植物质体基因工程调控元件研究进展

随着植物合成生物学的发展,质体逐渐成为许多具有商业价值的次生代谢产物和治疗性蛋白异源生产的理想平台。与核基因工程相比,质体基因工程在外源基因高效表达和生物安全性等方面具有其独特优势。然而,外源基因在质体系统中的组成型表达或对植物生长不利,因此需进一步挖掘、设计调控元件实现对外源基因的精准调控。本文概述了质体基因工程调控元件的研究进展,内容包括操纵子设计与优化思路、多基因共表达调控策略及新型表达调控元件的挖掘等,为植物合成生物学的发展提供参考。

Solute drag-controlled grain growth in magnesium investigated by quasi in-situ orientation mapping and level-set simulations

Critical properties of metallic materials,such as the yield stress,corrosion resistance and ductility depend on the microstructure and its grain size and size distribution.Solute atoms that favorably segregate to grain boundaries produce a pinning atmosphere that exerts a drag pressure on the boundary motion,which strongly affects the grain growth behavior during annealing.In the current work,the characteristics of grain growth in an annealed Mg-1 wt.%Mn-1 wt.%Nd magnesium alloy were investigated by advanced experimental and modeling techniques.Systematic quasi in-situ orientation mappings with a scanning electron microscope were performed to track the evolution of local and global microstructural characteristics as a function of annealing time.Solute segregation at targeted grain boundaries was measured using three-dimensional atom probe tomography.Level-set computer simulations were carried with different setups of driving forces to explore their contribution to the microstructure development with and without solute drag.The results showed that the favorable growth advantage for some grains leading to a transient stage of abnormal grain growth is controlled by several drivers with varying importance at different stages of annealing.For longer annealing times,residual dislocation density gradients between large and smaller grains are no longer important,which leads to microstructure stability due to predominant solute drag.Local fluctuations in residual dislocation energy and solute concentration near grain boundaries cause different boundary segments to migrate at different rates,which affects the average growth rate of large grains and their evolved shape.

Enhanced hydrodeoxygenation of lignin-derived anisole to arenes catalyzed by Mn-doped Cu/Al_(2)O_(3)

Lignin is a renewable carbon resource to produce arenes due to its abundant aromatic structures.For the liquid-phase hydrodeoxygenation(HDO)based on metallic catalysts,the preservation of aromatic rings in lignin or its derivatives remains a challenge.Herein,we synthesized Mndoped Cu/Al_(2)O_(3) catalysts from layered double hydroxides(LDHs)for liquid-phase HDO of lignin-derived anisole.Mn doping significantly enhanced the selective deoxygenation of anisole to arenes and inhibited the saturated hydrogenation on Cu/Al_(2)O_(3).With Mn doping increasing,the surface of Cu particles was modified with MnO_(x) along with enhanced generation of oxygen vacancies(Ov).The evolution of active sites structure led to a controllable adsorption geometry of anisole,which was beneficial for increasing arenes selectivity.As a result,the arenes selectivity obtained on 4Cu/8Mn4AlO_(x) was increased to be more than 6 folds of that value on 4Cu/4Al_(2)O_(3) over the synergistic sites between metal Cu and Ov generated on MnO_(x).

Interface tuning of Cu+/CuO by zirconia for dimethyl oxalate hydrogenation to ethylene glycol over Cu/SiO2 catalyst

