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Abstract Agricultural ecosystems play an important role in modulating the global carbon balance by taking up atmospheric carbon dioxide, while large differences and uncertainties exist in the estimated crop gross primary productivity (GPP) by terrestrial ecosystem models (TEMs). With the aim of reducing the parameter uncertainty in TEMs for crop GPP simulation, we developed a particle filtering data assimilation (DA) system based on the ecosystem model BEPS (Biosphere Exchange Process Simulator), that is, the BEPS_PF (v1.0). We investigated the feasibility of BEPS_PF on the multiple parameters optimization across typical crops (wheat, rice, soybean and corn) and on reducing the uncertainty of GPP over 32 cropland eddy covariance sites globally. With BEPS_PF DA, the average R2 between GPP and observed data at the hourly scale has been efficiently improved by 0.36 and root mean square error reduced by 0.18 gC m−2 hr−1. The DA system has successfully corrected the GPP from the irrigated croplands which was severely underestimated by the model's prior parameters. We found that the maximum carboxylation rate at 25°C (Vcmax25) as well as the leaf nitrogen content (Nleaf) were co‐varied with strong seasonal variations. The optimized Vcmax25 showed large differences among different crop types with ranges 27.07–62.95, 42.17–93.32, 31.89–105.81, and 38.34–89.29 μmol m−2 s−1 for corn, soybean, wheat, and rice respectively. We demonstrated that the BEPS_PF is an efficient tool for optimizing different processes in the ecosystems, and with the satellite data it can be extended to regional and global scales for more accurate estimation of carbon fluxes.

Alzheimer′s disease (AD) is a neurodegenerative disease with extremely complex pathogenesis, characterized by cognitive dysfunction and memory loss, involving in a variety of physiological and pathophysiological processes. Early diagnosis is a key factor for the prevention and treatment of AD. Positron emission tomography (PET) technology can accurately detect subtle physiological changes in neurons and brain tissues at the molecular level, providing evidence for early diagnosis of AD. Starting from the classification of biomarkers, the relevant targets of protein degeneration and neuronal damage in the brain were introduced, and the research status of various PET tracers was reviewed according to several important parameters such as affinity, half-life, binding region, pharmacokinetics, analysis method and correlation of results, etc. Additionally, the current problems faced by the development of PET tracers were pointed out, and it was believed that future research should be carried out from the following aspects: The development of PET tracers related to neuroinflammation; Further evaluation and optimization of existing tracers; Normalization and standardization of methods for the analysis of tracer results.

The non-racemic enantiomers may exist with very small %ee values, which formed by some asymmetric factors (such as symmetry breaking) during their synthesis in the prebiotic pool in the absence of other chiral sources. We now conclude a mathematic formula by concerning the organic reaction principles. We found that the tiny %ee (%ee1) values of non-racemic enantiomers can be enhanced to a reasonable large %ee values (%ee2) after the non-racemic enantiomers react with bis-functional group reagents (such as oxalaldehyde). Theoretically, if the %ee1 is extremely small, the enhancement/amplification multiples (%ee2/%ee1) should increase greatly. The is necessary to enrich the %ee values in prebiotic pool for the chiral compounds (such as L-amino acids) with very small %ee values. Finally, about 1% of L-tryptophan methyl ester （L-TME） was used to react with CHOCHO, and the %ee2 of the L-TME remained in solution increased to 3.4%. The largest amplification multiple is 1.9 (from 6.1% of %ee1 to enrich to 11.7% (%ee2)); The largest increasement of the %ee (Δ%ee=%ee2-%ee1) is 12.3% (from 44.2% to 56.5%).

