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Summary Marine microalgae demonstrate a notable capacity to adapt to high CO2 and warming in the context of global change. However, the dynamics of their evolutionary processes under simultaneous high CO₂ and warming conditions remain poorly understood. Here, we analyze the dynamics of evolution in experimental populations of a model marine diatom Phaeodactylum tricornutum. We conducted whole‐genome resequencing of populations under ambient, high‐CO2, warming and high CO2 + warming at 2‐yr intervals over a 4‐yr adaptation period. The common genes selected between 2‐ and 4‐yr adaptation were found to be involved in protein ubiquitination and degradation and the tricarboxylic acid (TCA) cycle, and were consistently selected regardless of the experimental conditions or adaptation duration. The unique genes selected only by 4‐yr adaptation function in respiration, fatty acid, and amino acid metabolism, facilitating adaptation to prolonged high CO2 with warming conditions. Corresponding changes at the metabolomic level, with significant alterations in metabolites abundances involved in these pathways, support the genomic findings. Our study, integrating genomic and metabolomic data, demonstrates that long‐term adaptation of microalgae to high CO2 and/or warming can be characterized by a complex and dynamic genetic process and may advance our understanding of microalgae adaptation to global change. [ABSTRACT FROM AUTHOR]

Malonyl‐coenzyme A (CoA) is a key precursor for the biosynthesis of multiple value‐added compounds by microbial cell factories, including polyketides, carboxylic acids, biofuels, and polyhydroxyalkanoates. Owing to its role as a metabolic hub, malonyl‐CoA availability is limited by competition in several essential metabolic pathways. To address this limitation, we modified a genome‐reduced Pseudomonas putida strain to increase acetyl‐CoA carboxylation while limiting malonyl‐CoA utilization. Genes involved in sugar catabolism and its regulation, the tricarboxylic acid (TCA) cycle, and fatty acid biosynthesis were knocked‐out in specific combinations towards increasing the malonyl‐CoA pool. An enzyme‐coupled biosensor, based on the rppA gene, was employed to monitor malonyl‐CoA levels in vivo. RppA is a type III polyketide synthase that converts malonyl‐CoA into flaviolin, a red‐colored polyketide. We isolated strains displaying enhanced malonyl‐CoA availability via a colorimetric screening method based on the RppA‐dependent red pigmentation; direct flaviolin quantification identified four engineered strains had a significant increase in malonyl‐CoA levels. We further modified these strains by adding a non‐canonical pathway that uses malonyl‐CoA as precursor for poly(3‐hydroxybutyrate) biosynthesis. These manipulations led to increased polymer accumulation in the fully engineered strains, validating our general strategy to boost the output of malonyl‐CoA–dependent pathways in P. putida. [ABSTRACT FROM AUTHOR]

Lysine β‐hydroxybutyrylation (Kbhb) is a post‐translational modification that has recently been found to regulate protein functions. However, whether and how protein Kbhb modification participates in Alzheimer's disease (AD) remains unknown. Herein, we carried out 4D label‐free β‐hydroxybutylation quantitative proteomics using brain samples of 8‐month‐old and 2‐month‐old APP/PS1 AD model mice and wild‐type (WT) controls. We identified a series of tricarboxylic acid (TCA) cycle‐associated enzymes including citrate synthase (CS) and succinate‐CoA ligase subunit alpha (SUCLG1), whose Kbhb modifications were decreased in APP/PS1 mice at pathological stages. Sodium β‐hydroxybutyrate (Na‐β‐OHB) treatment markedly increased Kbhb modifications of CS and SUCLG1 and their enzymatic activities, leading to elevated ATP production. We further found that Kbhb modifications at lysine 393 site in CS and at lysine 81 site in SUCLG1 were crucial for their enzymatic activities. Finally, we found that β‐OHB levels were decreased in the brain of APP/PS1 mice at pathological stages. While ketogenic diet not only significantly increased β‐OHB levels, Kbhb modifications and enzymatic activities of CS and SUCLG1, and ATP production, but also dramatically attenuated β‐amyloid plaque pathologies and microgliosis in APP/PS1 mice. Together, our findings indicate the importance of protein Kbhb modification for maintaining normal TCA cycle and ATP production and provide a novel molecular mechanism underlying the beneficial effects of ketogenic diet on energy metabolism and AD intervention. [ABSTRACT FROM AUTHOR]

The neuronal tricarboxylic acid and glutamate/glutamine (Glu/Gln) cycles play important roles in brain function. These processes can be measured in vivo using dynamic 1H–[13C] MRS during administration of 13C‐labeled glucose. Proton‐observed carbon‐edited (POCE) MRS enhances the signal‐to‐noise ratio (SNR) compared with direct 13C‐MRS. Ultra‐high field further boosts the SNR and increases spectral dispersion; however, even at 7 T, Glu and Gln 1H‐resonances may overlap. Further gain can be obtained with selective POCE (selPOCE). Our aim was to create a setup for indirect dynamic 1H–[13C] MRS in the human brain at 7 T. A home‐built non‐shielded transmit–receive 13C‐birdcage head coil with eight transmit–receive 1H‐dipole antennas was used together with a 32‐channel 1H‐receive array. Electromagnetic simulations were carried out to ensure that acquisitions remained within local and global head SAR limits. POCE‐MRS was performed using slice‐selective excitation with semi‐localization by adiabatic selective refocusing (sLASER) and stimulated echo acquisition mode (STEAM) localization, and selPOCE‐MRS using STEAM. Sequences were tested in a phantom containing non‐enriched Glu and Gln, and in three healthy volunteers during uniformly labeled 13C‐glucose infusions. In one subject the voxel position was alternated between bi‐frontal and bi‐occipital placement within one session. [4‐13C]Glu‐H4 and [4‐13C]Gln‐H4 signals could be separately detected using both STEAM‐POCE and STEAM‐selPOCE in the phantom. In vivo, [4,5‐13C]Glx could be detected using both sLASER‐POCE and STEAM‐POCE, with similar sensitivities, but [4,5‐13C]Glu and [4,5‐13C]Gln signals could not be completely resolved. STEAM‐POCE was alternately performed bi‐frontal and bi‐occipital within a single session without repositioning of the subject, yielding similar results. With STEAM‐selPOCE, [4,5‐13C]Glu and [4,5‐13C]Gln could be clearly separated. We have shown that with our setup indirect dynamic 1H–[13C] MRS at 7 T is feasible in different locations in the brain within one session, and by using STEAM‐selPOCE it is possible to separate Glu from Gln in vivo while obtaining high quality spectra. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have emerged as promising materials for triboelectric nanogenerators (TENGs), but the effects of ligand choice on triboelectric charge remain underexplored. Hence, this paper demonstrates the effect of single, binary, and ternary ligands on TENG performance of cobalt/cerium‐based (Co─Ce) bimetallic MOFs utilizing 2‐methylimidazole (2Melm), terephthalic acid (BDC), and benzene tricarboxylic acid (BTC) as ligands. The detailed structural characterization revealed that varying ligand chemistries led to distinct MOF features affecting TENG performance. Single ligand bimetallic MOFs (designated as CoCe‐2MeIm, CoCe‐BDC, CoCe‐BTC) has lower performance than binary ligand (designated as CoCe‐2MeIm‐BDC, CoCe‐2MeIm‐BTC, CoCe‐BDC‐BTC) and ternary ligand MOFs (designated as CoCe‐2MeIm‐BDC‐BTC). Among all, the binary ligand MOF, CoCe‐2MeIm‐BTC, shows the best results (598 V, 26.7 µA) due to the combined effect of imidazole ring and (─COO─) groups. This is attributed to lone pairs on nitrogen atoms and a delocalized π‐electron system in imidazole system in this material. CoCe‐BTC has the lowest results (31 V, 3.2 µA) due to the bulkier nature of the electron‐withdrawing (─COO─) groups and their impact on the π‐electron system of the benzene ring. This study showcases the potential of ligand chemistry manipulation to control triboelectric charge and thereby enhance MOF‐based TENG performance. [ABSTRACT FROM AUTHOR]

