{-}\) azide anion inside finite-size single-wall zigzag and armchair carbon nanotubes of different diameters has been studied by wave function and density functional theory. Unrelaxed and relaxed interaction energies have been computed, resulting in a favorable interaction between the guest and host system. In particular, the largest interaction has been observed for the confinement in an armchair (5,5) carbon nanotube, for which a natural population analysis as well as an investigation based on the molecular electrostatic potential has been carried out. The nature of the interaction between the two fragments appears to be mainly electrostatic, favored by the enhanced polarizability of the nanotube wall treated as a finite system and passivated by hydrogen atoms. The results obtained are promising for possible applications of this complex as a starting point for the stabilization of larger polynitrogen compounds, suitable as a high-energy density material.     

Migration through a Major Andean Ecogeographic Disruption as a Driver of Genetic and Phenotypic Diversity in a Wild Tomato Species

Evolutionary dynamics at the population level play a central role in creating the diversity of life on our planet. In this study, we sought to understand the origins of such population-level variation in mating systems and defensive acylsugar chemistry in Solanum habrochaites—a wild tomato species found in diverse Andean habitats in Ecuador and Peru. Using Restriction-site-Associated-DNA-Sequencing (RAD-seq) of 50 S. habrochaites accessions, we identified eight population clusters generated via isolation and hybridization dynamics of 4–6 ancestral populations. Detailed characterization of mating systems of these clusters revealed emergence of multiple self-compatible (SC) groups from progenitor self-incompatible populations in the northern part of the species range. Emergence of these SC groups was also associated with fixation of deleterious alleles inactivating acylsugar acetylation. The Amotape-Huancabamba Zone—a geographical landmark in the Andes with high endemism and isolated microhabitats—was identified as a major driver of differentiation in the northern species range, whereas large geographical distances contributed to population structure and evolution of a novel SC group in the central and southern parts of the range, where the species was also inferred to have originated. Findings presented here highlight the role of the diverse ecogeography of Peru and Ecuador in generating population differentiation, and enhance our understanding of the microevolutionary processes that create biological diversity.     

Protein phosphatases: possible bisphosphonate binding sites mediating stimulation of osteoblast proliferation

We investigated the existence of a bisphosphonate (BP) target site in osteoblasts. Binding assays using [³H]-olpadronate ([³H]OPD) in whole cells showed the presence of specific, saturable and high affinity binding for OPD (K_d = 1.39 ± 0.33 μM) in osteoblasts. [³H]OPD was displaced from its binding site by micromolar concentrations of lidadronate, alendronate and etidronate (K_d = 1.42 ± 0.15 μM, 2.00 ± 0.2 μM and 2.4 ± 0.4 μM, respectively), and by millimolar concentrations of the non-permeant protein phosphatase (PP) substrates p-nitrophenylphosphate and α-naphtylphosphate. PP inhibitors orthovanadate, NaF or vpb(bipy) did not displace [³H]OPD.As expected, specific OPD binding was detected in the plasma membrane of ROS 17/2.8 cells, although significant BP binding was also found intracellularly. Moreover, OPD increased DNA synthesis in these cells with a temporal profile similar to the protein tyrosine phosphatase (PTP) inhibitors, Na₃VO₄ and vpb(bipy); but different from a general PP inhibitor (NaF). The stimulatory effect of OPD and PTP inhibitors on osteoblast proliferation was inhibited by the protein tyrosine kinase inhibitors genistein and geldanamycin. These results provide new evidence on the existence of a BP target in osteoblastic cells, presumably a PTP, which may be involved in the stimulatory action of BPs on osteoblast proliferation.     

