Short- and long-term responses of leaf day respiration to elevated atmospheric CO2.

Evaluating leaf day respiration rate (RL), which is believed to differ from that in the dark (RDk), is essential for predicting global carbon cycles under climate change. Several studies have suggested that atmospheric CO2 impacts RL. However, the magnitude of such an impact and associated mechanisms remain uncertain. To explore the CO2 effect on RL, wheat (Triticum aestivum) and sunflower (Helianthus annuus) plants were grown under ambient (410 ppm) and elevated (820 ppm) CO2 mole fraction ([CO2]). RL was estimated from combined gas exchange and chlorophyll fluorescence measurements using the Kok method, the Kok-Phi method, and a revised Kok method (Kok-Cc method). We found that elevated growth [CO2] led to an 8.4% reduction in RL and a 16.2% reduction in RDk in both species, in parallel to decreased leaf N and chlorophyll contents at elevated growth [CO2]. We also looked at short-term CO2 effects during gas exchange experiments. Increased RL or RL/RDk at elevated measurement [CO2] were found using the Kok and Kok-Phi methods, but not with the Kok-Cc method. This discrepancy was attributed to the unaccounted changes in Cc in the former methods. We found that the Kok and Kok-Phi methods underestimate RL and overestimate the inhibition of respiration under low irradiance conditions of the Kok curve, and the inhibition of RL was only 6%, representing 26% of the apparent Kok effect. We found no significant long-term CO2 effect on RL/RDk, originating from a concurrent reduction in RL and RDk at elevated growth [CO2], and likely mediated by acclimation of nitrogen metabolism.

The response of mesophyll conductance to short-term CO2 variation is related to stomatal conductance.

The response of mesophyll conductance (gm) to CO2 plays a key role in photosynthesis and ecosystem carbon cycles under climate change. Despite numerous studies, there is still debate about how gm responds to short-term CO2 variations. Here we used multiple methods and looked at the relationship between stomatal conductance to CO2 (gsc) and gm to address this aspect. We measured chlorophyll fluorescence parameters and online carbon isotope discrimination (Δ) at different CO2 mole fractions in sunflower (Helianthus annuus L.), cowpea (Vigna unguiculata L.), and wheat (Triticum aestivum L.) leaves. The variable J and Δ based methods showed that gm decreased with an increase in CO2 mole fraction, and so did stomatal conductance. There were linear relationships between gm and gsc across CO2 mole fractions. gm obtained from A-Ci curve fitting method was higher than that from the variable J method and was not representative of gm under the growth CO2 concentration. gm could be estimated by empirical models analogous to the Ball-Berry model and the USO model for stomatal conductance. Our results suggest that gm and gsc respond in a coordinated manner to short-term variations in CO2, providing new insight into the role of gm in photosynthesis modelling.

In situ/Operando Synchrotron Radiation Analytical Techniques for CO2/CO Reduction Reaction: From Atomic Scales to Mesoscales.

Electrocatalytic carbon dioxide/carbon monoxide reduction reaction (CO(2)RR) has emerged as a prospective and appealing strategy to realize carbon neutrality for manufacturing sustainable chemical products. Developing highly active electrocatalysts and stable devices has been demonstrated as effective approach to enhance the conversion efficiency of CO(2)RR. In order to rationally design electrocatalysts and devices, a comprehensive understanding of the intrinsic structure evolution within catalysts and micro-environment change around electrode interface, particularly under operation conditions, is indispensable. Synchrotron radiation has been recognized as a versatile characterization platform, garnering widespread attention owing to its high brightness, elevated flux, excellent directivity, strong polarization and exceptional stability. This review systematically introduces the applications of synchrotron radiation technologies classified by radiation sources with varying wavelengths in CO(2)RR. By virtue of in situ/operando synchrotron radiationanalytical techniques, we also summarize relevant dynamic evolution processes from electronic structure, atomic configuration, molecular adsorption, crystal lattice and devices, spanning scales from the angstrom to the micrometer. The merits and limitations of diverse synchrotron characterization techniques are summarized, and their applicable scenarios in CO(2)RR are further presented. On the basis of the state-of-the-art fourth-generation synchrotron facilities, a perspective for further deeper understanding of the CO(2)RR process using synchrotron radiation analytical techniques is proposed.

