Rab27在消化系统肿瘤中的研究进展

Rab蛋白是一类小分子GTP结合蛋白,属于Ras蛋白超家族。目前,已经发现的Rab蛋白家族成员有70多个,广泛分布在多种生物细胞内不同的膜结构上,作为囊泡运输、蛋白质运输、膜靶向和融合的调节器,参与调节细胞生长、程序性死亡或凋亡。异常调控的Rab蛋白可通过破坏细胞膜运输、关键细胞信号通路和特殊分泌通路的稳态,进而影响癌症的细胞生理学。Rab27家族属于Rab蛋白家族,包括Rab27A和Rab27B两种亚型,二者具有相似但不相同的功能。Rab27A及Rab27B不但是调节囊泡运输的重要分子,而且与多种肿瘤的生长和侵袭转移有着紧密的联系,在肿瘤的治疗中可以作为治疗靶点和预后标志物。Rab27在肿瘤的发生发展中发挥重要作用。本文就Rab27在消化系统肿瘤中的研究进展进行综述。

稳定表达MVA途径基因提高番茄红素产量

萜类化合物的直接前体物质异戊烯焦磷酸(IPP)和二甲基烯丙基焦磷酸酯(DMAPP)可以由2-甲基-D-赤藻糖醇-4-磷酸途径(MEP途径)和甲羟戊酸途径(MVA途径)合成。在已经优化MEP合成途径、番茄红素合成途径关键基因表达的重组大肠杆菌LYC101中,引入MVA途径基因,进一步提高重组大肠杆菌合成萜类化合物的能力。质粒pALV23和pALV145是本实验室在研究MVA途径基因协调表达时,用核糖体结合位点(RBS)文库连接MVA途径各基因构建质粒文库,而筛选到的有效提高β-胡萝卜素产量的质粒。首先比较了两个质粒分别在低产和高产番茄红素的菌株中对番茄红素合成的影响。结果表明,两个质粒在高、低产番茄红素的菌株中都可以有效提高番茄红素产量。在高产菌LYC101中pALV23比pALV145使番茄红素产量更高。然后,用CRISPR-Cas9系统辅助同源重组的方法,将MVA途经基因和启动子一共6.7kb的条带整合到LYC101菌株的染色体上,得到遗传稳定的菌株LYC102。LYC102的番茄红素产率达40.9mg/g,是出发菌株LYC101产率的2.19倍,比用质粒表达MVA途径基因的菌株提高了20%。在重组大肠杆菌中同时表达MVA途径和MEP途径,可以有效提高萜类化合物产率;文中构建了不含质粒的、遗传稳定的高产番茄红素菌株,为产业化合成番茄红素提供基础;同时构建平台菌株,可以用于其他萜类化合物合成。

甲羟戊酸途径限速步骤研究及其在产番茄红素重组大肠杆菌中的应用

甲羟戊酸途径(MVA途径)被引入重组大肠杆菌中,能够提高重组大肠杆菌中萜类化合物的合成能力。但因重组大肠杆菌中萜类化合物合成途径中间产物积累,导致细胞生长和萜类化合物合成受到限制。本研究在稳定表达MVA途径以及优化2-甲基-D-赤藻糖醇-4-磷酸途径(MEP途径)、番茄红素合成途径关键基因表达的重组大肠杆菌LYC103中,用质粒高表达MVA途径和番茄红素合成途径关键基因,挖掘该途径的限速步骤。结果表明,ispA、crtE、mvaK1、idi和mvaD基因过表达后,细胞生长没有明显变化,番茄红素产量依次提高了13.5%、16.5%、17.95%、33.7%和61.1%,说明这几个基因可能是合成番茄红素的限速步骤。mvaK1、mvaK2、mvaD三个基因在同一操纵子上,用mRNA稳定区(RNA stabilizing region)进行启动子文库(mRSL)调控mvaK1,相当于对3个基因同时调控。用高效基因组编辑技术(CAGO)对mvaK1基因的mRNA稳定区进行启动子文库的调控,得到菌株LYC104。番茄红素产量与对照菌株LYC103相比增加了2倍,细胞生长提高了32%。然后,利用CRISPR-Cas9技术在染色体lacZ位点整合idi基因,得到LYC105菌株。与出发菌株LYC103相比,细胞生长提高了147%,番茄红素产量增加了2.28倍。本研究在染色体上具有完整MVA途径的基础上,利用质粒高表达单个基因挖掘限速步骤,用同源重组方法整合限速基因、解除限速,为代谢工程构建高产菌株提供新策略。

Ultraviolet-to-microwave room-temperature photodetectors based on three-dimensional graphene foams

Highly sensitive broadband photodetection is of critical importance for many applications.However,it is a great challenge to realize broadband photodetection by using a single device.Here we report photodetectors(PDs)based on three-dimensional(3 D)graphene foam(GF)photodiodes with asymmetric electrodes,which show an ultra-broadband photoresponse from ultraviolet to microwave for wavelengths ranging from 10~2 to 10~6 nm.Moreover,the devices exhibit a high photoresponsivity of 10~3 A·W^-1,short response time of 43 ms,and3 d B bandwidth of 80 Hz.The high performance of the devices can be attributed to the photothermoelectric(PTE,also known as the Seebeck)effect in 3 D GF photodiodes.The excellent optical,thermal,and electrical properties of 3 D GFs offer a superior basis for the fabrication of PTE-based PDs.This work paves the way to realize ultra-broadband and high-sensitivity PDs operated at room temperature.

