New alkaloids from Stemona tuberosa and structural revision of tuberostemonols P and R.

Three Stemona alkaloids named stemotuberines A-C (1-3) with unique C17N frameworks, presumably formed by elimination of the C-11-C-15 lactone ring of the stichoneurine skeleton, were isolated from the roots of Stemona tuberosa. Their structures were elucidated by spectroscopic analysis, X-ray diffraction, and computational methods. Compounds 2 and 3 showed inhibition (IC50 values of 37.1 and 23.2 µM, respectively) against LPS-induced nitric oxide production in RAW 264.7 cells. In addition, concern was expressed about the reported plant origin (S. sessilifolia) of the recently described alkaloids tuberostemonols O-R (4-7), which should be S. tuberosa. NMR calculations indicated structural misassignment of these compounds except for 6. Isolation of tuberostemonol P (5) from our material of S. tuberosa allowed for a close examination of the spectroscopic data leading to the revised structure 5a. Tuberostemonol R (7) was found to have identical 1H and 13C NMR data to the well-known alkaloid croomine, and therefore its structure including relative stereochemistry must be revised as 7a.

Mo-doping heterojunction: interfacial engineering in an efficient electrocatalyst for superior simulated seawater hydrogen evolution.

Exploring economical, efficient, and stable electrocatalysts for the seawater hydrogen evolution reaction (HER) is highly desirable but is challenging. In this study, a Mo cation doped Ni0.85Se/MoSe2 heterostructural electrocatalyst, Mox-Ni0.85Se/MoSe2, was successfully prepared by simultaneously doping Mo cations into the Ni0.85Se lattice (Mox-Ni0.85Se) and growing atomic MoSe2 nanosheets epitaxially at the edge of the Mox-Ni0.85Se. Such an Mox-Ni0.85Se/MoSe2 catalyst requires only 110 mV to drive current densities of 10 mA cm-2 in alkaline simulated seawater, and shows almost no obvious degradation after 80 h at 20 mA cm-2. The experimental results, combined with the density functional theory calculations, reveal that the Mox-Ni0.85Se/MoSe2 heterostructure will generate an interfacial electric field to facilitate the electron transfer, thus reducing the water dissociation barrier. Significantly, the heteroatomic Mo-doping in the Ni0.85Se can regulate the local electronic configuration of the Mox-Ni0.85Se/MoSe2 heterostructure catalyst by altering the coordination environment and orbital hybridization, thereby weakening the bonding interaction between the Cl and Se/Mo. This synergistic effect for the Mox-Ni0.85Se/MoSe2 heterostructure will simultaneously enhance the catalytic activity and durability, without poisoning or corrosion of the chloride ions.

[Effects of seeding pattern and phosphorus application on population structure, photosynthe-tic characteristics and yield of winter wheat]. / æ’­ç§æ–¹å¼å’Œæ–½ç£·å¯¹å†¬å°éº¦ç¾¤ä½“ç»“æž„ã€å ‰åˆç‰¹æ€§å’Œäº§é‡çš„å½±å“.

Under Xinjiang winter wheat seeding pattern, in order to sort out proper phosphorus application (PA) and find out the effects and mechanism of PA on population structure, photosynthesis characteristics and yield and provide reliable evidence for PA management of winter wheat, we arranged a two-factor complete split-plot design of wheat variety "Xindong 22". The main area consisted of two seeding ways: drill seeding pattern (D) and uniform seeding pattern (U), while in the sub-area there were four levels of PA(P2O5): 0, 60, 120, and 180 kg·hm-2(represented by P0, P60, P120 and P180 for those treatments, respectively). The results showed that the earbearing percentage in U was 15.9% higher than that in D, and the other features (PAR interception rate, extinction coefficient, leaf area index, SPAD and photosynthetic parameters) were more optimal in 120 kg·hm-2 treatment. Our results showed that the 120 kg·hm-2 treatment in U would be the optimal option with respect to population structure, photosynthetic characteristics, and yield.

