Nudix hydrolase 23 post-translationally regulates carotenoid biosynthesis in plants.

Carotenoids are essential for photosynthesis and photoprotection. Plants must evolve multifaceted regulatory mechanisms to control carotenoid biosynthesis. However, the regulatory mechanisms and the regulators conserved among plant species remain elusive. Phytoene synthase (PSY) catalyzes the highly regulated step of carotenogenesis and geranylgeranyl diphosphate synthase (GGPPS) acts as a hub to interact with GGPP-utilizing enzymes for the synthesis of specific downstream isoprenoids. Here, we report a function of Nudix hydrolase 23 (NUDX23), a Nudix domain-containing protein, in post-translational regulation of PSY and GGPPS for carotenoid biosynthesis. NUDX23 expresses highly in Arabidopsis (Arabidopsis thaliana) leaves. Overexpression of NUDX23 significantly increases PSY and GGPPS protein levels and carotenoid production, whereas knockout of NUDX23 dramatically reduces their abundances and carotenoid accumulation in Arabidopsis. NUDX23 regulates carotenoid biosynthesis via direct interactions with PSY and GGPPS in chloroplasts, which enhances PSY and GGPPS protein stability in a large PSY-GGPPS enzyme complex. NUDX23 was found to co-migrate with PSY and GGPPS proteins and to be required for the enzyme complex assembly. Our findings uncover a regulatory mechanism underlying carotenoid biosynthesis in plants and offer promising genetic tools for developing carotenoid-enriched food crops.

Carotenoid sequestration protein FIBRILLIN participates in CmOR-regulated ß-carotene accumulation in melon.

Chromoplasts are plant organelles with a unique ability to sequester and store massive carotenoids. Chromoplasts have been hypothesized to enable high levels of carotenoid accumulation due to enhanced sequestration ability or sequestration substructure formation. However, the regulators that control the substructure component accumulation and substructure formation in chromoplasts remain unknown. In melon (Cucumis melo) fruit, ß-carotene accumulation in chromoplasts is governed by ORANGE (OR), a key regulator for carotenoid accumulation in chromoplasts. By using comparative proteomic analysis of a high ß-carotene melon variety and its isogenic line low-ß mutant that is defective in CmOr with impaired chromoplast formation, we identified carotenoid sequestration protein FIBRILLIN1 (CmFBN1) as differentially expressed. CmFBN1 expresses highly in melon fruit tissue. Overexpression of CmFBN1 in transgenic Arabidopsis (Arabidopsis thaliana) containing ORHis that genetically mimics CmOr significantly enhances carotenoid accumulation, demonstrating its involvement in CmOR-induced carotenoid accumulation. Both in vitro and in vivo evidence showed that CmOR physically interacts with CmFBN1. Such an interaction occurs in plastoglobules and results in promoting CmFBN1 accumulation. CmOR greatly stabilizes CmFBN1, which stimulates plastoglobule proliferation and subsequently carotenoid accumulation in chromoplasts. Our findings show that CmOR directly regulates CmFBN1 protein levels and suggest a fundamental role of CmFBN1 in facilitating plastoglobule proliferation for carotenoid sequestration. This study also reveals an important genetic tool to further enhance OR-induced carotenoid accumulation in chromoplasts in crops.

Enhancing functionality and bioactivity of walnut protein through limited enzyme digestion.

BACKGROUND: Walnut protein (WP) is recognized as a valuable plant protein. However, the poor solubility and functional properties limit its application in the food industry. It is a great requirement to improve the physicochemical properties of WP. RESULTS: Following a 90 min restricted enzymatic hydrolysis period, the solubility of WP significantly increased from 3.24% to 54.54%, with the majority of WP hydrolysates (WPHs) possessing a molecular weight exceeding 50 kDa. Circular dichroism spectra showed that post-hydrolysis, the structure of the protein became more flexible, while the hydrolysis time did not significantly alter the protein's secondary structure. After hydrolysis, WP's surface hydrophobicity significantly increased from 2279 to 6100. Furthermore, WPHs exhibited a strong capacity for icariin loading and micelle formation with critical micelle concentration values of 0.71, 0.99 and 1.09 mg mL-1, respectively. Moreover, similar immuno-enhancement activities were observed in WPHs. After exposure to WPHs, the pinocytosis of RAW264.7 macrophages was significantly improved. WPH treatment also increased the production of nitric oxide, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in macrophages. Up-regulation of mRNA expressions of IL-6, inducible nitric oxide synthase (iNOS) and TNF-α was observed in a dose-dependent manner. CONCLUSION: The enhancement of functionality and bioactivity in WP can be achieved through the application of limited enzyme digestion with trypsin. This process effectively augments the nutritional value and utility of the protein, making it a valuable component in various dietary applications. © 2024 Society of Chemical Industry.

