Molecular Editing of Ketones through N-Heterocyclic Carbene and Photo Dual Catalysis.

The molecular editing of ketones represents an appealing strategy due to its ability to maximize the structural diversity of ketone compounds in a straightforward manner. However, developing efficient methods for the arbitrary modification of ketonic molecules, particularly those integrated within complex skeletons, remains a significant challenge. Herein, we present a unique strategy for ketone recasting that involves radical acylation of pre-functionalized ketones facilitated by N-heterocyclic carbene and photo dual catalysis. This protocol features excellent substrate tolerance and can be applied to the convergent synthesis and late-stage functionalization of structurally complex bioactive ketones. Mechanistic investigations, including experimental studies and density functional theory (DFT) calculations, shed light on the reaction mechanism and elucidate the basis of the regioselectivity.

Cooperation of selenium, iron and phosphorus for simultaneously minimizing cadmium and arsenic concentrations in rice grains.

Cadmium (Cd) and arsenic (As), two toxic elements to humans, are ubiquitously coexisting contaminant found in paddy fields. The accumulation of Cd and As in rice, a major food source for many people around the world, can pose a serious threat to food safety and human health. Therefore, it is crucial to be aware of these contaminants and take adequate measures to reduce the accumulation of these two elements in rice. Developing an effective method to simultaneously reduce the accumulation of Cd) and As in rice is challenging. In this study, a pot experiment was conducted to investigate the synergistic effects of selenium (Se), iron (Fe) and phosphorus (P) on the uptake, transport and accumulation of cadmium and arsenic in rice by analyzing the physical and chemical properties of the soil, the elemental concentrations and their interrelationships in the rice tissues, and the composition and morphology of the iron plaque (IP). The results showed that the combined treatments of Se, Fe and P had positive effects on reducing Cd and As accumulation in rice, reducing Cd concentrations in brown rice by 3.86-51.88 % and As concentrations by 25.37-40.81 %. The possible mechanisms for the reduction of As and Cd concentrations in rice grains were: (i) Combined application of Fe, P and Se can effectively reduce the soil available Cd and As concentration. (ii) Combined application significantly improved the formation of IP at the tillering stage and increased the crystalline iron oxides in IP, promoting the deposition of SiO2 in rice roots, thereby effectively inhibiting the uptake of Cd and As by rice roots. (iii) Interplay and interaction between elements facilitated by transporter proteins could contribute to the synergistic mitigation of Cd and As by Se, Fe and P. This study provides a valuable new approach for effective control of Cd and As concentration of rice grown in co-contaminated soil.

Molecular response to the influences of Cu(II) and Fe(III) on forming biogenic manganese oxides by Pseudomonas putida MnB1.

The biogeochemical cycle of biogenic manganese oxides (BioMnOx) is closely associated with the environmental behavior and fate of various pollutants. It is significantly interfered by many metals, such as Cu and Fe. However, the bacterial molecular responses are not clear. Here, the effects of Cu(II) and Fe(III) on oxidation of manganese by Pseudomonas putida MnB1 and the bacterial molecular response mechanisms have been studied. The bacterial oxidation of manganese were promoted by both Fe(III) and Cu(II) and the final manganese oxidation rate of the Cu(II) group exceeded 16 % that of the Fe(III) group. The results of transcriptome indicated that Cu(II) promoted manganese oxidation by up-regulating the expression levels of multicopper oxidase (MCO) and peroxidase(POD), and by stimulating electron transfer, while Fe(III) promoted this process by accelerating the electron transfer and nitrogen cycling, and activating POD. The protein-protein interaction (PPI) network indicated that the MCO genes (mnxG and mcoA) were directly linked to the copper homeostasis proteins (cusA, cusB, czcC and cusF). Cytochrome c was closely related to the genes related to nitrogen cycling (glnA, glnL, and putA) and electrons transfer (cycO, cycD, nuoA, nuoK, and nuoL), which also promoted manganese oxidation. This study provides a molecular level insight into the oxidation of Mn(II) by Pseudomonas putida MnB1 with Cu(II) and/or Fe(III) ions.

Simultaneously inhibit cadmium and arsenic uptake in rice (Oryza sativa L.) by Selenium enhanced iron plaque: Performance and mechanism.

