Activation Of Enzyme Research Articles

Corynebacterium glutamicum pyruvate:quinone oxidoreductase: an enigmatic metabolic enzyme with unusual structural features.

Pyruvate:quinone oxidoreductase (PQO) is a flavin-containing peripheral membrane enzyme catalyzing the decarboxylation of pyruvate to acetate and CO2 with quinone as an electron acceptor. Here, we investigate PQO activity in Corynebacterium glutamicum, examine purified PQO, and describe the crystal structure of the native enzyme and a truncated version. The specific PQO activity was highest in stationary phase cells grown in complex medium, lower in cells grown in complex medium containing glucose or acetate, and lowest in cells grown in minimal acetate-medium. A similar pattern with about 30-fold higher specific PQO activities was observed in C. glutamicum with plasmid-bound pqo expression under the control of the tac promoter, indicating that the differences in PQO activity are likely due to post-transcriptional control. Continuous cultivation of C. glutamicum at dilution rates between 0.05 and 0.4 h-1 revealed a negative correlation between PQO activity and growth rate. Kinetic analysis of PQO enzymes purified from cells grown in complex or in minimal acetate-medium revealed substantial differences in specific activity (72.3 vs. 11.9 U·mg protein-1) and turnover number (kcat: 440 vs. 78 s-1, respectively), suggesting post-translational modifications affecting PQO activity. Structural analysis of PQO revealed a homotetrameric arrangement very similar to the Escherichia coli pyruvate oxidase PoxB except for the C-terminal membrane binding domain, which exhibited a conformation markedly different from its PoxB counterpart. A truncated PQO variant lacking 17 C-terminal amino acids showed higher affinity to pyruvate and was independent of detergent activation, highlighting the importance of the C-terminus for enzyme activation and lipid binding.

An Unravelled Potential of Foliar Application of Micro and Beneficial Nutrients in Cereals for Ensuring Food and Nutritional Security

Micronutrient deficiency in soil and crops is a critical issue that contributes to what is known as hidden hunger. Hidden hunger refers to the lack of essential vitamins and minerals in people diets, often due to the poor nutrient content of staple crops, which can lead to significant health problems despite adequate caloric intake. Micronutrients are required in small amounts but are crucial for various physiological functions in plants, including cereals for enzyme activation, photosynthesis, nitrogen fixation, and synthesis of vital compounds. Corrective measures to address micronutrient deficiencies include soil application, seed treatment, foliar sprays, and genetic biofortification. Foliar sprays are particularly effective as they allow for the direct application of nutrients to plant leaves, ensuring quick absorption and utilization. This method can rapidly correct deficiencies, improve crop yields, and enhance the nutritional quality of the produce. Previous research has shown the efficacy of foliar sprays in addressing micronutrient deficiencies. Additionally, advancements in nanotechnology have led to the development of more efficient foliar spray formulations that enhance nutrient uptake and minimize environmental impact. Overall, addressing micronutrient deficiencies through foliar sprays and other agronomic practices is vital for improving crop health, yield, and nutritional quality, thereby contributing to food security and the alleviation of hidden hunger. However, specific dose of each micro- and beneficial nutrients are highly related to crops and cropping systems, season, agroclimatic conditions, materials used, and crop growth stage. The review article focuses on all issues and concerns with possible options for correcting micronutrient deficiency in cereals to ensure food and nutritional security and agricultural sustainability.

Superoxide to Peroxide Interconversion in Ni-TMC Complexes: The Significance of Structure and Spin States.

A deeper comprehension of the characteristics of metal-superoxide and metal-peroxide chemical species is imperative, considering their pivotal functions in oxygen transport, enzymatic activation, and catalytic oxygenations. O2 activation is mediated by the interconversion of superoxide and peroxide species. Even though there are multiple studies on metal-superoxide and -peroxide intermediates, robust examples of their interconversion processes are scarce synthetically. For example, Ni-superoxide/peroxide complexes have been characterized with N-Tetramethylated Cyclam (TMC) ligands with different ring sizes, i.e., Nickel(II)-superoxide complex is characterized with 14-TMC while Nickel(III)-peroxide complex with 12-TMC. Later, both complexes were obtained with 13-TMC ligand by employing different bases; interestingly, no evidence of interconversion between them was identified. What are the factors influencing these processes and why is this preference? We attempt a computational analysis of this issue and provide arguments based on our conclusions. 2-dimensional potential energy scan is performed on the 12-TMC, 13-TMC, and 14-TMC systems to identify the reaction path connecting superoxide and peroxide species. Analyses indicate that structure and spin states play a significant role in determining the probability of interconversion. The superoxide-peroxide interconversion process appears to be bound by their propensity for distinct structural features and spin states.

