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Summary: Starch accounts for up to 90% of the dry weight of rice endosperm and is a key determinant of grain quality. Although starch biosynthesis enzymes have been comprehensively studied, transcriptional regulation of starch‐synthesis enzyme‐coding genes (SECGs) is largely unknown. In this study, we explored the role of a NAC transcription factor, OsNAC24, in regulating starch biosynthesis in rice. OsNAC24 is highly expressed in developing endosperm. The endosperm of osnac24 mutants is normal in appearance as is starch granule morphology, while total starch content, amylose content, chain length distribution of amylopectin and the physicochemical properties of the starch are changed. In addition, the expression of several SECGs was altered in osnac24 mutant plants. OsNAC24 is a transcriptional activator that targets the promoters of six SECGs; OsGBSSI, OsSBEI, OsAGPS2, OsSSI, OsSSIIIa and OsSSIVb. Since both the mRNA and protein abundances of OsGBSSI and OsSBEI were decreased in the mutants, OsNAC24 functions to regulate starch synthesis mainly through OsGBSSI and OsSBEI. Furthermore, OsNAC24 binds to the newly identified motifs TTGACAA, AGAAGA and ACAAGA as well as the core NAC‐binding motif CACG. Another NAC family member, OsNAP, interacts with OsNAC24 and coactivates target gene expression. Loss‐of‐function of OsNAP led to altered expression in all tested SECGs and reduced the starch content. These results demonstrate that the OsNAC24‐OsNAP complex plays key roles in fine‐tuning starch synthesis in rice endosperm and further suggest that manipulating the OsNAC24‐OsNAP complex regulatory network could be a potential strategy for breeding rice cultivars with improved cooking and eating quality. [ABSTRACT FROM AUTHOR]

High‐valent iron‐oxo species are appealing for conducting O−O bond formation for water oxidation reactions. However, their high reactivity poses a great challenge to the dissection of their chemical transformations. Herein, we introduce an electron‐rich and oxidation‐resistant ligand, 2‐[(2,2′‐bipyridin)‐6‐yl]propan‐2‐ol to stabilize such fleeting intermediates. Advanced spectroscopies and electrochemical studies demonstrate a high‐valent FeV(O) species formation in water. Combining kinetic and oxygen isotope labelling experiments and organic reactions indicates that the FeV(O) species is responsible for O−O bond formation via water nucleophilic attack under the real catalytic water oxidation conditions. [ABSTRACT FROM AUTHOR]

Raising the configurational entropy in a solid solution ceramic is regarded as a promising strategy to improve the mechanical properties of ceramics, especially when five or more elements are mixed to form so‐called high‐entropy ceramics. However, in this study, we report that the binary (TiZr)C solid solution ceramics can demonstrate high hardness comparable or even superior to high‐entropy ceramics. Followed by a carbothermal reduction synthesis of carbide powders, the bulk ceramics were synthesized by hot pressing. Via increasing the hot pressing temperature to 2200°C, a full solid solution of equimolar (TiZr)C was obtained in contrast to phase separation at lower sintering temperatures, for example, 2000 and 2100°C. The dislocation networks are observed in the single‐phase (TiZr)C ceramic and should be the product of competition between enthalpy and entropy in a binary full solid solution. These defects finally contribute to the high nano‐hardness of 41.9 ± 1.4 GPa (H) and the Vickers hardness of 22.0 ± 0.6 GPa (HV at 49 N). [ABSTRACT FROM AUTHOR]

We report for the first time the synthesis of a core‐shell structured composite powder with a core of Zr(Ti,Ta)C and a shell of Ti,Ta(Zr)C at 1700°C and investigate the formation mechanism for the core‐shell structure. The medium‐entropy (Ti,Zr,Ta)C ceramics with fine grains (1.1 ± 0.4 μm) and relative density of 94.8% was prepared by hot‐pressing at 2100°C. The flexural strength of (Ti,Zr,Ta)C at 1000°C (493 ± 21 MPa) was close to the room temperature (511 ± 52 MPa). As the temperature increased from 1600°C to 1800°C, the flexural strength was increased significantly, with an ultra‐high flexural strength of 725 ± 32 MPa at 1800°C. The existence of the core‐shell structure in the powder suppressed the grain growth due to the sluggish diffusion effect. The ultra‐high strength of (Ti,Zr,Ta)C ceramics was attributed to its fine microstructures, high fracture toughness, and the reinforced the grain boundary strength. [ABSTRACT FROM AUTHOR]