Asymmetric [3 + 2] Photocycloaddition of ß-Keto Esters and Vinyl Azides by Dual Photoredox/Nickel Catalysis.

Photocatalytic [3 + 2] cycloadditions and control of stereochemistry have remained a substantial challenge, particularly in the context of heterocycle synthesis; sporadic successful examples have involved enantioselective [3 + 2] photocycloaddition between redox-active direct group-containing cyclopropanes and alkenes for creation of cyclopentanes. Herein, we report a cooperative catalytic system comprising a chiral nickel Lewis acid catalyst and an organic photocatalyst fueled by visible-light irradiation that allows for the hitherto elusive asymmetric [3 + 2] photocycloaddition of ß-keto esters with vinyl azides under redox-neutral conditions. This protocol enables highly enantioselective construction of polycyclic densely substituted 3,4-dihydro-2H-pyrrole heterocycles featuring two contiguous tetrasubstituted carbon stereocenters, including a useful chiral N,O-ketal motif that is not easily accessible with other catalytic methods. Mechanistic studies revealed that the overall reactivity relies on the seamless integration of dual roles of nickel catalysts by the catalytic formation of the substrate/Ni complex, assisting both photoredox event and enantioselective radical addition.

Suppression of GhGLU19 encoding ß-1,3-glucanase promotes seed germination in cotton.

BACKGROUND: In eudicots, germination begins with water uptake by the quiescent dry seed and is greatly related to the permeability of micropyle enriched callose layers. Once imbibition starts, seeds undergo a cascade of physiological, biochemical, and molecular events to initiate cellular activities. However, the effects of callose on water uptake and following seed metabolic events during germination are largely unknown. Cotton (Gossypium hirsutum) is a eudicot plant with natural fiber and edible oil production for humans. Here, we addressed this question by examining the role of GhGLU19, a gene encoding ß-1,3-glucanase, in cotton seed germination. RESULTS: GhGLU19 belongs to subfamily B and was expressed predominately in imbibed seeds and early seedlings. Compared to wild type, GhGLU19-suppressing and GhGLU19-overexpressing transgenic cotton lines showed the higher and lower seed germination percentage, respectively. Callose was enriched more at inner integument (ii) than that in embryo and seed coat in cotton seeds. In GhGLU19-suppressing lines, callose at ii of cotton seeds was greatly increased and brought about a prolonged water uptake process during imbibition. Both proteomic and transcriptomic analysis revealed that contrary to GhGLU19-overexpressing lines, the glycolysis and pyruvate metabolism was decreased, and abscisic acid (ABA) biosynthesis related genes were downregulated in imbibed seeds of GhGLU19-suppressing lines. Also, endogenous ABA was significantly decreased in GhGLU19-suppressing line while increased in GhGLU19-overexpressing line. CONCLUSIONS: Our results demonstrate that suppression of GhGLU19 improves cotton seed germination via accumulating callose of inner integument, modulating glycolysis and pyruvate metabolism, and decreasing ABA biosynthesis. This study provides a potential way for improving germination percentage in cotton seed production, and other eudicot crops.

Metal-Organic Complexes@Melamine Foam Template Strategy to Prepare Three-Dimensional Porous Carbon with Hollow Spheres Structures for Efficient Organic Vapor and Small Molecule Gas Adsorption.