Salinity Stress Acclimation Strategies in Chlamydomonas sp. Revealed by Physiological, Morphological and Transcriptomic Approaches.

Climate changes may include variations in salinity concentrations at sea by changing ocean dynamics. These variations may be especially challenging for marine photosynthetic organisms, affecting their growth and distribution. Chlamydomonas spp. are ubiquitous and are often found in extreme salinity conditions. For this reason, they are considered good model species to study salinity adaptation strategies. In the current study, we used an integrated approach to study the Chlamydomonas sp. CCMP225 response to salinities of 20‱ and 70‱, by combining physiological, morphological, and transcriptomic analyses, and comparing differentially expressed genes in the exponential and stationary growth phases under the two salinity conditions. The results showed that the strain is able to grow under all tested salinity conditions and maintains a surprisingly high photosynthetic efficiency even under high salinities. However, at the highest salinity condition, the cells lose their flagella. The transcriptomic analysis highlighted the up- or down-regulation of specific gene categories, helping to identify key genes responding to salinity stress. Overall, the findings may be of interest to the marine biology, ecology, and biotechnology communities, to better understand species adaptation mechanisms under possible global change scenarios and the potential activation of enzymes involved in the synthesis of bioactive molecules.

Unraveling the mechanism of small molecule induced activation of Staphylococcus aureus signal peptidase IB

Staphylococcus aureus signal peptidase IB (SpsB) is an essential enzyme for protein secretion. While inhibition of its activity by small molecules is a well-precedented mechanism to kill bacteria, the mode of activation is however less understood. We here investigate the activation mechanism of a recently introduced activator, the antibiotic compound PK150, and demonstrate by combined experimental and Molecular Dynamics (MD) simulation studies a unique principle of enzyme stimulation. Mass spectrometric studies with an affinity-based probe of PK150 unravel the binding site of PK150 in SpsB which is used as a starting point for MD simulations. Our model shows the localization of the molecule in an allosteric pocket next to the active site which shields the catalytic dyad from excess water that destabilizes the catalytic geometry. This mechanism is validated by the placement of mutations aligning the binding pocket of PK150. While the mutants retain turnover of the SpsB substrate, no stimulation of activity is observed upon PK150 addition. Overall, our study elucidates a previously little investigated mechanism of enzyme activation and serves as a starting point for the development of future enzyme activators.

Fabrication of functional diatomaceous earth with enhanced papain enzyme adsorption

Diatomaceous earth (DE) is a sedimentary rock comprising fossilized shells of diatoms, which are a type of algae. The shells of the diatoms are made of silicon dioxide, which is also the main component of DE. DE has excellent moisture absorption and desorption properties and is widely used as an adsorbent, abrasive, insulator, catalyst, and carrier in the stationary phase. It has also been widely studied for its application as a new silicon material in emerging growth fields, such as biosensors. However, because organic matter is adsorbed on the surface of DE, the organic matter must be removed to exploit the properties of mesoporous silica. In this study, the organic matter on the DE surface was removed by alkali treatment to expose the pores and increase the adsorption capacity. Additionally, papain was physisorbed onto DE using a rotator, and l-cysteine was added for papain activation. Under these optimised conditions, the activation of the papain enzyme was effective, resulting in improved DE performance. The adsorption power of DE was correlated with the amount of papain adsorbed, which, in turn, was correlated with its absorbance. Trichloroacetic acid was added to stop the reaction, and the absorbance was measured. The prepared samples were designated as papain/DE (P/DE) complexes. The final concentration of the P/DE was 1 mg/mL. In addition, cross-linked and non-cross-linked P/DE samples were prepared using N-hydroxysuccinimide and water-soluble carbodiimide in a 5:3 ratio and compared. The results showed that surface treatment and functionalisation of DE improved its functionality (enzyme activity), indicating its potential as a new DE material.

