D-box附近泛素化位点突变对Cdc20介导的Sp100蛋白降解的影响

前期的研究发现Cdc20介导Sp100通过泛素-蛋白酶体途径降解,Sp100中的D-box在底物识别过程中具有重要作用.尽管在PML和DAXX中都存在典型的D-box序列,但是这两种蛋白都不能被Cdc20所识别.本研究中,我们构建了一系列含D-box的Sp100截断体来探讨Cdc20底物识别的必要序列.研究发现GFP-Sp100(152-182)截断体包含D-box但是不能被APC/C-Cdc20降解.GFP-Sp100(151K→G)突变潜在泛素结合位点后,Sp100降解显著受到抑制.远离D-box的潜在泛素化位点(217K,219K,225K)破坏后对Sp100降解没有影响.我们的结果表明,Sp100蛋白中D-box附近泛素化位点(151K)在Cdc20介导的蛋白降解中是必要的.     

CdCl2通过破坏PML-NBs结构和促进PML降解诱导细胞凋亡

PML核体(PML-NBs)是一种相对稳定的结构,但其数目、大小和位置在细胞压力下可发生显著改变.如热休克及重金属会导致PML-NBs裂解成数目众多的小点.DNA损伤试剂,如Cisplatin和Alkylating试剂也可导致PML-NBs分散成更小的小体,甚至呈现一种弥散的状态.虽然先前的研究试图解释这些压力状态下PML-NBs的表型变化,但其机制仍知之甚少.在最近的研究中,我们用CdCl2处理Hela细胞,发现PML-NBs的稳定结构遭到破坏而弥散在整个细胞核中,有趣的是,部分PML蛋白迁徙到胞浆之中并与泛素蛋白共定位,进而引起PML蛋白的降解,最终使得PML-NBs无法恢复而诱导细胞发生凋亡.本研究为进一步认识PML和PML-NBs的功能提供了证据,也将对化学治疗药物的筛选有所帮助.     

体外APC/C活性体系的建立及其影响因素的研究

为获得具有细胞周期后期促进复合物(APC/C)活性的细胞裂解液并建立APC/C体外活性检测体系,以其底物Cyc-lin B及Securin的降解为检测指标,分别从细胞阻滞于有丝分裂期的时间,UBCH10(APC/C的E2酶)的浓度以及裂解液浓度等几个方面研究了各种处理因素对APC/C活性的影响,并且用体外翻译底物验证了其活性及相关结论。此项工作为进一步探索APC/C相关分子事件奠定了基础。     

TNF-α通过提高PML蛋白的表达及其SUMO化水平来促进PML-NBs形成

PML-NBs是一个动态的结构,这种结构在正常情况下趋于稳态,当在细胞应激反应状态下,核体的结构和位置都发生明显的变化.不同类型的基因毒性压力对PML-NBs的影响也各不相同,例如,UV照射或热休克处理,PML-NBs迅速地进行微斑重建,而IFN的刺激可以促进PML-NBs结构的稳固.先前的研究试图解释这些表型,然而不同压力下PML微结构的改变机理仍不完全明了.在最近的研究中,我们发现TNF-α可以诱导Hela细胞产生数目更多的PML-NBs,同时,TNF-α限制了Hela细胞内的PML蛋白被高表达的Ubiquitin诱导出核.进一步研究揭示,TNF-α是通过提高PML的表达及其SUMO化水平来促进PML-NBs形成,我们的研究为进一步探索PML和PML-NB的功能提供了证据,也将对化学治疗药物的筛选有所帮助.     