This review summarizes the very recent advances in organocatalytic asymmetric cycloaddition reactions involving ortho‐quinone methides (o‐QMs), a family of versatile species that have proven useful in a broad range of reactions to afford diverse chiral molecules. In the past years, different kinds of organocatalysts have been developed into a privileged class of catalytic systems in asymmetric synthesis. A number of remarkable achievements have been made by many groups around the world. Due to length limitation, this review only summarizes those works published from January 2016 to December 2020. Meanwhile, catalytic systems which combine metal catalysts and organocatalysts will not be discussed in this review. [ABSTRACT FROM AUTHOR]

Medium‐entropy (Ti,Zr,Hf)C ceramics were prepared by hot pressing a dual‐phase medium‐entropy carbide powder with low oxygen content (0.45 wt%). The results demonstrate that the medium‐entropy (Ti,Zr,Hf)C ceramics sintered at 2100°C had a relative density of 99.2% and an average grain size of 1.9 ± 0.6 μm. The flexural strength of (Ti,Zr,Hf)C carbide ceramics at room temperature was 579 ± 62 MPa. With an increase in temperature to 1600°C, the flexural strength showed an increase up to 619 ± 57 MPa, and had no significant degradation even up to 1800°C. The high‐temperature flexural strengths of (Ti,Zr,Hf)C were obviously higher than those of the monocarbide ceramics (TiC, ZrC, and HfC). The primary strengthening mechanism in (Ti,Zr,Hf)C could be attributed to the high lattice parameter mismatch effects between TiC and ZrC, which not only inhibited the fast grain coarsening of (Ti,Zr,Hf)C ceramics, but also increased the grain‐boundary strength of the obtained ceramics. [ABSTRACT FROM AUTHOR]

Summary: Lysine is the main limiting essential amino acid (EAA) in the rice seeds, which is a major energy and nutrition source for humans and livestock. In higher plants, the rate‐limiting steps in lysine biosynthesis pathway are catalysed by two key enzymes, aspartate kinase (AK) and dihydrodipicolinate synthase (DHDPS), and both are extremely sensitive to feedback inhibition by lysine. In this study, two rice AK mutants (AK1 and AK2) and five DHDPS mutants (DHDPS1–DHDPS5), all single amino acid substitution, were constructed. Their protein sequences passed an allergic sequence‐based homology alignment. Mutant proteins were recombinantly expressed in Escherichia coli, and all were insensitive to the lysine analog S‐(2‐aminoethyl)‐l‐cysteine (AEC) at concentrations up to 12 mm. The AK and DHDPS mutants were transformed into rice, and free lysine was elevated in mature seeds of transgenic plants, especially those expressing AK2 or DHDPS1, 6.6‐fold and 21.7‐fold higher than the wild‐type (WT) rice, respectively. We then engineered 35A2D1L plants by simultaneously expressing modified AK2 and DHDPS1, and inhibiting rice LKR/SDH (lysine ketoglutaric acid reductase/saccharopine dehydropine dehydrogenase). Free lysine levels in two 35A2D1L transgenic lines were 58.5‐fold and 39.2‐fold higher than in WT and transgenic rice containing native AK and DHDPS, respectively. Total free amino acid and total protein content were also elevated in 35A2D1L transgenic rice. Additionally, agronomic performance analysis indicated that transgenic lines exhibited normal plant growth, development and seed appearance comparable to WT plants. Thus, AK and DHDPS mutants may be used to improve the nutritional quality of rice and other cereal grains. [ABSTRACT FROM AUTHOR]