Recombinant Expression and Characterization of a Novel Thermo-Alkaline Lipase with Increased Solvent Stability from the Antarctic Thermophilic Bacterium Geobacillus sp. ID17.

Lipases are enzymes that hydrolyze long-chain carboxylic esters, and in the presence of organic solvents, they catalyze organic synthesis reactions. However, the use of solvents in these processes often results in enzyme denaturation, leading to a reduction in enzymatic activity. Consequently, there is significant interest in identifying new lipases that are resistant to denaturing conditions, with extremozymes emerging as promising candidates for this purpose. Lip7, a lipase from Geobacillus sp. ID17, a thermophilic microorganism isolated from Deception Island, Antarctica, was recombinantly expressed in E. coli C41 (DE3) in functional soluble form. Its purification was achieved with 96% purity and 23% yield. Enzymatic characterization revealed Lip7 to be a thermo-alkaline enzyme, reaching a maximum rate of 3350 U mg-1 at 50 °C and pH 11.0, using p-nitrophenyl laurate substrate. Notably, its kinetics displayed a sigmoidal behavior, with a higher kinetic efficiency (kcat/Km) for substrates of 12-carbon atom chain. In terms of thermal stability, Lip7 demonstrates stability up to 60 °C at pH 8.0 and up to 50 °C at pH 11.0. Remarkably, it showed high stability in the presence of organic solvents, and under certain conditions even exhibited enzymatic activation, reaching up to 2.5-fold and 1.35-fold after incubation in 50% v/v ethanol and 70% v/v isopropanol, respectively. Lip7 represents one of the first lipases from the bacterial subfamily I.5 and genus Geobacillus with activity and stability at pH 11.0. Its compatibility with organic solvents makes it a compelling candidate for future research in biocatalysis and various biotechnological applications.

Formulations of synergistic microbial consortia for enhanced systemic resistance against Fusarium wilt in cumin.

The study aimed to understand the dynamic interplay between plants and their associated microbes to develop an efficient microbial consortium for managing Fusarium wilt of cumin. A total of 601 rhizospheric and endophytic bacteria and fungi were screened for antagonistic activity against Fusarium oxysporum f.sp. cumini (Foc). Subsequently, ten bacteria and ten fungi were selected for characterizing their growth promotion traits and ability to withstand abiotic stress. Furthermore, a pot experiment was conducted to evaluate the bioefficacy of promising biocontrol isolates-1F, 16B, 31B, and 223B in mono and consortium mode, focusing on disease severity, plant growth, and defense responses in cumin challenged with Foc. Promising isolates were identified as Trichoderma atrobruneum 15F, Pseudomonas sp. 2B, Bacillus amyloliquefaciens 9B, and Bacillus velezensis 32B. In planta, results revealed that cumin plants treated with consortia of 15F, 2B, 9B, and 32B showed highest percent disease control (76.35%) in pot experiment. Consortia of biocontrol agents significantly enhanced production of secondary metabolites and activation of antioxidant-defense enzymes compared to individual strain. Moreover, consortium treatments effectively reduced electrolyte leakage over the individual strain and positive control. The four-microbe consortium significantly enhanced chlorophyll (~ 2.74-fold), carotenoid content (~ 2.14-fold), plant height (~ 1.8-fold), dry weight (~ 1.96-fold), and seed yield (~ 19-fold) compared to positive control in pot experiment. Similarly, four microbe consortia showed highest percent disease control (72.2%) over the positive control in field trial. Moreover, plant growth, biomass, yield, and yield attributes of cumin were also significantly increased in field trial over the positive control as well as negative control.

