Metallomimetic C–F Activation Catalysis by Simple Phosphines

Delivering metallomimetic reactivity from simple p-block compounds is highly desirable in the search to replace expensive, scarce precious metals by cheap and abundant elements in catalysis. This contribution demonstrates that metallomimetic catalysis, involving facile redox cycling between the P(III) and P(V) oxidation states, is possible using only simple, cheap, and readily available trialkylphosphines without the need to enforce unusual geometries at phosphorus or use external oxidizing/reducing agents. Hydrodefluorination and aminodefluorination of a range of fluoroarenes was realized with good to very good yields under mild conditions. Experimental and computational mechanistic studies show that the phosphines undergo oxidative addition of the fluoroaromatic substrate via a Meisenheimer-like transition state to form a fluorophosphorane. This undergoes a pseudotransmetalation step with a silane, via initial fluoride transfer from P to Si, to give experimentally observed phosphonium ions. Hydride transfer from a hydridosilicate counterion then leads to a hydridophosphorane, which undergoes reductive elimination of the product to reform the phosphine catalyst. This behavior is analogous to many classical transition-metal-catalyzed reactions and so is a rare example of both functional and mechanistically metallomimetic behavior in catalysis by a main-group element system. Crucially, the reagents used are cheap, readily available commercially, and easy to handle, making these reactions a realistic prospect in a wide range of academic and industrial settings

Counteracting the negative effects of copper limitations through the biostimulatory action of a tropical plant extract in grapevine under pedo-climatic constraints

In southern Mediterranean areas, vineyards are facing the combination of increasing air temperature, drought and frequency of extreme events (e.g., heat waves) due to climate change. Since most of the berry growth and ripening phases occur during the aridity period, such environmental constraints are responsible for limitations in yield and berry quality. Within this scenario, to achieve vineyard sustainability, renewed approaches in vineyard management have been proposed and the use of plant biostimulants seems a prominent and environmental friendly practice. The aim of this study was to test four combinations of a tropical plant extract and conventional chemicals for disease control on morpho-anatomical, physiological, biochemical and berry quality in Vitis vinifera L. subsp. vinifera “Aglianico.” In particular, we aimed to evaluate the possibility to counteract the negative effects of the reductions in copper distribution, by applying the tropical plant extract enriched with: micronutrients, enzymes involved in the activation of natural defense, aminoacids, and vitamins. The halved dose of Cu in combination with the tropical plant extract allowed maintaining a reduced vegetative vigor. In the second year of treatment, the addition of the plant extract significantly improved leaf gas exchanges and photochemistry as well as the synthesis of photosynthetic pigments. At berry level, the plant extract induced an increase in phenolics accompanied by a decrease in soluble sugars. The overall results showed that the expected differences in growth performance and productivity in vines are linked to different eco-physiological and structural properties induced by the various treatments. The tropical plant extract also primed plant defenses at the leaf and fruit levels, mainly due to modifications of some structural and biochemical traits, respectively

Metallomimetic C-F activation catalysis by simple phosphines

Delivering metallomimetic reactivity from simple p-block compounds is highly desirable in the search to replace expensive, scarce precious-metals by cheap and abundant elements in catalysis. This contribution demonstrates that metallomimetic catalysis, involving facile redox cycling between the P(III) and P(V) oxidation states, is possible using only simple, cheap and readily available trialkylphosphines with no need for complex ligand architectures or external oxidising/reducing agents. Hydrodefluorination and aminodefluorination of a range of fluoroarenes was realised with good to very good yields under mild conditions. Experimental and computational mechanistic studies show that the phosphines undergo oxidative addition of the fluoroaromatic substrate, via a Meisenheimer-like transition state, to form a fluorophosphorane. This undergoes a pseudo-transmetallation step with a silane, via initial fluoride transfer from P to Si, to give experimentally observed phosphonium ions. Hydride transfer from a hydridosilicate counterion then leads to a hydridophosphorane, which undergoes reductive elimination of the product to re-form the phosphine catalyst. This behaviour is analogous to many classical transition-metal catalysed reactions and so is a rare example of both functional and mechanistically metallomimetic behaviour in catalysis by a main-group element system. Crucially, the reagents used are cheap, readily available commercially and easy to handle, making these reactions a realistic prospect in a wide range of academic and industrial settings

Osteointegrative and microgeometric comparison between micro-blasted and alumina blasting/acid etching on grade II and V titanium alloys (Ti-6Al-4V).