Background: In humans with pheochromocytomas (PCCs), targeted metabolomics is used to determine the catecholamine phenotype or to uncover underlying pathogenic variants in tricarboxylic acid (TCA) cycle genes such as succinate dehydrogenase subunits (SDHx). Hypothesis/Objectives: To analyze catecholamine contents and TCA cycle metabolites of PCCs and normal adrenals (NAs). Animals: Ten healthy dogs, 21 dogs with PCC. Methods: Prospective observational study. Dogs diagnosed with PCC based on histopathological and immunohistochemical confirmation were included. Tissue catecholamine contents and TCA metabolites in PCCs and NAs were measured by liquid chromatography with mass spectrometry or electrochemical detection. Results: Compared to NAs, PCCs had significantly higher tissue proportion of norepinephrine (88% [median: range, 38%‐98%] vs 14% [11%‐26%]; P <.001), and significantly lower tissue proportion of epinephrine (12% [1%‐62%] vs 86% [74%‐89%]; P <.001). Pheochromocytomas exhibited significantly lower fumarate (0.4‐fold; P <.001), and malate (0.5‐fold; P =.008) contents than NAs. Citrate was significantly higher in PCCs than in NAs (1.6‐fold; P =.015). One dog in the PCC group had an aberrant succinate : fumarate ratio that was 25‐fold higher than in the other PCCs, suggesting an SDHx mutation. Conclusions and Clinical Importance: This study reveals a distinct catecholamine content and TCA cycle metabolite profile in PCCs. Metabolite profiling might be used to uncover underlying pathogenic variants in TCA cycle genes in dogs. [ABSTRACT FROM AUTHOR]

The regulation of complex energy metabolism is intricately linked to cellular energy demands. Caloric restriction (CR) plays a pivotal role in modulating the expression of genes associated with key metabolic pathways, including glycolysis, the tricarboxylic acid (TCA) cycle, and the glyoxylate cycle. In this study, the chronological lifespan (CLS) of 35 viable single‐gene deletion mutants under both non‐restricted and CR conditions, focusing on genes related to these metabolic pathways is evaluated. CR is found to increase CLS predominantly in mutants associated with the glycolysis and TCA cycle. However, this beneficial effect of CR is not observed in mutants of the glyoxylate cycle, particularly those lacking genes for critical enzymes like isocitrate lyase 1 (icl1Δ) and malate synthase 1 (mls1Δ). This analysis revealed an increase in isocitrate lyase activity, a key enzyme of the glyoxylate cycle, under CR, unlike the activity of isocitrate dehydrogenase, which remains unchanged and is specific to the TCA cycle. Interestingly, rapamycin, a compound known for extending lifespan, does not increase the activity of the glyoxylate cycle enzyme. This suggests that CR affects lifespan through a distinct metabolic mechanism. [ABSTRACT FROM AUTHOR]

In the realm of renewable energy technologies, the development of efficient and durable electrocatalysts is paramount, especially for applications like electrochemical water splitting. This research focuses on synthesizing a novel bimetallic metal‐organic framework (BMMOF11) using earth‐abundant elements, cobalt (Co) and cadmium (Cd). BMMOF11 showcases a distinctive structure with distorted octahedral chains of CoO and CdO, linked by benzene tricarboxylic acid (BTC). Our study primarily investigates the electrocatalytic efficiency of BMMOF11, particularly in water oxidation reactions. For practical analysis, BMMOF11 was anchored onto nickel foam, forming BMMOF11/NF, to evaluate its electrocatalytic properties. Electrochemical testing revealed that BMMOF11/NF begins water oxidation at an onset potential of 1.62 V versus RHE, demonstrating high activity with a lower overpotential of 0.4 V to achieve a current density of 10 mA/cm2. Moreover, BMMOF11/NF maintained stable water splitting performance, sustaining a current density of approximately 70 mA/cm2 under a voltage of 1.9 V relative to RHE. These findings indicate that BMMOF11/NF is a promising candidate for large‐scale electrochemical water splitting, offering a blend of high activity and stability. [ABSTRACT FROM AUTHOR]

The interplay between viral pathogens and host metabolism plays a pivotal role in determining the outcome of viral infections. Upon viral detection, the metabolic landscape of the host cell undergoes significant changes, shifting from oxidative respiration via the tricarboxylic acid (TCA) cycle to increased aerobic glycolysis. This metabolic shift is accompanied by elevated nutrient accessibility, which is vital for cell function, development, and proliferation. Furthermore, depositing metabolites derived from fatty acids, TCA intermediates, and amino acid catabolism accelerates the immunometabolic transition, facilitating pro‐inflammatory and antimicrobial responses. Immunometabolites refer to small molecules involved in cellular metabolism regulating the immune response. These molecules include nutrients, such as glucose and amino acids, along with metabolic intermediates and signaling molecules adenosine, lactate, itaconate, succinate, kynurenine, and prostaglandins. Emerging evidence suggests that immunometabolites released by immune cells establish a complex interaction network within local niches, orchestrating and fine‐tuning immune responses during viral diseases. However, our current understanding of the immense capacity of metabolites to convey essential cell signals from one cell to another or within cellular compartments remains incomplete. Unraveling these complexities would be crucial for harnessing the potential of immunometabolites in therapeutic interventions. In this review, we discuss specific immunometabolites and their mechanisms of action in viral infections, emphasizing recent findings and future directions in this rapidly evolving field. [ABSTRACT FROM AUTHOR]

For centuries, Gram‐negative pathogens have infected the human population and been responsible for numerous diseases in animals and plants. Despite advancements in therapeutics, Gram‐negative pathogens continue to evolve, with some having developed multi‐drug resistant phenotypes. For the successful control of infections caused by these bacteria, we need to widen our understanding of the mechanisms of host–pathogen interactions. Gram‐negative pathogens utilise an array of effector proteins to hijack the host system to survive within the host environment. These proteins are secreted into the host system via various secretion systems, including the integral Type III secretion system (T3SS). The T3SS spans two bacterial membranes and one host membrane to deliver effector proteins (virulence factors) into the host cell. This multifaceted process has multiple layers of regulation and various checkpoints. In this review, we highlight the multiple strategies adopted by these pathogens to regulate or maintain virulence via the T3SS, encompassing the regulation of small molecules to sense and communicate with the host system, as well as master regulators, gatekeepers, chaperones, and other effectors that recognise successful host contact. Further, we discuss the regulatory links between the T3SS and other systems, like flagella and metabolic pathways including the tricarboxylic acid (TCA) cycle, anaerobic metabolism, and stringent cell response. [ABSTRACT FROM AUTHOR]

Novel electrode and electrolyte materials are crucial for enhancing supercapacitor efficiency. Metal–organic frameworks (MOFs) have gained attention owing to their high porosity and surface area. However, their low capacity limits their usage. To tackle this, a highly effective mechanochemical annealing strategy is implemented to improve their efficiency. Three different forms of metal oxides NiCo2O4 are derived from bimetallic MOFs by incorporating Ni2+ and Co2+ with linkers 1,3,5‐benzene tricarboxylic acid (MO‐1), 2,6‐naphthalene dicarboxylic acid (MO‐2), and 1,2,4,5‐benzene tetracarboxylic acid (MO‐3). The synthesized metal oxides have different morphologies due to different linkers and displayed remarkable electrochemical performance, attributed to favorable charge transport paths and enhanced electrochemical double‐layer capacitance with an enlarged specific surface area. These metal oxides exhibit specific capacitance values of 913.3, 43.4, and 210 F g−1 at operating voltages of 0.55, 0.55, and 0.6 V for MO‐1, MO‐2, and MO‐3, respectively. Notably, MO‐1 shows extended discharging time and demonstrates the characteristic behavior of battery‐type supercapacitors, making it versatile. The fabricated hybrid supercapacitor (bimetal hybrid supercapacitor) shows pseudocapacitive behavior, reaching up to 1.5 V with a specific capacitance of 65.6 F g−1, energy density of 73.83 W h kg−1, and power density of 1181.2 W kg−1. [ABSTRACT FROM AUTHOR]

Summary: Over the past decade, there has been a surge in discoveries of how metabolic pathways regulate immune cell function in health and disease, establishing the field of immunometabolism. Specifically, pathways such as glycolysis, the tricarboxylic acid (TCA) cycle, and those involving lipid metabolism have been implicated in regulating immune cell function. Viral infections cause immunometabolic changes which lead to antiviral immunity, but little is known about how metabolic changes regulate interferon responses. Interferons are critical cytokines in host defense, rapidly induced upon pathogen recognition, but are also involved in autoimmune diseases. This review summarizes how metabolic change impacts interferon production. We describe how glycolysis, lipid metabolism (specifically involving eicosanoids and cholesterol), and the TCA cycle‐linked intermediates itaconate and fumarate impact type I interferons. Targeting these metabolic changes presents new therapeutic possibilities to modulate type I interferons during host defense or autoimmune disorders. [ABSTRACT FROM AUTHOR]

