Purple Light-Promoted Coupling of Bromopyridines with Grignard Reagents via SET.

Alkyl- and arylpyridines and 2,2'-bipyridines are conventionally prepared by Minisci reactions of pyridines and transition metal-catalyzed coupling reactions of halopyridines. Herein, purple light-promoted radical coupling reactions of 2- or 4-bromopyridines with Grignard reagents in Et2O or a mixture of Et2O and tetrahydrofuran in regular glassware without the need for a transition metal catalyst were disclosed for the first time. Methyl, primary and secondary alkyl, cycloalkyl, aryl, heteroaryl, pyridyl, and alkynyl Grignard reagents were compatible with the protocol. As a result, alkyl- and arylpyridines and 2,2'-bipyridines were easily prepared. Single electron transfer from the Grignard reagent to bromopyridine was stimulated by purple light. An electron extruded from the dimerization of the Grignard reagent worked as the catalyst. Light on/off experiments indicated that constant irradiation was required for product formation. Studies of radical clock substrates verified the involvement of a pyridyl radical from bromopyridine and the noninvolvement of an alkyl or aryl radical from the Grignard reagent. The available proof supports a photoinduced SRN mechanism for the new coupling reactions.

CsREV-CsTCP4-CsVND7 module shapes xylem patterns differentially between stem and leaf to enhance tea plant tolerance to drought.

Cultivating drought-tolerant tea varieties enhances both yield and quality of tea plants in northern China. However, the mechanisms underlying their drought tolerance remain largely unknown. Here we identified a key regulator called CsREV, which differentially regulates xylem patterns between leaves and stems, thereby conferring drought tolerance in tea plants. When drought occurs, upregulation of CsREV activates the CsVND7a-dependent xylem vessel differentiation. However, when drought persists, the vessel differentiation is hindered as CsVND7a is downregulated by CsTCP4a. This, combined with the CsREV-promoted secondary-cell-wall thickness of xylem vessel, leads to the enhanced curling of leaves, a characteristic closely associated with plant drought tolerance. Notably, this inhibitory effect of CsTCP4a on CsVND7a expression is absent in stems, allowing stem xylem vessels to continuously differentiate. Overall, the CsREV-CsTCP4-CsVND7 module is differentially utilized to shape the xylem patterns in leaves and stems, potentially balancing water transportation and utilization to improve tea plant drought tolerance.

IMPA2 promotes basal-like breast cancer aggressiveness by a MYC-mediated positive feedback loop.

Basal-like breast cancer (BLBC) is the most aggressive subtype with poor prognosis; however, the mechanisms underlying aggressiveness in BLBC remain poorly understood. In this study, we showed that in contrast to other subtypes, inositol monophosphatase 2 (IMPA2) was dramatically increased in BLBC. Mechanistically, IMPA2 expression was upregulated due to copy number amplification, hypomethylation of IMPA2 promoter and MYC-mediated transcriptional activation. IMPA2 promoted MI-PI cycle and IP3 production, and IP3 then elevated intracellular Ca2+ concentration, leading to efficient activation of NFAT1. In turn, NFAT1 up-regulated MYC expression, thereby fulfilling a positive feedback loop that enhanced aggressiveness of BLBC cells. Knockdown of IMPA2 expression caused the inhibition of tumorigenicity and metastasis of BLBC cells in vitro and in vivo. Clinically, high IMPA2 expression was strongly correlated with large tumor size, high grade, metastasis and poor survival, indicating poor prognosis in breast cancer patients. These findings suggest that IMPA2-mediated MI-PI cycle allows crosstalk between metabolic and oncogenic pathways to promote BLBC progression.

Magnesium transporter CsMGT10 of tea plants plays a key role in chlorosis leaf vein greening.

Magnesium (Mg2+), as the central atom of chlorophyll, is the most abundant divalent cation for plant growth and development in living cells. MRS2/MGT magnesium transporters play important roles in coping with magnesium stress, chloroplast development and photosynthesis. However, the molecular mechanism of MGT influencing tea plant leaf vein color remains unknown. Here, we demonstrate that CsMGT10 may be a potential transporter influencing leaf vein color. CsMGT10 belongs to Clade A member of MRS2/MGT family. CsMGT10 has the highest expression level in leaves of tea plants. And it is mainly expressed in aboveground parts, especially in vascular bundles. Moreover, CsMGT10 localizes to the chloroplast envelope of tea plants with a high affinity to Mg2+. And the GMN motif is required for its magnesium transport function. Ectopic expression of CsMGT10 in Arabidopsis leaf variegation mutant var5-1 can restore green color of chlorosis leaf veins, and the contents of chlorophyll and carotenoid change significantly, proving its essential role in leaf vein greening. Furthermore, the chlorophyll and carotenoid of tea leaves treated with CsMGT10 antisense oligonucleotides also decrease significantly. Our findings indicate that CsMGT10 mainly acts as Mg2+ transporter in chloroplast envelope of leaf veins, which may play a key role in leaf vein greening of tea plants.

gem-Bromonitroalkane Involved Radical 1,2-Aryl Migration of α,α-Diaryl Allyl Alcohol TMS Ether via Visible-Light Photoredox Catalysis.

A mild and efficient coupling method concerning the reactions of gem-bromonitroalkanes with α,α-diaryl allyl alcohol trimethylsilyl ethers was reported. A cascade consisting of visible-light-induced generation of an α-nitroalkyl radical and a subsequent neophyl-type rearrangement was key to realize the coupling reactions. Structurally diverse α-aryl-γ-nitro ketones, especially those bearing a nitrocyclobutyl structure, were prepared in moderate to high yields, which could be converted into spirocyclic nitrones and imines.