Three-dimensional (3D) porous carbon materials have received substantial attention owing to their unique structural features. However, the synthesis of 3D porous carbon, especially 3D porous carbon with hollow spheres structures at the connection points, still pose challenges. Herein, we first develop a metal-organic complexes@melamine foam (MOC@MF) template strategy, by using hot-pressing and carbonization method to synthesize 3D porous carbon with hollow spheres structures (denoted as NOPCs). The formation mechanism of NOPCs can be attributed to the difference in Laplace pressure and surface energy gradient between the carbonized MOC and carbonized MF. These rare 3D porous carbons exhibit high BET surface area (2453.8 m2 g-1), N contents (10.5%), and O contents (16.3%). Moreover, NOPCs show significant amounts of toluene and methanol at room temperature, reaching as high as 1360 and 1140 mg g-1. The adsorption amounts of SO2 and CO2 for NOPCs are up to 93.1 and 445 mg g-1. Theoretical calculation indicates surfaces of porous carbon with N and O coexistence could strongly enhance adsorption with high adsorption energy of -65.83 kJ mol g-1.

Photogenerated Neutral Nitrogen Radical Catalyzed Bifunctionalization of Alkenes.

Alkene bifunctionalizations are powerful tools for the rapid construction of structurally complex and valuable scaffolds, and such reactions typically involve the use of transition-metal catalysts or organocatalysts. Here, we report for the first time a photogenerated neutral nitrogen radical catalyzed intermolecular alkene bifunctionalization by using allyl sulfones as the source of both the carbon and the sulfone functionalities under mild conditions. The key to the success of this protocol involves the visible-light-mediated photocatalytic in situ generation of a nitrogen-centered radical from the N-(2-acetylphenyl) benzenesulfonamide catalyst, and its activation of the allyl sulfones to generate reactive species. The preliminary control experiments supported the postulated mechanism.

A Dual Associated-Functional Fluorescent Switch: From Alternate Detection Cycle for Fe(III) and pH to Molecular Logic Operations.

With the expansion and deepening of scientific research, dual-functional or multifunctional materials are urgently needed to replace those for single application. Herein, a fluorescence sensing system based on an In(III)-organic complex with in situ Lewis acid sites has been constructed, exhibiting high sensitivity for the detection of Fe(III) ions with a low detection limit of 3.95 µM and a short response time of within 10 s. It is noteworthy that the quenched fluorescence of the Fe(III)-incorporated sample could be reopened linearly with an increase of alkalinity, followed by the reactivation of its functionality to identify Fe(III) ions, forming an alternate detection cycle for Fe(III) and pH with off-on-off fluorescent switch characteristics. Considering its unique molecular recognition capability, an advanced three-input (Fe(III), EDTA, and OH-) and two-output (B440 and G489) Boolean logic operation comprising BUFF, NOT, OR, and AND logic gates was integrated, possessing potential applications in intelligent multianalyte sensing systems.

Analyzing the Impact of Traffic Congestion Mitigation: From an Explainable Neural Network Learning Framework to Marginal Effect Analyses.

Computational graphs (CGs) have been widely utilized in numerical analysis and deep learning to represent directed forward networks of data flows between operations. This paper aims to develop an explainable learning framework that can fully integrate three major steps of decision support: Synthesis of diverse traffic data, multilayered traffic demand estimation, and marginal effect analyses for transport policies. Following the big data-driven transportation computational graph (BTCG) framework, which is an emerging framework for explainable neural networks, we map different external traffic measurements collected from household survey data, mobile phone data, floating car data, and sensor networks to multilayered demand variables in a CG. Furthermore, we extend the CG-based framework by mapping different congestion mitigation strategies to CG layers individually or in combination, allowing the marginal effects and potential migration magnitudes of the strategies to be reliably quantified. Using the TensorFlow architecture, we evaluate our framework on the Sioux Falls network and present a large-scale case study based on a subnetwork of Beijing using a data set from the metropolitan planning organization.

Research on the Mechanism of Aggregation-Induced Emission through Supramolecular Metal-Organic Frameworks with Mechanoluminescent Properties and Application in Press-Jet Printing.