Pectobacterium cacticida (formerly Erwinia cacticida) causes soft rot disease of cactus plants. Its taxonomic status within the genus Pectobacterium remains questionable because no whole genome sequence of this species is available in public databases for reliable taxonomic analyses. Here, we present the complete genome sequence of the P. cacticida type strain CFCC 10813T (=1-12T = ATCC 49481T). P. cacticida can be classified into the genus Pectobacterium because it is on the deepest basal phylogenomic branch of the genus Pectobacterium, and its genome relatedness to other Pectobacterium species is at the border for the genus delimitation boundaries. This complete genome sequence provides the genome resource for elucidating P. cacticida pathogenicity and adaptation to plant hosts and environments. [Figure: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

It is very important to assign a stereogenic center in study of the chiral medicines.With the development of calculation methods and software,it is possible to use different theoretical methods to assign the absolute configuration of chiral compounds.Now,the methods are used for different calculation,such as specific optical rotation,optical rotatory dispersion,determinant in matrix of chiral compound,electronic circular dichroism and vibrational circular dichroism.The stereogenic centers can be determined by comparing the theoretical values with the experimental data.Until now,it has become a popular way by using two or more theoretical methods in absolute configuration determination.On the other hand,it is a key and popular method to use a simplified model to replace a complex chiral compound in various calculations.This review analyzed the fundamental science and introduced a new concept of “conformer pair” for the first time.

Burkholderia arboris, which belongs to the Burkholderia cepacia complex, has been shown to possess antifungal activity against several plant fungal pathogens; however, the antifungal compounds are yet to be identified. Here, we identified the antifungal compounds produced by B. arboris using genetic and metabolomic approaches. We generated a Tn5 transposon mutation library of 3,000 B. arboris mutants and isolated three mutants with reduced antifungal activity against the plant fungal pathogen Fusarium oxysporum. Among the mutants, the M464 mutant exhibited the weakest antifungal activity. In the M464 genome, the transposon was inserted into the cobA gene, encoding uroporphyrin-III methyltransferase. Deletion of the cobA gene also resulted in reduced antifungal activity, indicating that the cobA gene contributed to the antifungal activity of B. arboris. Furthermore, a comparison of the differential metabolites between wild type B. arboris and the ∆cobA mutant showed a significantly decreased level of tetrapeptide His-Ala-Phe-Lys (Hafk) in the ∆cobA mutant. Therefore, a Hafk peptide with D-amino acid residues was synthesized and its antifungal activity was evaluated. Notably, the Hafk peptide displayed significant antifungal activity against F. oxysporum and Botrytis cinerea, two plant pathogens that cause destructive fungal diseases. Overall, a novel antifungal compound (Hafk) that can be used for the biocontrol of fungal diseases in plants was identified in B. arboris.

Background Acute myocardial infarction (AMI) is a severe cardiovascular condition. Blocking the apoptosis of myocardial cells may mitigate AMI. Excessive expression of Stanniocalcin-1 (STC1) plays a protective role in the heart by inhibiting myocardial cell apoptosis. Here, we looked at the mechanism by which miR-382-5p regulates STC1 and affects myocardial cell apoptosis after AMI. Methods An AMI mouse model with a descending anterior ligament coronary artery and an HL-1 cell model with reproducible hypoxia/reoxygenation (H/R) were established. For pathological changes in myocardial tissues, terminal deoxynucleotidyl transferase dUTP nick end labelling staining and haematoxylin and eosin staining were performed. STC1 mRNA and miR-382-5p levels were measured using quantitative real-time PCR. Protein levels of STC1 and apoptosis-related proteins were measured by western blotting. The 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di- phenytetrazoliumromide assay was used to detect cell viability, and a dual-luciferase reporter assay was carried out to verify potential targets of miR-382-5p. Results The level of miR-382-5p was raised in myocardial tissues of AMI mice and H/R-induced HL-1 cells. Compared with the control group, the myocardial tissue cells in the AMI group were disordered, with evident necrosis of myocardial cells, apoptosis and inflammatory infiltration. Interference with miR-382-5p inhibited myocardial cell apoptosis after H/R, as well as inferior lactate dehydrogenase. Also, miR-382-5p adversely regulated STC1 and the expression of STC1 was increased after transfection with miR-382-5p antagomir. Furthermore, interference with miR-382-5p reduced myocardial cell apoptosis after H/R by increasing the expression level of STC1. Conclusion To summarise, our study showed an increase in miR-382-5p in myocardial tissues in the AMI mouse model. Interference with miR-382-5p reduced apoptosis of myocardial cells after AMI and the effect was achieved by increasing STC1 expression.

