A Systematic, Complexity-Reduction Approach to Dissect Microbiome: the Kombucha Tea Microbiome as an Example

One defining goal of microbiome research is to uncover mechanistic causation that dictates the emergence of structural and functional traits of microbiomes. However, the extraordinary degree of ecosystem complexity has hampered the realization of the goal. Here we developed a systematic, complexity-reducing strategy to mechanistically elucidate the compositional and metabolic characteristics of microbiome by using the kombucha tea microbiome as an example. The strategy centered around a two-species core that was abstracted from but recapitulated the native counterpart. The core was convergent in its composition, coordinated on temporal metabolic patterns, and capable for pellicle formation. Controlled fermentations uncovered the drivers of these characteristics, which were also demonstrated translatable to provide insights into the properties of communities with increased complexity and altered conditions. This work unravels the pattern and process underlying the kombucha tea microbiome, providing a potential conceptual framework for mechanistic investigation of microbiome behaviors.

Long noncoding RNA FAM225A promotes the malignant progression of gastric cancer through the miR-326/PADI2 axis

Gastric cancer (GC) is a global health problem and further studies of its molecular mechanisms are needed to identify effective therapeutic targets. Although some long noncoding RNAs (lncRNAs) have been found to be involved in the progression of GC, the molecular mechanisms of many GC-related lncRNAs remain unclear. In this study, a series of in vivo and in vitro assays were performed to study the relationship between FAM225A and GC, which showed that FAM225A levels were correlated with poor prognosis in GC. Higher FAM225A expression tended to be correlated with a more profound lymphatic metastasis rate, larger tumor size, and more advanced tumor stage. FAM225A also promoted gastric cell proliferation, invasion, and migration. Further mechanistic investigation showed that FAM225A acted as a miR-326 sponge to upregulate its direct target PADI2 in GC. Overall, our findings indicated that FAM225A promoted GC development and progression via a competitive endogenous RNA network of FAM225A/miR-326/PADI2 in GC, providing insight into possible therapeutic targets and prognosis of GC.

Isolation of Unusual N-Thiophenyl Ebselenamines and other Intermediates during the 77Se NMR Mechanistic Study of Azo-Bis-Ebselen: Their Antioxidant Behaviour against Oxidative Stress

Based on the traditional 77Se NMR spectroscopy investigation, a catalytic cycle for the formation of N-thiophenyl ebselenamine 12 involving diselenide 9, selenenyl sulfide 10 and ebselenamine 7a was reported by the reaction of azo-bis-ebselen 8 with PhSH and H2O2. The signals detected in the 77Se NMR spectrum corresponding to 7a, 10 and 12 were directly isolated from the NMR mixture. Mechanistic investigation for the formation of N-thiophenyl ebselenamine 12 was confirmed from an independent reaction of diselenide 9 and PhSSPh in the presence of H2O2. This was further supported by another diselenide 19 containing p-tolyl group with equimolar amount of H2O2 and PhSH in an independent experiment followed by the 77Se NMR spectroscopy, yielding similar observations. These results, which illustrated diselenide has been observed as the main precursor in the formation of all intermediates. The new novel selenium antioxidants quenched lipidperoxyl radicals much more efficiently than α-tocopherol and were regenerable by the aqueous ascorbic acid in a two-phase (chlorobenzene/water) azo-initiated peroxidation system. The notable benefit of the organoselenium biology, the novel ebselenamine analogues and their corresponding selenenyl sulfides were found to mimic the activity of the glutathione peroxidase enzymes better than ebselen in the coupled reductase assay.

Mechanistic investigations on a homogeneous ruthenium Guerbet catalyst in a flow reactor

A mechanistic investigation on the ethanol self-condensation reaction (Guerbet reaction) catalyzed by a bis(pyridylimino)isoindolate Ru(ii) catalyst was performed using a specifically designed continuously-stirred tank reactor (CSTR).

