Triterpenoids from Meehania fargesii with Cytotoxic Activity1

In the investigation of Meehania fargesii, eighteen triterpenoids were isolated and identified, including a previously unknown compound with an 13,27-cycloursane skeleton, using techniques like 1D and 2D NMR, and HR-MS. Furthermore, the cytotoxicity of these compounds were evaluated against HCT116, MCF-7, and AGS cell lines using the CCK-8 method to examine their structure–activity relationship. Remarkably, compounds 13 and 16 exhibited higher cytotoxicity across all three cell lines compared to the positive drug. Western blot analysis revealed that these compounds activated apoptosis in HCT116 cells by promoting the Bax protein and inhibiting the Bcl-2 protein. This suggests that compounds 13 and 16 have potential as apoptosis-inducing agents in HCT116 cells.     

Terpenoids from Euphorbia helioscopia and Their Cytotoxic Activities against H1975 Cells

Three previously undescribed diterpenoids, helioscopnoids A–C, and eight known compounds were isolated from the whole plants of Euphorbia helioscopia. Their structures were established by extensive analysis of spectra and data comparison with previous literatures. Among them, compound 4 was identified as 24,24-dimethoxy-25,26,27-trinoreuphan-3β-ol with revised configurations of C-13, C-14, and C-17 (13R*, 14R*, 17R*). Cytotoxicity assays revealed that all compounds exhibited varying levels of cytotoxicity against H1975 cells, with compound 9 displaying the most potent activity, as indicated by cell viability rates of 18.13 % and 20.76 % at concentrations of 20 μM and 5 μM, respectively. This study expands the understanding of E. helioscopia terpenoids’ structural diversity and biological activities, contributing to the exploration of potential therapeutic applications.     

Changing synaptic specificities in the nervous system of Caenorhabditis elegans: Differentiation of the DD motoneurons

During postembryonic development, the DD motoneurons in the nematode Caenorhabditis elegans completely reorganize their pattern of synapses. Ablation of a pair of embryonic precursors results in the absence of this entire class of motoneurons. In their absence animals exhibit two developmentally distinct locomotory defects. The transition period from one defect to the other is correlated with the synaptic reorganization of the DD mns. Mutations in a gene (unc-123) have been isolated that exhibit locomotory defects similar to those of the ablated adult animals. Genetic and cellular analyses of one of these alleles suggest that the unc-123 gene product may be involved in the reestablishment of functional synapses in these neurons. © 1993 John Wiley & Sons, Inc.     

Toward a hypothesis-free understanding of how phosphorylation dynamically impacts protein turnover

The turnover measurement of proteins and proteoforms has been largely facilitated by workflows coupling metabolic labeling with mass spectrometry (MS), including dynamic stable isotope labeling by amino acids in cell culture (dynamic SILAC) or pulsed SILAC (pSILAC). Very recent studies including ours have integrated themeasurement of post-translational modifications (PTMs) at the proteome level (i.e., phosphoproteomics) with pSILAC experiments in steady state systems, exploring the link between PTMs and turnover at the proteome-scale. An open question in the field is how to exactly interpret these complex datasets in a biological perspective. Here, we present a novel pSILAC phosphoproteomic dataset which was obtained during a dynamic process of cell starvation using data-independent acquisition MS (DIA-MS). To provide an unbiased “hypothesis-free” analysis framework, we developed a strategy to interrogate how phosphorylation dynamically impacts protein turnover across the time series data. With this strategy, we discovered a complex relationship between phosphorylation and protein turnover that was previously underexplored. Our results further revealed a link between phosphorylation stoichiometry with the turnover of phosphorylated peptidoforms. Moreover, our results suggested that phosphoproteomic turnover diversity cannot directly explain the abundance regulation of phosphorylation during cell starvation, underscoring the importance of future studies addressing PTM site-resolved protein turnover.     

Benzotriazole-Based Polymer Acceptor for High-Efficiency All-Polymer Solar Cells with High Photocurrent and Low Voltage Loss

The power conversion efficiencies (PCEs) of all-polymer solar cells (all-PSCs) have already exceeded 17%. However, the limited absorption range of an all-polymer system results in significantly reduced short-circuit current density (J_sc), which eventually influences the PCE improvement. To broaden the light absorption of polymer acceptors, herein, benzotriazole is introduced in the core unit of small molecule acceptors and thus two narrow-bandgap polymer acceptors named PTz-BO and PTz-C11 featuring the same molecular backbone and different side-chain length are synthesized. Compared with PTz-C11, the PTz-BO based-all PSCs deliver a slightly reduced J_sc, a large open-circuit voltage (V_oc) and a low voltage loss below 0.50 V. Moreover, ternary all-PSCs are constructed by introducing PTz-C11 as a guest component. Benefiting from the reduced recombination, improved exciton generation and dissociation, and balanced charge transport, a high efficiency of 16.58% is obtained for the ternary all-PSCs, with a high J_sc over 25 mA cm⁻² without sacrificing the V_oc. Such result represents the highest efficiency reported for benzotriazole-based all-PSCs in the literature thus far. This work demonstrates the great potential of benzotriazole for the synthesis of efficient narrow-bandgap polymer acceptors.     