Ferroptosis and apoptosis are key cell‐death pathways implicated in several human diseases including cancer. Ferroptosis is driven by iron‐dependent lipid peroxidation and currently has no characteristic biomarkers or gene signatures. Here a continuous phenotypic gradient between ferroptosis and apoptosis coupled to transcriptomic and metabolomic landscapes is established. The gradual ferroptosis‐to‐apoptosis transcriptomic landscape is used to generate a unique, unbiased transcriptomic predictor, the Gradient Gene Set (GGS), which classified ferroptosis and apoptosis with high accuracy. Further GGS optimization using multiple ferroptotic and apoptotic datasets revealed highly specific ferroptosis biomarkers, which are robustly validated in vitro and in vivo. A subset of the GGS is associated with poor prognosis in breast cancer patients and PDXs and contains different ferroptosis repressors. Depletion of one representative, PDGFA‐assaociated protein 1(PDAP1), is found to suppress basal‐like breast tumor growth in a mouse model. Omics and mechanistic studies revealed that ferroptosis is associated with enhanced lysosomal function, glutaminolysis, and the tricarboxylic acid (TCA) cycle, while its transition into apoptosis is attributed to enhanced endoplasmic reticulum(ER)‐stress and phosphatidylethanolamine (PE)‐to‐phosphatidylcholine (PC) metabolic shift. Collectively, this study highlights molecular mechanisms underlying ferroptosis execution, identified a highly predictive ferroptosis gene signature with prognostic value, ferroptosis versus apoptosis biomarkers, and ferroptosis repressors for breast cancer therapy. [ABSTRACT FROM AUTHOR]

[1′‐13C]Citric acid (1) was efficiently prepared from dimethyl 1,3‐acetonedicarboxylate in two steps as a probe for a breath test. The synthetic method was selected because of the yield and reproducibility. Compound 1 was orally administrated to rats, and the time course of the increase of 13CO2/12CO2 ratios (Δ13CO2) in their breath was successfully followed, indicating the metabolism of 1. Thus, the 13C‐breath test using 1 is a promising method to evaluate tricarboxylic acid (TCA) cycle flux. [ABSTRACT FROM AUTHOR]

Objective: Tumor cells can acquire a large amount of energy and structural components by reprogramming energy metabolism; moreover, metabolic profiles slightly differ according to cancer type. This study compared and assessed the metabolic profile of head and neck squamous cell carcinoma (HNSCC) and normal tissues, which were collected from patients without cancer. Subjects and Methods: Overall, 23 patients with HNSCC and 6 patients without cancer were included in the analysis. Metabolomic profiles were analyzed using capillary electrophoresis‐mass spectrometry. Gene expression was evaluated using real‐time reverse transcription‐polymerase chain reaction. Results: Glycolysis, the pentose phosphate pathway, tricarboxylic acid cycle, and glutamine metabolism were upregulated in HNSCC tissues based on gene expression analysis. HNSCC could then have enhanced energy production and structural component. The levels of lactate, succinate, glutathione, 2‐hydroxyglutarate, and S‐adenosylmethionine, considered as oncometabolites, increased and these had accumulated in HNSCC tissues. Conclusions: The level of metabolites and the expression of enzymes differ between HNSCC and normal tissues. Reprogramming metabolism in HNSCC provides an energy source as well as structural components, creating a system that offers rapid proliferation, progression, and is less likely to be eliminated. [ABSTRACT FROM AUTHOR]

Two organic cocrystals, one (1) based on benzene 1,3,5 tricarboxylic acid (TMA) plus 4‐amino pyridine and another (2) based on benzene 1,3,5 tricarboxylic acid (TMA) plus urea is reported. Cocrystals 1 and 2 are fully characterized by single crystal X ray diffraction, NMR and IR spectroscopy. The single crystal X ray diffraction shows the intermolecular H‐bonding interaction between components of the pairs TMA‐TMA as well as TMA‐4 amino pyridine and TMA‐Urea molecules. The conductivity studies for the cocrystal 1 shows semiconducting behavior whereas cocrystal 2remain as insulator under the same experimental condition. Computational studies with theoretically optimized structures as well as experimental X‐ray structures of both the cocrystals reveal the origin of conductivity as the H‐atom coupled charge transfer through the intermolecular H‐bonding between TMA and 4‐amino pyridine in cocrystal 1. [ABSTRACT FROM AUTHOR]

The Warburg effect‐related metabolic dysfunction of the tricarboxylic acid (TCA) cycle has emerged as a hallmark of various solid tumors, particularly renal cell carcinoma (RCC). RCC is characterized by high immune infiltration and thus recommended for immunotherapeutic interventions at an advanced stage in clinical guidelines. Nevertheless, limited benefits of immunotherapy have prompted investigations into underlying mechanisms, leading to the proposal of metabolic dysregulation‐induced immunoevasion as a crucial contributor. In this study, a significant decrease is found in the abundance of alpha‐ketoglutarate (αKG), a crucial intermediate metabolite in the TCA cycle, which is correlated with higher grades and a worse prognosis in clinical RCC samples. Elevated levels of αKG promote major histocompatibility complex‐I (MHC‐I) antigen processing and presentation, as well as the expression of β2‐microglobulin (B2M). While αKG modulates broad‐spectrum demethylation activities of histone, the transcriptional upregulation of B2M is dependent on the demethylation of H3K4me1 in its promoter region. Furthermore, the combination of αKG supplementation and PD‐1 blockade leads to improved therapeutic efficacy and prolongs survival in murine models when compared to monotherapy. Overall, the findings elucidate the mechanisms of immune evasion in anti‐tumor immunotherapies and suggest a potential combinatorial treatment strategy in RCC. [ABSTRACT FROM AUTHOR]

Bacterial infections of the gut are one of the major causes of morbidity and mortality worldwide. The interplay between the pathogen and the host is finely balanced, with the bacteria evolving to proliferate and establish infection. In contrast, the host mounts a response to first restrict and then eliminate the infection. The intestine is a rapidly proliferating tissue, and metabolism is tuned to cater to the demands of proliferation and differentiation along the crypt–villus axis (CVA) in the gut. As bacterial pathogens encounter the intestinal epithelium, they elicit changes in the host cell, and core metabolic pathways such as the tricarboxylic acid (TCA) cycle, lipid metabolism and glycolysis are affected. This review highlights the mechanisms utilized by diverse gut bacterial pathogens to subvert host metabolism and describes host responses to the infection. [ABSTRACT FROM AUTHOR]

Activation of cuproptosis pathway has been reported to hold great potential in the application of tumor treatment. But the efficacy of cuproptosis seriously limited by the insufficient accumulation in the tumor sites. Therefore, herein based on the strong stabilization effects of the metalloid element selenium (Se) on copper (Cu), a photothermic Cu2‐xSe nanoparticle encapsulated with bioresponsive dimethyl maleic anhydride (DMMA@Cu2‐xSe) as a copper‐carrier to improve the copper accumulation in tumor is constructed, thus achieving cuproptosis‐driven enhancement of thermotherapy. This nanosystem exhibits the enhancement of tumor cellular uptake by a weak acid‐triggered charge‐switching ability. Next step, the exposed Cu2‐xSe is oxidized and releases divalent copper by high‐level oxide. Then, the abundant copper induces more dihydrolipoamide S‐acetyltransferase oligomerization to down‐regulate FDX1 and tricarboxylic acid cycle‐related proteins, which leads to inhibiting aerobic respiration. Cuproptosis‐induced mitochondrial damage further improves thermotherapy by up‐regulating reactive oxygen species (ROS). In addition, the generated ROS also promotes copper release to strengthen cuproptosis, and eventually improves tumor thermotherapy in turn. In general, DMMA@Cu2‐xSe with sequentially triggered copper‐release, efficient cuproptosis, and appropriate photothermal is a self‐enhanced nanoplatform for cuproptosis‐driven enhancement of thermotherapy. [ABSTRACT FROM AUTHOR]