We now report that some chiral compounds, like alcohols, which are not sterically hindered atropisomers nor epimer mixtures, exhibit two sets of simultaneous NMR spectra in CDCl3. Some other chiral alcohols also simultaneously exhibit two different NMR spectra in the solid state because two different conformers, A and B had different sizes because their corresponding bond lengths and angles are different. These structures were confirmed in the same solid state by X-ray. We designate these as pseudo-resonance for a compound exhibiting several different corresponding lengths that simultaneously coexist in the solid state or liquid state. Variable-temperature NMR, 2D NMR methods, X-ray, neutron diffraction, IR, photo-luminesce (PL) and other methods were explored to study whether new aggregation states caused these heretofore unknown pseudo-resonance structures. Finally, eleven chiral alcohols or diols were found to co-exist in pseudo-resonance structures by X-ray crystallography in a search of the CDS database.

Two known azaphilone derivatives, 4,6-dimethylcurvulinic acid (1) and austdiol (2), and their novel heterotrimer, muyophilone A (3), were isolated and identified from an endophytic fungus, Muyocopron laterale 0307-2. Their structures and stereochemistry were established by extensive spectroscopic analyses including HRMS, NMR spectroscopy, electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) spectroscopic methods, as well as single crystal X-ray diffraction. In the structure of 3, two compound 2-derived azaphilone units were connected through an unprecedented five-membered carbon bridge which was proposed to be originated from compound 1. Compound 3 represents the first example of azaphilone heterotrimers.

With the rapid development of high performance computers and computational methods, including software, an increasing number of experimental chemists have tried to use computational methods such as optical rotation (OR, including the matrix model), optical rotatory dispersion (ORD), electronic circular dichroism (ECD or CD), vibrational circular dichroism (VCD), and magnetic shielding constants--nuclear magnetic resonance (NMR)--to explain and/or assign absolute configuration (AC) for various compounds. Such reports in the field of natural products have increased dramatically. However, every method has its range of application. This leads, in some cases, to incorrect conclusions by researchers who are not familiar with these methods. In this review, we provide experimental chemists and researchers with more computational details and suitable suggestions, and especially hope that this experience may help readers avoid computational pitfalls. Finally, we discuss the use of simplified models to replace original complex structures with a long side chain. The fundamental basis for using models to represent complex chiral compounds, such as in OR calculations, is the existence of conformation pairs with near canceling conformer contributions that justify the use of models rather than the original compounds. Using examples, we here introduce the transition state (TS) calculation, which may benefit readers in this area for use and mastery for their AC study. This review will summarize the general concepts involved in the study of AC determinations. [ABSTRACT FROM AUTHOR]

Accurately modeling gross primary productivity (GPP) is of great importance in diagnosing terrestrial carbon-climate feedbacks. Process-based terrestrial ecosystem models are often subject to substantial uncertainties, primarily attributed to inadequately calibrated parameters. Recent attention has identified carbonyl sulfide (COS) as a promising proxy of GPP, due to the close linkage between leaf exchange of COS and carbon dioxide (CO2) through their shared pathway of stomatal diffusion. However, most of the current modeling approaches for COS and CO2 did not explicitly consider the vegetation structural impacts, i.e. the differences between the sun-shade and sunlit leaves in COS uptake. This study used ecosystem COS fluxes data from 7 sites to optimize GPP estimation across various ecosystems with the Boreal Ecosystem Productivity Simulator (BEPS), which was further developed for simulating the leaf COS uptake under its state-of-the-art 'two-leaf' framework. Our results demonstrated the substantial improvement in GPP simulation across various ecosystems through the fusion of COS data into the 'two-leaf' model, with the ensemble mean of root mean square error (RMSE) for simulated GPP reduced by 18.99 % to 66.64 %. Notably, we also shed light on the remarkable identifiability of key parameters within the BEPS model, including the maximum carboxylation rate of Rubisco at 25 °C (Vcmax25), minimum stomatal conductance (...), and leaf nitrogen content (Nleaf), despite intricate interactions among COS-related parameters. Furthermore, our global sensitivity analysis delineated both shared and disparate sensitivities of COS and GPP to model parameters and suggested the unique treatment of parameters for each site in COS and GPP modeling. In summary, our study deepened insights into the sensitivity, identifiability, and interactions of parameters related to COS, and showcased the efficacy of COS in reducing uncertainty in GPP simulations. [ABSTRACT FROM AUTHOR]