An efficient ZrO2-doped Cu/SiO2 catalyst was fabricated through hydrolysis precipitation method(HP)and used to produce ethylene glycol(EG)through dimethyl oxalate(DMO)hydrogenation.The states for zirconia on copper catalyst and roles in DMO hydrogenation were investigated through various characterization tools,including N2 physical adsorption,XRD,H2-TPR,Methyl glycolate-TPD-MS,XPS,XAES as well.Compared with common ammonia evaporation and co-precipitation methods used in catalyst preparation,this HP method is found to effectively suppress the agglomeration and further size growth of copper nanoparticles by enhancing the interactions between copper and zirconia species.More importantly,uniform distribution of ZrO2 dopant is achieved due to the pseudo-homogeneous reactions in the mixing step of catalyst preparation.A proper amount of zirconium dopant helps achieve the desirable proportion of Cu+/(Cu++CuO)for surface copper species,especially promotes the production of Cu+species originated from Cu-ZrO2 species at the interface of copper and zirconia particles.In comparison with Cu+species formed from copper phyllosilicates reduction,the Cu+sites derived from Cu-ZrO2 species show higher adsorption ability of MG,an important intermediate species in ethylene glycol production.These adsorbed MG molecules further react with atomic hydrogen shifted from adjacent metallic copper surface,leading to a higher catalytic behavior.For the EG production via DMO hydrogenation,the turnover frequency(TOF)normalized by CuO species on CuZr/SiO2 catalyst is 1.8 times than that of traditional Cu/SiO2 counterpart.Due to the enhanced synergy effect between Cu+and Cuo active sites,a lower activation energy of ester hydrogenation on this ZrO2-doped Cu/SiO2 catalyst is believed to be responsible for the significant improvement.

Strategy for Synthesizing Novel Acetamidines as CO_2-Triggered Switchable Surfactants via Acetimidates

In this study, we developed a strategy for using the Scoggins procedure in the synthesis of acetamidines as novel C02-triggered switchable surfactants via acetimidates by effectively tuning the chemical equilibrium. The as-synthesized N'-alkyl-N,Ndiethylacetamidines exhibit excellent CO_2/N_2 switchability and their bicarbonate salts have the ability to emulsify oil-water mixtures.

Coupling effect of bifunctional ZnCe@SBA-15 catalyst in 1,3-butadiene production from bioethanol

A series of bifunctional Zn Ce@SBA-15 catalysts with different Zn/Ce ratios were prepared by a solid-state grinding strategy and used in the conversion of ethanol to 1,3-butadiene(ETB).For the supported metal oxides,Zn O serves as the active sites for the dehydrogenation of ethanol,and CeO_(2) promotes the aldolcondensation reaction.Based on the results of Py-FTIR and NH_(3)-TPD,it suggests that the yield of 1,3-butadiene is positively correlated with the number of weak Lewis acid sites on the catalyst surface,given their benefit for aldol-condensation reactions.The catalyst with an optimal Zn/Ce ratio of about 1:5 has the highest concentration of weak Lewis acid.Coupling with the Zn O sites,it contributes to a 98.4%conversion of ethanol and a 45.2%selective of 1,3-butadiene under relatively mild reaction conditions(375°C,101.325 k Pa,and 0.54 h^(-1)).

High-temperature CO_(2) sorbents with citrate and stearate intercalated Ca-Al hydrotalcite-like as precursor

CO_(2),one of the main components of greenhouse gases,increased rapidly because of the growing use of fossil fuels.And CaO sorbents possess the capability to be used in capture of CO_(2) at high temperature.In the work,Ca-Al complex oxides derived from citrate and stearate intercalated layered double hydroxides were fabricated and their CO_(2) adsorption capacity was compared with that from CO_(3)^(2-)intercalated layered double hydroxides.The results presented that the sorbents(Ca/Al=5)with Ca-Al-citrate layered double hydroxides as precursors performed best and displayed remarkable CO_(2) capture capacity of 52.0%(mass)at the carbonization temperature of 600℃without distinct recession during cycling adsorption/desorption tests.The excellent CO_(2) adsorption capacity of the sorbent was ascribed to its smaller crystallite size of calcinated particles,optimized pore size distribution as well as homogeneous distributed Ca and Al in the sorbent.