This study investigates the mechanism of AIE in the solid state through supramolecular metal-organic frameworks and mechanoluminescent materials for the first time. Herein, four novel differently substituted Schiff base building blocks, SB1-SB4, exhibit typical AIE properties with various fluorescence emissions from yellow to green. SB1-SB4 are linked through C-H···O hydrogen bonding interactions to construct supramolecular metal-organic frameworks (SMOFs): namely, SMOFSB1-SMOFSB4. Particularly, among these SMOFs, SMOFSB3 is observed to have micropores in the 3D supramolecular structure and exhibits mechanoluminescent properties (grinding). An emission turn-on mechanism occurs with destruction of micropores by grinding and blockage of intramolecular rotations of the methyl and acetonitrile in the micropores, resulting in emission turn-on in SMOFSB3. Single-crystal X-ray structures, powder X-ray diffraction, emission spectra at room temperature, temperature-dependent emission spectra, DFT calculations, and a charge separation hypothesis well demonstrate the emission turn-on mechanism, which is consistent with the mechanism of AIE. More importantly, the molecules demonstrated potential application for press-jet printing.

A Space-Time Network-Based Modeling Framework for Dynamic Unmanned Aerial Vehicle Routing in Traffic Incident Monitoring Applications.

It is essential for transportation management centers to equip and manage a network of fixed and mobile sensors in order to quickly detect traffic incidents and further monitor the related impact areas, especially for high-impact accidents with dramatic traffic congestion propagation. As emerging small Unmanned Aerial Vehicles (UAVs) start to have a more flexible regulation environment, it is critically important to fully explore the potential for of using UAVs for monitoring recurring and non-recurring traffic conditions and special events on transportation networks. This paper presents a space-time network- based modeling framework for integrated fixed and mobile sensor networks, in order to provide a rapid and systematic road traffic monitoring mechanism. By constructing a discretized space-time network to characterize not only the speed for UAVs but also the time-sensitive impact areas of traffic congestion, we formulate the problem as a linear integer programming model to minimize the detection delay cost and operational cost, subject to feasible flying route constraints. A Lagrangian relaxation solution framework is developed to decompose the original complex problem into a series of computationally efficient time-dependent and least cost path finding sub-problems. Several examples are used to demonstrate the results of proposed models in UAVs' route planning for small and medium-scale networks.

[Current situation of prevention and treatment of silicosis in Jinshan District of Shanghai, China].

OBJECTIVE: To study the current situation of the prevention and treatment of silicosis in Jinshan District of Shanghai, China, and to provide a scientific basis for the introduction of preventive and control measures for the disease. METHODS: An occupational hygienic investigation was carried out among enterprises exposed to silica dust hazard in Jinshan District using cross-sectional epidemiological study. Based on GBZ 159-2004 Specifications of air sampling for hazardous substances monitoring in the workplace and GBZ/T 192.1-2007 Method for determination of dust in the air of workplace Part 1: Total dust concentration, individual sampling and evaluation of test results were conducted among workers exposed to silica dust. RESULTS: A total of 302 workers in 30 enterprises were exposed to silica dust, and the coverage of employment injury insurance and occupational health inspection rate were 98.3% and 92.4%, respectively. The equipment rate of anti-dust respirators of the enterprises was 56.7%, and the qualification rate of silica dust monitoring in work place was 40.4%. The enterprises exposed to silica dust were mainly those who were operated in dry condition and engaged in manual work using opening-type equipment without negative pressure. CONCLUSION: Enterprises exposed to silica dust in Jinshan District of Shanghai have safety hazards like poor production and protective equipment, incomplete protective articles, and low qualification rate of silica dust test in workplace, so occupational health protection measures need to be strengthened.

Toward pulping process for enhancing the RS-black liquors as precursor of activated carbons for aqueous adsorbent purposes.

