基因转移的研究进展

本文从新的思路上介绍了基因转移的研究进展,首先论述了有性杂交与基因交流和物种进化的关系,重点论述了非有性杂交条件下生物体间、生物体内的基因水平转移研究概况,并讨论了基因转移与生物进化,突变和生物工程的关系及存在的有关问题。     

基因编辑技术研究进展与挑战

基因编辑技术是指对基因进行修饰而获得新的特征或功能的技术,当前研究最多的是始于2012年的第三代CRISPR/Cas9基因编辑系统及相关技术,其他近几年新兴起来的基因编辑系统包括单碱基基因编辑技术、引导编辑技术、RNA编辑技术等.基因编辑技术近年来蓬勃发展,技术本身得以不断改进,新成果加速涌现.基因编辑系统已在疾病治疗...     

科学家在拟南芥中发现抗高盐分基因

土壤盐分过高往往威胁植物生长 ,一个国际研究小组最近在一种名为拟南芥的植物中发现了可抵抗过多盐分侵袭的基因 ,并认为植入这种基因的农作物 ,在高盐分土壤中照样能够茁壮成长。有关资料表明 ,过高的盐分往往会破坏植物细胞的结构 ,并使细胞中的酶失去效用 ,从而造成植物脱水和死亡。全世界每年约有 1 0 0 0万公顷可耕地由于盐分过高而被荒废。法国国家农业研究所的科学家与日本、英国科学家合作研究后发现 ,拟南芥具有一种神奇的抵御高盐分侵袭的机制。拟南芥是一种芥菜 ,专家们发现它能把叶子中过多的盐分通过茎送回根部 ,再由根部将这…     

中国汉族人群中Vav2基因和Vav3基因多态性与原发性闭角型青光眼之间关系的研究

目的本实验的目的是研究沌以和Vav3基因多态性与中国汉族人群中原发性闭角型青光眼（Prim aryangle-closure glaucoma,PACG）的遗传性是否有联系。方法211名原发性闭角型青光眼患者和206名性别和种族匹配的健康对照者纳入到本病例对照研究中。2个单核苷酸多态（the single nucleotide polymorphisms,SNPs）rs2156323（Vav2）和rs2801219（vav3）的基因分型用聚合酶链反应的限制性片段长度多态性分析（polymerase chain reaction restriction fragment length polymorphism,PCR—RFLP）。这两个基因位点的多态性与PACG遗传性之间的关系用卡方检验来评价。结果rs2156323（Vav2）和rs2801219（Vav3）的基因频率在所有参与者中均没有偏离哈迪一温伯格平衡（Hardy-Weinberg Equilibrium,HWE,P〉0．05）。该两个位点的等位基因频率和基因型频率的分布在PACG患者和正常对照者之间均没有差异。结论本研究的结果显示rs2156323和rs2801219可能不是中国汉族PACG的易感基因位点,Vav2和Vav3基因可能不是中国汉族PACG患者的易感基因。     

空间基因:传承中华营城理念的城市设计路径——从苏州古城到雄安新区

全球化背景下中国城市历史文脉传承的形势严峻,深入理解中华营城理念的科学内涵、研发既延续历史又面向未来发展的城市设计新路径十分必要.中华营城理念通过空间要素组合关系表达超越形态本身的社会文化意义,这些稳定的空间要素组合关系正是“空间基因”研究的关键性内容.引入空间基因解析与传承技术,可为传承中华营城理念的城市设计提供科学清晰的技术路径.本文还对该技术路径在苏州古城、雄安新区等重大工程中的成功应用进行了介绍,为其他城市的规划建设提供了示范样本.     