Operando Stable Palladium Hydride Nanoclusters Anchored on Tungsten Carbides Mediate Reverse Hydrogen Spillover for Hydrogen Evolution.

Proton exchange membrane (PEM) electrolysis holds great promise for green hydrogen production, but suffering from high loading of platinum-group metals (PGM) for large-scale deployment. Anchoring PGM-based materials on supports can not only improve the atomic utilization of active sites but also enhance the intrinsic activity. However, in practical PEM electrolysis, it is still challenging to mediate hydrogen adsorption/desorption pathways with high coverage of hydrogen intermediates over catalyst surface. Here, operando generated stable palladium (Pd) hydride nanoclusters anchored on tungsten carbide (WCx) supports were constructed for hydrogen evolution in PEM electrolysis. Under PEM operando conditions, hydrogen intercalation induces formation of Pd hydrides (PdHx) featuring weakened hydrogen binding energy (HBE), thus triggering reverse hydrogen spillover from WCx (strong HBE) supports to PdHx sites, which have been evidenced by operando characterizations, electrochemical results and theoretical studies. This PdHx-WCx material can be directly utilized as cathode electrocatalysts in PEM electrolysis with ultralow Pd loading of 0.022 mg cm-2, delivering the current density of 1 A cm-2 at the cell voltage of ~1.66 V and continuously running for 200 hours without obvious degradation. This innovative strategy via tuning the operando characteristics to mediate reverse hydrogen spillover provide new insights for designing high-performance supported PGM-based electrocatalysts.

Tuning the Microenvironment in Monolayer MgAl Layered Double Hydroxide for CO2 -to-Ethylene Electrocatalysis in Neutral Media.

The electrocatalytic reduction of carbon dioxide provides a feasibility to achieve a carbon-neutral energy cycle. However, there are a number of bottleneck issues to be resolved before industrial application, such as the low conversion efficiency, selectivity and reaction rate, etc. Engineering local environment is a critical way to address these challenges. Here, a monolayer MgAl-LDH was proposed to optimize the local environment of Cu for stimulating industrial-current-density CO2 -to-C2 H4 electroreduction in neutral media. In situ spectroscopic results and theoretical study demonstrated that the Cu electrode modified by MgAl-LDH (MgAl-LDH/Cu) displayed a much higher surface pH value compared to the bare Cu, which could be attributed to the decreased energy barrier for hydrolysis on MgAl-LDH sites with more OH- ions on the surface of the electrode. As a result, MgAl-LDH/Cu achieved a C2 H4 Faradaic efficiency of 55.1 % at a current density up to 300 mA cm-2 in 1.0 M KHCO3 electrolyte.

[Mechanism of cellular uptake and transport mediated by integrin receptor targeting trimethyl chitosan nanoparticles].

This study investigated a nano drug delivery system built by one sort of modified trimethyl chitosan (TMC). The TMC was modified by cRGDyk, ligand of integrin receptor avß3. Single factor screening was used to optimize the prescription in which the particle sizes of TMC nanoparticle (TMC NPs) and cRGDyk modified TMC nanoparticle (C-TMC NPs) were (240.3 ± 4.2) nm and (259.5 ± 3.3) nm. Electric potential of those two nanoparticles were (33.5 ± 0.8) mV and (25.7 ± 1.6) mV. Encapsulation efficiencies were (76.0 ± 2.2) % and (74.4 ± 2.0) %. Drug loading efficacies were (50.1 ± 2.1) % and (26.1 ± 1.0) %. Then the cellular uptake, uptake mechanism and transport efficacy of TMC NPs and C-TMC NPs were investigated using Caco-2 cell line. The uptake rate and accumulating drug transit dose of C-TMC NPs were 1.98 and 2.84 times higher than TMC NPs, separately. Mechanism investigations revealed that caveolae-mediated endocytosis, clathrin-mediated endocytosis and macropinocytosis were involved in the intercellular uptake of both TMC NPs and C-TMC NPs. What is more, free cRGDyk could remarkably inhibit the uptake of C-TMC NPs.

Induction of ganoderic acid biosynthesis by Mn2+ in static liquid cultivation of Ganoderma lucidum.