SUMMARY: Heat stress triggers the accumulation of triacylglycerols in Arabidopsis leaves, which increases basal thermotolerance. However, how triacylglycerol synthesis is linked to thermotolerance remains unclear and the mechanisms involved remain to be elucidated. It has been shown that triacylglycerol and starch degradation are required to provide energy for stomatal opening induced by blue light at dawn. To investigate whether triacylglycerol turnover is involved in heat‐induced stomatal opening during the day, we performed feeding experiments with labeled fatty acids. Heat stress strongly induced both triacylglycerol synthesis and degradation to channel fatty acids destined for peroxisomal ß‐oxidation through the triacylglycerol pool. Analysis of mutants defective in triacylglycerol synthesis or peroxisomal fatty acid uptake revealed that triacylglycerol turnover and fatty acid catabolism are required for heat‐induced stomatal opening in illuminated leaves. We show that triacylglycerol turnover is continuous (1.2 mol% per min) in illuminated leaves even at 22°C. The ß‐oxidation of triacylglycerol‐derived fatty acids generates C2 carbon units that are channeled into the tricarboxylic acid pathway in the light. In addition, carbohydrate catabolism is required to provide oxaloacetate as an acceptor for peroxisomal acetyl‐CoA and maintain the tricarboxylic acid pathway for energy and amino acid production during the day. Significance Statement: Heat stress‐induced accumulation of triacylglycerols in Arabidopsis leaves increases basal thermotolerance. However, how triacylglycerol synthesis is linked to thermotolerance remains unclear. We show that fatty acids are channeled from membranes through the triacylglycerol pool to peroxisomes to produce acetyl‐CoA, which enters the tricaboxylic acid pathway for amino acid and energy production. Heat stress increases the flux of fatty acids through this pathway, which is required for efficient stomatal opening for transpirational cooling. [ABSTRACT FROM AUTHOR]

Purpose: To monitor the metabolic turnover of β‐hydroxybutyrate (BHB) oxidation using 2H‐MRS in conjunction with intravenous administration of 2H labeled BHB. Methods: Nine‐month‐old mice were infused with [3,4,4,4]‐2H4‐BHB (d4‐BHB; 3.11 g/kg) through the tail vein using a bolus variable infusion rate for a period of 90 min. The labeling of downstream cerebral metabolites from the oxidative metabolism of d4‐BHB was monitored using 2H‐MRS spectra acquired with a home‐built 2H surface coil on a 9.4T preclinical MR scanner with a temporal resolution of 6.25 min. An exponential model was fit to the BHB and glutamate/glutamine (Glx) turnover curves to determine rate constants of metabolite turnover and to aid in the visualization of metabolite time courses. Results: Deuterium label was incorporated into Glx from BHB metabolism through the tricarboxylic acid (TCA) cycle, with an increase in the level of [4,4]‐2H2‐Glx (d2‐Glx) over time and reaching a quasi‐steady state concentration of ∼0.6 ± 0.1 mM following 30 min of infusion. Complete oxidative metabolic breakdown of d4‐BHB also resulted in the formation of semi‐heavy water (HDO), with a four‐fold (10.1 to ∼42.1 ± 7.3 mM) linear (R2 = 0.998) increase in its concentration by the end of infusion. The rate constant of Glx turnover from d4‐BHB metabolism was determined to be 0.034 ± 0.004 min−1. Conclusion: 2H‐MRS can be used to monitor the cerebral metabolism of BHB with its deuterated form by measuring the downstream labeling of Glx. The integration of 2H‐MRS with deuterated BHB substrate provides an alternative and clinically promising MRS tool to detect neurometabolic fluxes in healthy and disease conditions. [ABSTRACT FROM AUTHOR]

In recent years, significant advances have been made in the precise control of the physical properties of metal–organic frameworks (MOFs) via the linker‐modulated method in which modulators compete with linkers and impose kinetic limitations through crystal growth. In this regard, the structure of a new barium–organic framework [Ba(H2BTC)2(H2O)4]n, BaBTC (BTC = 1,3,5‐benzene tricarboxylic acid) is introduced, which allows the competitive coordination strategy and growth orientation of an alkaline‐earth metal–organic framework (AEMOF) to be probed without sacrificing phase purity, porosity and crystallinity. The modulator effect of an assortment of amino acids on the particle size and morphology of BaBTC is investigated. Additionally, another new MOF [Ba(BTC)2(H2O)3]n.nH2O, BaBTC‐2, is synthesized through a change in the ligand concentration. This work gives a successful example of a modulation method for AEMOF synthesis by amino acids that may contribute towards targeting future avenues of nanomaterial synthesis. [ABSTRACT FROM AUTHOR]

Rationale: Nasopharyngeal carcinoma (NPC) is a malignant tumor that is endemic in Southeast Asia, North Africa, and southern China. There is an urgent need for effective early diagnosis and treatment of this disease since NPC is currently often detected at advanced stages. Methods: To reveal the underlying metabolic mechanisms and discover potential diagnostic biomarkers of NPC, we employed ultrahigh‐performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry (UHPLC‐Q‐TOF‐MS) and UHPLC‐Q‐Exactive Orbitrap MS, respectively, to analyze 54 serum samples and 54 urine samples from 27 patients with NPC and 27 healthy control individuals. Results: A total of 1230 metabolites were determined in serum samples, and 181 of the 1230 metabolites were significantly changed in NPC patients. The 181 metabolites were enriched in 16 pathways, including biosynthesis of unsaturated fatty acids, cholesterol metabolism, and ferroptosis. A total of 2509 metabolites were detected in the urine samples. Among them, 179 metabolites were significantly altered in NPC patients, and these metabolites were enriched in eight pathways, including the tricarboxylic acid (TCA) cycle and caffeine metabolism. Seven metabolites, including creatinine and paraxanthine, were found to be significantly changed in both NPC serum and urine samples. Based on them, further biomarker analysis revealed that the panel of three serum metabolites, octanoylcarnitine, creatinine, and decanoyl‐l‐carnitine, displayed a perfect diagnostic performance (area under the curve [AUC] = 0.973) to distinguish NPC patients from controls, while the other three‐metabolite biomarker panel, consisting of stachydrine, decanoyl‐l‐carnitine, and paraxanthine, had an AUC = 0.809 to distinguish NPC and control in urine samples. Conclusion: This work highlights the key metabolites and metabolic pathways disturbed in NPC and presents potential biomarkers for effective diagnosis of this disease. [ABSTRACT FROM AUTHOR]

As a major cause of clinical chronic infection, microbial biofilms/microcolonies in host tissues essentially live in 3D‐constrained microenvironments, which potentially modulate their spatial self‐organization and morphodynamics. However, it still remains unclear whether and how mechanical cues of 3D confined microenvironments, for example, extracellular matrix (ECM) stiffness, exert an impact on antibiotic resistance of bacterial biofilms/microcolonies. With a high‐throughput antibiotic sensitivity testing (AST) platform, it is revealed that 3D ECM rigidities greatly modulate their resistance to diverse antibiotics. The microcolonies in 3D ECM with human tissue‐specific rigidities varying from 0.5 to 20 kPa show a ≈2–10 000‐fold increase in minimum inhibitory concentration, depending on the types of antibiotics. The authors subsequently identified that the increase in 3D ECM rigidities leads to the downregulation of the tricarboxylic acid (TCA) cycle, which is responsible for enhanced antibiotic resistance. Further, it is shown that fumarate, as a potentiator of TCA cycle activity, can alleviate the elevated antibiotic resistance and thus remarkably improve the efficacy of antibiotics against bacterial microcolonies in 3D confined ECM, as confirmed in the chronic infection mice model. These findings suggest fumarate can be employed as an antibiotic adjuvant to effectively treat infections induced by bacterial biofilms/microcolonies in a 3D‐confined environment. [ABSTRACT FROM AUTHOR]

The sluggish ion‐transport in electrodes and low utilization of active materials are critical limitations of organic cathodes, which lead to the slow reaction dynamics and low specific capacity. In this study, the hierarchical tube is constructed by iron‐hexaazatrinaphthalene tricarboxylic acid coordination polymer (Fe‐HATNTA), using HATNTA as the self‐engaged template to coordinate with Fe2+ ions. This Fe‐HATNTA tube with hierarchical porous structure ensures the sufficient contact between electrolyte and active materials, shortens the diffusion distance, and provides more favorable transport pathways for ions. When employed as the cathode for rechargeable Li‐ion batteries, Fe‐HATNTA delivers a high specific capacity (244 mAh g−1 at 50 mA g−1, 91% of theoretical capacity), excellent rate capability (128 mAh g−1 at 9 A g−1), and a long‐term cycle life (73.9% retention over 3000 cycles at 5 A g−1). Moreover, the Li+ ions storage and conduction mechanisms are further disclosed by the ex situ and in situ characterizations, kinetic analyses, and theoretical calculations. This work is expected to boost further enthusiasm for developing the hierarchical structured metal‐organic coordination polymers with superb ionic storage and transport as high‐performance organic cathodes. [ABSTRACT FROM AUTHOR]

