嗜黏蛋白阿克曼氏菌治疗疾病的潜力与作用机制研究进展

嗜黏蛋白阿克曼氏菌(Akkermansia muciniphila, AKK)可促进肠道黏液分泌,维持肠道黏液动态平衡,调节肠黏膜屏障功能,在机体代谢调节、免疫应答中发挥重要作用。AKK对肠道炎症、神经炎症、机体代谢紊乱和癌症等疾病具有显著改善作用,被视为极具潜力的下一代益生菌。本文分别从消化系统、神经系统、代谢性紊乱和癌症等角度入手,系统概述AKK在疾病治疗中的潜力及作用分子机制。     

黔西水城晚二叠世长兴期钙藻和有孔虫及其古环境意义

在黔西水城地区的K576井长兴组共鉴定钙藻3属3种,包括Gymnocodium bellerophontis、Permocalculus sp.和Tauridiumkurdistanensis;有孔虫8属10种,其中(虫筳)类2属2种,有孔虫动物群主要由Reichelinasp.indet.、Nankinella sp.、Pachyphloia schwageri、Pachyphloia sp.、Geinitzina sp.、Nestellorella sp. indet.、Howchinella sp.、Hemigordius aff. saranensis、Hemigordius sp.和Midiella sp. indet.组成。将本井按照生物特征分为有孔虫-钙藻-介形虫组合、有孔虫-腕足类-介形虫组合、介形虫-双壳类-腹足类组合、有孔虫-钙藻-双壳类组合、有孔虫-腕足类-介形虫组合、有孔虫-钙藻-双壳类组合和介形虫组合等7个组合。按照层序地层划分、垂向沉积序列特征和测井资料的分析,有孔虫-钙藻-介形虫组合(SQ3-3)和有孔虫-腕足类-介形虫组合(SQ3-4)时期地层为三角洲前...     

The potato StMKK5-StSIPK module enhances resistance to Phytophthora pathogens through activating the salicylic acid and ethylene signalling pathways

Mitogen-activated protein kinase (MAPK) cascades play pivotal roles in plant responses to both biotic and abiotic stress. A screen of a Nicotiana benthamiana cDNA virus-induced gene silencing (VIGS) library for altered plant responses to inoculation with Phytophthora infestans previously identified an NbMKK gene, encoding a clade D MAPKK that we renamed as NbMKK5, which is involved in immunity to P. infestans. To study the role of the potato orthologous gene, referred to as StMKK5, in the response to P. infestans, we transiently overexpressed StMKK5 in N. benthamiana and observed that cell death occurred at 2 days postinfiltration. Silencing of the highly conserved eukaryotic protein SGT1 delayed the StMKK5-induced cell death, whereas silencing of the MAPK-encoding gene NbSIPK completely abolished the cell death response. Further investigations showed that StMKK5 interacts with, and directly phosphorylates, StSIPK. Furthermore, both StMKK5 and StSIPK trigger salicylic acid (SA)- and ethylene (Eth)-related gene expression, and co-expression of the salicylate hydroxylase NahG with the negative regulator of Eth signalling CTR1 hampers StSIPK-triggered cell death. This observation indicates that the cell death triggered by StMKK5-StSIPK is dependent on the combination of SA- and Eth-signalling. By introducing point mutations, we showed that the kinase activity of both StMKK5 and StSIPK is required for triggering cell death. Genetic analysis showed that StMKK5 depends on StSIPK to trigger plant resistance. Thus, our results define a potato StMKK5-SIPK module that positively regulates immunity to P. infestans via activation of both the SA and Eth signalling pathways.     

-cyano-substituted analogoues of decarboxylated S-adenosylmethionine as enzyme activated, irreversible inhibitors of S-adenosylmethionine decarboxylase

A pair of -cyano analogues of decarboxylated S-adenosylmethionine (2a and 2b) were synthesized as potential enzyme activated, irreversible inhibitors of the[pyruvoyl enzyme S-adenosylmethionine decarboxylase (AdoMet-DC). Each of these analogues acts as an irreversible inactivator for ADoMet-DC from Escherichia coli (IC₅₀ values of 9 and 50 μM, respectively). These analogues also inactivate human AdoMet-DC, with K_I values of 246.6 and 7.2 μM, and k_inact values of 0.29 and 0.03 min⁻¹, respectively.     