Metal ions affect cell physiology and metabolism significantly, but the role of Mn(2+) in the secondary metabolism of mushrooms is yet unclear. In static liquid cultivation of Ganoderma lucidum for producing antitumor ganoderic acids (GAs), the Mn(2+) addition was performed. Addition of 10 mM Mn(2+) at the start of the static liquid cultivation resulted in 2.2-fold improvement of total GAs production. The expression levels of GA biosynthetic and Ca(2+) sensors' genes were up-regulated with Mn(2+) induction while down-regulated by adding cyclosporin A (calcineurin inhibitor), suggesting that higher GA production might result from calcineurin signal regulation. Intracellular Ca(2+) imaging and calcineurin inhibitor study revealed that addition of Mn(2+) led to Ca(2+) influx from medium to the cells to trigger calcineurin signals. Mn(2+) addition was therefore an efficient induction strategy for improving GAs production, whose regulation mechanism was via calcineurin signaling transduction.

Poliumoside protects against type 2 diabetes-related osteoporosis by suppressing ferroptosis via activation of the Nrf2/GPX4 pathway.

BACKGROUND: Type 2 diabetes is often linked with osteoporosis (T2DOP), a condition that accelerates bone degeneration and increases the risk of fractures. Unlike conventional menopausal osteoporosis, the diabetic milieu exacerbates the likelihood of fractures and osteonecrosis. In particular poliumoside (Pol), derived from Callicarpa kwangtungensis Chun, has shown promising anti-oxidant and anti-inflammatory effects. Yet, its influence on T2DOP remains to be elucidated. PURPOSE: The focus of this study was to elucidate the influence of Pol in HGHF-associated ferroptosis and its implications in T2DOP. STUDY DESIGN: A murine model of T2DOP was established using a minimal dosage of streptozotocin (STZ) through intraperitoneal infusion combined with a diet high in fat and sugar. Concurrently, to mimic the diabetic condition in a lab environment, bone mesenchymal stem cells (BMSCs) were maintained in a high-glucose and high-fat (HGHF) setting. METHODS: The impact of Pol on BMSCs in an HGHF setting was determined using methods, such as BODIPY-C11, FerroOrange staining, mitochondrial functionality evaluations, and Western blot methodologies, coupled with immunoblotting and immunofluorescence techniques. To understand the role of Pol in a murine T2DOP model, techniques including micro-CT, hematoxylin and eosin (H&E) staining, dual-labeling with calcein-alizarin red, and immunohistochemistry were employed for detailed imaging and histological insights. RESULTS: Our findings suggest that Pol acts against HGHF-induced bone degradation and ferroptosis, as evidenced by an elevation in glutathione (GSH) and a decline in malondialdehyde (MDA) levels, lipid peroxidation, and mitochondrial reactive oxygen species (ROS). Furthermore, Pol treatment led to increased bone density, enhanced GPX4 markers, and reduced ROS in the distal femur region. On investigating the underlying mechanism of action, it was observed that Pol triggers the Nrf2/GPX4 pathway, and the introduction of lentivirus-Nrf2 negates the beneficial effects of Pol in HGHF-treated BMSCs. CONCLUSION: Pol is effective in treating T2DOP by activating the Nrf2/GPX4 signaling pathway to inhibit ferroptosis.

Induced effect of Na(+) on ganoderic acid biosynthesis in static liquid culture of Ganoderma lucidum via calcineurin signal transduction.

Na(+)/Ca(2+) exchange is important to cell physiology and metabolism, but its role in the secondary metabolite biosynthesis by fungi is yet unclear. In this work, in static liquid cultures of Ganoderma lucidum, which is an efficient process for hyper-production of anti-tumor ganoderic acids (GAs), it was interestingly found that Na(+) addition could enhance the GAs production, but K(+) did not. Further investigation by intracellular Ca(2+) imaging and using a calcineurin inhibitor (i.e., cyclosporin A) revealed that addition of Na(+) led to the influx of Ca(2+) from culture broth to the cells and calcineurin signals were also triggered. Addition of 100 mM Na(+) at the beginning of the static liquid cultivation, in which the addition dosage and timing were optimized, resulted in 2.8-fold improvement of total GAs production. Quantitative gene transcription analysis indicated that the expression levels of the genes of Ca(2+) sensors and GA biosynthesis were upregulated with Na(+) induction while downregulated by using the calcineurin inhibitor, implying that higher GA production might result from higher expression of those genes. This work not only provided a simple and efficient induction strategy by Na(+) addition for the improved GAs production but also suggested the regulation mechanism of Na(+) on the GA biosynthesis through calcineurin signaling transduction.