We previously reported that interleukin (IL)‐6 in the red nucleus (RN) is involved in the maintenance of neuropathic pain induced by spared nerve injury (SNI), and exerts a facilitatory effect via Janus‐activated kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) and extracellular signal‐regulated kinase (ERK) signal transduction pathways. The present study aimed at investigating the roles of tumor necrosis factor‐α (TNF‐α) and IL‐1β in RN IL‐6‐mediated maintenance of neuropathic pain and related signal transduction pathways. Being similar to the elevation of RN IL‐6 three weeks after SNI, increased protein levels of both TNF‐α and IL‐1β were also observed in the contralateral RN three weeks after the nerve injury. The upregulations of TNF‐α and IL‐1β were closely correlative with IL‐6 and suppressed by intrarubral injection of a neutralizing antibody against IL‐6. Administration of either the JAK2 antagonist AG490 or the ERK antagonist PD98059 to the RN of rats with SNI remarkably increased the paw withdrawal threshold (PWT) and inhibited the up‐regulations of local TNF‐α and IL‐1β. Further experiments indicated that intrarubral injection of exogenous IL‐6 in naive rats apparently lowered the PWT of the contralateral hindpaw and boosted the local expressions of TNF‐α and IL‐1β. Pretreatment with AG490 could block IL‐6‐induced tactile hypersensitivity and suppress the up‐regulations of both TNF‐α and IL‐1β. However, injection of PD98059 in advance only inhibited the upregulation of IL‐1β, but not TNF‐α. These findings indicate that RN IL‐6 mediates the maintenance of neuropathic pain by inducing the productions of TNF‐α and IL‐1β. IL‐6 induces the expression of TNF‐α through the JAK2/STAT3 pathway, and the production of IL‐1β through the JAK2/STAT3 and ERK pathways. [ABSTRACT FROM AUTHOR]

A tandem phospha‐Michael addition/N‐acylation/intramolecular Wittig reaction of in situ formed aza‐o‐QMs is disclosed. This approach features high functional group tolerance and provides a convenient and practical access to biologically significant indole derivatives (37 examples, up to 91% yield) under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Summary: Purple carrots, the original domesticated carrots, accumulate highly glycosylated and acylated anthocyanins in root and/or petiole. Previously, a quantitative trait locus (QTL) for root‐specific anthocyanin pigmentation was genetically mapped to chromosome 3 of carrot. In this study, an R2R3‐MYB gene, namely DcMYB113, was identified within this QTL region. DcMYB113 expressed in the root of 'Purple haze', a carrot cultivar with purple root and nonpurple petiole, but not in the roots of two carrot cultivars with a purple root and petiole (Deep purple and Cosmic purple) and orange carrot 'Kurodagosun', which appeared to be caused by variation in the promoter region. The function of DcMYB113 from 'Purple haze' was verified by transformation in 'Cosmic purple' and 'Kurodagosun', resulting in anthocyanin biosynthesis. Transgenic 'Kurodagosun' carrying DcMYB113 driven by the CaMV 35S promoter had a purple root and petiole, while transgenic 'Kurodagosun' expressing DcMYB113 driven by its own promoter had a purple root and nonpurple petiole, suggesting that root‐specific expression of DcMYB113 was determined by its promoter. DcMYB113 could activate the expression of DcbHLH3 and structural genes related to anthocyanin biosynthesis. DcUCGXT1 and DcSAT1, which were confirmed to be responsible for anthocyanins glycosylation and acylation, respectively, were also activated by DcMYB113. The WGCNA identified several genes co‐expressed with anthocyanin biosynthesis and the results indicated that DcMYB113 may regulate anthocyanin transport. Our findings provide insight into the molecular mechanism underlying root‐specific anthocyanin biosynthesis and further modification in carrot and even other root crops. [ABSTRACT FROM AUTHOR]

A [4+2]‐cycloaddition of para‐quinone methides with hexahydro‐1,3,5‐triazines is reported. The reaction occurs under very mild conditions (catalyst‐, ligand‐, and base‐free), exhibits a broad substrate scope and excellent functional group tolerance, and affords a series of biologically important 1,3‐benzoxazine derivatives in good to excellent yields. Moreover, the successful late‐stage functionalization of pharmaceutically relevant compounds further renders the approach valuable. [ABSTRACT FROM AUTHOR]

