Nitrogen fixation is essential for the maintenance of life and development of society, however, the large bond dissociation energy and nonpolarity of the triple bond constitute a considerable ...challenge. The transition metals, by virtue of their combination of empty and occupied d orbitals, are prevalent in the nitrogen fixation studies and are continuing to receive a significant focus. The main group metals have always been considered incapable in dinitrogen activation owing to the absence of energetically and symmetrically accessible orbitals. The past decades have witnessed significant breakthroughs in the dinitrogen activation with the main group elements and compounds
via
either matrix isolation, theoretical calculations or synthetic chemistry. The successful reactions of the low-valent species of the main group elements with inert dinitrogen have been reported
via
the π back-donation from either the d orbitals (Ca, Sr, Ba) or p orbitals (Be, B, C...). Herein, the significant achievements have been briefly summarized, along with predicting the future developments.
In this tutorial, we introduced the fundamental aspects of nitrogen fixation, summarized the recent progresses with main group elements and tried to make clear the clue for further developments.
A
bstract
In this paper we re-investigate the model of the anti-de Sitter gravity coupled to Maxwell and charged scalar fields, which has been studied as the gravitational dual to a superconductor ...for a long time since the famous work
Phys. Rev. Lett.
101
(2008) 031601. By numerical method, we present a novel family of solutions of holographical superconductor with excited states, and find there exists a lower critical temperature in the corresponding excited state. Moreover, we study the condensate and conductivity in the excited states. It is very interesting that the conductivity
σ
of each excited state has an additional pole in Im
σ
and a delta function in Re
σ
arising at the low temperature inside the gap, which is just the evidence of the existence of excited states.
During 2018-2020, we isolated 32 Eurasian avian-like swine influenza A(H1N1) viruses and their reassortant viruses from pigs in China. Genomic testing identified a novel reassortant H3N1 virus, which ...emerged in late 2020. Derived from G4 Eurasian H1N1 and H3N2 swine influenza viruses. This virus poses a risk for zoonotic infection.
Toward promising candidates of quantum information processing, the rapid development of lanthanide-based single-molecule magnets (Ln-SMMs) highlights design strategies in consideration of the local ...symmetry of lanthanide ions. In this review, crystal-field theory is employed to demonstrate the electronic structures according to the semiquantitative electrostatic model. Then, specific symmetry elements are analysed for the elimination of transverse crystal fields and quantum tunnelling of magnetization (QTM). In this way, high-performance Ln-SMMs can be designed to enable extremely slow relaxation of magnetization, namely magnetic blocking; however, their practical magnetic characterization becomes increasingly challenging. Therefore, we will attempt to interpret the experimental behaviours and clarify some issues in detail. Finally, representative Ln-SMMs with specific local symmetries are summarized in combination with the discussion on the symmetry strategies, and some of the underlying questions are put forward.
Based on crystal-field theory, design strategies in consideration of local symmetry are highlighted for lanthanide-based single-molecule magnets, accompanied by practical concerns about magnetic studies and representative cases.
Nitric oxide (NO) has been shown to play an important role in the plant response to biotic and abiotic stresses in Arabidopsis mutants with lower or higher levels of endogenous NO. The exogenous ...application of NO donors or scavengers has also suggested an important role for NO in plant defense against environmental stress. In this study, rice plants under drought and high salinity conditions showed increased nitric oxide synthase (NOS) activity and NO levels. Overexpression of rat neuronal NO synthase (nNOS) in rice increased both NOS activity and NO accumulation, resulting in improved tolerance of the transgenic plants to both drought and salt stresses. nNOS-overexpressing plants exhibited stronger water-holding capability, higher proline accumulation, less lipid peroxidation and reduced electrolyte leakage under drought and salt conditions than wild rice. Moreover, nNOS-overexpressing plants accumulated less H2O2, due to the observed up-regulation of OsCATA, OsCATB and OsPOX1. In agreement, the activities of CAT and POX were higher in transgenic rice than wild type. Additionally, the expression of six tested stress-responsive genes including OsDREB2A, OsDREB2B, OsSNAC1, OsSNAC2, OsLEA3 and OsRD29A, in nNOS-overexpressing plants was higher than that in the wild type under drought and high salinity conditions. Taken together, our results suggest that nNOS overexpression suppresses the stress-enhanced electrolyte leakage, lipid peroxidation and H2O2 accumulation, and promotes proline accumulation and the expression of stress-responsive genes under stress conditions, thereby promoting increased tolerance to drought and salt stresses.