Photosynthetic resource-use efficiency trade-offs triggered by vapour pressure deficit and nitrogen supply in a C4 species.

Trade-offs in resource-use efficiency (including water-, nitrogen-, and light-use efficiency, i.e., WUE, NUE, and LUE) are an important acclimation strategy of plants to environmental stresses. C4 photosynthesis, featured by a CO2 concentrating mechanism, is believed to be more efficient in using resources compared to C3 photosynthesis. However, response of photosynthetic resource-use efficiency trade-offs in C4 plants to vapour pressure deficit (VPD) and N supply has rarely been studied. Here, we studied the photosynthetic acclimation of Cleistogenes squarrosa, a perennial C4 grass, to controlled growth conditions with high or low VPD and N supply. High VPD increased WUE by 12% and decreased NUE by 16%, the ratio of net photosynthetic rate (A) to electron transport rate (J) (A/J) by 7% and the apparent quantum yield by 6%. High N supply tended to reduce NUE and increased maximum phosphoenol pyruvate carboxylation rate by 71% and slightly increased WUE. Stomatal conductance showed acclimation to VPD according to the Ball-Berry model, while a balanced cost of carboxylation and transpiration capacity was found across VPD and N treatments based on the least-cost model. WUE correlated negatively with NUE and LUE indicating that there was a trade-off between them, which is likely associated with acclimations in stomatal conductance and CO2 concentrating mechanisms.

Enhancement of ganoderic acid accumulation by overexpression of an N-terminally truncated 3-hydroxy-3-methylglutaryl coenzyme A reductase gene in the basidiomycete Ganoderma lucidum.

Ganoderic acids produced by Ganoderma lucidum, a well-known traditional Chinese medicinal mushroom, exhibit antitumor and antimetastasis activities. Genetic modification of G. lucidum is difficult but critical for the enhancement of cellular accumulation of ganoderic acids. In this study, a homologous genetic transformation system for G. lucidum was developed for the first time using mutated sdhB, encoding the iron-sulfur protein subunit of succinate dehydrogenase, as a selection marker. The truncated G. lucidum gene encoding the catalytic domain of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) was overexpressed by using the Agrobacterium tumefaciens-mediated transformation system. The results showed that the mutated sdhB successfully conferred carboxin resistance upon transformation. Most of the integrated transfer DNA (T-DNA) appeared as a single copy in the genome. Moreover, deregulated constitutive overexpression of the HMGR gene led to a 2-fold increase in ganoderic acid content. It also increased the accumulation of intermediates (squalene and lanosterol) and the upregulation of downstream genes such as those of farnesyl pyrophosphate synthase, squalene synthase, and lanosterol synthase. This study demonstrates that transgenic basidiomycete G. lucidum is a promising system to achieve metabolic engineering of the ganoderic acid pathway.

Isolation and analysis of differentially expressed genes during asexual sporulation in liquid static culture of Ganoderma lucidum by suppression subtractive hybridization.

Ganoderma lucidum differentiates in liquid static culture by forming aerial mycelia and asexual spores, and this differentiation process is accompanied by higher production of anti-tumor compounds ganoderic acids. To gain an insight into the molecular events during asexual sporulation of G. lucidum, comparative transcriptome analysis using suppression subtractive hybridization (SSH) technique was performed to identify preferentially expressed genes in liquid static culture vs. in traditional shaking culture. After macroarray analysis of 1920 cDNAs from SSH library, 147 unigenes which exhibited high expression in static culture were identified. Among these sequences, putative translations of 88 unigenes possessed much similarity to known proteins involved in cell organization, signal transduction, cell metabolism, protein biosynthesis and transcription regulation; 13 had significant similarity to hypothetical proteins; the remaining 46 showed little or no similarity to GenBank sequences. RT-qPCR analysis confirmed increases in transcripts of selected genes under liquid static culture condition. The results of this study present the useful application of EST analysis on G. lucidum and provide preliminary indication of gene expression putatively involved in asexual sporulation process.