Selenium (Se) fortification is witnessed to simultaneously inhibit absorbing Cadmium (Cd) and Arsenic (As) by rice plants, but the mechanism is unclear. Here, the effects of Se on the root morphology, iron plaque (IP) content, soil Fe2+ content, radial oxygen loss (ROL), and enzyme activities of the rice plants in the soil contaminated by Cd and As were intensively investigated through the hydroponic and soil experiments. Se effectively alleviated the toxic effects of Cd and As on the plants and the dry weight, root length, and root width were increased by 203.18%, 33.41%, and 52.81%, respectively. It also elucidated that ROL was one of the key factors to elevate IP formation by Se and the specific pathways of Se enhancing ROL were identified. ROL of the plants in the experiment group treated by Se was increased 36.76%, and correspondingly IP was magnified 50.37%, compared to the groups with Cd and As. It was owing to Se significantly increased the root porosity (62.11%), facilitating O2 transport to the roots. Additionally, Se enhanced the activities of catalase (CAT) and superoxide dismutase (SOD) to promote the catalytic degradation of ROS induced by Cd and As stress. It indirectly increased O2 release in the rhizosphere, which benefit to form more robust IP serve as stronger barrier to Cd and As. The results of our study provide a novel molecular level insight for Se promoting root IP to block Cd and As uptake by the rice plants.

N-Heterocyclic carbene catalytic 1,2-boron migrative acylation accelerated by photocatalysis.

The transformation of organoboron compounds plays an important role in synthetic chemistry, and recent advancements in boron-migration reactions have garnered considerable attention. Here, we report an unprecedented 1,2-boron migrative acylation upon photocatalysis-facilitated N-heterocyclic carbene catalysis. The design of a redox-active boronic ester substrate, serving as an excellent ß-boron radical precursor, is the linchpin to the success of this chemistry. With the established protocol, a wide spectrum of ß-boryl ketones has been rapidly synthesized, which could further undergo various C─B bond transformations to give multifunctionalized products. The robustness of this catalytic strategy is underscored by its successful application in late-stage modification of drug-derived molecules and natural products. Preliminary mechanistic investigations, including several control experiments, photochemistry measurements, and computational studies, shed light on the catalytic radical reaction mechanism.

PICKLE and HISTONE DEACETYLASE6 coordinately regulate genes and transposable elements in Arabidopsis.

Chromatin dynamics play essential roles in transcriptional regulation. The chromodomain helicase DNA-binding domain 3 (CHD3) chromatin remodeler PICKLE (PKL) and HISTONE DEACETYLASE6 (HDA6) are required for transcriptional gene silencing, but their coordinated function in gene repression requires further study. Through a genetic suppressor screen, we found that a point mutation at PKL could partially restore the developmental defects of a weak Polycomb repressive complex 1 (PRC1) mutant (ring1a-2 ring1b-3), in which RING1A expression is suppressed by a T-DNA insertion at the promoter. Compared to ring1a-2 ring1b-3, the expression of RING1A is increased, nucleosome occupancy is reduced, and the histone 3 lysine 9 acetylation (H3K9ac) level is increased at the RING1A locus in the pkl ring1a-2 ring1b-3 triple mutant. HDA6 interacts with PKL and represses RING1A expression similarly to PKL genetically and molecularly in the ring1a-2 ring1b-3 background. Furthermore, we show that PKL and HDA6 suppress the expression of a set of genes and transposable elements (TEs) by increasing nucleosome density and reducing H3K9ac. Genome-wide analysis indicated they possibly coordinately maintain DNA methylation as well. Our findings suggest that PKL and HDA6 function together to reduce H3K9ac and increase nucleosome occupancy, thereby facilitating gene/TE regulation in Arabidopsis (Arabidopsis thaliana).

Development and application of machine learning models for prediction of soil available cadmium based on soil properties and climate features.

