大麦黄花叶病毒抗性突破株系的分子变异

通过大麦黄花叶病毒(BaYMV)抗性突破株系的核酸RNA1全序列分析并与野生株系比较表明.抗性突破株系在病毒复制酶或转运蛋白区域(6K2)和核酸RNA复制酶区域(NIb)存在二个变异位点.在这二个位点上抗性突破株系核酸分子编码的氨基酸分别为脯氨酸(Pro)和苏氨酸(Fhr),而野生株系分别为缬氨酸(Val)和丙氨酸(Ala).对该两种酶蛋白质二级结构分析显示,氨基酸的变异可能导致了蛋白质的结构、功能与性质的改变,并且此种变异与抗BaYMV冬大麦中抗性基因ym4的功能丧失有关,同时也说明了大麦品种田间致病性的差异与病毒核酸分子中的点突变关系密切.     

大麦黄花叶病毒抗性突破株系的分子变异

通过大麦黄花叶病毒 (Ba YMV)抗性突破株系的核酸 RNA1全序列分析并与野生株系比较表明 ,抗性突破株系在病毒复制酶或转运蛋白区域 (6K2 )和核酸 RNA复制酶区域 (NIb)存在二个变异位点 .在这二个位点上抗性突破株系核酸分子编码的氨基酸分别为脯氨酸 (Pro)和苏氨酸 (Thr) ,而野生株系分别为缬氨酸(Val)和丙氨酸 (Ala) .对该两种酶蛋白质二级结构分析显示 ,氨基酸的变异可能导致了蛋白质的结构、功能与性质的改变 ,并且此种变异与抗 Ba YMV冬大麦中抗性基因 ym4的功能丧失有关 ,同时也说明了大麦品种田间致病性的差异与病毒核酸分子中的点突变关系密切 .     

八氢番茄红素脱氢酶的分子结构及其与达草灭相互作用分析

八氢番茄红素脱氢酶(Phytoene desaturase,PDS)是除草剂达草灭的靶点,作者对野生型和两种定点突变型PDS的二维和三维结构进行预测,并通过DOCK6.5进行PDS与达草灭的分子对接比较,利用Gromacs进行分子动力学模拟,使用Amber9中的mm_pbsa.pl分析能量分布及变化,使用LIGPLOT+软件进行氢键分析确认结合氨基酸位点.结果表明突变对二维和三维结构无影响,但是在达草灭存在的情况下,突变的PDS有更高的结合能以及更弱的结合稳定性,更难以与达草灭结合,找到突变PDS蛋白对达草灭具有抗性的分子证据.     

N端延长对大肠杆菌铁蛋白结构稳定性及其自组装的影响

【目的】研究延长的N端肽链对铁蛋白结构稳定性及蛋白自组装的影响,为在N端融合生物分子构建功能性纳米材料奠定基础。【方法】在大肠杆菌铁蛋白N端添加6个组氨酸残基,所得重组蛋白采用体积排阻色谱、非变性凝胶电泳和圆二色谱等手段与野生型铁蛋白的聚合态、二级结构及热力学稳定性进行对比分析。【结果】体积排阻色谱表明野生型铁蛋白在溶液中以24聚体和二聚体混合物形式存在,但突变蛋白仅以二聚体的形式存在; 非变性凝胶电泳实验结果与体积排阻色谱结果吻合,即突变蛋白仅显示1条带,且与野生型铁蛋白的2聚体迁移位置基本相同; 圆二色谱结果表明突变蛋白的二级结构与野生型类似,呈典型的α-螺旋结构,突变蛋白的T_m值比野生型降低了1.1 ℃。【结论】在大肠杆菌铁蛋白亚基的N端增加6个组氨酸残基所得突变蛋白的二级结构没有发生明显变化,但却无法形成24聚体壳状结构,在溶液中仅以二聚体的形式存在,且热力学稳定性有所降低。N端的延长可能导致铁蛋白单体构型发生改变,因而无法进一步组装成壳状结构。     

同源建模方法预测蛋白质突变结构的适用性分析

通过从Protein Data Bank(PDB)结构数据库中提取单氨基酸突变的晶体结构,构建了一组无冗余的测试数据集,对目前应用最广泛的两款同源建模预测软件(SWISS-MODEL和MODELLER)进行了测试分析,发现它们对蛋白质的整体结构预测效果良好,均方根偏差小于0.5埃(RMSD0.5),但在突变导致结构显著变化(RMSD1.5)的情况下却均不能得到准确结果.分类统计显示,发生在蛋白质结构内部和极性氨基酸之间的突变结构变化小,两款软件预测效果较好(RMSD1.0).突变导致结构显著变化的可能性不高(5%),但它对蛋白质功能的影响不可忽视,因此应用同源建模方法对于蛋白质突变的模拟并不完全适用,还需要开发新方法来提高准确性.     