Kinetic effects of nanosecond discharge on ignition delay time

The effects of nanosecond discharge on ignition characteristics of a stoichiometric methane–air mixture without inert diluent gas were studied by numerical simulation at 0.1 MPa and an initial temperature of 1300 K. A modified non-equilibrium plasma kinetic model was developed to simulate the temporal evolution of particles produced during nanosecond discharge and its afterglow. As important roles in ignition, path fluxes of O and H radicals were analyzed in detail. Different strength of E/N and different discharge duration were applied to the discharge process in this study. And the results presented that a deposited energy of 1–30 m J·cm^(-3) could dramatically reduce the ignition delay time. Furthermore, temperature and radicals analysis was conducted to investigate the effect of non-equilibrium plasma on production of intermediate radicals. Finally, sensitivity analysis was employed to have further understanding on ignition chemistries of the mixture under nanosecond discharge.

Identification of the cytochrome P450s responsible for the biosynthesis of two types of aporphine alkaloids and their de novo biosynthesis in yeast

Aporphine alkaloids have diverse pharmacological activities;however,our understanding of their biosynthesis is relatively limited.Previous studies have classified aporphine alkaloids into two categories based on the configuration and number of substituents of the D-ring and have proposed preliminary biosynthetic pathways for each category.In this study,we identified two specific cytochrome P450 enzymes(CYP80G6 and CYP80Q5)with distinct activities toward(S)-configured and(R)-configured substrates from the herbaceous perennial vine Stephania tetrandra,shedding light on the biosynthetic mechanisms and stereochemical features of these two aporphine alkaloid categories.Additionally,we characterized two CYP719C enzymes(CYP719C3 and CYP719C4)that catalyzed the formation of the methylenedioxy bridge,an essential pharmacophoric group,on the A-and D-rings,respectively,of aporphine alkaloids.Leveraging the functional characterization of these crucial cytochrome P450 enzymes,we reconstructed the biosynthetic pathways for the two types of aporphine alkaloids in budding yeast(Saccharomyces cerevisiae)for the de novo production of compounds such as(R)-glaziovine,(S)-glaziovine,and magnoflorine.This study provides key insight into the biosynthesis of aporphine alkaloids and lays a foundation for producing these valuable compounds through synthetic biology.

Engineering the microenvironment of P450s to enhance the production of diterpenoids in Saccharomyces cerevisiae

Cytochrome P450 enzymes play a crucial role as catalysts in the biosynthesis of numerous plant natural products(PNPs).Enhancing the catalytic activity of P450s in host microorganisms is essential for the efficient production of PNPs through synthetic biology.In this study,we engineered Saccharomyces cerevisiae to optimize the microenvironment for boosting the activities of P450s,including coexpression with the redox partner genes,enhancing NADPH supply,expanding the endoplasmic reticulum(ER),strengthening heme biosynthesis,and regulating iron uptake.This created a platform for the efficient production 11,20-dihydroxyferruginol,a key intermediate of the bioactive compound tanshinones.The yield was enhanced by 42.1-fold through 24 effective genetic edits.The optimized strain produced up to 67.69±1.33 mg/L 11,20-dihydroxyferruginol in shake flasks.Our work represents a promising advancement toward constructing yeast cell factories containing P450s and paves the way for microbial biosynthesis of tanshinones in the future.

PRMT6 promotes tumorigenicity and cisplatin response of lung cancer through triggering 6PGD/ENO1 mediated cell metabolism