This work deals with providing a green pulping process of rice straw with zero waste discharged, via valorization of its by-product as a promising precursor for production of carbon nanostructures. The carbon nanostructures (BL-CNSs) from rice straw pulping liquors (BLs) are prepared in one step with phosphoric acid activation. The carbon nanostructures (BL-CNSs) from rice straw pulping liquors (BLs) are prepared in one step with phosphoric acid activation. The optimal pulping approach for achieving effective adsorbent (BL-CNSs) of cationic and anionic dyes is recommended from using different BLs precursors resulting from different reagents (alkaline, neutral, and acidic reagents). The carbon precursors are characterized by elemental, thermal (TGA and DTG) and ATR FTIR analyses. While the impact of pulping route on performance of CNSs is evaluated by their adsorption of iodine, cationic dye and anionic dye, as well as ATR-FTIR, textural characterization, and SEM. The data of elemental analysis displayed a high Carbon content ranges from 57.85 to 66.69% suitable for CNSs preparation, while the TGA showed that Sulphur-containing BLs (Kraft, neutral sulfite and acidic sulfite) have higher degradation temperature and activation energies as compared with other BLs. The optimum BL-CNSs adsorbent is prepared from the disposed neutral sulfite black liquor, with the following characteristics: cationic dye adsorption capacity 163.9 mg/g, iodine value 336.9 mg/g and SBET 310.6 m2/g. While the Kraft-CNSs provided highest anionic adsorption (70.52 mg/g). The studies of equilibrium and kinetic adsorption of dyes showed that the adsorption equilibrium of all investigated BL-CNSs toward MB follow the Langmuir and mainly Freundlich models for BB adoption. Their adsorption kinetics are a good fit with the pseudo-second-order model. The textural characterization and SEM revealed the CNSs exhibit a mixture of mesoporous and microporous structure.

Co-chaperoning of chlorophyll and carotenoid biosynthesis by ORANGE family proteins in plants.

Chlorophylls and carotenoids are essential photosynthetic pigments. Plants spatiotemporally coordinate the needs of chlorophylls and carotenoids for optimal photosynthesis and fitness in response to diverse environmental and developmental cues. However, how the biosynthesis pathways of these two pigments are coordinated, particularly at posttranslational level to allow rapid control, remains largely unknown. Here, we report that the highly conserved ORANGE (OR) family proteins coordinate both pathways via posttranslationally mediating the first committed enzyme in each pathway. We demonstrate that OR family proteins physically interact with magnesium chelatase subunit I (CHLI) in chlorophyll biosynthesis pathway in addition to phytoene synthase (PSY) in carotenoid biosynthesis pathway and concurrently stabilize CHLI and PSY enzymes. We show that loss of OR genes hinders both chlorophyll and carotenoid biosynthesis, limits light-harvesting complex assembly, and impairs thylakoid grana stacking in chloroplasts. Overexpression of OR safeguards photosynthetic pigment biosynthesis and enhances thermotolerance in both Arabidopsis and tomato plants. Our findings establish a novel mechanism by which plants coordinate chlorophyll and carotenoid biosynthesis and provide a potential genetic target to generate climate-resilient crops.

The synthesis of bacterial cellulose-chitosan zwitterionic hydrogels with pH responsiveness for drug release mechanism of the naproxen.

The human digestive and absorption system has a specific pH environment, which makes it difficult to for accurate drug-release. Zwitterionic hydrogel, as a kind of drug carrier, is a feasible response strategy. In this work, a facile method was employed to prepare a series zwitterionic hydrogels composed of BC and chitosan. The composite gels could in-situ formed via Schiff's base reaction between partially oxidated bacterial cellulose and chitosan which exhibited relatively well mechanical properties. Besides, the rich amino and carboxyl groups endowed the hydrogels with excellent pH responsive performance. The minimum swelling rate of the hydrogels appeared at pH 3.5-pH 5.0. In lower or higher pH solutions, the swelling rate was greatly increased. The drug (naproxen) loading of the hydrogels was above 110 mg/g. The release amount of naproxen in the simulated gastric juice was less than intestinal fluid with the sustained release time exceeded 24 h. Through kinetic simulation analysis, the drug release behavior is in accordance with zero-order release model. Such kind of composite hydrogel is suggested to be a potential drug carrier for clinical therapy.

Plant carotenoids: recent advances and future perspectives.

Carotenoids are isoprenoid metabolites synthesized de novo in all photosynthetic organisms. Carotenoids are essential for plants with diverse functions in photosynthesis, photoprotection, pigmentation, phytohormone synthesis, and signaling. They are also critically important for humans as precursors of vitamin A synthesis and as dietary antioxidants. The vital roles of carotenoids to plants and humans have prompted significant progress toward our understanding of carotenoid metabolism and regulation. New regulators and novel roles of carotenoid metabolites are continuously revealed. This review focuses on current status of carotenoid metabolism and highlights recent advances in comprehension of the intrinsic and multi-dimensional regulation of carotenoid accumulation. We also discuss the functional evolution of carotenoids, the agricultural and horticultural application, and some key areas for future research.