Preparation of the pure diastereomeric forms of S- (5′-deoxy-5′-adenosyl)-1-ammonio-4-methylsulfonio-2- cyclopentene and their evaluation as irreversible inhibitors of S-adenosylmethionine decarboxylase from Escherichia coli

The conformationally restricted S-adenosylmethionine analogue AdoMac (S-(5′-deoxy-5′-adenosyl)-1-ammonio-4-methylsulfonio-2-cyclopentene has been shown to act as an enzyme activated, irreversible inhibitor of theEscherichia coli form of the enzyme S-adenosylmethionine decarboxylase. Inactivation of the enzyme is presumably initiated by formation of an imine linkage between the inhibitor and the terminal pyruvate of the enzyme, followed by base-catalyzed elimination of methylthioadenosine and generation of a latent electrophile. Removal of the driving force for the elimination of methylthioadenosine resulted in a reversibly binding inhibitor. Thus, the thioether analogue corresponding to AdoMac, and the corresponding dihydro derivative (H₂-AdoMac), reversibly inhibit the enzyme. AdoMac was resolved into its four pure diastereomeric forms, and each diastereomer was evaluated as an irreversible inhibitor of the enzyme. The K_I values for the individual diastereomers range between 3.83 and 39.6 μM, with the cis-1S,4R diastereomer being the most potent inhibitor. However, the k_inact values for the four diastereomers are not significantly different, suggesting that the binding of each diastereomer to the enzyme is configuration-dependent, while the subsequent inactivation likely proceeds through a single intermediate which is formed from each of the four diastereomers. Since each pure diastereomer represents a distinct conformational mimic exhibiting restricted sidechain rotation, the data suggests that these and related analogues may be useful as conformational probes for the catalytic site of AdoMet-DC.     

Reduced Application of Nitrogen Fertilizer Affects the Carbon Metabolism of Leaves and Maintains the Number of Flowers in Coreopsis tinctoria

This study examined the effects of nitrogen (N) fertilizer reduction on the carbon (C) metabolism and yield of Coreopsis tinctoria. A two-year (2020–2021) hydroponic experiment was conducted in accordance with a randomized complete group design with five N levels [0.875 mM Ca(NO₃)₂ (N1), 1.750 mM Ca(NO₃)₂ (N2), 3.500 mM Ca(NO₃)₂ (N3), 7.000 mM Ca(NO₃)₂ (N4), and 14.000 mM Ca(NO₃)₂ (N5)] and three replications. The results showed that low N significantly affected the functional leaf weight, C metabolism, and flower bud (or flower) numbers of C. tinctoria at harvest. Lower-N levels, especially those of the N2 treatment, significantly increased Rubisco, sucrose synthase (SS), sucrose phosphate synthase (SPS), soluble acid invertase (SAI), glucose 6-phosphate dehydrogenase (G6PDH), and 6-phosphogluconate dehydrogenase (6PGDH) activity and maintained the flower number of C. tinctoria. In addition, the balance of carbohydrates (sucrose, starch, glucose, and fructose) and ATP contents was more efficiently maintained under relatively low-N levels. These findings might suggest that reduced application of N fertilizer affects the C metabolism of leaves and maintains the number of flowers in Coreopsis tinctoria. Applying relatively low-N fertilizer levels is also a promising cultivation strategy for C. tinctoria.

     

Steel Anti-Corrosion Strategy Enables Long-Cycle Zn Anode

The progress of aqueous zinc batteries (AZBs) is limited by the poor cycling life due to Zn anode instability, including dendrite growth, surface corrosion, and passivation. Inspired by the anti-corrosion strategy of steel industry, a compounding corrosion inhibitor (CCI) is employed as the electrolyte additive for Zn metal anode protection. It is shown that CCI can spontaneously generate a uniform and ≈30 nm thick solid-electrolyte interphase (SEI) layer on Zn anode with a strong adhesion via Zn O bonding. This SEI layer efficiently prohibits water corrosion and guides homogeneous Zn deposition without obvious dendrite formation. This enables reversible Zn deposition and dissolution for over 1100 h under the condition of 1 mA cm⁻² and 1 mAh cm⁻² in symmetric cells. The Zn-MnO₂ full cells with CCI-modified electrolyte deliver an ultralow capacity decay rate (0.013% per cycle) at 0.5 A g⁻¹ over 1000 cycles. Such an innovative strategy paves a low-cost way to achieve AZBs with long lifespan.     

Soil amendment with biochar and manure alters wood stake decomposition and fungal community composition

Biochar and manure can be used for sustainable land management. However, little is known about how soil amendments might affect surface and belowground microbial processes and subsequent wood decomposition. In a split-split-split plot design, we amended soil with two rates of manure (whole plot; 0 and 9 Mg ha⁻¹) and biochar (split plot; 0 and 10 Mg ha⁻¹). Wood stakes of three species (hybrid poplar, triploid Populus tomentosa Carr.; aspen, Populus tremuloides Michx.; and pine, Pinus taeda L.) were placed in two positions (horizontally on the soil surface, and inserted vertically in the mineral soil), which served as a substrate for fungal growth. In 3 years, the decomposition rate (density loss), moisture content, and fungal community (via high-throughput sequencing methods) of stakes were evaluated. Results indicated that biochar and/or manure increased the wood stake decomposition rates, moisture content, and operational taxonomic unit abundance. However, the richness and diversity of fungi were dependent on wood stake position (surface > mineral), species (pine > the two Populus), and sample dates. This study highlights that soil amendment with biochar and/or manure can alter the fungal community, which in turn can enhance an important soil process (i.e., decomposition).