Metabolic reprogramming is a hallmark of cancer,including lung cancer.However,the exact underlying mechanism and therapeutic potential are largely unknown.Here we report that protein arginine methyltransferase 6(PRMT6)is highly expressed in lung cancer and is required for cell metabolism,tumorigenicity,and cisplatin response of lung cancer.PRMT6 regulated the oxidative pentose phosphate pathway(PPP)flux and glycolysis pathway in human lung cancer by increasing the activity of 6-phosphogluconate dehydrogenase(6PGD)and a-enolase(ENO1).Furthermore,PRMT6 methylated R324 of 6PGD to enhancing its activity;while methylation at R9 and R372 of ENO1 promotes formation of active ENO1 dimers and 2-phosphoglycerate(2-PG)binding to ENO1,respectively.Lastly,targeting PRMT6 blocked the oxidative PPP flux,glycolysis pathway,and tumor growth,as well as enhanced the antitumor effects of cisplatin in lung cancer.Together,this study demonstrates that PRMT6 acts as a posttranslational modification(PTM)regulator of glucose metabolism,which leads to the pathogenesis of lung cancer.It was proven that the PRMT6-6PGD/ENO1 regulatory axis is an important determinant of carcinogenesis and may become a promising cancer therapeutic strategy.

IFE based nanosensor composed of UCNPs and Fe(Ⅱ)-phenanthroline for detection of hypochlorous acid and periodic acid

Oxidizing CIO^(-)and IO_(4)^(-)exist widely in environment and are closely related to the health of organisms.Accordingly,fast,sensitive,and direct detection of the two species is significant.Using IFE in UCNPs@PAA and Fe(Ⅱ)-phenanthroline system,an elegant ratiometric fluorescent nanosensor,without noble metal nanoparticle,was designed for the detection of CIO-and IO4-.Fe(Ⅱ)-phenanthroline complex is used as fluorescent absorber,which can quench green light of UCNPs with gradually varied extent depending on the concentration of Fe(Ⅱ).The linear zone extends to 800 and 120μmol/L while the detection limit is 1.30 and 0.58μmol/L for NaCIO and NaIO_(4),respectively.Finally,the nanosensor was successfully applied to detect NaCIO and NaIO4spiked in milk,spring water,and tap water with good recoveries.

Reconstruction of Cu-ZnO catalyst by organic acid and deactivation mechanism in liquid-phase hydrogenation of dimethyl succinate to 1,4-butanediol

A reconstructed Cu-ZnO catalyst with improved stability was fabricated by organic acid treatment method for the liquid-phase hydrogenation of dimethyl succinate to 1,4-butanediol.According to the characterization results of the fresh Cu-ZnO and reconstructed Cu-ZnO,three different forms of ZnO were suggested to be presented on the catalysts:ZnO having strong interaction with Cu species,ZnO that weakly interacted with Cu species and isolated ZnO.The first form of ZnO was believed to be beneficial to the formation of efficient active site Cu^(+),while the latter two forms of ZnO took the main responsibility for the deactivation of Cu-ZnO catalysts in the liquid-phase hydrogenation of diesters.The reconstruction of the Cu-ZnO catalyst by the organic acid treatment method resulted in a new Cu-ZnO catalyst with more Cu^(+)and less ZnO species that leads to deactivation.Furthermore,the deactivation mechanism of Cu-ZnO catalysts in liquid-phase diester hydrogenation in continuous flow system was proposed:the deposition of the polyesters on the catalysts via transesterification catalyzed by weakly interacted ZnO and isolated ZnO leads to the deactivation.These results provided meaningful instructions for designing highly efficient Cu-Zn catalysts for similar ester hydrogenation systems.

Reductive amination of n-hexanol to n-hexylamine over Ni-Ce/γ-Al_(2)O_(3) catalysts

The amination of alkyl alcohols is one of the most promising paths in synthesis of aliphatic amines.Herein,cerium doped nickel-based catalysts were synthesized and tested in a gas-phase amination of n-hexanol to n-hexylamine.It was found that the activity of the Ni/γ-Al_(2)O_(3)catalyst is significantly improved by doping an appropriate amount of cerium.The presence of cerium effectively inhibits the agglomeration of nickel particle,resulting in better Ni dispersion.As Ni particle size plays critical role on the catalytic activity,higher turnover frequency of n-hexanol amination was achieved.Cerium doping also improves the reduction ability of nickel and enhances the interactions between Ni and the catalyst support.More weak acid sites were also found in those cerium doped catalysts,which promote another key step—ammonia dissociative adsorption in this reaction system.The overall synergy of Ni nanoparticles and acid sites of this Ni-Ce/γ-Al_(2)O_(3)catalyst boosts its superior catalytic performance in the amination of n-hexanol.