The Role of an Inert Electrode Support in Plasmonic Electrocatalysis

Plasmonic nanostructures loaded onto catalytically inert conductive support materials are believed to be advantageous for maximizing photocatalytic effects in photoelectrochemical systems due to the increased efficiency of Schottky barrier-free architectures in collecting hot charge carriers. However, the systematic mechanistic investigation and description of the inert electrode support contribution to plasmonic electrocatalysis is missing. Herein, we systematically investigated the effect of the supporting electrode material on the observed photocatalytic enhancement by comparing photoelectrocatalytic properties of AuNPs supported on highly oriented pyrolytic graphite (HOPG) and on indium tin oxide (ITO) electrodes using electrocatalytic benzyl alcohol (BnOH) oxidation as a model system. Upon illumination, only ~(3 ± 1)% enhancement in catalytic current was recorded on the AuNP/ITO electrodes in contrast to ~(42 ± 6)% enhancement on AuNP/HOPG electrodes. Our results showed that the local heating due to light absorption by the electrode material itself independent of localized surface plasmon effects is the primary source of the observed significant photo-induced enhancement on the HOPG electrodes in comparison to the ITO electrodes. Moreover, we demonstrated that an increased interfacial charge transfer at elevated temperatures, and not faster substrate diffusion is the main source of the enhancement. This work highlights the importance of systematic evaluation of contributions of all parts, even if they are catalytically inert, to the light-induced facilitation of catalytic reactions in plasmonic systems.

A mechanistic investigation of enhanced nitrogen use efficiency in wheat seedlings after treatment with an Ascophyllum nodosum biostimulant

ABSTRACTReduction in the emissions of the greenhouse gas nitrous oxide and nitrogen (N) pollution of ground water by improving nitrogen use efficiency (NUE) in crops is urgently required in pursuit of a sustainable agricultural future. Utilising an engineered biostimulant (PSI-362) derived from the brown seaweed Ascophyllum nodosum, we examined its effect on wheat seedling growth dynamics and mechanistic spatiotemporal changes at transcriptional and biochemical levels in relation to N uptake, assimilation and NUE. PSI-362-mediated biomass increase was associated with increased nitrate uptake and N assimilation in the form of glutamate, glutamine, free amino acids, soluble proteins and total chlorophyll. Phenotypical and biochemical analysis were supported by evaluation of differential expression of genetic markers involved in nitrate perception and transport (TaNRT1.1/NPF6.3), and assimilation (TaNR1 and TaNiR1, TaGDH2, TaGoGAT, TaGS1). Finally, a comparative analysis of the PSI-362 and two generic Ascophyllum nodosum extracts (ANEs) demonstrated that the NUE effect greatly differs depending on the ANE biostimulant used. In the current context of climate warming the transition of agriculture to a more sustainable model is urgently required. Application and adoption of precision biostimulants creates an opportunity for sustainable crop management, reduced production cost and environmental pollution, while maintaining yields.

Adsorption Performance of Human-like Collagen by Alkali-modified Kapok Fiber: A Kinetic, Equilibrium, and Mechanistic Investigation

Collagen-based dressings achieve excellent repair of the skin during metical cosmetology, which has received a lot of attention recently. Although great progress has been made on using biomass fiber as dressing carrier, more research is required on developing novel biomass fibers because of the limitations of (i.e., high cost and complex processing) of existing materials. In this study, the adsorption behaviors of two human-like collagen were studied by examining the Kapok fiber that was modified using alkali consisting of various amounts of the mass fraction. Results show that the alkali-modified Kapok fiber surface becomes rough with vertically arranged grooves, and the cross-section depicts the hollow cavity structure. The composition analysis of alkali modified Kapok shows that alkali dissolves part of the hemicellulose and lignin. Additionally, the surface energy rises sharply and the water contact angle changed from hydrophobic to hydrophilic. The adsorption amount of raw Kapok fiber is around 0.6g/g, which accounts for only one twenty-first of the adsorption amount of alkali-treated Kapok (around 12.6g/g), while the equilibrium adsorption amount was not sensitive to alkali concentration. The kinetics of human-like collagen followed both Quasi first and Quasi second order kinetic model, implying that the adsorption process where characterized by both physisorption and chemisorption. Finally, characterization of the AKF-2 coupled with the studies based on the inter-particle diffusion model showed a three-step of human-like collagen diffusion consisting of surface diffusion, inter-fiber diffusion and fiber' hollow cavity diffusion. Our results demonstrate a perfect high absorption performance of Kapok fiber providing a potential for application of collagen-base dressings.