From the whole plants of E. ritroL., the three new sesquiterpenoids 3α,4α,6α3,13dihydroxyguaia711,1014dieno12,6lactone 1, 3α,4α,6α,11β3hydroxyguai110eno12,6lactone 2, and 11α11,13dihydroarglanilic acid methyl ester =4β,6α,11α4,6dihydroxy1oxoeudesm2en12oic acid methyl ester; 3, together with eight known sesquiterpenoids, were isolated. Their structures were elucidated through analysis of spectroscopic data including extensive 2DNMR. [ABSTRACT FROM AUTHOR]

Two novel cyclic hexapeptides containing both anthranilic acid and dehydroamino acid units, sclerotides A (1) and B (2), were isolated from the marine-derived halotolerant Aspergillus sclerotiorumPT06-1 in a nutrient-limited hypersaline medium. Both 1and 2are photointerconvertible and could be interconverted via a radical reaction initiated by direct photoisomerization. Both compounds showed moderate antifungal activity. Compound 2also showed weak cytotoxicity and antibacterial activity. [ABSTRACT FROM AUTHOR]

Two new C20diterpenoid alkaloids named naviculine A 1 and naviculine B 2, were isolated from Aconitum naviculareStapf. Their structures were established by spectral methods, especially 2DNMR spectra 1H,1HCOSY, HMQC, HMBC, and NOESY and DFT methods at the B3LYP6311++G2d,pB3LYP631Gd level, respectively. They were assayed for their antiHIV1 activity. [ABSTRACT FROM AUTHOR]

Background With the acceleration of the aging process in society, the demand for hospice services is increasing. The development of hospice care in China started relatively late, and relevant institutional construction standards and management norms are still in the trial stage. As one of the important integrated medical and nursing service institutions, elderly care institutions currently lack an effective and homogeneous model and service system for hospice services. Objective To establish a scientific, standardized and feasible hospice service model for elderly care institutions. Methods From April to May in 2020, Chinese/English databases were systematically searched to obtain the literature related to hospice services. Five experts in the field of hospice care were invited to carry out semi-structured interviews, and the initial index system was constructed based on the results of literature retrieval and semi-structured interviews. In May 2020, a purposive sampling method was used to select fifteen experts in the field of hospice care to conduct two rounds of correspondence, and the indicator system was determined based on the analysis of the research group and expert suggestions. After two rounds of correspondence, an expert group interview was conducted to further optimize and adjust the formed indicator system. Results In both rounds of correspondence, the questionnaire response rate was 100.0%, with expert authority coefficients of 0.89 and 0.94, respectively. The Kendall's W coefficients for the first level indicator were 0.54 and 0.59, respectively, and the Kendall's W coefficients for the second level indicator were 0.18 and 0.10, respectively. The final constructed indicator system for the hospice service model of elderly care institutions included three primary indicators of necessary resources and conditions, content and processes, assessment indicators, and 36 secondary indicators. In the second round of inquiry, the average importance score of the indicator was 3.87 to 5.00 points, the coefficient of variation was 0 to 0.25, and the full score rate was 63.0% to 100.0%. Conclusion The scientificity and reliability of the model hospice service model for elderly care institutions constructed in this study are good, which can provide reference for elderly care institutions to provide high-quality medical services for elderly patients at the end of their lives.