Regulating electronic environment on alkali metal-doped Cu@NS-SiO_(2) for selective anisole hydrodeoxygenation

Lignin utilization is a potential approach for replacing fossil energy and releasing the environment pressure.Herein,we synthesized a series of novel Cu-based catalysts,Cu@NS-SiO_(2)(NS=nano sphere)and alkali metals(Na,K,Rb,and Cs)doped Cu@NS-SiO_(2),and applied them in hydrodeoxygenation reaction of anisole.High Cu dispersion was presented on all catalysts.The modification of alkali metals on Cu@NS-SiO_(2) significantly enhanced the electron density of Cu sites in the following order:Cs>Rb>K>Na,among which Cs decreased the Cu_(2)p_(3)/2 binding energy most(by 0.7 eV).Moreover,the modification did not substantially affect the geometric structure of Cu species.This regulable electronic environment of Cu sites was crucial for selective deoxygenation and inhibiting the hydrogenation of aromatic rings in anisole,and thus promoted the selectivity of benzene.Compared with Cu@NS-SiO_(2)(~59%),the highest benzene selectivity was obtained on Cs/10Cu@NS-SiO_(2) at~83%.

高分辨率CT影像组学联合传统影像学征象预测肺腺癌微血管浸润的价值

目的探讨高分辨率CT(HRCT)影像组学联合传统影像学征象的综合模型预测肺腺癌微血管浸润的价值。方法回顾性分析2015年6月至2019年4月于青岛大学附属医院就诊的微血管浸润状态明确的肺腺癌患者65例(微血管浸润阳性30例、阴性35例),其中,男性33例、女性32例,年龄34~83(60.7±10.3)岁。以患者HRCT检查时间为编号,通过系统随机抽样方法将患者按约3∶1等距抽样分为2组:训练组46例,验证组19例。训练组用于模型的建立,验证组用于模型的效能评价。通过两独立样本t检验、χ2检验或Fisher确切概率法筛选训练组中微血管浸润阳性与阴性患者间差异有统计学意义的传统影像学征象。勾画2组患者的肿瘤三维感兴趣区并提取影像组学特征,通过单因素方差分析和Lasso-Logistic回归分析筛选训练组中有鉴别价值的最优影像组学特征,计算影像组学得分。通过Logistic回归分析构建联合影像组学得分和传统影像学征象预测肺腺癌微血管浸润的综合模型,并绘制列线图,进行效能评价。结果共提取影像组学特征1308个,最终得到6个最优影像组学特征。传统影像学征象中仅肿瘤最大径在微血管浸润阳性与阴性患者间的差异有统计学意义[(28.10±11.39)mm对(22.32±6.26)mm;t=5.580,P=0.035],其在训练组中的曲线下面积(AUC)为0.648(95%CI:0.493~0.783)、灵敏度为38.1%、特异度为88.0%;在验证组中的AUC为0.783(95%CI:0.538~0.936)、灵敏度为88.9%、特异度为70.0%。预测肺腺癌微血管浸润的综合模型在训练组中的AUC为0.880(95%CI:0.750~0.957),灵敏度为90.5%,特异度为72.0%;在验证组中的AUC为0.811(95%CI:0.568~0.951),灵敏度为88.9%,特异度为80.0%。结论基于HRCT影像组学联合传统影像学征象的综合模型对肺腺癌微血管浸润具有较高的预测价值,有助于肺腺癌患者的术前评估。

RuCl_3 anchored onto post-synthetic modification MIL-101(Cr)-NH_2 as heterogeneous catalyst for hydrogenation of CO_2 to formic acid