The interconversion of guanosine triphosphate (GTP) and guanosine diphosphate (GDP) is known to be integral to a wide variety of biological cellular activities, yet to date there are no analytical methods available to directly detect the ratio of intracellular GTP to GDP. Herein, we report GRISerHR, a genetically encoded fluorescent biosensor to monitor the GTP : GDP ratio in multiple cell types and in various organelles under metabolic perturbation. Additionally, we characterized the differential mitochondrial GTP : GDP ratios resulting from genetic modulation of two isoforms of a tricarboxylic acid (TCA) cycle enzyme (succinyl‐CoA synthetase; SCS‐ATP and SCS‐GTP) and of a phosphoenolpyruvate (PEP) cycle enzyme (PEPCK‐M). Thus, our GRISerHR sensor achieves spatiotemporally precise detection of dynamic changes in the endogenous GTP : GDP ratio in living cells and can help deepen our understanding about the energy metabolic contributions of guanosine nucleotides in biology. [ABSTRACT FROM AUTHOR]

Summary: Riboflavin is the precursor of essential cofactors for diverse metabolic processes. Unlike animals, plants can de novo produce riboflavin through an ancestrally conserved pathway, like bacteria and fungi. However, the mechanism by which riboflavin regulates seed development is poorly understood. Here, we report a novel maize (Zea mays L.) opaque mutant o18, which displays an increase in lysine accumulation, but impaired endosperm filling and embryo development. O18 encodes a rate‐limiting bifunctional enzyme ZmRIBA1, targeted to plastid where to initiate riboflavin biosynthesis. Loss of function of O18 specifically disrupts respiratory complexes I and II, but also decreases SDH1 flavinylation, and in turn shifts the mitochondrial tricarboxylic acid (TCA) cycle to glycolysis. The deprivation of cellular energy leads to cell‐cycle arrest at G1 and S phases in both mitosis and endoreduplication during endosperm development. The unexpected up‐regulation of cell‐cycle genes in o18 correlates with the increase of H3K4me3 levels, revealing a possible H3K4me‐mediated epigenetic back‐up mechanism for cell‐cycle progression under unfavourable circumstances. Overexpression of O18 increases riboflavin production and confers osmotic tolerance. Altogether, our results substantiate a key role of riboflavin in coordinating cellular energy and cell cycle to modulate maize endosperm development. [ABSTRACT FROM AUTHOR]

Haematococcus pluvialis is the most commercially valuable microalga for the production of natural astaxanthin, showing enhanced production of astaxanthin with the treatments of high-intensity light and hormones. The molecular mechanisms regulating the biosynthesis of astaxanthin in H. pluvialis treated with white light, blue light, and blue light with salicylic acid (SA) were investigated based on the transcriptome analysis. Results showed that the combined treatment with both blue light and SA generated the highest production of astaxanthin. A total of 109,443 unigenes were identified to show that the genes involved in the tricarboxylic acid (TCA) cycle, the pentose phosphate pathway (PPP), and the astaxanthin biosynthesis were significantly upregulated to increase the production of the substrates for the synthesis of astaxanthin, i.e., pyruvate and glyceraldehyde-3-phosphate generated in the TCA cycle and PPP, respectively. Results of transcriptome analysis were further verified by the quantitative real-time PCR (qRT-PCR) analysis, showing that the highest content of astaxanthin was obtained with the expression of the bkt gene significantly increased. Our study provided the novel insights into the molecular mechanisms regulating the synthesis of astaxanthin and an innovative strategy combining the exogenous hormone and physical stress to increase the commercial production of astaxanthin by H. pluvialis. [ABSTRACT FROM AUTHOR]

Fertilization with nitrogen (N)‐rich compounds leads to increased growth but may compromise phenology and winter survival of trees in boreal regions. During autumn, N is remobilized from senescing leaves and stored in other parts of the tree to be used in the next growing season. However, the mechanism behind the N fertilization effect on winter survival is not well understood, and it is unclear how N levels or forms modulate autumn senescence. We performed fertilization experiments and showed that treating Populus saplings with inorganic nitrogen resulted in a delay in senescence. In addition, by using precise delivery of solutes into the xylem stream of Populus trees in their natural environment, we found that delay of autumn senescence was dependent on the form of N administered: inorganic N (NO3−) delayed senescence, but amino acids (Arg, Glu, Gln, and Leu) did not. Metabolite profiling of leaves showed that the levels of tricarboxylic acids, arginine catabolites (ammonium, ornithine), glycine, glycine‐serine ratio and overall carbon‐to‐nitrogen (C/N) ratio were affected differently by the way of applying NO3− and Arg treatments. In addition, the onset of senescence did not coincide with soluble sugar accumulation in control trees or in any of the treatments. We propose that different regulation of C and N status through direct molecular signaling of NO3− and/or different allocation of N between tree parts depending on N forms could account for the contrasting effects of NO3− and tested here amino acids (Arg, Glu, Gln, and Leu) on autumn senescence. [ABSTRACT FROM AUTHOR]

Summary: Succinate dehydrogenase (SDH, complex II), which plays an essential role in mitochondrial respiration and tricarboxylic acid metabolism, requires the assembly of eight nuclear‐encoded subunits and the insertion of various cofactors. Here, we report on the characterization of an Arabidopsis thaliana leucine‐tyrosine‐arginine (LYR) protein family member SDHAF1, (At2g39725) is a factor required for SDH activity. SDHAF1 is located in mitochondria and can fully complement the yeast SDHAF1 deletion strain. Knockdown of SDHAF1 using RNA interference resulted in a decrease in seedling hypocotyl elongation and reduced SDH activity. Proteomic analyses revealed a decreased abundance of various SDH subunits and assembly factors. Protein interaction assays revealed that SDHAF1 can interact exclusively with the Fe‐S cluster‐containing subunit SDH2 and HSCB, a cochaperone involved in Fe‐S cluster complex recruitment. Therefore, we propose that in Arabidopsis, SDHAF1 plays a role in the biogenesis of SDH2 to form the functional complex II, which is essential for mitochondrial respiration and metabolism. Significance Statement: The establishment of a functional mitochondrial complex II requires the insertion and assembly of eight individual subunits. Here, we have characterized the complex II assembly factor SDHAF1, which is able to interact with the complex II subunit SDH2 and is needed for complex II activity in Arabidopsis. [ABSTRACT FROM AUTHOR]

Copper based Metal‐Organic Gels (MOGs) were evaluated for their efficiency as drug carrier for four anti‐inflammatory drugs viz. 5‐Fluorouracil (5FU), Phenidone (PN), Ibuprofen (IBP) and Cisplatin (CP). Copper(II)‐benzene tricarboxylic acid (CuBTC) was used as a precursor for the loading and releasing of these drugs. The distinctive porous nature of the gel provided the high loading efficiency for these anti‐inflammatory drugs. Among all the drugs evaluated, CuBTC@5FU exhibited maximum drug loading (88.1 %) and releasing (95 %) efficiency at physiological pH 5.2, which was attributed to the strong hydrogen bonding interactions between CuBTC and fluoride of 5FU. [ABSTRACT FROM AUTHOR]

Summary: NtrC‐mediated production of exopolysaccharides (EPS), essential components for Vibrio vulnificus biofilms, is highly increased in the presence of dicarboxylic or tricarboxylic acids. Gel‐shift assays showed that regulation of the EPS‐gene cluster I (EPS‐I cluster) by NtrC was direct via binding of phosphorylated NtrC (p‐NtrC) to the regulatory region of the EPS‐I cluster. In contrast, p‐NtrC did not bind to the EPS‐II and EPS‐III clusters, suggesting that NtrC regulation was not direct and another transcription factor belonging to an NtrC‐regulon might play a role in activating their transcription. A candidate transcription factor, DctD, of which expression was induced by NtrC, activated the expression of the EPS‐II and EPS‐III clusters via direct binding to their upstream regions. Under growth conditions with either dicarboxylic or tricarboxylic acids, the expression of NtrC was induced and the transcription of dctD was activated. Furthermore, DctD exhibited higher transcriptional activity under the conditions with dicarboxylic acids than with tricarboxylic acids. Therefore, this study demonstrates that under dicarboxylate‐rich conditions, both the abundance and activity of DctD were markedly induced, which activates the expression of two EPS clusters to maximize biosynthesis of EPS facilitating biofilm maturation in V. vulnificus. [ABSTRACT FROM AUTHOR]