Identifying the key influencing factors in soil available cadmium (Cd) is crucial for preventing the Cd accumulation in the food chain. However, current experimental methods and traditional prediction models for assessing available Cd are time-consuming and ineffective. In this study, machine learning (ML) models were developed to investigate the intricate interactions among soil properties, climate features, and available Cd, aiming to identify the key influencing factors. The optimal model was obtained through a combination of stratified sampling, Bayesian optimization, and 10-fold cross-validation. It was further explained through the utilization of permutation feature importance, 2D partial dependence plot, and 3D interaction plot. The findings revealed that pH, surface pressure, sensible heat net flux and organic matter content significantly influenced the Cd accumulation in the soil. By utilizing historical soil surveys and climate change data from China, this study predicted the spatial distribution trend of available Cd in the Chinese region, highlighting the primary areas with heightened Cd activity. These areas were primarily located in the eastern, southern, central, and northeastern China. This study introduces a novel methodology for comprehending the process of available Cd accumulation in soil. Furthermore, it provides recommendations and directions for the remediation and control of soil Cd pollution.

The Histone Variant H3.3 Is Required for Plant Growth and Fertility in Arabidopsis.

Histones are the core components of the eukaryote chromosome, and have been implicated in transcriptional gene regulation. There are three major isoforms of histone H3 in Arabidopsis. Studies have shown that the H3.3 variant is pivotal in modulating nucleosome structure and gene transcription. However, the function of H3.3 during development remains to be further investigated in plants. In this study, we disrupted all three H3.3 genes in Arabidopsis. Two triple mutants, h3.3cr-4 and h3.3cr-5, were created by the CRISPR/Cas9 system. The mutant plants displayed smaller rosettes and decreased fertility. The stunted growth of h3.3cr-4 may result from reduced expression of cell cycle regulators. The shorter stamen filaments, but not the fertile ability of the gametophytes, resulted in reduced fertility of h3.3cr-4. The transcriptome analysis suggested that the reduced filament elongation of h3.3cr-4 was probably caused by the ectopic expression of several JASMONATE-ZIM DOMAIN (JAZ) genes, which are the key repressors of the signaling pathway of the phytohormone jasmonic acid (JA). These observations suggest that the histone variant H3.3 promotes plant growth, including rosette growth and filament elongation.

A review on the transformation of birnessite in the environment: Implication for the stabilization of heavy metals.

Birnessite is ubiquitous in the natural environment where heavy metals are retained and easily transformed. The surface properties and structure of birnessite change with the changes in external environmental conditions, which also affects the fate of heavy metals. Clarifying the effect and mechanism of the birnessite phase transition process on heavy metals is the key to taking effective measures to prevent and control heavy metal pollution. Therefore, the four transformation pathways of birnessite are summarized first in this review. Second, the relationship between transformation pathways and environmental conditions is proposed. These relevant environmental conditions include abiotic (e.g., co-existing ions, pH, oxygen pressure, temperature, electric field, light, aging, pressure) and biotic factors (e.g., microorganisms, biomolecules). The phase transformation is achieved by the key intermediate of Mn(III) through interlayer-condensation, folding, neutralization-disproportionation, and dissolution-recrystallization mechanisms. The AOS (average oxidation state) of Mn and interlayer spacing are closely correlated with the phase transformation of birnessite. Last but not least, the mechanisms of heavy metals immobilization in the transformation process of birnessite are summed up. They involve isomorphous substitution, redox, complexation, hydration/dehydration, etc. The transformation of birnessite and its implication on heavy metals will be helpful for understanding and predicting the behavior of heavy metals and the crucial phase of manganese oxides/hydroxides in natural and engineered environments.

"Structure-function" analysis using starches isolated from Lycoris chinensis bulbs of different developmental stages.

In this study, Lycoris chinensis bulbs of four developmental stages were compared for starch characteristics. Based on correlation analysis and hierarchical cluster analysis, the relationships among 36 traits were discussed. Compared to commonly consumed starches, L. chinensis starch had higher amylose content (33.4-43.2 %) and weight-average molar mass (36410-82,781 kDa), lower gelatinization temperature (61.8-68.1 °C), gel hardness (19.0-39.5 g) and viscosities. Among developmental stages, starches varied significantly in characteristics. As compared to juvenile stage (S1), mature bulbs (S4) had higher amylose content, lower gelatinization temperature, weight-average molar mass and degree of polymorphism. Correlation analysis revealed that the molecular weight-related traits had significantly positive correlations to gelatinization temperature (Tp, p < 0.05), positive but weak correlations to traits of particle size distribution, significantly negative correlations to AAC and many parameters of viscosity properties (p < 0.05). Based on the results of correlation analysis and hierarchical cluster analysis, the 36 traits of starch characteristics were proposed to be divided into three groups: particle size-related traits, molecular weight-related traits and AAC-related traits. The information presented in the current study are useful for future studies on starches of Lycoris and other bulb species, and instructive for future studies in investigating the "Structure-Function" relationship in starch.