LEA蛋白质11-氨基酸基序与植物抗旱性

分析了8种重要农作物第三组LEA蛋白质序列中的94个11-氨基酸基序.得出一致性序列为TAEAAKQKAGE.LEA 3蛋白质中11-氨基酸基序呈多拷贝串联排列,其长度占蛋白质序列总长度的40%～60%.带电荷/ 极性氨基酸和疏水氨基酸数目分别占重复序列氨基酸总数的70.89%和29.11%.11-氨基酸基序的二级结构多呈α-螺旋结构.其中第1,2,4,5,9位疏水氨基酸形成螺旋蛋白质分子的疏水界面,其余位置的氨基酸形成螺旋分子的亲水界面.LEA 3蛋白质全序列平均亲水指数为-0.95～-1.22.无信号肽序列.8种LEA 3蛋白分子的上述特性与植物的抗旱性有关.     

大阪鲫鱼两种卵黄蛋白紫外吸收特性的研究

采用大柱制备电泳的办法从大阪鲫鱼卵巢中提纯出两种蛋白质:卵黄脂磷蛋白和类似于卵黄高磷蛋白的卵黄蛋白L。分析了两种蛋白的氨基酸组成,并对两种蛋白的紫外吸收和紫外吸收四阶导数谱特性进行了分析研究。发现卵黄脂磷蛋白在溶液的pH改变(pH3.12-8.12-11.00)时。紫外吸收谱和四阶导数谱未发生明显变化,而卵黄蛋白L在溶液的pH改变(pH7,66-9,35-11,89)时,其紫外吸收谱最大吸收波长红移,紫外吸收四阶导数谱出现新的未知峰,发生显著变化。这表明卵黄脂磷蛋白所含的大量脂类存在于蛋白质分子的表面,从而影响了蛋白质分子中产生紫外吸收的氨基酸—酪氮酸、色氨酸、苯丙氨酸的紫外吸收。在卵黄蛋白L中,这几种氨基酸则位于蛋白质分子的表面,从而对溶液pH的变化尤为敏感。     

血红蛋白变异体(β15Trp→Leu)的功能与结构

目的 :用基因工程菌制造血红蛋白变异体 (β15Trp→Leu) ,并测定其生物功能 ,探讨血红蛋白分子结构与功能的关系 .方法 :通过对质粒pHE7的DNA分子操作用中性氨基酸Leu取代β15Trp ,利用层析分离技术等把血红蛋白变异体从基因工程菌中提取纯化出来 ,在确定其为目标蛋白质后进行稳定性、亲氧力与协同变构效应能力的测定 ,并对变异体生物功能特性进行分子结构的分析 .结果 :血红蛋白变异体 (β15Trp→Leu)结构稳定 ,与正常血红蛋白比较 ,亲氧力增强 ,协同变构效应能力下降 .结论 :β15Trp在血红蛋白分子结构中相当重要 ,由其与对应的氨基酸所形成的氢键与蛋白分子的生物功能关系密切 ,该氢键的失去使血红蛋白改变正常功能 ,亲氧力增强 ,协同变构效应能力下降 .     

红尾沙蜥鸟氨酸脱羧酶1高原适应的分子机理

运用基因组学、转录组学、分子进化和计算生物学等分析方法对红尾沙蜥鸟氨酸脱羧酶1(ODC1)基因结构、表达量、正选择位点以及蛋白质理化性质和结构展开研究,旨在阐明ODC1基因在沙蜥属不同海拔物种中的表达模式和在高海拔红尾沙蜥中低氧适应的分子机理.结果显示,ODC1基因在红尾沙蜥4个组织中的表达量约为荒漠沙蜥的2.25、 1.14、 2.51和4.82倍,其中在肝脏、脑和心脏组织中的表达量显著高于荒漠沙蜥.红尾沙蜥ODC1蛋白质的总平均亲水性系数和不稳定性系数分别为-0.122和46.51,较荒漠沙蜥亲水性更高、结构更稳定.红尾沙蜥ODC1蛋白质位于β/α桶状结构域的222Gly→Ala(潜在的正选择位点)和228Ser→Asn两个突变使得该区域结构更紧凑,并使得蛋白质活性中心体积由荒漠沙蜥的0.734 3 nm³增大到红尾沙蜥的0.744 8 nm³,且活性中心亲水性增大.位于β层片结构域的446Ile→Met氨基酸突变使得该区域的无规则卷曲被α螺旋取代,蛋白质稳定性增强.红尾沙蜥ODC1基因表达量的显著上调和氨基酸突变导致的蛋白质结构稳定性增...     

不同折叠类型蛋白中基于密码子的二级结构偏向性分析

在传统的Chou-Fasman蛋白质二级结构预测方法的基础上引入同义密码子使用的信息,计算了200个蛋白(49种全α结构蛋白,69种全β结构蛋白,38种仅α β结构蛋白,44种α/β结构蛋白)中不同密码子对应的氨基酸形成不同二级结构(α：螺旋,β：折叠,C：卷曲)的偏向性参数．通过对这些密码子对应氨基酸二级结构偏向性的分析,得到了氨基酸二级结构偏向性分析中所忽略的同义密码子的蛋白结构信息．这些新的信息量对于指导蛋白质设计以及提高蛋白质二级结构预测的准确率有着一定的作用．     

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