Transition-metal-catalyzed addition of aryl halides across carbonyls remains poorly developed, especially for aliphatic aldehydes and hindered substrate combinations. We report here that simple ...nickel complexes of bipyridine and PyBox can catalyze the addition of aryl halides to both aromatic and aliphatic aldehydes using zinc metal as the reducing agent. This convenient approach tolerates acidic functional groups that are not compatible with Grignard reactions, yet sterically hindered substrates still couple in high yield (33 examples, 70% average yield). Mechanistic studies show that an arylnickel, and not an arylzinc, adds efficiently to cyclohexanecarboxaldehyde, but only in the presence of a Lewis acid co-catalyst (ZnBr2).
Soil nutrient acquisition and exchanges through symbiotic plant–fungus interactions in the rhizosphere are key features for the current agricultural and environmental challenges. Improved crop yield ...and plant mineral nutrition through a fungal symbiont has been widely described. In return, the host plant supplies carbon substrates to its fungal partner. We review here recent progress on molecular players of membrane transport involved in nutritional exchanges between mycorrhizal plants and fungi. We cover the transportome, from the transport proteins involved in sugar fluxes from plants towards fungi, to the uptake from the soil and exchange of nitrogen, phosphate, potassium, sulfate, and water. Together, these advances in the comprehension of the mycorrhizal transportome will help in developing the future engineering of new agro-ecological systems.
Plant growth and development are highly dependent on rhizosphere nutrient availability which is often a limiting factor. This constraint has forced land plants to evolve various strategies, including beneficial interactions with soil microorganisms.
The symbiotic interactions between plant roots and fungi, termed mycorrhizal symbiosis, provide reciprocal benefits for both partners, as for instance for the plant partner the acquisition of nitrogen (N), phosphate (P), potassium (K), and sulfate (S), the primary macronutrients used in plant fertilizer.
Plant and fungal transport systems display ‘mycorrhiza-specific’ and ‘fine-tuning’ regulation to control nutrient fluxes towards the symbiotic interface, delimiting the site of reciprocal nutrient exchanges between the partners.
The selection and engineering of mycorrhizal partners based on the plant and fungal transportome, targeting the key transporters resulting from the massive generation and analysis of ‘omics’ data, will ensure agro-ecological improvement of crop nutrition.
Arbuscular mycorrhizal (AM) fungi interact with the roots of most land plants and help them to acquire various mineral resources from the soil, including potassium (K
+
). However, tracking K
+
...movement in AM symbiosis remains challenging. Recently, we reported that rubidium can be used as a proxy for K
+
in mycorrhizal Medicago truncatula. In the present work, we investigated the possibility of using cesium (Cs
+
) as another proxy for K
+
in AM symbiosis. Plants were placed in growing systems that include a separate compartment only accessible to the AM fungus Rhizophagus irregularis isolate 09 and in which various amounts of cesium chloride (0 mM, 0.5 mM, 1.5 mM, or 3.75 mM) were supplied. Plants were watered with sufficient K
+
or K
+
-free nutrient solutions, and shoot and root biomass, fungal colonization, and K
+
and Cs
+
concentrations were recorded seven weeks after inoculation. Our results indicate that Cs
+
accumulated in plant tissues only when K
+
was present in the nutrient solution and when the highest concentration of Cs
+
was used in the fungal compartment. Consequently, we conclude that Cs
+
could be used as a proxy for K
+
in AM symbiosis, but with serious limitations.
Although alcohols are one of the largest pools of alkyl substrates, approaches to utilize them in cross-coupling and cross-electrophile coupling are limited. We report the use of 1° and 2° alcohols ...in cross-electrophile coupling with aryl and vinyl halides to form C(sp3)–C(sp2) bonds in a one-pot strategy utilizing a very fast (<1 min) bromination. The reaction’s simple benchtop setup and broad scope (42 examples, 56% ± 15% average yield) facilitates use at all scales. The potential in parallel synthesis applications was demonstrated by successfully coupling all combinations of 8 alcohols with 12 aryl cores in a 96-well plate.