A series of efficient ruthenium chloride (RuCl_3)-anchored MOF catalysts,such as RuCl_3@MIL-101 (Cr)-Sal,and RuCl_3@MIL-101 (Cr)-DPPB, have been successfully synthesized by post-synthetic modification (PSM)of the terminal amino of MIL-101(Cr)-NH_2 with salicylaldehyde, 2-diphenylphosphinobenzaldehyde (DPPBde) and anchoring of Ru (Ⅲ) ions. The stronger coordination electron donor interaction between Ru (Ⅲ) ions and chelating groups in the RuCl_3@MIL-101 (Cr)-DPPB enhances its catalytic performance for CO_2 hydrogenation to formic acid. The turnover number (TON) of formic acid was up to 831 in reaction time of 2 h with dimethyl sulfoxide (DMSO) and water (H_2O) as mixed solvent, trimethylamine (Et_3N) as organic base, and PPh_3 as electronic additive.

New ZnCe catalyst encapsulated in SBA-15 in the production of 1,3-butadiene from ethanol

ZnO-CeO2/SBA-15 catalysts were prepared by two kinds of solid-state grinding method and used for the production of 1,3-butadiene(1,3-BD) from ethanol.A mixture of SBA-15(with or without organic template) and metal precursors were ground in solid-state.The obtained catalysts were characterized by TG,N2 adsorption-desorption,TEM,XRD,Py-FTIR and NH_3-TPD techniques.Superior dispersion of metal oxides and more exposed acid sites were achieved on the catalyst lOZn_1Ce_5-AS with the presence of organic template in SBA-15 during the solid-state grinding process.The catalytic performance was evaluated in a fixed-bed reactor and a 1,3-butadiene selectivity of as high as 45% is achieved.This is attributed to the coupling effect of Zn and Ce species in the mesopores of SBA-15,in which Zn promotes ethanol dehydrogenation and Ce enhances aldol-condensation,respectively.Additionally,solvent-free method inspires new catalyst synthesis strategy for the production of 1,3-butadiene from ethanol.

Molecular cloning and functional identification of sterol C24-methyltransferase gene from Tripterygium wilfordii

Sterol C24-methyltransferase(SMT) plays multiple important roles in plant growth and development. SMT1, which belongs to the family of transferases and transforms cycloartenol into 24-methylene cycloartenol, is involved in the biosynthesis of 24-methyl sterols. Here, we report the cloning and characterization of a cDNA encoding a sterol C24-methyltransferase from Tripterygium wilfordii(Tw SMT1). Tw SMT1(Gen Bank access number KU885950) is a 1530 bp cDNA with a 1041 bp open reading frame predicted to encode a 346-amino acid, 38.62 k Da protein. The polypeptide encoded by the SMT1 cDNA was expressed and purified as a recombinant protein from Escherichia coli(E. coli) and showed SMT activity. The expression of Tw SMT1 was highly up-regulated in T. wilfordii cell suspension cultures treated with methyl jasmonate(Me JA). Tissue expression pattern analysis showed higher expression in the phellem layer compared to the other four organs(leaf, stem, xylem and phloem), which is about ten times that of the lowest expression in leaf. The results are meaningful for the study of sterolbiosynthesis of T. wilfordii and will further lay the foundations for the research in regulating both the content of other main compounds and growth and development of T. wilfordii.

酯加氢制乙二醇/乙醇高效铜基催化剂的构筑

酯加氢反应是由合成气制高附加值大宗含氧化学品的关键步骤之一,也是天然油脂、生物质衍生物等转化利用的关键环节.铜基催化剂因其良好的C=O/C–O键选择性加氢性能被广泛应用于酯加氢反应中,受到了越来越多的关注.本文重点综述了近几年铜基催化剂在酯加氢催化作用机制与构效关系解析方面的最新进展,探讨了催化剂构筑策略及其反应-吸附-扩散耦合作用规律,介绍了催化剂的工业实践及发展方向.