比较研究啮齿类动物基因组中的散在重复序列

散在重复序列又称转座子元件(transposable element,TE),是细胞中能够通过切割、复制、重新整合等一系列过程改变自身位置的一段DNA序列。TEs可以影响基因组的大小,能够直接或间接促成基因组重排,还可以影响基因表达水平,改写基因调控网络,因此在基因组进化中有重要的意义。本文利用Repeatmasker软件识别小鼠,裸鼹鼠,地松鼠,兔子基因组中的散在重复序列,结合其物种进化关系,比较研究4个物种基因组中TEs类别、拷贝数等情况,为理解重复序列在啮齿类动物中的进化提供了参考信息。     

用核糖体DNA的ITS序列探讨裂叶沙参的系统位置——兼论ITS片段在沙参属系统学研究中的价值

本文采用PCR直接测序方法，对来自沙参属全部2组7亚组的10个种和作为外类群的风铃草属2个种的核糖体DNA　ITS片段进行了序列分析。在重点探讨裂叶沙参分类地位的同时，分析了ITS片段序列在沙参属系统发育重建中的价值。结果表明，在沙参属中，ITS片段在长度、GC含量和位点变异量上均比较一致；长度539bp～541 bp，GC含量57％～60％，信息位点只占总位点的3．9～6％。采用PAUP软件进行的系统发育分析表明，裂叶沙参A．lobophylla与大花盘亚组的A．himalayana组成一支，而不是象以往形态学和杂交试验所推断的与泡沙参A．potaninii或A．stenanthina近缘。可见，ITS序列进一步支持将裂叶沙参移出泡沙参复合体甚至移出有齿亚组的推论，但同时也表明将其作为A．stenanthina的近缘种是不适宜的。尽管本研究所测定的类群已涵盖了整个沙参属，但种间序列的两两比较表明，沙参属种间在ITS片段上的分化很小(0.0～3.9％)，相比之下，沙参属类群与风铃草属类群间的分化却很高(17.8％～19.2％)。这大概和沙参属起源较晚、遗传分化较小有关。本文还就ITS片段在沙参属和桔梗科系统学研究中的价值进行了讨论。     

CRISPR-Cas系统PAM依赖的新间隔序列获取的结构及分子机制

<正>原核生物的基因组中成簇有规律的间隔短回文重复序列(CRISPR)及其辅助蛋白(Cas蛋白)一同构成CRISPR-Cas系统,保护细菌和古菌等原核生物免受外界噬菌体和质粒的侵染。CRISPR阵列由长度序列完全相同的repeat序列和长度相近序列可变的spacer序列交替排列,其中spacer序列来自于     

rDNA片段的序列分析在苦苣苔亚科系统学研究中的应用

本文测定了苦苣苔亚科4族、5属、5种植物的核糖体DNA中的内转录间隔区(ITS)序列及5．8s rRNA基因的3′端序列。这几种苦苣苔亚科植物的ITS-1的长度范围为234～258 bp,ITS-2的长度范 围为218～246bp。Whytockia bijieensis的ITS-1(258bP)和ITS-2(218 bp)在长度、序列及GC含量上 均与其它几个种有较大差异,其代表的尖舌苣苔族可能很早就自苦苣苔亚科的祖先沿单独的一个分支 演化。以w．bijieensis作为功能性外类群,运用PAUP软件分析仅得到一个最简约树。在简约树上, Cyrtandra umbelliferm、Briggsia longipes和Anna mollifolia形成一个单系群,bootstrap分析对该分支的 支持强度达97％,Chirita crasslfolia位于该分支的基部。由于系统树上Cyrtandra umbellifera代表的 浆果苣苔族和Anna mollifolid代表的芒毛苣苔族均起源于长蒴苣苔族,结合这3个族在形态上存在过渡系列,建议将浆果苣苔族和芒毛苣苔族均并入长蒴苣苔族。     

拉萨野生棕色蘑菇的全基因组测序

本研究采用Illumina Hiseq二代测序和GridION Nanopore纳米孔三代测序结合对拉萨市野生棕色蘑菇进行基因组测序获得4083207300bp的原始数据,数据经过处理后,拼接获得18条完整的染色体,开放阅读框和基因数为3798个,合计30069126bp,最小的染色体长度为46397bp,最大的3600717bp,全基因组的GC含量为46.53%,每条染色体平均长度为1.67Mbp。利用KOG对3798个基因进行功能注释,主要分为24类功能。同时使用MISA程序对参考基因组序列中的微卫星重复位点进行分析,得到3134个微卫星标记位点。     