Facial Skin Microbiota-Mediated Host Response to Pollution Stress Revealed by Microbiome Networks of Individual.

Urban living has been reported to cause various skin disorders. As an integral part of the skin barrier, the skin microbiome is among the key factors associated with urbanization-related skin alterations. The role of skin microbiome in mediating the effect of urban stressors (e.g., air pollutants) on skin physiology is not well understood. We generated 16S sequencing data and constructed a microbiome network of individual (MNI) to analyze the effect of pollution stressors on the microbiome network and its downstream mediation effect on skin physiology in a personalized manner. In particular, we found that the connectivity and fragility of MNIs significantly mediated the adverse effects of air pollution on skin health, and a smoking lifestyle deepened the negative effects of pollution stress on facial skin microbiota. This is the first study that describes the mediation effect of the microbiome network on the skin's physiological response toward environmental factors as revealed by our newly developed MNI approach and conditional process analysis. IMPORTANCE The association between the skin microbiome and skin health has been widely reported. However, the role of the skin microbiome in mediating skin physiology remains a challenging and yet priority subject in the field. Through developing a novel MNI method followed by mediation analysis, we characterized the network signature of the skin microbiome at an individual level and revealed the role of the skin microbiome in mediating the skin's responses toward environmental stressors. Our findings may shed new light on microbiome functions in skin health and lay the foundation for the design of a microbiome-based intervention strategy in the future.

Production of individual ganoderic acids and expression of biosynthetic genes in liquid static and shaking cultures of Ganoderma lucidum.

Two-stage culture was efficient in enhancing total ganoderic acid (GA) production by Ganoderma lucidum (Fang and Zhong, Biotechnol Prog 18:51-54, 2002). As different GAs have different bioactivities, it is critical to understand the kinetics of individual GA production during fermentation, but no related information is yet available. To understand the regulation of GA biosynthesis, investigation of the accumulation of intermediate (lanosterol) and by-product (ergosterol) and of the expression of three important biosynthetic genes was also conducted in liquid shaking and static cultures of G. lucidum. The results showed that the content of individual GAs increased rapidly in the liquid static culture, and their maximum value was 6- to 25-fold that of shaking culture while lanosterol content in the former was lower than the latter. The transcript of squalene synthase (SQS), lanosterol synthase and 3-hydroxy-3-methylglutaryl coenzyme A reductase in liquid static culture was 4.3-, 2.1-, and 1.9-fold that of the shaking culture, respectively. Higher GA content in liquid static culture was related to increased transcription of those genes especially SQS. The work is helpful to the production of individual GAs and provided an insight into why the liquid static culture was superior to the shaking culture in view of biosynthetic gene expression.

Impacts of calcium signal transduction on the fermentation production of antitumor ganoderic acids by medicinal mushroom Ganoderma lucidum.

Recently signal transduction engineering of secondary metabolism is receiving great interest as a powerful tool towards efficient production of valuable secondary metabolites. This work found that the calcineurin-signal transduction was significant to triterpene biosynthesis by higher fungus (mushroom). Addition of calcium ion (at 10mM) to static liquid cultures of Ganoderma lucidum, a famous traditional medicinal mushroom, was proved as a useful strategy to enhance the production of antitumor ganoderic acids (GAs), which resulted in 3.7-, 2.6-, 4.5-, 3.2- and 3.8-fold improvement of total GAs, individual GA-Mk, -T, -S, and -Me, respectively. Experiments using Ca2+ sensor inhibitors indicated the involvement of calcineurin signal in regulating GAs biosynthesis. Quantitative gene transcription analysis revealed that the expression levels of genes of GAs biosynthesis and Ca2+ sensor were up-regulated with calcium addition while down-regulated under the inhibitors addition, suggesting that higher GAs production may be resulted from higher expressions of those genes. Based on the results obtained, a possible model on the effect of external calcium ion on the GAs biosynthesis via calcineurin signal transduction pathway was proposed.