A silver-catalyzed Minisci-type acylation reaction is reported here. Acylation of electron-deficient N-heterocycles is achieved in aqueous solution through dehydrogenation cross-coupling of aldehydes ...and N-heteroarenes in open air without external Brønsted acid. Selectfluor® is used as a mild oxidant. This method has been successfully employed in acylation of a variety of N-heteroarenes with aldehydes. This strategy provides an efficient and mild method for acylation of N-heteroarenes.
Ag-catalyzed acylation of N-heterocycles in aqueous solution was reported. The reaction was compatible with various atoms and groups, using aldehydes as the source of the acyl radical precursors. Display omitted
The hazardous effects of plastic and plastic leachates on organisms, even bacteria, have attracted widespread attention, but only a limited effort has been devoted to explore the response of fungi to ...plastic leachate induced by light irradiation. Here, we performed plastic leaching experiments to obtain leachates from polyethylene (PE), polyethylene terephthalate (PET) and polypropylene (PP), and optical properties of plastic leachates were analysed to determine the influence of light conditions and plastic materials on that. The effects of plastic leachates on the production of fungal enzyme and the biodegradation of heterocyclic dye by fungi were evaluated. Results indicated that the UV light greatly enhanced the release of leachates from the three plastics. Both plastic polymers and light irradiation affected the plastic-derived dissolved organic carbon (DOC) and their aromaticity, but the molecular weight of plastic leachates showed no dependency on light irradiation types, and PE was the easiest to photo age and leached more DOC. Plastic leachates had no dose-effect on the production of extracellular enzymes by fungi. PE leachates showed long-term toxicities to fungi, and no manganese peroxidase activities were detected after a 42-day incubation, while that of controls were up to 73.64 ± 8.81 U/L. However, the PE and PP leachates greatly promoted methylene blue degradation by the fungi, but PET leachates relieved the decolouration of methylene blue, probably because of the benzene ring structure in the PET monomer. Fusarium oxysporum had a stronger degradation ability than Phanerochaete chrysosporium. Our results indicate that plastic leachates can influence the production and secretion of fungi ligninolytic extracellular enzymes, and regulate the fungal degradation of heterocyclic dye.
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•UV light enhanced the release of plastic leachates.•Plastic leachates had a long-term toxicity in fungi.•PE and PP leachates promoted methylene blue degradation by fungi.
Photosynthetic carbon sequestration and microbial carbon metabolism are major processes of algae-bacteria interactions, affecting pollutant degradation as well as fundamental biogeochemical cycles in ...aquatic systems. Human-induced land-use changes greatly alter the molecular composition and input of terrestrial dissolved organic matter (DOM) in inland lakes. However, how the origin of DOM leads to varying effects on phycosphere microbial communities or molecular composition of DOM, e.g., via carbon metabolism, has been little studied in freshwater. Here, we incubated the cyanobacterium Microcystis aeruginosa and a bacterial community from natural lakes to establish an alga-bacteria model system. This allowed us to investigate how DOM from different sources affects phycosphere microbial diversity and DOM diversification. We showed that Suwannee River fulvic acid (SRFA), Suwannee River natural organic matter (SRNOM) and cropland lake DOM promote algal growth, whereas DOM from an urban lake inhibits algal growth. Algal metabolites and DOM together shaped the chemotaxis response of phycosphere communities. High-resolution mass spectrometry analysis demonstrated that DOM chemo-diversity tended to become uniform after interactions of diverse DOM sources with the algae-bacteria symbiosis system. Molecular thermodynamic analysis of DOM based on a substrate-explicit model further verified that microbial interactions render DOM less bioavailable and thus increase recalcitrant DOM formation. Metabolome analysis uncovered that DOM addition intensifies metabolic pathways related to labile and recalcitrant DOM utilization (mainly lignin/carboxyl-rich alicyclic molecule (CRAM)-like DOM, unsaturated hydrocarbon), whereby cofactor and vitamin metabolism represented an extremely strong activity in all metabolic pathways. Our results highlight covariation and interactions of DOM with microbial metabolism at the molecular level and expands our understanding of microbially mediated DOM shaping aquatic carbon cycling.
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•DOM affects algal growth while stimulating recalcitrant DOM production.•Algal metabolites and DOM together shaped the chemotaxis of phycosphere communities.•DOM chemo-diversity becomes uniform in algae-bacteria symbiosis systems.•DOM intensifies metabolic pathways of labile and recalcitrant DOM utilization.
Dissolved organic matter (DOM) is one of the most important fluxes in the global carbon cycle but its response to light exposure remains unclear at a molecular-level. The chemical response of DOM to ...light should vary with its molecular composition and environmental conditions while some basic hypotheses are still unclear, such as the balance between photobleaching and photo-humification and the question of oxidative properties. Here we exposed aquatic DOM from diverse freshwaters impacted by different levels of anthropogenic activity and algal exudates to environmentally-realistic light conditions. We found that photobleaching occurred in DOM with relatively high initial humic content producing low H/C molecules, whereas DOM with low initial humic content was humified. DOM pools with relatively high initial saturation and low aromaticity were prone to transform towards more unsaturated molecular formulae and high H/C molecules with a distinct decrease of bioavailability. Photo-transformation was mainly influenced by reactive intermediates, with reactive oxygen species (ROS) playing a dominant role in humification when the initial humus content of DOM was high. In contrast, for algal DOM with high protein content, it was likely that the autoxidation of excited state DOM was more important than indirect oxidation involving ROS. Our results reveal how photo-transformation patterns depend on the initial composition of DOM and provide new insights into the role of photochemical processes in biogeochemical cycling of DOM.