基于线粒体12S rRNA基因部分序列的6种浙南海域舌鳎属鱼类系统进化研究

对浙江南部沿海的6种舌鳎属鱼类线粒体12S rRNA序列进行扩增,得到长度约为346 bp的片段。利用MEG Aversion3.0软件分析了6种鱼类的序列特征,检测到100个变异位点,其中简约信息位点43个,插入缺失位点11个;平均A+T∶C+G为57.2%∶43.8%。所有序列的转换颠换比(TS/TV)为2.8,突变未达到饱和。并以鳎科的塞内加尔鳎作为外群,利用PAUP Version4.0 b10软件构建了NJ、MP、ML系统进化树。结果显示在3种进化系统树中6种舌鳎的拓扑结构基本一致,大部分舌鳎间的系统进化关系与传统形态分类的结论吻合,但长吻红舌鳎的分类地位表现出较大分歧,研究认为以侧线和鳞片数量这两个形态特征作为评估舌鳎系统进化的重要性需要重新评估。     

杭州地区玉米病毒病dsRNA序列分析

从杭州地区采集花叶症状的玉米,抽提双链RNA(double-stranded RNA,dsRNA).用单引物扩增方法(Single primer amplification technique,SPAT)对dsRNA进行RT-PCR扩增,获得了三条dsRNA片段的cDNA克隆并测定全序列.核苷酸水平上,三条片段(长度分...     

基于模式与熵的随机序列研究

本文从双色球开奖结果出发,探讨真随机序列中暗含的＂模式＂：真随机序列有时表现得并不那么＂随机＂。这是因为人们认为,随机应是无序的。事实证明,并非如此。另一方面,人为产生的伪随机序列,大多经过了消除重复的步骤以使序列本身较为＂随机＂——看起来是无序的。本文使用Mersenne Twister算法产生伪随机序列,测试这种人为因素对随机序列统计特性的影响。为了进一步研究＂无序＂序列与随机序列的差异,本文基于熵,提出了一种简便的伪随机数发生器。通过对有序序列进行次数可控的交换来逐步实现无序化。对无序化后的序列进行均匀性和图像加密测试。通过无序的方法产生的序列,其随机性在一定范围内是可以信赖的。     

DNA分子标记技术在水生动物遗传多样性研究中的应用

简要阐述了几种常见DNA分子标记技术,如限制性片断长度多态性(restriction fragment length polymorphism,RFLP)、随机扩增多态性DNA(random amplified polymorphie DNA,RAPD)、扩增片断长度多态性(amplified fragment length polymorphism,AFLP)、简单重复序列或微卫星标记(simpie sequencerepeat,SSR)、内部简单重复序列(inter-simple sequence repeat,ISSR)和单核苷酸多态性(single nucleotidepelymorphisms,SNP)等的基本原理、技术上的优缺点及其在水生动物遗传多样性研究中的应用,包括遗传多样性的鉴定、品种亲缘关系与分类的研究和种质资源的鉴定等.最后,对DNA分子标记技术在水生动物遗传多样性应用中的存在问题进行了简单的讨论.     

艾滋病毒学会规避人体免疫系统

日、英、美等国科学家报告称,开发艾滋病毒(HIV)疫苗可能比想象中更加困难。因为HIV不仅会对抗病毒药产生抗性,而且会进化产生规避人类免疫系统的方法。研究人员在来自9种人群、共2 875名HIV感染者身上检查了人类白细胞抗原(HLA)突变体与HIV之间的交互作用。研究人员最初聚焦的是已知能减轻患者感染的HLA-B51,但研究人员发现,在携带HLA-B51的患者身上,     

Conceptualising the heterogeneity of research-based spin-offs: A multi-dimensional taxonomy

Research-based spin-offs (RBSOs) have become an important aspect of the technology transfer process. Emanating from what is conventionally a non-commercial environment, RBSOs pose major challenges if they are to realise their potential to meet the objectives of their founders and the parent research organisations (PROs) from which they emerge. An important issue is to understand the heterogeneity of RBSOs. This paper reviews the literature on RBSO typologies to develop a taxonomy of RBSOs. We identify common themes in relation to these typologies in relation to (1) spin-off creation and (2) spin-off development. The dimensions that differentiate between firms are the type of resources, the business model and the institutional link. We identify gaps in current typologies in order to propose avenues for future conceptual and empirical research.     

Coevolution of job automation risk and workplace governance

This paper analyses the interplay between the allocation of authority within firms and workers’ exposure to automation risk. We propose an evolutionary model to study the complementary fit of job design and workplace governance as resulting from the adoption of worker voice institutions, in particular employee representation (ER). Two organizational conventions are likely to emerge in our framework: in one, workplace governance is based on ER and job designs have low automation risk; in the other, ER is absent and workers are involved in automation-prone production tasks. Using data from a large sample of European workers, we document that automation risk is negatively associated with the presence of ER, consistently with our theoretical framework. Our analysis helps to rationalize the historical experience of Nordic countries, where simultaneous experimentation with codetermination rights and job enrichment programmes has taken place. Policy debates about the consequences of automation on labour organization should avoid technological determinism and devote more attention to socio-institutional factors shaping the future of work.     