Autumn senescence in aspen (Populus tremula) is precisely timed every year to relocate nutrients from leaves to storage organs before winter. Here we demonstrate how stem girdling, which leads to the accumulation of photosynthates in the crown, influences senescence. Girdling resulted in an early onset of senescence, but the chlorophyll degradation was slower and nitrogen more efficiently resorbed than during normal autumn senescence. Girdled stems accumulated or retained anthocyanins potentially providing photoprotection in senescing leaves. Girdling of one stem in a clonal stand sharing the same root stock did not affect senescence in the others, showing that the stems were autonomous in this respect. One girdled stem with unusually high chlorophyll and nitrogen contents maintained low carbon‐to‐nitrogen (C/N) ratio and did not show early senescence or depleted chlorophyll level unlike the other girdled stems suggesting that the responses depended on the genotype or its carbon and nitrogen status. Metabolite analysis highlighted that the tricarboxylic acid (TCA) cycle, salicylic acid pathway, and redox homeostasis are involved in the regulation of girdling‐induced senescence. We propose that disrupted sink‐source relation and C/N status can provide cues through the TCA cycle and phytohormone signaling to override the phenological control of autumn senescence in the girdled stems. [ABSTRACT FROM AUTHOR]

Fatty‐acid degradation is an oxidative process that involves four enzymatic steps and is referred to as the β‐oxidation pathway. During this process, long‐chain acyl‐CoAs are broken down into acetyl‐CoA, which enters the mitochondrial tricarboxylic acid (TCA) cycle, resulting in the production of energy in the form of ATP. Enoyl‐CoA hydratase (ECH) catalyzes the second step of the β‐oxidation pathway by the syn addition of water to the double bond between C2 and C3 of a 2‐trans‐enoyl‐CoA, resulting in the formation of a 3‐hydroxyacyl CoA. Here, the crystal structure of ECH from Thermus thermophilus HB8 (TtECH) is reported at 2.85 Å resolution. TtECH forms a hexamer as a dimer of trimers, and wide clefts are uniquely formed between the two trimers. Although the overall structure of TtECH is similar to that of a hexameric ECH from Rattus norvegicus (RnECH), there is a significant shift in the positions of the helices and loops around the active‐site region, which includes the replacement of a longer α3 helix with a shorter α‐helix and 310‐helix in RnECH. Additionally, one of the catalytic residues of RnECH, Glu144 (numbering based on the RnECH enzyme), is replaced by a glycine in TtECH, while the other catalytic residue Glu164, as well as Ala98 and Gly141 that stabilize the enolate intermediate, is conserved. Their putative ligand‐binding sites and active‐site residue compositions are dissimilar. [ABSTRACT FROM AUTHOR]

SUMMARY: The tricarboxylic acid (TCA) cycle is one of the most important metabolic pathways in nature. Oxygenic photoautotrophic bacteria, cyanobacteria, have an unusual TCA cycle. The TCA cycle in cyanobacteria contains two unique enzymes that are not part of the TCA cycle in other organisms. In recent years, sustainable metabolite production from carbon dioxide using cyanobacteria has been looked at as a means to reduce the environmental burden of this gas. Among cyanobacteria, the unicellular cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis 6803) is an optimal host for sustainable metabolite production. Recently, metabolite production using the TCA cycle in Synechocystis 6803 has been carried out. Previous studies revealed that the branch point of the oxidative and reductive TCA cycles, oxaloacetate metabolism, plays a key role in metabolite production. However, the biochemical mechanisms regulating oxaloacetate metabolism in Synechocystis 6803 are poorly understood. Concentrations of oxaloacetate in Synechocystis 6803 are extremely low, such that in vivo analysis of oxaloacetate metabolism does not seem realistic. Therefore, using purified enzymes, we reconstituted oxaloacetate metabolism in Synechocystis 6803 in vitro to reveal the regulatory mechanisms involved. Reconstitution of oxaloacetate metabolism revealed that pH, Mg2+ and phosphoenolpyruvate are important factors affecting the conversion of oxaloacetate in the TCA cycle. Biochemical analyses of the enzymes involved in oxaloacetate metabolism in this and previous studies revealed the biochemical mechanisms underlying the effects of these factors on oxaloacetate conversion. In addition, we clarified the function of two l‐malate dehydrogenase isozymes in oxaloacetate metabolism. These findings serve as a basis for various applications of the cyanobacterial TCA cycle. Significance Statement: In vitro reconstitution of oxaloacetate metabolism in the tricarboxylic acid (TCA) cycle in the model cyanobacterium Synechocystis sp. PCC 6803 revealed important factors that directly affect the conversion of oxaloacetate and clarified the functional difference between two l‐malate dehydrogenase isozymes. Our findings will be useful for understanding the biochemical regulation of oxaloacetate metabolism in the cyanobacterial TCA cycle and serve as a basis for various applications of this cycle. [ABSTRACT FROM AUTHOR]

Background: Cyclosporine A (CsA) is routinely used to treat patients with steroid-refractory acute severe ulcerative colitis (ASUC). Here, we studied the underlying mechanisms of CsA-mediated alleviation in ASUC patients. Methods: Neutrophil functions including expression of cytokines, apoptosis, andmigration were measured by qRT-PCR, flow cytometry, and Transwell assay. Dynamic changes of glycolysis and tricarboxylic acid (TCA) cyclewere measured by a Seahorse extracellular flux analyzer. Gene differences were determined and verified by RNA sequencing, qRT-PCR, and Western blotting. Small interfering RNA and inhibitors were used to knock down Sirtuin 6 (SIRT6) in HL-60 cells and block expression of SIRT6, hypoxia-inducible factor-1α (HIF-1α), and pyruvate dehydrogenase lipoamide kinase isozyme 4 (PDK4) in neutrophils. Results:We found thatHIF-1α expression and glycolysis significantly increased, while the release of IL-8, myeloperoxidase (MPO) and reactive oxygen species (ROS), the apoptosis, and ability of migrationmarkedly decreased in neutrophils of ASUC patients who responded to CsA (Response group) compared with those who did not respond to CsA (Nonresponse group). We also observed that CsAinduced functional alternation of neutrophils was initiated through suppressing SIRT6 expression, which is responsible for expression of the downstream signaling molecules (e.g., HIF-1α, PFKFB3) and PDK4 ubiquitination, leading to fueling neutrophil glycolysis and TCA cycle. Furthermore, blockage of SIRT6 signaling demonstrated to be the same functional changes as CsA to decrease the migration of neutrophils. Conclusions: The data reveal a novel mechanism of CsA in alleviating ASUC by promoting neutrophil HIF-1α expression and restricting excessive neutrophil activation in a SIRT6--HIF-1α--glycolysis axis, suggesting SIRT6 as a candidate target for maintaining mucosal homeostasis and treating intestinal inflammation. [ABSTRACT FROM AUTHOR]

Summary: Leaf respiration in the dark (Rdark) is often measured at a single time during the day, with hot‐acclimation lowering Rdark at a common measuring temperature. However, it is unclear whether the diel cycle influences the extent of thermal acclimation of Rdark, or how temperature and time of day interact to influence respiratory metabolites.To examine these issues, we grew rice under 25°C : 20°C, 30°C : 25°C and 40°C : 35°C day : night cycles, measuring Rdark and changes in metabolites at five time points spanning a single 24‐h period.Rdark differed among the treatments and with time of day. However, there was no significant interaction between time and growth temperature, indicating that the diel cycle does not alter thermal acclimation of Rdark. Amino acids were highly responsive to the diel cycle and growth temperature, and many were negatively correlated with carbohydrates and with organic acids of the tricarboxylic acid (TCA) cycle. Organic TCA intermediates were significantly altered by the diel cycle irrespective of growth temperature, which we attributed to light‐dependent regulatory control of TCA enzyme activities.Collectively, our study shows that environmental disruption of the balance between respiratory substrate supply and demand is corrected for by shifts in TCA‐dependent metabolites. [ABSTRACT FROM AUTHOR]