Ectomycorrhizal (ECM) symbioses are among the most widespread associations between roots of woody plants and soil fungi in forest ecosystems. These associations contribute significantly to the ...sustainability and sustainagility of these ecosystems through nutrient cycling and carbon sequestration. Unfortunately, the molecular mechanisms controlling the mutual recognition between both partners are still poorly understood. Elegant work has demonstrated that effector proteins from ECM and arbuscular mycorrhizal (AM) fungi regulate host defenses by manipulating plant hormonal pathways. In parallel, genetic and evolutionary studies in legumes showed that a ‘common symbiosis pathway’ is required for the establishment of the ancientAM symbiosis and has been recruited for the rhizobia–legume association. Given that genes of this pathway are present in many angiosperm trees that develop ectomycorrhizas, we propose their potential involvement in some but not all ECM associations. The maintenance of a successful long-term relationship seems strongly regulated by resource allocation between symbiotic partners, suggesting that nutrients themselves may serve as signals. This review summarizes our current knowledge on the early and late signal exchanges between woody plants and ECM fungi, and we suggest future directions for decoding the molecular basis of the underground dance between trees and their favorite fungal partners.
Legumes form tripartite interactions with arbuscular mycorrhizal fungi and rhizobia, and both root symbionts exchange nutrients against carbon from their host. The carbon costs of these interactions ...are substantial, but our current understanding of how the host controls its carbon allocation to individual root symbionts is limited. We examined nutrient uptake and carbon allocation in tripartite interactions of Medicago truncatula under different nutrient supply conditions, and when the fungal partner had access to nitrogen, and followed the gene expression of several plant transporters of the Sucrose Uptake Transporter (SUT) and Sugars Will Eventually be Exported Transporter (SWEET) family. Tripartite interactions led to synergistic growth responses and stimulated the phosphate and nitrogen uptake of the plant. Plant nutrient demand but also fungal access to nutrients played an important role for the carbon transport to different root symbionts, and the plant allocated more carbon to rhizobia under nitrogen demand, but more carbon to the fungal partner when nitrogen was available. These changes in carbon allocation were consistent with changes in the SUT and SWEET expression. Our study provides important insights into how the host plant controls its carbon allocation under different nutrient supply conditions and changes its carbon allocation to different root symbionts to maximize its symbiotic benefits.
Legumes are simultaneously colonized with arbuscular mycorrhizal fungi and rhizobia bacteria, and both root symbionts play a key role for the nutrient uptake of this agronomically important group of plants. The host plant allocates a significant amount of its photosynthates to both root symbionts, and this carbohydrate supply acts as an important trigger for symbiont function. We studied the nutrient uptake and carbon allocation in tripartite interactions and examined the gene expression of several plant transporters of the Sucrose Uptake Transporter (SUT) and Sugars Will Eventually be Exported Transporter (SWEET) family and found that plant nutrient demand but also fungal access to nutrients play an important role for the carbon transport to both root symbionts. The expression of several SUT and SWEET transporters was consistent with the observed changes in carbon allocation, and our study provides novel insights into the regulatory mechanisms that control the carbon transport to both root symbionts.