This study evaluated the effect of alumina-blasted/acid-etched (AB/AE) or microabrasive blasting (C3-Microblasted) surface treatment on the osseointegration of commercially-pure Ti (grade II) and Ti-6Al-4V alloy (grade V) implants compared to as-machined surfaces. Surface characterization was performed by scanning electron microscopy and optical interferometry (IFM) to determine roughness parameters (Sa and Sq, n=3 per group). One-hundred forty-four implants were placed in the radii of 12 beagle dogs, for histological (n=72, bone-to-implant contact - BIC and bone-area-fraction occupancy -BAFO) and torque to interface failure test at 3 and 6 weeks (n=72). SEM and IFM revealed a significant increase in surface texture for AB/AE and C3-Microblasted surfaces compared to machined surface, regardless of titanium substrate. Torque-to-interface failure test showed significant increase in values from as-machined to AB/AE and to C3-Microblasted. Considering time in vivo, alloy grade, and surface treatment, the C3-microblasted presented higher mean BIC values relative to AB/AE and machined surfaces for both alloy types. BAFO levels were significantly higher for both textured surfaces groups relative to the machined group at 3 weeks, but differences were not significant between the three surfaces for each alloy type at 6 weeks. Surface treatment resulted in roughness that improved osseointegration in Grade II and V titanium substrates

Data for "The mycorrhizal root-shoot axis elicits Coffea arabica growth under low phosphate conditions"

This folder contains relevant datasets generated in the study: Chialva M., Patono D.L, de Souza L.P., Novero M., Vercellino S., Maghrebi M., Morgante M., Lovisolo C., Vigani G., Fernie A., Fiorilli V., Lanfranco L., Bonfante P. (2023) The mycorrhizal root-shoot axis elicits Coffea arabica growth under low phosphate conditions. The New Phytol, in press. RNA-seq dataset and annotations RNAseq_raw_counts.tsv > Raw mRNA-seq reads counts obtained by pseudo-aligning reads on the C. arabica reference transcriptome (NCBI reference genome accession GCF_003713225.1) using Salmon software in selective alignment mode and summarized using 'tximport' library in R. interproscan_proteins.local.tsv > the parsed InterProScan analysis output run on known Coffea arabica proteins (NCBI reference genome accession GCF_003713225.1). gene2ko.tsv > Protein IDs to Kegg Orthologs (KO) IDs obtained using KAAS server. Orthogroups inference Orthogroups predicted with Orthofinder (v.2.5.4) on Coffea arabica, C. canephora, C. eugenioides, S. lycopersicum, P. trichocarpa, M. truncatula, and Vitis vinifera proteomes HOGs_N0.tsv > Phylogenetic Hierachical Orthogroups (HOGs) predicted by Orthofinder on proteomes at N0 hierachical level Orthogroups.tsv > Orthogroups predicted by Orthofinder (v.2.5.4) on proteomes (old-way) OGs.tsv > refined OGs used in this study (manually integrating some missing genes) Metabolomics Metabolites_DB.xlsx > An exhaustive list of detected coffee metabolites in previous studies used to enhance annotation of LC-MS spectra generated in this study. Note: Sample names are coded by condition (M or MYC=mycorrhizal plants, C or NM=non-mycorrhized controls) and by organ type (s=leaves, r=roots)</p

Detection of a novel intracellular microbiome hosted in arbuscular mycorrhizal fungi

Arbuscular mycorrhizal fungi (AMF) are important members of the plant microbiome. They are obligate biotrophs that colonize the roots of most land plants and enhance host nutrient acquisition. Many AMF themselves harbor endobacteria in their hyphae and spores. Two types of endobacteria are known in Glomeromycota: rod-shaped Gram-negative Candidatus Glomeribacter gigasporarum, CaGg, limited in distribution to members of the Gigasporaceae family, and coccoid Mollicutes-related endobacteria, Mre, widely distributed across different lineages of AMF. The goal of the present study is to investigate the patterns of distribution and coexistence of the two endosymbionts, CaGg and Mre, in spore samples of several strains of Gigaspora margarita. Based on previous observations, we hypothesized that some AMF could host populations of both endobacteria. To test this hypothesis, we performed an extensive investigation of both endosymbionts in G. margarita spores sampled from Cameroonian soils as well as in the Japanese G. margarita MAFF520054 isolate using different approaches (molecular phylotyping, electron microscopy, fluorescence in situ hybridization and quantitative real-time PCR). We found that a single AMF host can harbour both types of endobacteria, with Mre population being more abundant, variable and prone to recombination than the CaGg one. Both endosymbionts seem to retain their genetic and lifestyle peculiarities regardless of whether they colonize the host alone or together. These findings show for the first time that fungi support an intracellular bacterial microbiome, in which distinct types of endobacteria coexist in a single cell