Background: Mesenchymal stem cells (MSCs) have therapeutic potential for multiple ischemic diseases. However, in vitro expansion of MSCs before clinical application leads to metabolic reprogramming from glycolysis to oxidative phosphorylation, drastically impairing their proliferative and therapeutic capacities. This study aimed to define the regulatory effects of Sirtuin 5 (SIRT5) on the proliferative and therapeutic functions of adipose‐derived MSCs (ADMSCs) during in vitro expansion. Methods: ADMSCs were isolated from wild‐type (WT) and Sirt5‐knockout (Sirt5−/−) mice. Cell counting assay was used to investigate the proliferative capacities of the ADMSCs. Dihydroethidium and senescence‐associated β‐galactosidase stainings were used to measure intracellular ROS and senescence levels. Mass spectrometry was used to analyze protein succinylation. Oxygen consumption rates and extra cellular acidification rates were measured as indicators of mitochondrial respiration and glycolysis. Metabolic‐related genes expression were verified by quantitative PCR and western blot. Hind limb ischemia mouse model was used to evaluate the therapeutic potentials of WT and Sirt5−/− ADSMCs. Results: SIRT5 protein levels were upregulated in ADMCs during in vitro expansion. Sirt5−/− ADMSCs exhibited a higher proliferation rate, delayed senescence, and reduced ROS accumulation. Furthermore, elevated protein succinylation levels were observed in Sirt5−/− ADMSCs, leading to the reduced activity of tricarboxylic acid cycle‐related enzymes and attenuated mitochondrial respiration. Glucose uptake, glycolysis, and pentose phosphate pathway were elevated in Sirt5−/− ADMSCs. Inhibition of succinylation by glycine or re‐expression of Sirt5 reversed the metabolic alterations in Sirt5−/‐ ADMSCs, thus abolishing their enhanced proliferative capacities. In the hind limb ischemia mouse model, SIRT5−/− ADMSCs transplantation enhanced blood flow recovery and angiogenesis compared with WT ADMSCs. Conclusions: Our results indicate that SIRT5 deficiency during ADMSC culture expansion leads to reversed metabolic pattern, enhanced proliferative capacities, and improved therapeutic outcomes. These data suggest SIRT5 as a potential target to enhance the functional properties of MSCs for clinical application. [ABSTRACT FROM AUTHOR]

Metal organic frameworks are considered as an efficient and promised adsorbent for separation of several ions and compounds from solutions due to its unique geometric structure. Herein, copper‐benzyl tricarboxylic acid based metal organic frameworks have showed a high efficiency in enrichment and microextraction of malathion from food and water samples. The microextraction procedures were followed by determination of malathion by ultra high performance liquid chromatography with tandem mass spectrometry. The optimum recoveries for malathion were obtained at pH 6, and with using 2 mL of ethyl acetate as the eluent. The microextraction procedures showed a detection limits and the quantification limits of 4.0 and 10.0 µg/L, respectively. The intra‐ and interday precision showed a relative standard deviation% less than 10. The feasibility of the proposed procedure was determined by evaluating the addition/recovery studies of malathion from the real samples. The absolute recovery% was ≥92%. Furthermore, some ions were tested as cointerfering ions, and the recovery% was 93‐100%. These results confirm that the developed microextraction procedure based on copper‐benzyl tricarboxylic acid based metal organic frameworks as extractor for dispersive solid phase microextraction is matrix‐independent, and can be applied for various real samples including different matrix or various malathion content. [ABSTRACT FROM AUTHOR]

Background and aims: Most physiological and biochemical studies on salt stress are NaCl‐based. However, other ions (e.g., K+, Ca2+, Mg2+, and SO42-) also contribute to salt stress in special circumstances. In this study, salt stress induced by various salts was investigated for a better understanding of salinity. Methods: Arabidopsis thaliana plants were stepwise acclimated to five iso‐osmotic salts as follows: NaCl, KCl, Na2SO4, K2SO4, and CaCl2. Results and Conclusions: Exposure to KCl and K2SO4 led to more severe toxicity symptoms, smaller biomass, and lower level of chlorophyll than exposure to NaCl and Na2SO4, indicating that Arabidopsis plants are more sensitive to potassium salts. The strongly reduced growth was negatively correlated with the accumulation of soluble sugars observed in KCl‐ and K2SO4‐treated plants, suggesting a blockage in the utilization of sugars for growth. We found that exposure to KCl and K2SO4 suppressed or even blocked sucrose degradation, thus leading to strong accumulation of sucrose in shoots, which then probably inhibited photosynthesis via feedback inhibition. Moreover, K+ was more accumulated in shoots than Na+ after corresponding potassium or sodium salt treatments, thus resulting in decreased Ca2+ and Mg2+ concentrations in response to KCl and K2SO4. However, K2SO4 caused more severe toxicity symptoms than iso‐osmotic KCl, even when the K+ level was lower in K2SO4‐treated plants. We found that Na2SO4 and K2SO4 induced strong accumulation of tricarboxylic acid intermediates, especially fumarate and succinate which might induce oxidative stress. Thus, the severe toxicity symptoms found in K2SO4‐treated plants were also attributed to SO42- in addition to the massive accumulation of K+. [ABSTRACT FROM AUTHOR]

SUMMARY: Mitochondria have critical functions in the acclimation to abiotic and biotic stresses. Adverse environmental conditions lead to increased demands in energy supply and metabolic intermediates, which are provided by mitochondrial ATP production and the tricarboxylic acid (TCA) cycle. Mitochondria also play a role as stress sensors to adjust nuclear gene expression via retrograde signalling with the transcription factor (TF) ANAC017 and the kinase CDKE1 key components to integrate various signals into this pathway. To determine the importance of mitochondria as sensors of stress and their contribution in the tolerance to adverse growth conditions, a comparative phenotypical, physiological and transcriptomic characterisation of Arabidopsis mitochondrial signalling mutants (cdke1/rao1 and anac017/rao2) and a set of contrasting accessions was performed after applying the complex compound stress of submergence. Our results showed that impaired mitochondrial retrograde signalling leads to increased sensitivity to the stress treatments. The multi‐factorial approach identified a network of 702 co‐expressed genes, including several WRKY TFs, overlapping in the transcriptional responses in the mitochondrial signalling mutants and stress‐sensitive accessions. Functional characterisation of two WRKY TFs (WRKY40 and WRKY45), using both knockout and overexpressing lines, confirmed their role in conferring tolerance to submergence. Together, the results revealed that acclimation to submergence is dependent on mitochondrial retrograde signalling, and underlying transcriptional re‐programming is used as an adaptation mechanism. Significance Statement: Mitochondria provide the energy and metabolic building blocks allowing plants to respond to adverse environmental conditions. Our results show that plant mitochondria also have a function as stress sensors, and that corresponding signalling pathways that lead to the adjustment of gene expression are used for the adaptation to stress. [ABSTRACT FROM AUTHOR]

Summary: Upon competence‐inducing nutrient‐limited conditions, only part of the Bacillus subtilis population becomes competent. Here, we separated the two subpopulations by fluorescence‐assisted cell sorting (FACS). Using RNA‐seq, we confirmed the previously described ComK regulon. We also found for the first time significantly downregulated genes in the competent subpopulation. The downregulated genes are not under direct control by ComK but have higher levels of corresponding antisense RNAs in the competent subpopulation. During competence, cell division and replication are halted. By investigating the proteome during competence, we found higher levels of the regulators of cell division, MinD and Noc. The exonucleases SbcC and SbcD were also primarily regulated at the post‐transcriptional level. In the competent subpopulation, yhfW was newly identified as being highly upregulated. Its absence reduces the expression of comG, and has a modest, but statistically significant effect on the expression of comK. Although expression of yhfW is higher in the competent subpopulation, no ComK‐binding site is present in its promoter region. Mutants of yhfW have a small but significant defect in transformation. Metabolomic analyses revealed significant reductions in tricarboxylic acid (TCA) cycle metabolites and several amino acids in a ΔyhfW mutant. RNA‐seq analysis of ΔyhfW revealed higher expression of the NAD synthesis genes nadA, nadB and nadC. [ABSTRACT FROM AUTHOR]

