非整倍体和人类生殖健康

非整倍体即染色体数目异常,发生于生殖细胞则可能导致不育不孕、自发流产和先天出生缺陷.精子非整倍体发生率为5%～7%,卵子非整倍体发生率为22%～90%;在早期自然流产中,非整倍体率高达50%.绝大多数临床上常见的非整倍体患儿的异常染色体来自卵子(母亲),而且母亲减数分裂I同源染色体不分离是除13和18号染色体以外的各种常见染色体非整倍体的主要原因.母亲的年龄是迄今唯一被证实的与生殖细胞非整倍体发生密切相关的流行病学因素,减数分裂遗传重组(频率和位点分布)异常可能是导致减数分裂I同源染色体不分离的主要细胞学和遗传学因素,减数分裂前最后一次DNA复制时cohesin复合体的加载及其之后的维持异常则可能是引起减数分裂染色体不分离的分子生物学因素.减数分裂遗传重组和cohesin复合体的加载均发生于女性胚胎发育的8～30周,而非整倍体卵子的形成多发生在35岁以上的女性,因此我们认为导致非整倍体卵子形成的"罪恶种子"早在35年前即已埋下,随着女性年龄增大,其体内保障染色体精确分离的保护机制如纺锤体聚合检验点被"磨损"削弱,而最终导致减数分裂时染色体分离异常.未来的研究应着重探讨遗传重组改变的原因、机理及如何导致减数分裂染色体不分离,了解卵母细胞中cohesin复合体、纺锤体聚合检验点的功能是否随女性年龄增大而减弱及其生物学机制,从而为有效防止非整倍体的发生、减少人类生殖相关非整倍体疾病的发生提供理论基础.     

云南松小孢子母细胞减数分裂的研究

以小孢子材料为对象,全程观察并分析了云南松减数分裂各个时期染色体行为及特征.云南松减数分裂构型为11.72II0 0.24II1 0.04I,配对指数为98.67%,环状二价体的频率和配对指数高于其他裸子植物.染色体交叉平均数目(2.42)和染色体异常分裂现象频率(4%)远低于其他裸子植物.云南松在减数分裂过程中染色体的行为表现出高度保守性,与其高度保守的有丝分裂核型较一致.这也说明云南松所在的松属是松科中较原始的类群.     

小麦染色体配对基因Ph1结构剖析及调控机制研究进展

近年来,关于小麦抑制部分同源染色体配对基因Ph1的研究有了突破性进展.本文对该基因的结构和调控机理的最新研究进行综述.通过创造和分子标记鉴定Ph1缺失突变体,利用分子生物学及比较基因组学技术,该基因位点被界定于5BL上一个2.5 Mb的区域内,含有一个类cdk基因簇,且在该类cdk基因簇中插入一个亚端粒异染色质片段.细胞学研究显示,Ph1基因通过控制亚端粒的互作启始染色体识别和配对伙伴选择.与此同时,生物信息学揭示,这些类cdk基因与人类和老鼠的cdk2基因高度同源,它们与细胞周期中DNA复制、染色质凝集、碱基错配修复等事件相关.减数分裂时,该基因位点通过"感知"染色体的同源性程度而触发染色质的构象变化,从而控制染色体的配对和重组.此外,小麦中可能存在一种与Ph1相关的类似于酵母中的粗线期检查点机制.预测未来的研究将可能集中在Ph1对染色体同源性的"感知"机制、Ph1的开启与关闭、植物减数分裂重组的忠实性及减数分裂过程的检查点机制等方面.     

高温影响拟南芥减数分裂染色质上5-甲基胞嘧啶的分布（英文）

在许多植物中,DNA甲基化的水平和分布能够影响DNA双链断裂和同源交叉在染色体上的形成和分布.在拟南芥中,高温会抑制DNA双链断裂和联会复合体的形成,从而影响同源交叉的形成和分布.然而,表观遗传修饰尤其是染色体的DNA甲基化是否会影响同源重组对高温的反应尚不清楚.研究利用针对5mC的抗体,对高温处理过的拟南芥前期染色体上5-甲基胞嘧啶（5mC）的分布进行了初步分析.在对照温度下,5mC信号主要位于4’,6-二氨基-2-苯基吲哚（DAPI）染色较深的染色体区域,即异染色质区域.而在高温条件下,5mC在不同的染色质区域的分布均发生了改变,这表明DNA甲基化位置在温度升高的情况下发生了改变.研究结果暗示环境温度升高可能通过改变DNA甲基化在染色体上的分布从而影响DNA双链断裂和/或同源交叉的模式.     