Characterizing the rock geological time by terahertz spectrum

In the field of geology,it is necessary to get the information about the rock geological time,which includes absolute geologic age and relative geologic age .Tracing the evolutionary history of the earth is one of the research tasks of earth science.Time,space,material and motivation are the basic elements for studying geological processes and enviromnental evolution,and time is the basis for studying geological problems.A clear understanding of the interaction between the above elements will be able to clearly make sure the evolution of the earth and the conditions of rock formation.Nowadays,it is urgent to get the geochronological data of rocks for wide range comparison,so as to study the evolution trend and development rule of the earth's crust .

Self-powered,flexible,and ultrabroadband ultraviolet-terahertz photodetector based on a laser-reduced graphene oxide/CsPbBr3 composite

Self-powered and flexible ultrabroadband photodetectors(PDs)are desirable in a wide range of applications.The current PDs based on the photothermoelectric(PTE)effect have realized broadband photodetection.However,most of them express low photoresponse and lack of flexibility.In this work,high-performance,self-powered,and flexible PTE PDs based on laser-scribed reduced graphene oxide(LSG)∕CsPbBr3 are developed.The comparison experiment with LSG PD and fundamental electric properties show that the LSG∕CsPbBr3 device exhibits enhanced ultrabroadband photodetection performance covering ultraviolet to terahertz range with high photoresponsivity of 100 mA/W for 405 nm and 10 mA/W for 118μm at zero bias voltage,respectively.A response time of 18 ms and flexible experiment are also acquired at room temperature.Moreover,the PTE effect is fully discussed in the LSG∕CsPbBr3 device.This work demonstrates that LSG∕CsPbBr3 is a promising candidate for the construction of high-performance,flexible,and self-powered ultrabroadband PDs at room temperature.

Environment-friendly antisolvent tert-amyl alcohol modified hybrid perovskite photodetector with high responsivity

The preparation of high-quality perovskite films with optimal morphologies is important for achieving highperformance perovskite photodetectors(PPDs). An effective strategy to optimize the morphologies is to add antisolvents during the spin-coating steps. In this work, a novel environment-friendly antisolvent tert-amyl alcohol(TAA) is employed first to improve the quality of perovskite films, which can effectively regulate the formation of an intermediate phase staged in between a liquid precursor phase and a solid perovskite phase due to its moderate polarity and further promote the homogeneous nucleation and crystal growth, thus leading to the formation of high-quality perovskite films and enhanced photodetector performance. As a result, the responsivity of the PPD reaches 1.56 A/W under the illumination of 532 nm laser with the power density of 6.37 μW=cm^(2) at a bias voltage of -2 V, which is good responsivity for PPDs with the vertical structure and only CH_(3)NH_(3)PbI_(3) perovskite as the photosensitive material. The corresponding detectivity reaches 1.47×10^(12) Jones, while the linear dynamic range reaches 110 dB. These results demonstrate that our developed green antisolvent TAA has remarkable advantages for the fabrication of high-performance PPDs and can provide a reference for similar research work.

Magnetic property recovery in Nd-Fe-B bonded magnet wastes with chemical reaction and physical dissolution

The main difficulty for the recovery of Nd-Fe-B bonded magnet wastes is how to completely remove the epoxy resins.In this study,chemical reaction and physical dissolution were combined to remove the epoxy resins by adding ammonia-water and mixed organic solvents.Ammonia-water can react with the epoxy functional group of epoxy resin to generate polyols.Mixed organic solvents of alcohol,dimethyl formamide(DMF),and tetrahydrofuran(THF) can dissolve the generated polyols and residual epoxy resins.Under the optimum processing conditions,the epoxy resins in the waste magnetic powders are substantially removed.The oxygen and carbon contents in the recycled magnetic powder are reduced from 13500 × 10^(-6) to 1600 × 10^(-6) and from 19500 × 10^(-6) to 2100 × 10^(-6) with the reduction ratio of88.1% and 89.2%,respectively.The recycled magnetic powder presents improved magnetic properties with MS of 1.306 × 10^(-1) A·m^(2)/g,Mr of 0.926 × 10^(-1) A·m^(2)/g,Hcj of 1.170 T,and(BH)max of 125.732 kJ/m^(3),which reach 99.8%,99.4%,95.9%,and 96.9% of the original magnetic powders,respectively.

Self-powered lead-free quantum dot plasmonic phototransistor with multi-wavelength response

Because they possess excellent visible light absorption properties, lead-free colloidal copper-based chalcogenide quantum dots(QDs) have emerged in photoelectronic fields. By means of localized surface plasmonic resonance(LSPR), the absorption properties of QDs can be enhanced. In this paper, we fabricate a lead-free CuInSe2 QD field effect phototransistor(FEpT) by utilizing the LSPR enhancement of Au nanoparticles(NPs). The plasmonic FEpT demonstrates responsivity up to 2.7 μA· W^(-1) and a specific detectivity of 7 × 10~3 Jones at zero bias under illumination by a 532 nm laser, values that are enhanced by approximately 200% more than devices without Au NPs. Particularly, the FEpT exhibits a multi-wavelength response, which is photoresponsive to 405, 532,and 808 nm irradiations, and presents stability and reproducibility in the progress of ON–OFF cycles.Furthermore, the enhancement induced by Au NP LSPR can be interpreted by finite-difference time domain simulations. The low-cost solution-based process and excellent device performance strongly underscore leadfree CuInSe2 QDs as a promising material for self-powered photoelectronic applications, which can be further enhanced by Au NP LSPR.