ABSTRACT
Bacterial communities play crucial roles in the biogeochemical cycle of the surface sediments of freshwater lakes, but previous studies on bacterial community changes in this habitat have ...mostly been based on the total bacterial community (DNA level), while an exploration of the active microbiota at the RNA level has been lacking. Herein, we analysed the bacterial communities in the surface sediments of Lake Taihu at the DNA and RNA levels. Using MiSeq sequencing and real-time quantification, we found that the sequencing and quantitative results obtained at the RNA level compared with the DNA level were more accurate in responding to the spatiotemporal dynamic changes of the bacterial community. Although both sequencing methods indicated that Proteobacteria, Chloroflexi, Acidobacteria, Nitrospirae, Bacteroidetes and Actinobacteria were the dominant phyla, the co-occurrence network at the RNA level could better reflect the close relationship between microorganisms in the surface sediment. Additionally, further analysis showed that Prochlorococcus and Microcystis were the most relevant and dominant genera of Cyanobacteria in the total and active bacterial communities, respectively; our results also demonstrated that the analysis of Cyanobacteria-related groups at the RNA level was more ‘informative’.
From the quantitative and qualitative results, we demonstrated that the analysis of the sediment bacterial communities at the RNA level was more informative than that at the DNA level.
Bacterial Rhs proteins containing toxic domains are often secreted by type VI secretion systems (T6SSs) through unclear mechanisms. Here, we show that the T6SS Rhs-family effector TseI of Aeromonas ...dhakensis is subject to self-cleavage at both the N- and the C-terminus, releasing the middle Rhs core and two VgrG-interacting domains (which we name VIRN and VIRC). VIRC is an endonuclease, and the immunity protein TsiI protects against VIRC toxicity through direct interaction. Proteolytic release of VIRC and VIRN is mediated, respectively, by an internal aspartic protease activity and by two conserved glutamic residues in the Rhs core. Mutations abolishing self-cleavage do not block secretion, but reduce TseI toxicity. Deletion of VIRN or the Rhs core abolishes secretion. TseI homologs from Pseudomonas syringae, P. aeruginosa, and Vibrio parahaemolyticus are also self-cleaved. VIRN and VIRC interact with protein VgrG1, while the Rhs core interacts with protein TecI. We propose that VIRN and the Rhs core act as T6SS intramolecular chaperones to facilitate toxin secretion and function.
Background & Aims
Epidemiological evidence linking fibroblast growth factor 21 (FGF21) with hepatocellular carcinoma (HCC) prognosis lacked. We aimed to evaluate the associations between serum FGF21 ...levels and HCC survival in a large prospective cohort.
Methods
825 newly diagnosed, previously untreated HCC patients from the Guangdong Liver Cancer Cohort were enrolled between September 2013 and April 2017. Serum FGF21 levels were measured by ELISA. Liver cancer‐specific survival (LCSS) and overall survival (OS) were calculated. Multivariable Cox proportional hazards models were performed to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs).
Results
Compared with patients in the lowest tertile of serum FGF21 levels, patients in the highest tertile had inferior survival outcomes. HRs in the fully adjusted models were 1.44 (95% CI: 1.07, 1.94; P‐trend = .014) and 1.48 (95% CI: 1.12, 1.97; P‐trend = .002) for LCSS and OS, respectively. The associations were not significantly modified by selected metabolic disorder diseases or state such as arterial hypertension, diabetes, dyslipidemia, fatty liver, cirrhosis, and body mass index ≥25.0 kg/m2, except for that stronger associations were observed in patients co‐occurred more than three metabolic disorder diseases (P‐interaction = .046 for OS and .151 for LCSS), with an HR of 2.01 (95% CI: 1.04, 3.85; P‐trend = .009) for OS and 1.51 (95% CI: 0.73, 3.10; P‐trend = .195) for LCSS.