加拿大披碱草×老芒麦杂种F_1加倍一代株系Ⅱ花粉母细胞减数分裂行为的观察

[目的]探讨植物远缘杂交不育的原因,以期为后期作物远缘杂交育种提供理论依据。[方法]利用常规的压片方法对加拿大披碱草×老芒麦杂种F1加倍一代株系Ⅱ花粉母细胞减数分裂过程中的染色体行为进行研究。[结果]结果发现加拿大披碱草×老芒麦杂种F1加倍一代株系Ⅱ花粉母细胞减数分裂过程中出现了一些异常分裂现象,即发现在加拿大披碱草×老芒麦杂种F1加倍一代株系Ⅱ花粉母细胞减数分裂过程中一些染色体行为不规则的现象,出现如:单价体、四价体、多价体、染色体桥及染色体断片、落后染色体、微核等一系列异常现象。[结论]加拿大披碱草×老芒麦杂种F1加倍一代株系Ⅱ花粉母细胞减数分裂过程高频率异常现象的发生直接导致其大部分花粉发育异常,表现出远缘杂种的不育。     

减数分裂同源染色体重组交换的改变在男性不育发生中的作用

在第一次减数分裂前期,同源染色体之间需进行配对、联会和遗传物质的重组交换等一系列重要事件.重组交换对染色体正确分离、配子正常形成至关重要.重组交换改变可导致不同程度的精子异常,如精子发生停滞而出现不育,或精子染色体异常导致非整倍体出现.而不育症是一个世界性的问题,影响着10%～15%夫妇,由男方因素所引起的占一半,其中多数病因和机制不明,关于因减数分裂错误导致精子发生失败的机制仍知之甚少.近年来发展的荧光免疫遗传学技术可直视减数分裂前期的重要事件,为研究人类精子形成的调节提供了开拓性的进展.本文围绕重组交换与精子发生之间的关系综述了在这个领域内的研究进展.     

普通小麦×黑麦杂种F_1～F_5代的减数分裂行为与育性研究

对普通小麦×黑麦杂种F_1～F_6代的减数分裂时期染色体的异常行为、花粉育性和结实率进行了调查。对观察资料进行的统计分析表明:(1)杂种在F_1～F_5代间的减数分裂异常率的差异极显著(P<0.01);(2)减数分裂不同时期的染色体异常率有显著差异(P<0.05);(3)减数分裂异常率与自交代数、花粉育性之间呈强负相关(r=-0.9327;r=-0.9352),花粉育性与结实率之间呈强正相关(r=0.8802)。     

一种新的植物染色体制片方法

本文提供了一种能同时得到植物有丝分裂和减数分裂染色体标本的制片方法,去壁——低渗——Giemsa染色法.利用植物花粉母细胞进入减数分裂期,花药壁细胞也能同时进行有丝分裂的特点,选用进入减数分裂期的花蕾(花器小的植物)或花药作材料,用酶解,低渗制片法、Giemsa染色,能同时在一块载片上得到有丝分裂和减数分裂分裂相,且染色体完整而图相背景清晰,染色体染成紫红色,更适合于黑白片的显微摄影,此法对染色体数目多、形态小或根尖材料难取的植物,特别是对材料稀少的诱变体或突变枝条进行染色体的鉴定,更显示出它的优越性.     

三种松科植物(白皮松 Pinus bungeana,油松 Pinus tabulaeformis,白杄 Picea meyeri)小孢子母细胞减数分裂中的次级配对和多极分裂现象

对白皮松(Pinus bungeana)、油松(Pinus tabulaeformis)、白杆(Picea meyeri)三种松科(Pinaceae)植物小孢子母细胞减数分裂过程的观察,确定了这三种植物的染色体数目为2n=24。发现这三种植物在第一次减数分裂的终变期中都出现染色体的次级配对现象,中期都出现多极分裂现象;结合三种植物减数分裂过程中出现的其它一些行为异常,如出现染色单体桥和提前分离的现象,以及三种植物的生育能力较低等等;我们认为现存松科的这些2n=24的物种可能是来自2n=12的早已灭绝的同缘或近缘的物种。     

柳杉花粉母细胞减数分裂进程及异常行为

【目的】观察柳杉花粉母细胞减数分裂进程及染色体的变化和异常行为,为进一步开展柳杉的生殖生物学与分子细胞遗传学研究提供参考。【方法】以柳杉的雄球花(小孢子叶球)为材料,采用压片法研究柳杉花粉母细胞减数分裂的变化规律。【结果】柳杉花粉母细胞减数分裂的胞质分裂类型为同时型,其进程一般开始于10月中下旬并持续到11月上旬。观察发现柳杉雄球花外观颜色的变化与减数分裂进程有关,同一侧枝上柳杉雄球花的发育不一致,同一花序中的不同小孢子叶球的花粉母细胞减数分裂进程也不同步。通过观察柳杉的花粉母细胞减数分裂过程,发现存在单价染色体、不等价二价体、滞后染色体、分裂不同步、不均等分裂、异常四分体等异常现象。【结论】柳杉雄球花外观颜色的变化与减数分裂进程密切相关,其减数分裂过程中染色体存在异常现象。     

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.     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with