Influence of Educational Background on Untreated Dental Caries and Gingival Bleeding.

Objective: This study aims to investigate the impact of educational background on the occurrence of untreated dental caries and gingival bleeding, shedding light on the potential implications for public health policy and dental care. Methods: The study was conducted among 160 80 Shenggong Technology Company employees. An online questionnaire survey was administered to collect relevant data, focusing on the participants' educational backgrounds, income levels, and oral hygiene practices. Educational achievements were categorized into two groups: MSDB: middle school degree or below, and CDA: college degree or above. A team of three experienced dentists conducted comprehensive oral health assessments, evaluating untreated dental caries and the presence of gingival bleeding. Dental caries results were categorized as follows: less than 2 untreated dental caries, 2-4 untreated dental caries, or more than 4 untreated dental caries. Gingival bleeding results were classified as 0, slight, or severe. Statistical analysis was performed using SPSS software (IBM, Armonk, NY, USA), employing Fisher's exact test to compare untreated dental caries and gingival bleeding prevalence between the two educational background groups. Significance was determined at P < .05. Results: The analysis included 40 participants with an MSDB and 40 with a CDA. The findings revealed no significant differences in age or gender distribution between these groups. However, participants with an MSDB exhibited a significantly higher incidence of untreated dental caries (P = .0008) and were more likely to experience gingival bleeding (P = .0397) compared to their counterparts with a college degree or above. Conclusions: This study underscores that individuals with an educational background of a middle school degree or below are more prone to both untreated dental caries and gingival bleeding compared to those with a higher educational background.

Base-Promoted Formal (3 + 2) Cycloaddition of α-Halohydroxamates with Electron-Deficient Alkenyl-iminoindolines To Synthesize Spiro-indolinepyrrolidinones.

Construction of pyrrolidinyl-spiroindoles with easily available starting materials has attracted considerable attention from the synthesis community and is in great demand. Here, we describe a base-promoted formal (3 + 2) cycloaddition of α-halohydroxamates with alkenyl-iminoindolines. The present methodology features mild reaction conditions and a broad substrate scope with up to 99% yield and excellent diastereoselectivity. The versatility of this approach is demonstrated through valuable synthetic transformations. Preliminary mechanistic studies shed light on the mechanism of this cycloaddition process.

A novel slow-release selenium approach for cadmium reduction and selenium enrichment in rice (Oryza sativa L.).

In this study, a novel slightly-soluble selenium (Se) fertilizer (SSF) was successfully applied to address the problems of Cd pollution in paddy soil and rice, and Se deficiency in human beings. The pot and field experiments showed that Cd content in the rice grains was reduced by 48.4%-82.89% and Se content was increased nearly by 30-fold comparing the control group. The application of SSF increased the soil pH and significantly reduced the DGT-extracted Cd in the soil. Moreover, DCB-extractable Fe content on the surface of roots was prompt by SSF, which formed a physical barrier, namely iron plaque (IP), to inhibit Cd translocation to the above-ground tissues of the rice plants. The Cd content in the IP was also decreased before the filling period, possibly contributing to the reduction in major Cd accumulation in the rice grains. In addition, the continuous Se increase and Cd reduction in the IP by the SSF gradually exceeded that of water-soluble Se during the three periods of rice plant growth. This suggests that SSF has high potential to be an effective Se fertilizer for inhibiting Cd uptake and enriching Se in rice.

Direct Acylation of Unactivated Alkyl Halides with Aldehydes through N-Heterocyclic Carbene Organocatalysis.

Catalytic acylation of organohalides with aldehydes is an ideal strategy for the direct synthesis of ketones. However, the utilization of unactivated alkyl halides in such a transformation remains a formidable challenge. In this study, we developed a cross-coupling reaction of aldehydes with unactivated alkyl halides through N-heterocyclic carbene catalysis. With this protocol, various ketones could be rapidly synthesized from readily available starting materials under mild conditions. This organocatalytic system was successfully applied in the late-stage functionalization of pharmaceutical derivatives. Mechanistic investigations suggest a closed-shell nucleophilic substitution mechanism for this reaction.