The pathogenic T42A mutation in SHP2 rewires the interaction specificity of its N-terminal regulatory domain

Mutations in the tyrosine phosphatase Src homology-2 domain-containing protein tyrosine phosphatase-2 (SHP2) are associated with a variety of human diseases. Most mutations in SHP2 increase its basal catalytic activity by disrupting autoinhibitory interactions between its phosphatase domain and N-terminal SH2 (phosphotyrosine recognition) domain. By contrast, some disease-associated mutations located in the ligand-binding pockets of the N- or C-terminal SH2 domains do not increase basal activity and likely exert their pathogenicity through alternative mechanisms. We lack a molecular understanding of how these SH2 mutations impact SHP2 structure, activity, and signaling. Here, we characterize five SHP2 SH2 domain ligand-binding pocket mutants through a combination of high-throughput biochemical screens, biophysical and biochemical measurements, and molecular dynamics simulations. We show that while some of these mutations alter binding affinity to phosphorylation sites, the T42A mutation in the N-SH2 domain is unique in that it also substantially alters ligand-binding specificity, despite being 8 to 10 Å from the specificity-determining region of the SH2 domain. This mutation exerts its effect on sequence specificity by remodeling the phosphotyrosine-binding pocket, altering the mode of engagement of both the phosphotyrosine and surrounding residues on the ligand. The functional consequence of this altered specificity is that the T42A mutant has biased sensitivity toward a subset of activating ligands and enhances downstream signaling. Our study highlights an example of a nuanced mechanism of action for a disease-associated mutation, characterized by a change in protein-protein interaction specificity that alters enzyme activation.

Activation of angiotensin converting enzyme 2 promotes hippocampal neurogenesis via activation of Wnt/β-catenin signaling in hypertension

Hypertension-induced brain renin-angiotensin system (RAS) activation and neuroinflammation are hallmark neuropathological features of neurodegenerative diseases. Previous studies from our lab have shown that inhibition of ACE/Ang II/AT1R axis (by AT1R blockers or ACE inhibitors) reduced neuroinflammation and accompanied neurodegeneration via up-regulating adult hippocampal neurogenesis. Apart from this conventional axis, another axis of RAS also exists i.e., ACE2/Ang (1–7)/MasR axis, reported as an anti-hypertensive and anti-inflammatory. However, the role of this axis has not been explored in hypertension-induced glial activation and hippocampal neurogenesis in rat models of hypertension. Hence, in the present study, we examined the effect of ACE2 activator, Diminazene aceturate (DIZE) at 2 different doses of 10 mg/kg (non-antihypertensive) and 15 mg/kg (antihypertensive dose) in renovascular hypertensive rats to explore whether their effect on glial activation, neuroinflammation, and neurogenesis is either influenced by blood-pressure. The results of our study revealed that hypertension induced significant glial activation (astrocyte and microglial), neuroinflammation, and impaired hippocampal neurogenesis. However, ACE2 activation by DIZE, even at the low dose prevented these hypertension-induced changes in the brain. Mechanistically, ACE2 activation inhibited Ang II levels, TRAF6-NFκB mediated inflammatory signaling, NOX4-mediated ROS generation, and mitochondrial dysfunction by upregulating ACE2/Ang (1–7)/MasR signaling. Moreover, DIZE-induced activation of the ACE2/Ang (1–7)/MasR axis upregulated Wnt/β-catenin signaling, promoting hippocampal neurogenesis during the hypertensive state. Therefore, our study demonstrates that ACE2 activation can effectively prevent glial activation and enhance hippocampal neurogenesis in hypertensive conditions, regardless of its blood pressure-lowering effects.

Effects of kaempherol-3-rhamnoside on metabolic enzymes and AMPK in the liver tissue of STZ-induced diabetes in mice

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by persistent hyperglycemia. It involves disturbances in carbohydrate, fat, and protein metabolism due to defects in insulin secretion, insulin action, or both. Novel therapeutic approaches are continuously being explored to enhance metabolic control and prevent complications associated with the disease. This study investigates the therapeutic potential of kaempherol-3-rhamnoside, a flavonoid, in managing diabetes by modulating the AMP-activated protein kinase (AMPK) pathway and improving metabolic enzyme activities in streptozotocin (STZ) -induced diabetic mice. Diabetic mice were treated with varying doses of kaempherol-3-rhamnoside and/or insulin over a 28-day period. Glycolytic and gluconeogenesis enzyme activities in the liver, fasting blood glucose levels, serum insulin levels, lipid profiles and oxidative stress markers were assessed. Treatment with kaempherol-3-rhamnoside significantly improved glycolytic enzyme activities, reduced fasting blood glucose, and enhanced insulin levels compared to diabetic controls. The compound also normalized lipid profiles and reduced oxidative stress in the liver, suggesting its potential in reversing diabetic dyslipidemia and oxidative damage. Furthermore, kaempherol-3-rhamnoside activated the AMPK pathway, indicating a mechanism through which it could exert its effects. Kaempherol-3-rhamnoside exhibits promising antidiabetic properties, potentially through AMPK pathway activation and metabolic enzyme modulation. These findings support its potential use as an adjunct therapy for diabetes management. Further clinical studies are warranted to validate these results in human subjects.