To explore the regulatory mechanisms involved in the adaption to nitrogen (N) deficiency of wild soybean, the ion balance, photosynthetic characteristics, metabolic and transcriptional changes in leaves of common and low N (LN)‐tolerant wild soybean seedlings under LN stress were determined. The LN‐tolerant wild soybean seedlings showed a stronger ability to maintain photosynthesis and nutrient balance than common wild soybean. A total of 52 differentially accumulated metabolites, mainly related to carbon and N metabolism, were identified between the control and the LN treatment group. In general, tricarboxylic acid (TCA) cycle, shikimic acid pathway, synthetase/glutamate synthase (GS/GOGAT) cycle and accumulation of most organic acids were enhanced in LN‐tolerant wild soybean, while reduced in common wild soybean under LN stress compared with their respective control group. Moreover, glycolysis, sugar and polyol and fatty acid metabolism increased in both wild soybean genotypes, and increased more in LN‐tolerant wild soybean. A total of 3381 differentially expressed genes (DEGs) were identified in leaves of both wild soybean genotypes and the expressed level of DEGs associated with sugars, polyols, fatty acids and energy metabolism was significantly higher in LN‐tolerant wild soybean than in common wild soybean, consistent with changes in metabolite level. Our results suggest new ideas for the study of LN tolerance of wild soybean and provide a theoretical basis for development and utilization of wild soybean resources. [ABSTRACT FROM AUTHOR]

Promiscuous enzymes and spontaneous chemical reactions can convert normal cellular metabolites into noncanonical or damaged metabolites. These damaged metabolites can be a useless drain on metabolism and may be inhibitory and/or reactive, sometimes leading to toxicity. Thus, mechanisms to prevent metabolite damage from occurring (metabolite damage preemption) or to convert damaged metabolites back to physiological forms (metabolite repair) are essential for sustained operation of metabolic networks. Some iconic examples of metabolite damage and its repair or preemption are associated with the tricarboxylic acid (TCA) cycle, and other metabolite damage control systems are likely to exist here due to the inherent promiscuity of TCA cycle enzymes and reactivity of TCA cycle intermediates. Here, we review known metabolite damage reactions and metabolite damage control systems associated with the TCA cycle. This includes a previously unrecognized metabolite damage control system – an oxaloacetate (OAA) enol‐keto tautomerase activity that is 'built‐in' to the TCA cycle. This activity is required to remove the highly inhibitory enol form of OAA and is likely to be critical for TCA cycle operation. By cataloging these instances, we show that metabolite damage and its repair or preemption is a prevalent feature of the TCA cycle and suggest many more metabolite damage control systems are likely to exist. [ABSTRACT FROM AUTHOR]

Current dogma holds that the heart balances energy demand and supply effectively and sustainably by sequestering enough Ca2+ into mitochondria during heartbeats to stimulate metabolic enzymes in the tricarboxylic acid (TCA) cycle and electron transport chain (ETC). This process is called excitation‐contraction‐bioenergetics (ECB) coupling. Recent breakthroughs in identifying the mitochondrial Ca2+ uniporter (MCU) and its associated proteins have opened up new windows for interrogating the molecular mechanisms of mitochondrial Ca2+ homeostasis regulation and its role in ECB coupling. Despite remarkable progress made in the past 7 years, it has been surprising, almost disappointing, that germline MCU deficiency in mice with certain genetic background yields viable pups, and knockout of the MCU in adult heart does not cause lethality. Moreover, MCU deficiency results in few adverse phenotypes, normal performance, and preserved bioenergetics in the heart at baseline. In this review, we briefly assess the existing literature on mitochondrial Ca2+ homeostasis regulation and then we consider possible explanations for why MCU‐deficient mice are spared from energy crises under physiological conditions. We propose that MCU and/or mitochondrial Ca2+ may have limited ability to set ECB coupling, that other mitochondrial Ca2+ handling mechanisms may play a role, and that extra‐mitochondrial Ca2+ may regulate ECB coupling. Since the heart needs to regenerate a significant amount of ATP to assure the perpetuation of heartbeats, multiple mechanisms are likely to work in concert to match energy supply with demand. [ABSTRACT FROM AUTHOR]

Various biological behaviors are fueled by "respiration", which is an example of catabolism. So far, we have reported various self‐oscillating soft materials exhibiting bioinspired dynamic movements. These autonomous polymer systems are driven by the Belousov–Zhabotinsky (BZ) reaction, which is analogous to the tricarboxylic acid (TCA) cycle that is an integral part of respiration. However, in the BZ reaction, the external addition of an oxidizing agent is necessary to initiate the oxidation process, which is realized by intracellular moieties such as ubiquinone in living systems. Herein, we realized self‐oscillating micelles that are driven without the external addition of an oxidizing agent. This was achieved by embedding the oxidizing source into the structure of the self‐oscillating AB diblock copolymers. This strategy introduces a new function equivalent to intracellular oxidizing moieties, and is useful for the design of completely autonomous bioinspired materials. [ABSTRACT FROM AUTHOR]

Citrate synthase (CS) catalyzes the conversion of oxaloacetate and acetyl coenzyme A into citrate and coenzyme A in the mitochondrial tricarboxylic acid (TCA) cycle. In plants, mitochondrial metabolism, including the TCA cycle, occurs in interaction with photosynthetic metabolism. The controlled regulation of several enzymes in the TCA cycle, such as CS, is important in plants. Here, the first crystal structure of a plant mitochondrial CS, CSY4 from Arabidopsis thaliana (AtCSY4), has been determined. Structural comparison of AtCSY4 with mitochondrial CSs revealed a high level of similarity. Inhibition analysis showed a similar manner of inhibition as in mitochondrial CSs. The effect of oxidation on one of a pair of cysteine residues in AtCSY4 was speculated upon based on the folded structure. [ABSTRACT FROM AUTHOR]

While dehydrogenases play crucial roles in tricarboxylic acid (TCA) cycle of cell metabolism, which are extensively explored for biomedical and chemical engineering uses, it is a big challenge to overcome the shortcomings (low stability and high costs) of recombinant dehydrogenases. Herein, it is shown that two‐dimensional (2D) SnSe is capable of mimicking native dehydrogenases to efficiently catalyze hydrogen transfer from 1‐(R)‐2‐(R′)‐ethanol groups. In contrary to susceptible native dehydrogenases, lactic dehydrogenase (LDH) for instance, SnSe is extremely tolerant to reaction condition changes (pH, temperature, and organic solvents) and displays extraordinary reusable capability. Structure–activity analysis indicates that the single‐atom structure, Sn vacancy, and hydrogen binding affinity of SnSe may be responsible for their catalytic activity. Overall, this is the first report of a 2D SnSe nanozyme to mimic key dehydrogenases in cell metabolism. [ABSTRACT FROM AUTHOR]

Summary: Solute uptake and release by plant cells are frequently energized by coupling to H+ influx supported by the proton motive force (pmf). The pmf results from a stable pH difference between the apoplast and the cytosol, with bulk values ranging from 4.9 to 5.8 and from 7.1 to 7.5, respectively, in combination with a negative electrical membrane potential. The P‐type H+ ATPases pumping H+ from the cytosol into the apoplast at the expense of ATP hydrolysis are generally viewed as the only pmf source, exclusively linking membrane transport to energy metabolism. However, recent evidence suggests that pump activity may be insufficient to energize transport, particularly under stress conditions. Indeed, cytosolic H+ scavenging and apoplastic H+ generation by metabolism (denoted as 'active' buffering in contrast to the readily exhausted 'passive' matrix buffering) also stabilize the pH gradient. In the cytosol, H+ scavenging is mainly associated with malate decarboxylation catalyzed by malic enzyme, and via the GABA shunt of the tricarboxylic acid (TCA) cycle involving glutamate decarboxylation. In the apoplast, formation of bicarbonate from CO2, the end‐product of respiration, generates H+ at pH ≥ 6. Membrane potential is stabilized by K+ release and/or by anion uptake via ion channels. Finally, thermodynamic aspects of active buffering are discussed. [ABSTRACT FROM AUTHOR]

A new coordination polymer (CP), namely, [Cd(HL)(4,4′‐bipy)] (1) (H3L = 4‐(5‐carboxy‐pyridine‐3‐yloxy)‐phthalic acid, 4,4′‐bipy = 4,4′‐bipyridine), was synthesized employing a V‐shaped asymmetric tricarboxylic acid ligand under hydrothermal condition. Single‐crystal X‐ray diffraction analysis indicates that compound 1 exhibits a novel three‐dimensional (3D) framework with (3, 5)‐connected (63)(69·8) topology. Meanwhile, it shows high selectivity and sensitivity for oxoanion pollutants CrO42–, Cr2O72–, and MnO4– anions in aqueous solutions with detection limits of 4.12 × 10–6 M, 1.75 × 10–6 M, and 6.47 × 10–7 M, respectively. The high selectivity and low detection limit indicate that the compound is promising functional luminescence probe for CrO42–, Cr2O72–, and MnO4–. The mechanisms of the quenching effect and sensing properties were discussed in detail. [ABSTRACT FROM AUTHOR]