国家法团主义:当代中国半官方社团的浮现——以K省建材行业协会为例

随着1978年中国改革开放政策的启动,市场力量得到空前释放。与此相适应,国家权力的谨慎转移为民间组织的发育提供了规模适度的合法性空间。行政机构改革运动伴生了一批半官方性质的社团。该文借助国家法团主义理论对K省建材行业协会进行实证分析,试图展示当代中国半官方社团的生存困境与演变路径。     

Some determinants of cost distributions in the process of technological innovation

Industrial research and development (R&D) is a set of activities within the broader set of decisions and activities: the process of technological innovation (TI). It is technology transfer (commercialization of the innovation) that leads to technology diffusion that permits production and employment expansion and hence economic growth — an important goal of industrial policy. Firms' managements and government policy- makers should recognize the close relationships among the phases of TI and direct their policy, planning, budgeting and control decisions to the complete process. Many policies currently focus their attention to only one or a few points (such as R&D).In this study we conducted a detailed cost analysis of a limited number of innovation projects and studied the distributions of TI cost over the process phases. We find that almost half of TI costs are devoted to R&D, which implies that government support of this phase is important. Different cost patterns emerge when we classify innovations by industrial sectors, firms' sizes and project complexity. Complex innovations require larger and more variable (risky) R&D budgets. Smaller firms need more assistance in technology transfer. These are only a few important policy implications. This study emphasizes the importance of post-R&D phases and concludes that differential industrial policy may be required for technological innovations.     

Graph Cuts算法实现过程中的关键问题研究

Graph Cuts（GC）算法是一个基于图论的交互式目标提取算法,该方法将图像建模为一个区域和边缘的约束模型,通过求解该模型的最小割获得一个优化的目标分割边界。在使用程序实现该算法时会遇到种种问题,详细叙述了GC算法的实现过程,为进一步研究GC相关方法奠定基础。     

心理咨询与治疗模式转换的探索

在心理咨询与治疗日益为当代人所接受的同时,其疗效也就成为了从业者研究的热点,当前心理咨询与治疗的流派已近百种,但真正意义上能解决心理问题的方法却少之又少,其原因是疗法的着眼点仅仅是意识层面。当意识层面受到"价值条件化"的作用后,人们的思维完全进入了自动化的加工过程,来访者有时能够意识到观念的错误但却无法改变它们。本文从模式转换的角度探讨心理咨询与治疗的疗效,力图使心理咨询与治疗更加卓有成效。     

陕西安康地区紫阳县富硒作物分析

本文通过详细的野外地质及采样和室内分析化验工作，发现本区不同地区的农作物的含硒量是不同的，不少地区的玉米、茶叶、土豆、水稻等的含硒量在0.1-6.6ppm范围内，是一般同类作物的含硒量（+-0.036）的3-200倍；农作物的含硒量与基岩的含硒量、结构造成及地貌地     

General picture revealed about origin of new genes in fruit flies

Gene, the very basic unit of heredity in a living organism, has long heldthe limelight in modern biological studies. One fundamental truth revealed by scientists is the origination of new genes is a driving force behind evolutionary innovation in all organisms. However, except a few case studies, they are not very clear how the novel genes have been created in Nature. Now, with the help of molecular biology, scholars strive to understand the mechanisms underlying their origination.     

Access to UK academic networks

Computer networks are assuming an increasingly important role in the transmission and manipulation of information. The implementation of the Joint Academic Network (JANET) provides for the first time a truly integrated, private academic network linking all UK universities. Based on a set of standard communication protocols, JANET has largely superseded earlier regional networks, and their associated interconnection procedures which were complex and unwieldy. An in-depth survey of six UK universities and two polytechnic institutions was undertaken with the objective of examining the principal issues to emerge in the field of academic networking in Great Britain. The survey also considered the implications of current network developments for new categories of services and users that are likely to emerge (by contrast with existing network traffic which is primarily associated with data processing and computation).     

利用现代信息技术促进我国对外贸易发展

近几年来，信息技术和信息网络风靡全球。围绕信息技术和信息网络的发展，许多新兴产业纷纷涌现，不断扩大我国对外贸易发展。本文首先给出了信息技术的含义，并通过对现代信息技术的阐释和信息技术对我国国际贸易的影响，写出利用信息技术促进对外贸易发展的必要性。