Effect of Diminazene Aceturate, an ACE2 activator, on platelet CD40L signaling induced glial activation in rat model of hypertension

Hypertension causes platelet activation and adhesion in the brain resulting in glial activation and neuroinflammation. Further, activation of Angiotensin-Converting Enzyme 2/Angiotensin (1–7)/Mas Receptor (ACE2/Ang (1–7)/MasR) axis of central Renin-Angiotensin System (RAS), is known to reduce glial activation and neuroinflammation, thereby exhibiting anti-hypertensive and anti-neuroinflammatory properties. Therefore, in the present study, the role of ACE2/Ang (1–7)/MasR axis was studied on platelet-induced glial activation and neuroinflammation using Diminazene Aceturate (DIZE), an ACE2 activator, in astrocytes and microglial cells as well as in rat model of hypertension. We found that the ACE2 activator DIZE, independently of its BP-lowering properties, efficiently prevented hypertension-induced glial activation, neuroinflammation, and platelet CD40-CD40L signaling via upregulation of ACE2/Ang (1–7)/MasR axis. Further, DIZE decreased platelet deposition in the brain by reducing the expression of adhesion molecules on the brain endothelium. Activation of ACE2 also reduced hypertension-induced endothelial dysfunction by increasing eNOS bioavailability. Interestingly, platelets isolated from hypertensive rats or activated with ADP had significantly increased sCD40L levels and induced significantly more glial activation than platelets from DIZE treated group. Therefore, injection of DIZE pre-treated ADP-activated platelets into normotensive rats strongly reduced glial activation compared to ADP-treated platelets. Moreover, CD40L-induced glial activation, CD40 expression, and NFкB-NLRP3 inflammatory signaling are reversed by DIZE. Furthermore, the beneficial effects of ACE2 activation, DIZE was found to be significantly blocked by MLN4760 (ACE2 inhibitor) as well as A779 (MasR antagonist) treatments. Hence, our study demonstrated that ACE2 activation reduced the platelet CD40-CD40L induced glial activation and neuroinflammation, hence imparted neuroprotection.

Dynamic changes in the proximitome of neutral sphingomyelinase-2 (nSMase2) in TNFα stimulated Jurkat cells.

Ceramides generated by the activity of the neutral sphingomyelinase 2 (nSMase2) play a pivotal role in stress responses in mammalian cells. Dysregulation of sphingolipid metabolism has been implicated in numerous inflammation-related pathologies. However, its influence on inflammatory cytokine-induced signaling is yet incompletely understood. Here, we used proximity labeling to explore the plasma membrane proximal protein network of nSMase2 and TNFα-induced changes thereof. We established Jurkat cells stably expressing nSMase2 C-terminally fused to the engineered ascorbate peroxidase 2 (APEX2). Removal of excess biotin phenol substantially improved streptavidin-based affinity purification of biotinylated proteins. Using our optimized protocol, we determined nSMase2-proximal biotinylated proteins and their changes within the first 5min of TNFα stimulation by quantitative mass spectrometry. We observed significant dynamic changes in the nSMase2 microenvironment in response to TNFα stimulation consistent with rapid remodeling of protein networks. Our data confirmed known nSMase2 interactors and revealed that the recruitment of most proteins depended on nSMase2 enzymatic activity. We measured significant enrichment of proteins related to vesicle-mediated transport, including proteins of recycling endosomes, trans-Golgi network, and exocytic vesicles in the proximitome of enzymatically active nSMase2 within the first minutes of TNFα stimulation. Hence, the nSMase2 proximal network and its TNFα-induced changes provide a valuable resource for further investigations into the involvement of nSMase2 in the early signaling pathways triggered by TNFα.