Aflatoxin B1 in poultry liver: Toxic mechanism.

Aflatoxin B1 (AFB1) is the most common carcinogenic toxin in livestock and poultry feed, seriously endangering poultry production and public health. Liver is the most important organ for the metabolism of exogenous and endogenous substances in the body. AFB1 produces toxicity under the biotransformation of cytochrome P450 microparticle oxidase (CYP450). Hepatocytes are the most important cells for synthesizing CYP450 enzymes, so that AFB1 has the most significant effect on the liver. AFB1 can induce liver cell damage in poultry through a variety of molecular mechanisms, and the main of damage mechanisms have been discovered so far include oxidative damage, promoting apoptosis, influencing hepatocyte gene expression, interfering with hepatocyte autophagy, pyroptosis and necroptosis. This article reviewed the molecular mechanism of AFB1 inducing liver injury in poultry, hopefully, to provid a new direction and theoretical basis for the development of a new AFB1 detoxification method.

Capture gaseous arsenic in flue gas by amorphous iron manganese oxides with high SO2 resistance.

In non-ferrous metal smelting, the problem of gaseous arsenic in high-sulfur flue gas is difficult to solve. Now we have developed oxygen-enriched amorphous iron manganese oxide (AFMBO) based on the unique superiority of iron-manganese oxide for arsenic capture to realize the effective control of gaseous arsenic in the non-ferrous smelting flue gas. The experimental results show that the arsenic adsorption capacity of AFMBO is up to 102.7 mg/g, which has surpassed most of the current adsorbents. In particular, AFMBO can effectively capture gaseous arsenic even at 12% v/v SO2 concentrations (88.45 mg/g). Moreover, the spent AFMBO possesses pronounced magnetic characteristics that make it easier to separate from dust, which is conducive to reducing the secondary environmental risk of arsenic. In terms of mechanism study, various characterization methods are used to explain the important role of lattice oxygen and adsorbed oxygen in the capture process of gaseous arsenic. Moreover, the reason for the efficient arsenic removal performance of AFMBO is also reasonably explained at the microscopic level. This study provides ideas and implications for gaseous arsenic pollution control research.

SWATH-MS-Based Proteomics Reveals the Regulatory Metabolism of Amaryllidaceae Alkaloids in Three Lycoris Species.

Alkaloids are a class of nitrogen-containing alkaline organic compounds found in nature, with significant biological activity, and are also important active ingredients in Chinese herbal medicine. Amaryllidaceae plants are rich in alkaloids, among which galanthamine, lycorine, and lycoramine are representative. Since the difficulty and high cost of synthesizing alkaloids have been the major obstacles in industrial production, particularly the molecular mechanism underlying alkaloid biosynthesis is largely unknown. Here, we determined the alkaloid content in Lycoris longituba, Lycoris incarnata, and Lycoris sprengeri, and performed a SWATH-MS (sequential window acquisition of all theoretical mass spectra)-based quantitative approach to detect proteome changes in the three Lycoris. A total of 2193 proteins were quantified, of which 720 proteins showed a difference in abundance between Ll and Ls, and 463 proteins showed a difference in abundance between Li and Ls. KEGG enrichment analysis revealed that differentially expressed proteins are distributed in specific biological processes including amino acid metabolism, starch, and sucrose metabolism, implicating a supportive role for Amaryllidaceae alkaloids metabolism in Lycoris. Furthermore, several key genes collectively known as OMT and NMT were identified, which are probably responsible for galanthamine biosynthesis. Interestingly, RNA processing-related proteins were also abundantly detected in alkaloid-rich Ll, suggesting that posttranscriptional regulation such as alternative splicing may contribute to the biosynthesis of Amaryllidaceae alkaloids. Taken together, our SWATH-MS-based proteomic investigation may reveal the differences in alkaloid contents at the protein levels, providing a comprehensive proteome reference for the regulatory metabolism of Amaryllidaceae alkaloids.

Cooperative effect of slow-release ferrous and phosphate for simultaneous stabilization of As, Cd and Pb in soil.