Protein-protein interaction techniques to investigate post-translational regulation of carotenogenesis.

Carotenoids are indispensable to plants. The regulatory mechanisms underlying carotenoid metabolism have been subjected to intensive investigation. Post-translational regulation is critically important to rapidly modulate enzyme protein level and activity in fine-tuning carotenoid production in living organisms. However, the regulatory controls at the post-translational level are poorly understood. This chapter highlights the recent advances in this area of research and presents the protein-protein interaction protocols to study the post-translational regulation of carotenogenesis.

Green tea polyphenols bind to soy proteins and decrease the activity of soybean trypsin inhibitors (STIs) in heated soymilk.

The interaction between epigallocatechin gallate (EGCG) and soy proteins at room temperature (25 °C) and after heating at 100 and 121 °C, and their effects on the inactivation of soybean trypsin inhibitors (STIs) in soymilk were investigated. The results of the nitroblue tetrazolium (NBT) staining assay showed that soy proteins can covalently bind to EGCG. The α/α' and A subunits in heated soymilk preferred to bind to EGCG because of their soluble state. More thiols were trapped when EGCG was added before thermal processing, and the free amino groups were depleted more with EGCG addition after heating. Circular dichroism and fluorescence spectroscopy showed that EGCG addition before or after heating induced different secondary and tertiary structural changes for soy proteins. The exposed aromatic amino acids preferred to react with EGCG before protein aggregation in the heating process. The random coil of soymilk proteins increased more when EGCG was added in soymilk after heating, resulting in more disordered structures in protein conformation. The binding between EGCG and soy proteins promoted protein aggregation, which was confirmed by the particle size distribution and gel electrophoresis. The trypsin and chymotrypsin inhibitory activity (TIA and CIA) in soymilk significantly reduced to 693 U mL-1 and 613 U mL-1, respectively, under the conditions of 2 mM EGCG addition after 100 °C heating for 10 min (p < 0.05). Consequently, the influence of EGCG on STI inactivation in soymilk only worked when EGCG was added after heating.

Phytoene Synthase: The Key Rate-Limiting Enzyme of Carotenoid Biosynthesis in Plants.

Phytoene synthase (PSY) catalyzes the first committed step in the carotenoid biosynthesis pathway and is a major rate-limiting enzyme of carotenogenesis. PSY is highly regulated by various regulators and factors to modulate carotenoid biosynthesis in response to diverse developmental and environmental cues. Because of its critical role in controlling the total amount of synthesized carotenoids, PSY has been extensively investigated and engineered in plant species. However, much remains to be learned on its multifaceted regulatory control and its catalytic efficiency for carotenoid enrichment in crops. Here, we present current knowledge on the basic biology, the functional evolution, the dynamic regulation, and the metabolic engineering of PSY. We also discuss the open questions and gaps to stimulate additional research on this most studied gene/enzyme in the carotenogenic pathway.

Structure characterization of soybean peptides and their protective activity against intestinal inflammation.

Soybean peptides serve as functional foods with impressive health benefits. The structure characteristics of peptides are highly related to the health benefits. The structure-activity relationship and mechanism underlined are important scientific questions in this field. To answer these questions, soybean peptides were produced by combinatory enzymatic hydrolysis in this work. Fifty-two peptide sequences were identified by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The anti-inflammatory activities of these peptides were investigated by using a lipopolysaccharide (LPS)-induced inflammation cell model. Soybean peptides could significantly promote cell proliferation. Additionally, soybean peptides could alleviate LPS-induced inflammation by reducing the production and expression of nitric oxide (NO), tumor necrosis factor alpha (TNF-α), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6). Moreover, soybean peptides could promote the mRNA expression of proteins related to inflammation inhibition (IL-10) and tight junction modulation. The structure-activity relationship was addressed. The results documented the potential of soybean peptides as functional foods.