DNA barcoding of Cymbidium by genome skimming: Call for next-generation nuclear barcodes

Cymbidium is an orchid genus that has undergone rapid radiation and has high ornamental, economic, ecological and cultural importance, but its classification based on morphology is controversial. The plastid genome (plastome), as an extension of plant standard DNA barcodes, has been widely used as a potential molecular marker for identifying recently diverged species or complicated plant groups. In this study, we newly generated 237 plastomes of 50 species (at least two individuals per species) by genome skimming, covering 71.4% of members of the genus Cymbidium. Sequence-based analyses (barcoding gaps and automatic barcode gap discovery) and tree-based analyses (maximum likelihood, Bayesian inference and multirate Poisson tree processes model) were conducted for species identification of Cymbidium. Our work provides a comprehensive DNA barcode reference library for Cymbidium species identification. The results show that compared with standard DNA barcodes (rbcL + matK) as well as the plastid trnH-psbA, the species identification rate of the plastome increased moderately from 58% to 68%. At the same time, we propose an optimized identification strategy for Cymbidium species. The plastome cannot completely resolve the species identification of Cymbidium, the main reasons being incomplete lineage sorting, artificial cultivation, natural hybridization and chloroplast capture. To further explore the potential use of nuclear data in identifying species, the Skmer method was adopted and the identification rate increased to 72%. It appears that nuclear genome data have a vital role in species identification and are expected to be used as next-generation nuclear barcodes.     

A new strategy for cellulases application in high temperature industrial scenarios with syringic acid assisting

In the process of bioethanol production, more stable and active cellulase in high temperature condition is required. In this study, syringic acid was applied in cellulase hydrolysis system. At 70°C, TvEG3 activity increased 201.36%, CtBglA activity decreased 72.79% by syringic acid. With syringic acid assisting, TvEG3 thermostability was improved, CtBglA thermostability was reduced. Syringic acid scarcely affected CtCBH. In hydrolysis system with the cellulases containing TvEG3, CtCBH, and CtBglA, the reducing sugar yield improved by 28.37% with syringic acid assisting. With the molecular dynamic simulation in syringic acid system, the backbone root-mean-square deviation (RMSD) and the residue root-mean-square fluctuation (RMSF) of TvEG3, CtCBH reduced, while the RMSD and RMSF of CtBglA increased. The reduction in the number of secondary structures, especially α-helix, caused the structure of CtBglA in the presence of syringic acid to collapse at high temperature. More secondary structures in TvEG3 and more α-helix in CtCBH in the presence of syringic acid make them more stable at high temperatures. These means syringic acid can stabilize TvEG3 and CtCBH structure, destabilize CtBglA structure at high temperature. In summary, this study not only provides insight into cellulase hydrolysis at high temperature with syringic acid assisting but also demonstrates the promoting mechanism of syringic acid.     

The legacy effect of biochar application on soil nitrous oxide emissions

Existing studies suggest that biochar application can reduce soil nitrous oxide (N₂O) emissions, mainly based on short-term results. However, it remains unclear what the effects (i.e., legacy effects) and underlying mechanisms are on N₂O emissions after many years of a single application of biochar. Here, we collected intact soil columns from plots without and with biochar application in a subtropical tea plantation 7 years ago for an incubation experiment. We used the N₂O isotopocule analysis combined with ammonia oxidizer-specific inhibitors and molecular biology approaches to investigate how the legacy effect of biochar affected soil N₂O emissions. Results showed that the soil in the presence of biochar had lower N₂O emissions than the control albeit statistically insignificant. The legacy effect of biochar in decreasing N₂O emissions may be attributed to the reduced effectiveness of the soil substrate, nitrification and denitrification activities, and the promotion of the further reduction of N₂O. The legacy effect of biochar reduced the relative contribution of nitrifier denitrification/bacterial denitrification, nitrification-related N₂O production, and the relative abundance of several microorganisms involved in the nitrogen cycle. Our global meta-analysis also showed that the reduction of N₂O by biochar increased with increasing application rate but diminished and possibly even reversed with increasing experimental time. In conclusion, our findings suggest that the abatement capacity of biochar on soil N₂O emissions may weaken over time after biochar application, but this remains under further investigation.