Peroxidase-like activity of bimetal Cu-Zn oxide mesoporous nanospheres for the determination of o-aminophenol.

To enhance the peroxidase-like performance and its application in detection of toxic o-aminophenol (o-AP), a kind of bimetal Cu-Zn oxide-based mesoporous nanosphere (Cu2/3Zn1/3O PNPs) was constructed under microwave-radiation conditions. Its mesoporous microstructure and peroxidase-like catalytic activity were investigated in detail. The results showed that Cu2/3Zn1/3O PNPs possessed a high specific surface area of 34.89 m2g-1 and a well-distributed mesoporous size of approximate 6.07 nm, which endowed the superior peroxidase-like performance. The material catalyzes the oxidization of 3,3',5,5'-tetramethylbenzidine (TMB) with Km/Vmax of 0.104 mM/3.79 × 10-8 M·s-1 in the presence of H2O2. Especially o-AP could exclusively deteriorate the characteristic UV-Vis absorbance intensity at 653 nm (A653) of the Cu2/3Zn1/3O PNPs-TMB-H2O2 system with obvious color change from blue to colorless. Under the optimal conditions, the effect of some interfering substances was low and the limit of detection (LOD) for o-AP was 1.65 × 10-8 mol/L (S/N = 3). When applied to the colorimetric detection of o-AP in practice, the recovery was between 96.1 and 107.2% with R.S.D. less than 2.04%. The mechanism of synergic-enhancement peroxidase-mimic activity of Cu2/3Zn1/3O PNPs and its exclusive colorimetric response to o-AP were proposed as well.

HIST1H1B Promotes Basal-Like Breast Cancer Progression by Modulating CSF2 Expression.

BACKGROUND: Basal-like breast cancer (BLBC) is associated with a poor clinical outcome; however, the mechanism of BLBC aggressiveness is still unclear. It has been shown that a linker histone functions as either a positive or negative regulator of gene expression in tumors. Here, we aimed to investigate the possible involvement and mechanism of HIST1H1B in BLBC progression. EXPERIMENTAL DESIGN: We analyzed multiple gene expression datasets to determine the relevance of HIST1H1B expression with BLBC. We employed quantitative real-time PCR, transwell assay, colony formation assay, and mammosphere assay to dissect the molecular events associated with the expression of HIST1H1B in human breast cancer. We studied the association of HIST1H1B with CSF2 by ChIP assay. Using tumorigenesis assays, we determine the effect of HIST1H1B expression on tumorigenicity of BLBC cells. RESULTS: Here, we show that the linker histone HIST1H1B is dramatically elevated in BLBC due to HIST1H1B copy number amplification and promoter hypomethylation. HIST1H1B upregulates colony-stimulating factor 2 (CSF2) expression by binding the CSF2 promoter. HIST1H1B expression promotes, whereas knockdown of HIST1H1B expression suppresses tumorigenicity. In breast cancer patients, HIST1H1B expression is positively correlated with large tumor size, high grade, metastasis and poor survival. CONCLUSION: HIST1H1B contributes to basal-like breast cancer progression by modulating CSF2 expression, indicating a potential prognostic marker and therapeutic target for this disease.

The positivity principle: do positive instructors improve learning from video lectures?

The positivity principle states that people learn better from instructors who display positive emotions rather than negative emotions. In two experiments, students viewed a short video lecture on a statistics topic in which an instructor stood next to a series of slides as she lectured and then they took either an immediate test (Experiment 1) or a delayed test (Experiment 2). In a between-subjects design, students saw an instructor who used her voice, body movement, gesture, facial expression, and eye gaze to display one of four emotions while lecturing: happy (positive/active), content (positive/passive), frustrated (negative/active), or bored (negative/passive). First, learners were able to recognize the emotional tone of the instructor in an instructional video lecture, particularly by more strongly rating a positive instructor as displaying positive emotions and a negative instructor as displaying negative emotions (in Experiments 1 and 2). Second, concerning building a social connection during learning, learners rated a positive instructor as more likely to facilitate learning, more credible, and more engaging than a negative instructor (in Experiments 1 and 2). Third, concerning cognitive engagement during learning, learners reported paying more attention during learning for a positive instructor than a negative instructor (in Experiments 1 and 2). Finally, concerning learning outcome, learners who had a positive instructor scored higher than learners who had a negative instructor on a delayed posttest (Experiment 2) but not an immediate posttest (Experiment 1). Overall, there is evidence for the positivity principle and the cognitive-affective model of e-learning from which it is derived.

Model-Driven Architecture of Extreme Learning Machine to Extract Power Flow Features.

Probabilistic power flow (PPF) calculation is an important power system analysis tool considering the increasing uncertainties. However, existing calculation methods cannot simultaneously achieve high precision and fast calculation, which limits the practical application of the PPF. This article designs a specific architecture of the extreme learning machine (ELM) in a model-driven pattern to extract the power flow features and therefore accelerate the calculation of PPF. ELM is selected because of the unique characteristics of fast training and less intervention. The key challenge is that the learning capability of the ELM for extracting complex features is limited compared with deep neural networks. In this article, we use the physical properties of the power flow model to assist the learning process. To reduce the learning complexity of the power flow features, the feature decomposition and nonlinearity reduction method is proposed to extract the features of the power flow model. An enhanced ELM network architecture is designed. An optimization model for the hidden node parameters is established to improve the learning performance. Based on the proposed model-driven ELM architecture, a fast and accurate PPF calculation method is proposed. The simulations on the IEEE 57-bus and Polish 2383-bus systems demonstrate the effectiveness of the proposed method.