Predictive and therapeutic value of lipoprotein-associated phospholipaseA2 in sarcopenia in chronic obstructive pulmonary disease

BackgroundSarcopenia, characterized by progressive muscle dysfunction, is a common complication of chronic obstructive pulmonary disease (COPD). Our previous study revealed serum Lipoprotein-associated phospholipaseA2 (Lp-PLA2) level significantly increased in COPD and associated with exercise tolerance. This study further investigated the functions and target potential of Lp-PLA2 for sarcopenia in COPD. MethodsThe circulating Lp-PLA2 level/enzyme activity in COPD patients and age-matched healthy volunteers were measured. Clinical parameters on skeletal muscle were measured and their correlations with Lp-PLA2 were analyzed. We explored the involvement of Lp-PLA2 in vivo and treatment effectiveness of darapladib (a specific Lp-PLA2 inhibitor) in CS-induced muscle dysfunction models. ResultsCirculating Lp-PLA2 level/enzyme activity was elevated in COPD patients compared with healthy controls, negatively associated with skeletal muscle mass and function. In CS-induced muscle dysfunction murine models, up-regulated serum Lp-PLA2 level/enzyme activity was verified again. In CS-exposed mouse models, darapladib treatment reversed muscle mass loss and muscle dysfunction, meanwhile rescued upregulation of MuRF1 and atrogin-1, and activation of inflammatory factors, oxidant enzymes and NF-κB signaling. ConclusionsLp-PLA2 could be a potential indicator for sarcopenia in COPD. Darapladib, a Lp-PLA2 inhibitor, can alleviate CS-induced skeletal muscle dysfunction and represents a potential therapeutic for sarcopenia in COPD.

Molecular and biochemical evaluation of oxidative effects of cord blood CD34+ MPs on hematopoietic cells

A graft source for allogeneic hematopoietic stem cell transplantation is umbilical cord blood, which contains umbilical cord blood mononuclear cells (MNCs and mesenchymal stem cells, both an excellent source of extracellular microparticles (MPs). MPs act as cell communication mediators, which are implicated in reactive oxygen species formation or detoxification depending on their origin. Oxidative stress plays a crucial role in both the development of cancer and its treatment by triggering apoptotic mechanisms, in which CD34+ cells are implicated. The aim of this work is to investigate the oxidative stress status and the apoptosis of HL-60 and mononuclear cells isolated from umbilical cord blood (UCB) following a 24- and 48-hour exposure to CD34 + microparticles (CD34 + MPs). The activity of superoxide dismutase, glutathione reductase, and glutathione S-transferase, as well as lipid peroxidation in the cells, were employed as oxidative stress markers. A 24- and 48-hour exposure of leukemic and mononuclear cells to CD34 + -MPs resulted in a statistically significant increase in the antioxidant activity and lipid peroxidation in both cells types. Moreover, CD34 + MPs affect the expression of BCL2 and FAS and related proteins and downregulate the hematopoietic differentiation program in both HL-60 and mononuclear cells. Our results indicate that MPs through activation of antioxidant enzymes in both homozygous and nonhomozygous cells might serve as a means for graft optimization and enhancement.

Mass Spectrometric Detection and Differentiation of Enzymatically Active Abrin and Ricin Combined with a Novel Affinity Enrichment Technique.

Abrin and ricin are toxic proteins produced by plants. Both proteins are composed of two subunits, an A-chain and a B-chain. The A-chain is responsible for the enzymatic activity, which causes toxicity. The B-chain binds to glycoproteins on the cell surface to direct the A-chain to its target. Both toxins depurinate 28S rRNA, making it impossible to differentiate these toxins based on only their enzymatic activity. We developed an analytical workflow for both ricin and abrin using a single method and sample. We have developed a novel affinity enrichment technique based on the ability of the B-chain to bind a glycoprotein, asialofetuin. After the toxin is extracted with asialofetuin-coated magnetic beads, an RNA substrate is added. Then, depurination is detected by a benchtop matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectrometer to determine the presence or absence of an active toxin. Next, the beads are subjected to tryptic digest. Toxin fingerprinting is done on a benchtop MALDI-TOF MS. We validated the assay through sensitivity and specificity studies and determined the limit of detection for each toxin as nanogram level for enzymatic activity and μg level for toxin fingerprinting. We examined potential cross-reactivity from proteins that are near neighbors of the toxins and examined potential false results in the presence of white powders.