体外反应体系中APC/C活性及相关研究

为获得具有细胞周期后期促进复合物（APC/C）活性的细胞裂解液并建立APC/C体外活性检测体系,以其底物Cyclin B及Securin的降解为检测指标,分别从细胞阻滞于有丝分裂期的时间, UBCH10（APC/C的E2酶）的浓度以及裂解液浓度等几个方面研究了各种处理因素对APC/C活性的影响,并且用体外翻译底物验证了其活性及相关结论。此项工作为进一步探索APC/C相关分子事件奠定了基础。     

Degron——细胞蛋白的快速降解及可逆调控技术

蛋白质的正常表达及降解对维持细胞功能平衡至关重要,当蛋白质功能异常或生物合成等发生错误时,会被识别、标记并被迅速降解,从而保证细胞生存环境的稳定.细胞内的蛋白降解,依赖于蛋白酶体系统对特定氨基酸序列或构象变化的识别.利用这一特性,近年来建立了一种快速并可逆诱导体内蛋白降解的技术——蛋白降解子(Degron).通过与目的基因进行融合,Degron可以靶向调控几乎任何蛋白的表达,成为研究蛋白功能及信号传导等细胞分子机制的利器.本文综述了这一技术的原理和发展概况,并介绍了几种成熟的Degron系统.     

TRAPP复合物与自噬关系的研究进展

转运蛋白颗粒(TRAPP)是一种高度保守的多亚基蛋白复合物，参与囊泡运输、细胞自噬等过程.细胞自噬是真核生物中高度保守的降解和循环通路，在维持细胞稳态和应对环境压力中起着重要作用.近年来，TRAPP复合物与自噬关系的研究较为广泛，研究表明多个TRAPP复合物亚基参与自噬过程，且TRAPP复合物不同亚基的突变或缺失也与多种人类疾病有关.对TRAPP复合物参与调控细胞自噬机制的深入研究有助于了解一些人类疾病的发生和发展.     

我国科学家揭示全新DNA复制起始位点调控机制

<正>DNA复制是一个确保遗传信息精确传递的生命过程。细胞在DNA合成前期G1期时,复制起始识别复合物识别染色质上的复制位点,进一步招募DNA解旋酶MCM(Minichromosome maintenance)等,形成复制前体复合物,完成复制起始位点的认证。而当细胞进入复制期S期时,被认证的复制起始位点被选择性地激活使用。真核生物DNA复制起始位点的选择受DNA序列和表观遗传因素共同调控。目前,表观遗传因素对染色质上DNA复制起始位点的选择机制仍然不清楚。     

人源m6A甲基转移酶复合物METTL3-METTL14的表达、纯化和透射电镜观察

N⁶-腺苷酸甲基化(m⁶A)是一种重要的mRNA和长链非编码RNA的内部修饰方式，通过影响RNA代谢的各个方面，参与调控人体一系列生理过程。METTL3和METTL14组成的甲基转移酶复合物可以有效地催化甲基基团的转移，但其具体的催化机制尚不完全清楚。本研究通过进行蛋白质结构无序度分析及三维模型预测发现，二者除MTD结构域外其他区域基本处于无序或低复杂度状态。为了进一步探索METTL3-METTL14复合物实现甲基基团转移的结构基础，本研究在哺乳动物细胞HEK293S GnTI^-中成功表达了全长序列的人源METTL3-METTL14蛋白复合物，并通过镍柱亲和层析、离子交换及凝胶过滤层析获得了高纯度的METTL3-METTL14蛋白复合物，并推测全长METTL3和METTL14以1∶1的比例组成复合物。通过120 kV透射电子显微镜观察发现，蛋白颗粒大小均一，颗粒直径在10～12 nm。     

细胞凋亡与DNA裂解因子研究进展

DNA裂解因子(DNA fragmentation factor,DFF)也叫CAD(caspase-activated DNase),是细胞凋亡执行和调控过程中起重要作用的蛋白质之一。DFF是由40 kDa和45 kDa两个蛋白亚基组成,分别被称为DFF40/CAD和DFF45/ICAD(inhibitor of caspase-activated Dnase),DFF45是caspases-3的底物,当凋亡信号激活caspases-3,后者识别切割位点并对复合物进行切割时,可以导致DFF45与DFF40之间的作用区域的破坏,继而使DFF40从复合物中快速游离出来而活化,被释放的DFF40形成催化性的活化的同型低聚物,降解染色体DNA。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that