A visible light‐ and heat‐promoted C‐O coupling reaction of phenols and aryl halides has been described. Compared to the traditional C‐O coupling reactions promoted by visible light, this strategy avoids the use of transition metals, photocatalysts and ligands. Moreover, the reaction has good substrate universality, suitable for substituted phenol, naphthol and heterocyclic phenol derivatives. [ABSTRACT FROM AUTHOR]

A visible‐light‐induced cascade radical cyclization of aroyl chlorides with 2‐(allyloxy)‐benzaldehyde derivatives has been developed. The method takes advantages of unactivated C=C bonds as the acyl radical acceptors and offers a mild and green approach for the synthesis of 1,4‐diketones bearing biologically important chroman‐4‐one skeletons with moderate to good yields. [ABSTRACT FROM AUTHOR]

The first example of a catalytic asymmetric formal [4+1] annulation reaction between sulfur ylides and in situ generated ortho-quinone methides (o-QMs) is reported in this work. A C2-symmetric chiral urea was identified to be the best H bonding catalyst, affording a wide range of chiral 2,3-dihydrobenzofurans in high yields and moderate enantioselectivities [70-98 % yields, up to 89:11 e.r. (enantiomeric ratio)]. [ABSTRACT FROM AUTHOR]

Photocatalysis enables the cascade reactions of indoles and CBr4 in MeOH through a C(sp2)H functionalization/methanolysis sequence. The title reaction provides an efficient access to indole 2- and 3-carboxylates in a single operation (no preinstallation of protecting as well as directing groups was required) with good yields under mild reaction conditions. [ABSTRACT FROM AUTHOR]

The gold-catalyzed synthesis of methylidene 2,3-cyclobutane-indoles is documented through a combined experimental/computational investigation. Besides optimizing the racemic synthesis of the tricyclic indole compounds, the enantioselective variant is presented to its full extent. In particular, the scope of the reaction encompasses both aryloxyallenes and allenamides as electrophilic partners providing high yields and excellent stereochemical controls in the desired cycloadducts. The computational (DFT) investigation has fully elucidated the reaction mechanism providing clear evidence for a two-step reaction. Two parallel reaction pathways explain the regioisomeric products obtained under kinetic and thermodynamic conditions. In both cases, the dearomative CC bond-forming event turned out to be the rate-determining step. [ABSTRACT FROM AUTHOR]

Aims Alterations in the expression of several long non-coding RNAs (lnc RNAs) have been found in primary nasopharyngeal carcinoma ( NPC). However, the effect of lnc RNA expression on primary NPC as well as the molecular mechanism of lnc RNA remains vague. This study was to identify differentially expressed lnc RNAs involved in NPC on a genome-wide scale and predict their potential functions. Methods and results Using high-throughput microarray with 30 586 lnc RNA and 26 109 mRNA probes, 856 lnc RNAs and 767 mRNAs were expressed differentially between NPC and chronic nasopharyngitis tissues. Bioinformatic analysis (clustering analysis, gene ontology analysis and pathway analysis) was used for further research. Differentially expressed lnc RNAs were subgrouped into three types and differentially expressed mRNAs were clustered into 28 pathways. The first coexpression network analysis revealed that 46 lnc RNAs interacting with three mRNAs involved the Janus kinase-signal transducer and activator of transcription ( JAK- STAT) signalling pathway. Quantitative real-time polymerase chain reaction ( PCR) verified 11 up- and down-regulated lnc RNAs and eight mRNAs in NPC. The second coexpression network analysis showed that 23 significantly aberrantly expressed mRNAs interacted with three validated lncRNAs. Conclusions This study could provide new insight into the molecular mechanisms of lnc RNAs and their potential role in NPC for further study. These differentially expressed lnc RNAs may act as novel biomarkers and therapeutic targets for NPC. [ABSTRACT FROM AUTHOR]