Enzymatic Activation and Continuous Electrochemical Production of Methane from Dilute CO2 Sources with a Self-Healing Capsule.

Converting dilute CO2 source into value-added chemicals and fuels is a promising route to reduce fossil fuel consumption and greenhouse gas emission, but integrating electrocatalysis with CO2 capture still faced marked challenges. Herein, we show that a self-healing metal-organic macrocycle functionalized as an electrochemical catalyst to selectively produce methane from flue gas and air with the lowest applied potential so far (0.06 V vs reversible hydrogen electrode, RHE) through an enzymatic activation fashion. The capsule emulates the enzyme' pocket to abstract one in situ-formed CO2-adduct molecule with the commercial amino alcohols, forming an easy-to-reduce substrate-involving clathrate to combine the CO2 capture with electroreduction for a thorough CO2 reduction. We find that the self-healing system exhibited enzymatic kinetics for the first time with the Michaelis-Menten mechanism in the electrochemical reduction of CO2 and maintained a methane Faraday efficiency (FE) of 74.24% with a selectivity of over 99% for continuous operation over 200 h. A consecutive working lab at 50 mA·cm-2, in an eleven-for-one (10 h working and 1 h healing) electrolysis manner, gives a methane turnover number (TON) of more than 10,000 within 100 h. The integrated electrolysis with CO2 capture facilitates the thorough reduction of flue gas (ca. 13.0% of CO2) and first time of air (ca. 400 ppm of CO2 to 42.7 mL CH4 from 1.0 m3 air). The new self-healing strategy of molecular electrocatalyst with an enzymatic activation manner and anodic shifting of the applied potentials provided a departure from the existing electrochemical catalytic techniques.

Mitigation of Abiotic Stresses in Plants through Nutrient Management

The food demand over the world is increasing due to the rapid increase in the population. Direct and indirect effects of climate change have severely affected the growth and development of crops. Of these, abiotic stress factors are reported to cause a reduction in crop productivity ranging from 51 percent to 82 percent. Abiotic stresses like drought, waterlogging stress, salt stress, soil acidity, metal toxicities and temperature variations have overwhelming impact on the growth and productivity of crops. Abiotic stress causes increase in reactive oxygen species (ROS) levels and affects various physiological processes, causing reduction in plant growth and yield. Nutrient management proves to be an effective strategy for alleviating various abiotic stress factors affecting agricultural crops. Nutrients such as nitrogen, potassium, calcium and magnesium increase the production of antioxidant enzymes such as superoxide dismutase, peroxidase, catalase and reduces ROS production. Micronutrients such as iron, boron and zinc as well as biofertilizers improve plant adaptation to various stresses through activation of antioxidant enzymes. Current review focuses on the impact of mineral nutrients, organic amendments and biofertilizers in alleviating abiotic stress in agricultural crops.

Characterization of Physiological and Biochemical Attributes of Neem (Azadirachta indica A. Juss) under Salinity Stress

Salinity poses a significant threat to agricultural productivity worldwide, with its detrimental effects on plant growth and physiological processes. Understanding the mechanisms by which plants respond to salt stress is crucial for developing strategies to mitigate its impact on crop yield and sustainability. To address this issue, a pot study was conducted to determine the effect of salt stress on the physiological and biochemical attributes of neem (Azdiarchta indica A. Juss). Plants were grown for 10 months in pots filled with soil having different salinity levels of 3, 6, 9, 12, 15, and 18 dS m−1 and compared with a control of 1.7 dS m−1. The results showed that plant growth and chlorophyll contents declined as salinity levels increased. Due to oxidative stress, the contents of H2O2 increased under higher salt levels. The mitigation of oxidative stress was achieved through the activation of antioxidant enzymes (catalase, ascorbate peroxidase, peroxidase, and superoxide dismutase). Multivariate analysis indicated that Na+ accumulation in plants was positively related to H2O2 production and enzymatic activities, and negatively related to plant biomass, chlorophyll contents, root and shoot K+ concentration, and root K+/Na+. The experimental results suggest that neem plants can be grown in moderate saline soils.