The striped catfish Pseudoplatystoma magdaleniatum is a large-sized migratory species from the north Andes region, endemic to Magdalena basin and one of the major fishery resources. Despite the ...estimated reduction of over 80% of the fisheries production of this species throughout the basin in recent decades, its population in the lower Magdalena-Cauca basin showed healthy genetics after molecular analyses. However, the current conservation status of this species and several habitat disturbances demand the re-evaluation of its population genetics to infer evolutionary risks and assess potential changes. This work analyzed a total of 164 samples from the Cauca River collected downstream the Ituango Dam between 2019-2021 using species-specific microsatellite markers to compare the genetic diversity and structure in samples collected between 2010-2014 from the lower Magdalena-Cauca basin, previously analyzed. Our results showed a relatively stable panmictic population over time (4 to 10 years), with high genetic diversity and evidence of recent bottleneck. Promoting habitat connectivity to conserve gene flow, characterizing diversity and genetic structure over the entire basin, and integrating the results with future monitoring are important aspects for the management planning for P. magdaleniatum in the Magdalena-Cauca basin.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The ability to confine light down to atomic scales is critical for the development of applications in optoelectronics and optical sensing as well as for the exploration of nanoscale quantum ...phenomena. Plasmons in metallic nanostructures with just a few atomic layers in thickness can achieve this type of confinement, although fabrication imperfections down to the subnanometer scale hinder actual developments. Here, narrow plasmons are demonstrated in atomically thin crystalline silver nanostructures fabricated by prepatterning silicon substrates and epitaxially depositing silver films of just a few atomic layers in thickness. Specifically, a silicon wafer is lithographically patterned to introduce on‐demand lateral shapes, chemically process the sample to obtain an atomically flat silicon surface, and epitaxially deposit silver to obtain ultrathin crystalline metal films with the designated morphologies. Structures fabricated by following this procedure allow for an unprecedented control over optical field confinement in the near‐infrared spectral region, which is here illustrated by the observation of fundamental and higher‐order plasmons featuring extreme spatial confinement and high‐quality factors that reflect the crystallinity of the metal. The present study constitutes a substantial improvement in the degree of spatial confinement and quality factor that should facilitate the design and exploitation of atomic‐scale nanoplasmonic devices for optoelectronics, sensing, and quantum‐physics applications.
Ultrathin crystalline silver structures of <3 nm in thickness are fabricated by lighographically prepatterning a silicon wafer and subsequently depositing a few atomic layers of metal under ultrahigh vacuum conditions. The method has great flexibility regarding the size and morphology of the structures, which are demonstrated to sustain plasmon resonances with quality factors as high as ten.
Phosphorus is an essential macronutrient required for plant growth and development. It is central to many biological processes, including nucleic acid synthesis, respiration, and enzymatic activity. ...However, the strong adsorption of phosphorus by minerals in the soil decreases its availability to plants, thus reducing the productivity of agricultural and forestry ecosystems. This has resulted in a complete dependence on non-renewable chemical fertilizers that are environmentally damaging. Alternative strategies must be identified and implemented to help crops acquire phosphorus more sustainably. In this review, we highlight recent advances in our understanding and utilization of soil microbes to both solubilize inorganic phosphate from insoluble forms and allocate it directly to crop plants. Specifically, we focus on arbuscular mycorrhizal fungi, ectomycorrhizal fungi, and phosphate-solubilizing bacteria. Each of these play a major role in natural and agroecosystems, and their use as bioinoculants is an increasing trend in agricultural practices.
Abstract
Serum (1→3)-β-D-glucan (BDG), is an adjunct test in the diagnosis of invasive fungal disease (IFD). Fungitell STAT™, a facile, rapid, single patient option, executable for one or more ...patient specimens in approximately an hour, has been developed to address a need for rapid in-house testing. This method presents qualitative information concerning serum BDG levels, using an index value that allows the rapid categorization of patients as positive, negative, or indeterminate relative to serum BDG titer. The categorical and analytical performance of Fungitell STAT was evaluated. The categorical agreement between methods was established by testing patient samples which had been previously categorized with Fungitell. Receiver Operating Characteristic curves were used to identify cut-offs using 93 de-identified patient specimens. Subsequently, using these cutoffs, an independent group of 488 patient specimens was analyzed. Positive percent agreement (PPA) with, and without, indeterminate results was 74% and 99%, respectively. Negative percent agreement (NPA) was 91% and 98% with, and without, indeterminate results, respectively. Additionally, commercially available normal off-the-clot sera were spiked with Saccharomyces cerevisiae-derived (1→3)-β-D-glucan to produce analytical samples. Analytical reproducibility using spiked samples was excellent with 94% of the CV (coefficient of variation) values ≤10% among three independent laboratories. Good correlation with the predicate method was demonstrated with correlation coefficients of 0.90 or better with patient samples and 0.99 with spiked samples. The Fungitell STAT index assay provides a rapid and suitable method for serum BDG testing.
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