An unprecedented Zn(OTf)2-catalyzed asymmetric Michael addition/cyclization cascade of 3-nitro-2 H-chromenes with 3-isothiocyanato oxindoles has been disclosed. This transformation provides an efficient access to various synthetically important polycyclic spirooxindoles in a highly stereoselective manner under mild conditions (72-99 % yields, up to >95:5 d.r. and >99 % ee). The reaction leads to the formation of three consecutive stereocenters, including 1,3-nonadjacent tetrasubstituted carbon stereocenters, in a single operation. A bifunctional activation model of the chiral Zn(OTf)2/bis(oxazoline) complex was proposed based on control experiments, wherein the ZnII moiety serves as a Lewis acid and the N atom of the free NH group acts as a Lewis base by a hydrogen-bonding interaction. [ABSTRACT FROM AUTHOR]

Get asymmetric! Asymmetric [4+1] annulation of sulfur ylides and N‐(ortho‐chloromethyl)aryl amides allowed the formation of the desired cycloadduct with moderate to high yields and enantioselectivities (see scheme). The described strategy, taking advantage of chiral sulfur ylides, represents a direct procedure to access chiral 2‐substituted indolines. [ABSTRACT FROM AUTHOR]

A visible light-induced, aerobic oxyamidation reaction of indoles, using air as the sole oxidant, has been developed. This process serves as a photocatalytic strategy to generate efficiently tetrahydro-5 H-indolo[2,3- b]quinolinols, which may have interesting biological and pharmacological activities owing to their privileged indoline structure. [ABSTRACT FROM AUTHOR]

Ein neuer Ring für Indol: Eine neuartige Cu ‐ katalysierte enantioselektive Kaskade aus Friedel ‐ Crafts ‐ Alkylierung und N ‐ Halbacetalisierung setzt Indole mit β,γ ‐ ungesättigten α ‐ Ketoestern um. Diese milde Strategie eröffnet einen enantioselektiven Zugang zu präparativ und biologisch wichtigen 2,3 ‐ Dihydro ‐ 1H ‐ pyrrolo[1,2 ‐ a]indolen. [ABSTRACT FROM AUTHOR]

Immobilizing molecular catalysts on electro‐conductive supports (for example, multi‐walled carbon nanotubes, CNTs) represent a promising way to well‐defined catalyst/support interfaces, which has shown appreciable performance for catalytic transformation. However, their full potential is far from achieved due to insufficient utilization of the intrinsic activity for each immobilized molecular catalyst, especially at loadings that should allow decent current densities. In the present work, we discover host–guest interaction between tetra‐crown ether substituted cobalt phthalocyanine and metal ions, for example K+ ions, not only eliminate catalyst aggregation at immobilization procedures but also reinforce catalyst/support interactions by additional electrostatic attractions under operational conditions. Through simple dip‐coating procedures, a successful single molecular dispersion is achieved. Such a catalyst/electrode interface is stable and can selectively catalyze CO2‐to‐CO conversion with Faradaic efficiency over 96%. Importantly, this interface maintains an almost unchanged turnover frequency (TOF) across all loading conditions, implying a full utilization of the intrinsic activity of supported molecular catalysts. Therefore, a simultaneous achievement of high TOF and high current density (TOF of 111 s−1 at 38 mA cm−2) is achieved, in an aqueous H‐type electrolyzer at an overpotential of 570 mV. [ABSTRACT FROM AUTHOR]

A photoredox-mediated carboxylation of heterocycles and even electron-rich benzenes is described. [ABSTRACT FROM AUTHOR]

Highly enantioenriched spiro-epoxyoxindoles are obtained from isatins and chiral sulfur ylides generated in situ from camphor-derived sulfonium salts. [ABSTRACT FROM AUTHOR]

Asymmetric [4 + 1] annulation of axial chiral sulfur ylides (I) and N-(ortho-chloromethyl)aryl amides represents a direct procedure to access chiral 2-substituted indolines. [ABSTRACT FROM AUTHOR]

The title approach is advantageous with regards to simple experimental procedure and mild reaction conditions. [ABSTRACT FROM AUTHOR]