Conclusions
Higher serum FGF21 levels were associated with worse survival in HCC patients, suggesting that serum FGF21 may be used as a novel metabolism‐related prognostic biomarker for HCC.
Peanut skin (PS) contains various flavonoids and phenols that have antitumor and antioxidant effects. However, no research has been conducted on PS and hepatocellular carcinoma (HCC). Therefore, this ...study sought to explore the potential mechanism of PS in treating HCC. PS was searched for in the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform and SYMMAP databases. HCC targets were searched for in five major databases. Protein‐protein interaction network, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes analyses were performed. Molecular docking and molecular dynamics simulation were used for verification. Furthermore, in vitro experiments were used to verify the regulation of PS on human HCC (HepG2) cells. Ten ingredients and 95 common targets were identified for PS and HCC, respectively. The key targets of ingredients mainly relate to pathways such as hepatitis B, lipid and atherosclerosis, advanced glycation end products (AGEs)‐AGE receptors (RAGEs) signaling pathway in diabetic complications, interleukin‐17 (IL‐17) signaling pathway, mitogen activated kinase‐like protein (MAPK) signaling pathway, the PI3K‐Akt signaling pathway. In addition, the molecular docking and molecular dynamics simulation analysis indicated the ingredients had strong binding ability with the targets. Moreover, in vitro experiments confirmed that luteolin can promote the apoptosis of HepG2 cells by controlling the expression of phosphorylated protein‐tyrosine kinase (p‐AKT). This study provides preliminary evidence that PS produces a marked effect in regulating multiple signaling pathways in HCC through multiple ingredients acting on multiple core genes, including AKT serine/threonine kinase 1 (AKT1), MYC, caspase 3 (CASP3), estrogen receptor 1 (ESR1), epidermal growth factor receptor (EGFR), jun proto‐oncogene(JUN), and provides the basis for follow‐up research to verify the mechanism of action of PS in treating HCC.
In this study, PS was searched through Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) and SYMMAP database. Then search for HCC targets in the five major databases. Next, we created a network and performed Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. In addition, molecular docking and molecular dynamics simulation were used for verification. Finally, cell experiments were used to verify the regulation of PS on human hepatocellular carcinoma (HepG2) cells. The results displayed ten ingredients and 95 common targets are identified for PS and HCC. And, it preliminarily showed that in the treatment of HCC, PS produces a marked effect in regulating multiple signaling pathways through multiple ingredients acting on multiple core genes, such as AKT1, MYC, CASP3, ESR1, EGFR, JUN, and provides the basis for follow‐up research to verify the mechanism of action of PS in treating HCC.
Parkinson's disease (PD) is a prevalent type of neurodegenerative disease. There is mounting evidence that the gut microbiota is involved in the pathogenesis of PD. Sodium butyrate (NaB) can regulate ...gut microbiota and improve brain functioning in neurological disorders. Hence, we examined whether the neuroprotective function of NaB on PD was mediated by the modulation of gut microbial dysbiosis and revealed its possible mechanisms. Mice were administered 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for 7 consecutive days to construct the PD model. NaB gavage was given 2 h after the daily MPTP injections for 21 days. NaB improved the motor functioning of PD mice, increased striatal neurotransmitter levels, and reduced the death of dopaminergic neurons. The 16S rRNA sequencing analysis revealed that NaB restored the gut microbial dysbiosis. NaB also attenuated the intestinal barrier's disruption and reduced serum, colon, and striatal pro-inflammatory cytokines, along with inhibiting the overactivation of glial cells, suggesting an inhibitory effect on inflammation from NaB throughout the gut-brain axis of the PD mice. Mechanistic studies revealed that NaB treatment suppressed the TLR4/MyD88/NF-kB pathway in the colon and striatum. In summary, NaB had a neuroprotective impact on the PD mice, likely linked to its regulation of gut microbiota to inhibit gut-brain axis inflammation.
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