P-356 Fertility preservation for patients with breast cancer: altered response to ovarian stimulation and loss of cholesterol homeostasis in ovarian follicles

Abstract Study question Does the presence of breast cancer alter the ovarian response to hormonal stimulation and the cholesterol homeostasis in ovarian follicles? Summary answer The deleterious impact of breast cancer on the ovarian response might be link to an alteration of the cholesterol biosynthesis in cumulus cells. What is known already Breast cancer is the most frequent cancer in reproductive-aged women. The cancer itself seems to exert a deleterious impact on the ovarian functions. Indeed, cancer patients who undergo fertility preservation before cancer therapy initiation show a poorer response to ovarian stimulation than healthy women. Nevertheless, this impact remains controversial, and the mechanisms by which the cancer impairs the ovarian functions are poorly understood. To our knowledge, no study has yet evaluated the impact of breast cancer on the cholesterol biosynthesis pathway in human cumulus cells, a pathway essential for oocyte competence to maturation and fertilization. Study design, size, duration 30 patients with breast cancer (10 triple negative (TNBC), 10 hormone-receptor positive (HR+) and 10 HER2 positive (HER2+)) and 30 women oocytes donors undergoing oocyte cryopreservation will be included from January 2019. We assess ovarian response to stimulation (number, quality of retrieved oocytes; total FSH dose). We quantify the level of enzymes and regulators of the cholesterol biosynthesis pathway in cumulus cells (CC) by RT-qPCR. We plan to quantify cholesterol levels in follicular fluids (FF). Participants/materials, setting, methods Since January 2019, 25 breast cancer patients (9 TNBC, 8 HR+ and 8 HER2+) and 30 oocytes donors (control group) under 37 years old have been included. Ovarian stimulation was performed with antagonist protocol. Following ovarian pick up and denudation, CC and FF were collected. After total RNAs extraction from CC, the expression levels of enzymes and regulators of the cholesterol biosynthesis pathway were quantified by RT-qPCR. Cholesterol levels will be quantified in FF. Main results and the role of chance The clinico-biological characteristics (age, BMI) are comparable between cancer patients and the control group (p > 0.05). Serum AMH levels are lower in the TNBC subgroup (2.3±1.6 ng/mL) than in the control group (4.7±2.8 ng/mL, p = 0.04). A poorer ovarian response to ovarian stimulation is observed in the breast cancer group compared with the control group (number of mature oocytes: 9.4±5.2 vs. 14.5±7.7, p = 0.007). Among the cancer patients group, the TNBC subgroup shows the poorest ovarian response to stimulation (number of mature oocytes: 7.6±4.3 vs. 14.5±7.7 in control group, p = 0.006) despite the highest total administered FSH dose (2480±880 IU vs. 1831±460 IU in control group, p = 0.02). Dysregulation of the cholesterol biosynthesis pathway is observed in the breast cancer group. For TNBC and HR+ cancer patients, we observed an increase in the transcripts levels of CYP51 enzyme (respectively 3.28±1.69 vs. 1.84±2.33, p = 0.0098 and 1.77±1.78 vs. 1.84±2.33, p = 0.03) and SREBP2 activator (respectively 2.04±0.95 vs. 1.27±1.13, p = 0.003 and 1.12±0.47 vs. 1.27±1.13, p = 0.02) of the cholesterol biosynthesis pathway compared to the control group. In HER2+ cancer patients, a significant decrease in the expression levels of SQLE (0.39±0.34 vs 1.81±3.99, p = 0.001) and DHRC7 enzymes (0.33±0.32 vs 1.21±0.88, p = 0.0002) is observed compared to the control group. Limitations, reasons for caution Our preliminary results should be confirmed with the analysis of a larger number of participants. We should confirm that the observed modulations in the expression levels of enzymes and regulators of the cholesterol biosynthesis pathway led to a loss of cholesterol homeostasis by quantifying cholesterol in FF. Wider implications of the findings Our findings strengthen the hypothesis that cancer exerts a deleterious impact on the ovarian functions, as we observed a lower ovarian response in patients with breast cancer. This project will have clinical implications, such as to adapt the fertility preservation approach according to the breast cancer subtype. Trial registration number Not applicable