Genes in sweeping competition

Analysis of DNA variation is a powerful tool for detecting adaptation at the genomic level. The contribution of adaptive evolution is evident from examples of rapidly evolving genes, which represent the likely targets for strong selection. More subtle adaptation is also an integral component of routine maintenance of gene performance, continuously applied to every gene. Adaptive changes in the population are accomplished through selective sweeps, i.e. complete or partial fixation of beneficial alleles. The evidence is accumulating that selective sweeps are quite frequent events which, together with associated genetic hitchhiking, represent dominant forces that influence molecular evolution by shaping the variability pattern in the genome. Received 5 May 2000; revised 22 August 2000; accepted 24 August 2000     

Getting there and being there in the cerebral cortex

The mammalian neocortex is composed of functional areas that are specified to process particular aspects of information. How is this specification achieved during development? Since cells migrate to their final positions in the developing nervous system, a central issue is the relation between cellular migration and positional information. This review combines evidence for early positional specification in the developing cortex with evidence for cellular dispersion during migration. A model is suggested whereby stable cues provide positional information and minorities of ‘displaced’ cells are respecified accordingly. Comparison with other parts of the CNS reveals that cellular dispersal is ubiquitous and has to be included in any mechanism relaying positional specification. Ontogenetic and phylogenetic considerations suggest that radial glial cells might provide the positional information in the developing nervous system.     

Improved synthesis of bradykinin

Zusammenfassung Eine neue Methode zur Entfernung der Schutzgruppe von N^G-Tos-Arg mittels wasserfreier Flußsäure und ihre Anwendung für die Synthese von Bradykinin wird beschrieben.     

Genes involved in breast cancer metastasis to bone

Metastasis to bone occurs frequently in advanced breast cancer and is accompanied by debilitating skeletal complications. Current treatments are palliative and new therapies that specifically prevent the spread of breast cancer to bone are urgently required. While our understanding of interactions between breast cancer cells and bone cells has greatly improved, we still know little about the molecular determinants that regulate specific homing of breast cancer cells to the bone. In this review, we focus on genes that have been implicated in migration and adhesion of breast cancer cells to bone, as well as genes that promote tumor cell proliferation in the bone microenvironment. In addition, the review discusses new technologies, including better animal models, that will further assist with the identification of the molecular determinants of bone metastasis and will guide the development of new therapies. Received 25 January 2002; received after revision 27 March 2002; accepted 5 April 2002 RID="*" ID="*"Corresponding author.     

Improved methods of combining forecasts

It is well known that a linear combination of forecasts can outperform individual forecasts. The common practice, however, is to obtain a weighted average of forecasts, with the weights adding up to unity. This paper considers three alternative approaches to obtaining linear combinations. It is shown that the best method is to add a constant term and not to constrain the weights to add to unity. These methods are tested with data on forecasts of quarterly hog prices, both within and out of sample. It is demonstrated that the optimum method proposed here is superior to the common practice of letting the weights add up to one.     

PCR快速检测常见具有毒性质粒的沙门氏菌

针对常见具毒性质粒的沙门氏菌的spvR基因,设计出PCR特异引物spvRP35-P36,以便快速检测出具有毒性质粒的沙门氏菌。验证采用13株沙门氏菌和4株非沙门氏菌,其中6株常见具有毒性质粒的沙门氏菌均获得特异性扩增,7株不舍毒性质粒的沙门氏菌均未获得特异性扩增,4株非沙门氏茵检测结果为阴性。结果表明,本文中设计的引物具有高度的特异性,适用于常见具有毒性质粒沙门氏菌的快速检测,此引物已获国家发明专利。     

脊椎动物基因注释中的大基因问题

为了找出编码蛋白质的基因，注释流程结合了“从头开始的基因预测方法”和“与已知基因相似性比较”这两种方法。“从头开始的基因预测方法”虽然有很高的假阳性但是假阴性却很低；相形之下，结合了相似性比对的方法之后虽然能够降低假阳性，但是却大大提高了假阴性。我们发现，在这当中与基因预测正确率相关的最重要因素就是基因大小(包括内含子在内)——大基因尤其容易产生预测错误。     

一种改进的Knockout抠图方法

通过对Knockout算法的研究分析,针对其在实际应用中需要用户大量的交互工作以及因模型简单造成的抠图不精确问题,提出了一种改进算法。该算法用区域生长方法将用户输入的前、背景线段生长聚合成前、背景区域;然后用轮廓查找方法找到两个区域的轮廓作为Trimap的前、背景轮廓线;最后使用优化颜色样本的方法对每个未知像素点的样本进行优化,提高抠图的精确度。实验结果表明,改进后的算法需要用户较少的工作量,能够得到传统Knockout算法更好的抠图效果。