New κ-PNN′- and κ-PNN′O-polydentate ligands: Synthesis, coordination and structural studies

The three-step synthesis of new mixed P/N/N′/O-donor ligands C₆H₃(OH){2-NHC(O)CH₂NCHC₆H₄PPh₂}(4-CH₃) 3a·HH and C₆H₄(OH){3-NHC(O)CH₂NCHC₆H₄PPh₂} 3b·HH, by Schiff base condensation of the 1° amines C₆H₃(OH){2-NHC(O)CH₂NH₂}(4-CH₃) 2a or C₆H₄(OH){3-NHC(O)CH₂NH₂} 2b with C₆H₄(CHO)(2-PPh₂) in refluxing EtOH, is described. Reaction of 1 equiv. of 3a·HH or 3b·HH with MCl₂(cod) (M = Pt, Pd; cod = cycloocta-1,5-diene) affords the κ²-PN-chelate complexes MCl₂(3a·HH) (M = Pd 4a; M = Pt 4b) and MCl₂(3b·HH) (M = Pt 4c). The dichlorometal(II) complexes 4d and 4e, bearing instead a pendant 4-phenolic group, were similarly prepared (in >90% yield). Chloro-bridge cleavage of [Pd(μ-Cl)(η³-C₃H₅)]₂ with 3a·HH or 3b·HH gave the monocationic κ²-PN-chelate complexes [Pd(η³-C₃H₅)(3a·HH)]Cl 5a or [Pd(η³-C₃H₅)(3b·HH)]Cl 5b, respectively. Elimination of cod, and single CH₃ protonation, from Pt(CH₃)₂(cod) upon reaction with 1 equiv. of 3a·HH or 3b·HH in C₇H₈ at room temperature afforded the neutral complexes C₆H₃(OH){2-NC(O)CH₂NCHC₆H₄PPh₂Pt(CH₃)}(4-CH₃) 6a and C₆H₄(OH){3-NC(O)CH₂NCHC₆H₄PPh₂Pt(CH₃)} 6b, respectively bearing a monoanionic (3a·H⁻ or 3b·H⁻) κ³-PNN′-tridentate ligand. Amide and phenol deprotonation were readily achieved, using KO^tBu as base, to give high yields of the κ⁴-PNN′O-tetradentate complexes C₆H₃(O){2-NC(O)CH₂NCHC₆H₄PPh₂Pd}(4-CH₃) 7a and C₆H₃(O){2-NC(O)CH₂NCHC₆H₄PPh₂Pt}(4-CH₃) 7b bearing the dianionic ligand 3a²⁻. All new compounds have been characterised by multinuclear NMR, FTIR, mass spectroscopy and microanalysis. Single crystal X-ray studies have been performed on compounds 1b·1.5CH₂Cl₂, 3b·HH·0.5Et₂O, 6b·CHCl₃ and 7b·0.5Et₂O.     

Integrative expression system for delivery of antibody fragments by lactobacilli

A series of expression cassettes which mediate secretion or surface display of antibody fragments was stably integrated in the chromosome of Lactobacillus paracasei. L. paracasei producing surface-anchored variable domain of llama heavy chain (VHH) (ARP1) directed against rotavirus showed efficient binding to rotavirus and protection in the mouse model of rotavirus infection.     

A review of wild boar Sus scrofa diet and factors affecting food selection in native and introduced ranges

相似文献   

Next generation modeling in GWAS: comparing different genetic architectures

The continuous advancement in genotyping technology has not been accompanied by the application of innovative statistical methods, such as multi-marker methods (MMM), to unravel genetic associations with complex traits. Although the performance of MMM has been widely explored in a prediction context, little is known on their behavior in the quantitative trait loci (QTL) detection under complex genetic architectures. We shed light on this still open question by applying Bayes A (BA) and Bayesian LASSO (BL) to simulated and real data. Both methods were compared to the single marker regression (SMR). Simulated data were generated in the context of six scenarios differing on effect size, minor allele frequency (MAF) and linkage disequilibrium (LD) between QTLs. These were based on real SNP genotypes in chromosome 21 from the Spanish Bladder Cancer Study. We show how the genetic architecture dramatically affects the behavior of the methods in terms of power, type I error and accuracy of estimates. Markers with high MAF are easier to detect by all methods, especially if they have a large effect on the phenotypic trait. A high LD between QTLs with either large or small effects differently affects the power of the methods: it impairs QTL detection with BA, irrespectively of the effect size, although boosts that of small effects with BL and SMR. We demonstrate the convenience of applying MMM rather than SMR because of their larger power and smaller type I error. Results from real data when applying MMM suggest novel associations not detected by SMR.