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•Photobleaching and photo-humification co-occur in photo-transformation of DOM.•Initial DOM humification degree determines photo-transformation patterns.•Photo-transformation of high humic DOM is mainly caused by ROS-induced oxidation.•Photo-humification of algal-derived DOM is mainly caused by autoxidation of 3DOM*.
A silver‐catalyzed Minisci‐type reaction is reported here. Alkylation of electron‐deficient N‐heterocycles is achieved in aqueous solution through decarboxylative cross‐coupling of aliphatic acids ...and N‐heteroarenes in open air without external Brønsted acid. Selectfluor is used as a mild oxidant. Different substituents on heterocycles and acids are tolerated. Primary and secondary alkyl could be introduced efficiently into the heteroarenes.
A silver‐catalyzed Minisci‐type decarboxylative alkylation of electron‐deficient N‐heteroarenes in aqueous solution was reported. Selectfluor was used as the oxidant and no external acid was needed.
The effect of pyrolysis on the microstructure and moisture adsorption of lignite was investigated with low field nuclear magnetic resonance spectroscopy. Changes in oxygen-containing groups were ...analyzed by Fourier transform infrared spectroscopy （FTIR）, and H20 adsorption mechanism on the surface of lignite pyrolysis was inferred. Two major changes in the pore structure of lignite char were observed as temperature increased in 105-200 ℃ and 500-700 ℃. Pyrolysis temperature is a significant factor in removing carboxyl and phenolic hydroxyl from lignite. Variation of ether bond content can be divided into three stages; the content initially increased, then decreased, and finally increased. The equilibrium adsorption ratio, content of oxygen-containing groups, and variation of pore volume below 700° were closely correlated with each other. The amount of adsorbed water on char pyrolyzed at 700 ℃ increased. Moreover, the adsorption capacity of the lignite decreased, and the adsorption state changed.
Alzheimer's disease (AD) is a neurodegenerative disease that causes late-onset dementia. The R47H variant of the microglial receptor TREM2 triples AD risk in genome-wide association studies. In mouse ...AD models, TREM2-deficient microglia fail to proliferate and cluster around the amyloid-β plaques characteristic of AD. In vitro, the common variant (CV) of TREM2 binds anionic lipids, whereas R47H mutation impairs binding. However, in vivo, the identity of TREM2 ligands and effect of the R47H variant remain unknown. We generated transgenic mice expressing human CV or R47H TREM2 and lacking endogenous TREM2 in the 5XFAD AD model. Only the CV transgene restored amyloid-β-induced microgliosis and microglial activation, indicating that R47H impairs TREM2 function in vivo. Remarkably, soluble TREM2 was found on neurons and plaques in CV- but not R47H-expressing 5XFAD brains, although in vitro CV and R47H were shed similarly via Adam17 proteolytic activity. These results demonstrate that TREM2 interacts with neurons and plaques duing amyloid-β accumulation and R47H impairs this interaction.
Glia have been implicated in Alzheimer's disease (AD) pathogenesis. Variants of the microglia receptor triggering receptor expressed on myeloid cells 2 (TREM2) increase AD risk, and activation of ...disease-associated microglia (DAM) is dependent on TREM2 in mouse models of AD. We surveyed gene-expression changes associated with AD pathology and TREM2 in 5XFAD mice and in human AD by single-nucleus RNA sequencing. We confirmed the presence of Trem2-dependent DAM and identified a previously undiscovered Serpina3n
C4b
reactive oligodendrocyte population in mice. Interestingly, remarkably different glial phenotypes were evident in human AD. Microglia signature was reminiscent of IRF8-driven reactive microglia in peripheral-nerve injury. Oligodendrocyte signatures suggested impaired axonal myelination and metabolic adaptation to neuronal degeneration. Astrocyte profiles indicated weakened metabolic coordination with neurons. Notably, the reactive phenotype of microglia was less evident in TREM2-R47H and TREM2-R62H carriers than in non-carriers, demonstrating a TREM2 requirement in both mouse and human AD, despite the marked species-specific differences.
One of the hallmarks of Alzheimer's disease is the presence of extracellular diffuse and fibrillar plaques predominantly consisting of the amyloid-β (Aβ) peptide. Apolipoprotein E (ApoE) influences ...the deposition of amyloid pathology through affecting the clearance and aggregation of monomeric Aβ in the brain. In addition to influencing Aβ metabolism, increasing evidence suggests that apoE influences microglial function in neurodegenerative diseases. Here, we characterize the impact that apoE has on amyloid pathology and the innate immune response in APPPS1ΔE9 and APPPS1-21 transgenic mice. We report that
deficiency reduced fibrillar plaque deposition, consistent with previous studies. However, fibrillar plaques in
-deficient mice exhibited a striking reduction in plaque compaction. Hyperspectral fluorescent imaging using luminescent conjugated oligothiophenes identified distinct Aβ morphotypes in
-deficient mice. We also observed a significant reduction in fibrillar plaque-associated microgliosis and activated microglial gene expression in
-deficient mice, along with significant increases in dystrophic neurites around fibrillar plaques. Our results suggest that apoE is critical in stimulating the innate immune response to amyloid pathology.
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