The different chemical behavior of anionic As and cationic Cd and Pb makes the simultaneous stabilization of soils contaminated with arsenic (As), cadmium (Cd), and lead (Pb) challenging. The use of soluble, insoluble phosphate materials and iron compounds cannot simultaneously stabilize As, Cd, and Pb in soil effectively due to the easy re-activation of heavy metals and poor migration. Herein, we propose a new strategy of "cooperatively stabilizing Cd, Pb, and As with slow-release ferrous and phosphate". To very this theory, we developed ferrous and phosphate slow-release materials to simultaneously stabilize As, Cd, and Pb in soil. The stabilization efficiency of water-soluble As, Cd and Pb reached 99% within 7d, and the stabilization efficiencies of NaHCO3-extractable As, DTPA-extractable Cd and Pb reached 92.60%, 57.79% and 62.81%, respectively. The chemical speciation analysis revealed that soil As, Cd and Pb were transformed into more stable states with the reaction time. The proportion of residual fraction of As, Cd, and Pb increased from 58.01% to 93.82%, 25.69 to 47.86%, 5.58 to 48.54% after 56 d, respectively. Using ferrihydrite as a representative soil component, the beneficial interactions of phosphate and slow-release ferrous material in stabilizing Pb, Cd, and As were demonstrated. The slow-release ferrous and phosphate material reacted with As and Cd/Pb to form stable ferrous arsenic and Cd/Pb phosphate. Furthermore, the slow-release phosphate converted the adsorbed As into dissolved As, then the dissolved As reacted with released ferrous to form a more stable form. Concurrently, As, Cd and Pb were structurally incorporated into the crystalline iron oxides during the ferrous ions-catalyzed transformation of amorphous iron (hydrogen) oxides. The results demonstrates that the use of slow-release ferrous and phosphate materials can aid in the simultaneous stabilization of As, Cd, and Pb in soil.

Systematic control technologies for gaseous pollutants from non-ferrous metallurgy.

Air pollutant emissions represent a critical challenge in the green development of the non-ferrous metallurgy industry. This work studied the emission characteristics, formation mechanisms, phase transformation and separation of typical air pollutants, such as heavy metal particles, mercury, sulfur oxides and fluoride, during non-ferrous smelting. A series of purification technologies, including optimization of the furnace throat and high-temperature discharge, were developed to collaboratively control and recover fine particles from the flue gas of heavy metal smelting processes, including copper, lead and zinc. Significant improvements have been realized in wet scrubbing technology for removing mercury, fluoride and SO2 from flue gas. Gas-liquid sulfidation technology by applying H2S was invented to recycle the acid scrubbing wastewater more efficiently and in an eco-friendly manner. Based on digital technology, a source reduction method was designed for sulfur and fluoride control during the whole aluminum electrolysis process. New desulfurization technologies were developed for catalytic reduction of the sulfur content in petroleum coke at low temperature and catalytic reduction of SO2 to elemental sulfur. This work has established the technology for coupling multi-pollutant control and resource recovery from the flue gas from non-ferrous metallurgy, which provides the scientific theoretical basis and application technology for the treatment of air pollutants in the non-ferrous metallurgy industry.

The determinants of effective defluorination by the LiAl-LDHs.

Millions of people in poor areas are still under the threat of fluoride contamination. How to effectively separate fluorine in water is an important step to reduce the ecological risk. In this paper, we performed a systematic DFT calculation focused on the defluorination behavior between the LiAl- and MgAl-LDHs. The results indicated that the LiAl-LDHs exhibited high chemical activity before the defluorination, because of the better electronic structure. After the defluorination, the LiAl-LDHs with adsorbed-F- were also more stable than the MgAl-LDHs. In addition, the existence of coordination covalent bond for the adsorbed-F- attached to the LiAl-LDHs was confirmed. This is an important reason for the high defluorination efficiency by the LiAl-LDHs. In addition, a series of weak interaction, including hydrogen bond and van der Waals interaction were also observed. Finally, a LiAl-LDHs with excellent fluoride removal properties were synthesized well by simple hydrothermal method. The results showed that our synthesized LiAl-LDHs with the capacity of 156.09 mg/g, could be effectively defluorinated in water. Notably, it surpasses most materials and has potential applications.