Simultaneously measuring multiple protein interactions and their correlations in a cell by Protein-interactome Footprinting.

Quantitatively detecting correlations of multiple protein-protein interactions (PPIs) in vivo is a big challenge. Here we introduce a novel method, termed Protein-interactome Footprinting (PiF), to simultaneously measure multiple PPIs in one cell. The principle of PiF is that each target physical PPI in the interactome is simultaneously transcoded into a specific DNA sequence based on dimerization of the target proteins fused with DNA-binding domains. The interaction intensity of each target protein is quantified as the copy number of the specific DNA sequences bound by each fusion protein dimers. Using PiF, we quantitatively reveal dynamic patterns of PPIs and their correlation network in E. coli two-component systems.

MicroRNA-18a modulates P53 expression by targeting IRF2 in gastric cancer patients.

BACKGROUND AND AIM: MicroRNA-18a (miR-18a) has been reported to be upregulated in gastric cancer (GC) tissues compared with normal gastric tissues. However, little is known about its prognostic value and biological roles. METHODS: In this study, miR-18a expression in gastric adenocarcinoma (GAC) tissues and adjacent non-tumor tissues was validated by in situ hybridization, and the predictive values of miR-18a were explored. The biological roles of miR-18a and the underlying signal pathway were investigated in GC cell lines. RESULTS: Overexpressed intra-tumoral miR-18a was associated with poor survival rate and was an independent prognostic factor for overall survival rate (P < 0.001) in GC patients. Forced expression of miR-18a remarkably enhanced cell proliferation, migration, and invasion in GC cells, while inhibition of miR-18a caused the opposite effects. Further study showed that miR-18a suppressed the expression of interferon regulatory factor 2 (IRF2) by directly binding to its 3'-untranslated region. Moreover, miR-18a expression levels are inversely correlated with IRF2 in human GC tissues. Western blot showed that forced expression of miR-18a could not only downregulate the expression of IRF2, but also inhibit the expression of P53, suggesting that IRF2 might play as a tumor suppressor by regulating P53 signaling in GC. CONCLUSION: miR-18a modulated P53 expression by directly targeting IRF2 and had a high predictive value for prognosis of GAC patients. These results may lead to identification of therapeutic candidates of GC.

[Metabotropic glutamate receptor 8 activation promotes the apoptosis of lung carcinoma A549 cells in vitro].

This study aims to detect the expression of metabotropic glutamate receptors (mGluRs) in lung carcinoma A549 cells, and to investigate the effects of mGluR8 and mGluR4 activation on the growth of A549 cells in vitro. The mRNA expression levels of the 8 subtypes of mGluRs in A549 cells were determined by real-time PCR. Immunohistochemistry was used to analyze the protein expression of mGluR4 and mGluR8 in A549 cells and lung tissue sections obtained from lung adenocarcinoma patients. To observe the effects of mGluR8 and mGluR4 activation on the growth of A549 cells, the cultured cells were treated with (S)-3,4-DCPG (an agonist of mGluR8) and VU0155041 (an agonist of mGluR4), respectively, and then the cell viability was analyzed by CCK-8 kit, the percentage of DNA synthesis was detected by EdU incorporation, and the apoptosis of the cells was measured by hoechst 33258 staining and flow cytometry. The results showed that there were low expressions of mGluR1, mGluR5, mGluR6, mGluR7 mRNA, no expression of mGluR2 and mGluR3 mRNA, and high expressions of mGluR8 and mGluR4 mRNA in A549 cells. Accordingly, there were also mGluR4 and mGluR8 protein expressions in the A549 cells and the lung adenocarcinoma tissue sections. VU0155041 had no effect on the growth of A549 cells, but (S)-3,4-DCPG significantly decreased the cells' growth in a dose-dependent manner and increased the apoptosis of the cells. The results revealed a role of mGluR8 in the growth and apoptosis of A549 cells and suggested a potential target for clinical treatment of lung cancer.