植物表达序列标签(EST)标记及其应用研究进展

简要介绍了植物表达序列标签(EST)标记的研究现状,并对几种植物中利用EST建立分子标记的几种策略和EST标记在绘制遗传图谱、资源分析、品种鉴定及比较基因组学研究方面的应用等进行了综合评述。     

EST技术及其在哺乳动物早期胚胎研究中的应用

EST(expressed sequence tags ,EST) 是一段长约150～500 bp的基因表达的外源序列片段,是由大规模随机挑取的cDNA克隆测序得到的组织或细胞基因组的表达序列标签。一个EST代表生物某一时期的某种组织或细胞的一个表达基因。本文主要综述了EST技术的原理方法,哺乳动物早期胚胎研究的理论基础以及EST技术在早期胚胎研究方面的应用,并讨论了利用EST进行研究分析的发展趋势。     

EST-SSR及其在植物基因组学研究中的应用

数量迅速增加的表达序列标签已经成为开发分子标记的重要资源。EST—SSR是基于表达序列标签开发微卫星的一种新型分子标记,与基因组SSR相比,EST-SSR具有在植物物种之间可转移性的优点。目前,EST—SSR被广泛应用于植物基因组学研究如遗传图谱构建、比较作图、遗传多样性评价、种质鉴定、系统发育与进化研究等方面。该文介绍了EST—SSR原理、引物开发、实验方法,并对其物种间通用性以及其在植物基因组研究中的应用进行了评述。     

静电纺丝的主要参数对PLGA纤维支架形貌和纤维直径的影响

EST(expressed sequence tags,EST)是一段长约150～500bp基因表达的外源序列片段,是由大规模随机挑取的cDNA克隆测序得到的组织或细胞基因组的表达序列标签。一个EST代表生物某一时期的某种组织或细胞的一个表达基因。主要综述了EST技术的原理方法,哺乳动物早期胚胎研究的理论基础以及EST技术在早期胚胎研究方面的应用,并讨论了利用EST进行研究分析的发展趋势。     

基于EST的新基因克隆策略

表达序列标签(expressed sequence tags, EST) 是从随机选择的cDNA 克隆进行单向测序获得的短的cDNA序列, 代表一个完整基因的一部分。随着生物信息学和基因定位的迅猛发展, EST已成为基因定位、基因克隆、基因表达分析的有力工具。近年来, 由于EST数据库的迅速扩张, 运用EST来克隆和定位基因, 使得新基因克隆的策略发生了革命性变革。尽管存在一些不足, 实践证明EST可大大加速新基因的发现与研究。本文将就EST技术尤其是它在新基因克隆中的应用策略作详细介绍。     

植物基因组表达序列标签(EST)计划研究进展

植物表达序列标签(EST)计划是随机挑选cDNA克隆,并对其3′或5′端进行大规模一次性测序,将得到的150～500 bp长度的DNA片段与数据库中的序列进行比较,获得对基因组结构、组织、表达等认识的基因组研究策略.就近年来国际植物EST计划的实施情况、植物EST计划的研究范围、生物信息学在EST研究中的应用、EST数据库及查询、植物EST研究中遇到的问题等方面内容进行了综述.     

花生EST数据库的分析、评价和应用前景

花生是我国重要的油料和经济作物。花生产业的发展对我国国民经济具有重要战略意义。随着分子生物学的发展,植物基因工程和功能基因组学的先进技术将有效推动花生种质创新和科技进步。分析了现有的花生EST数据,结合其他作物功能基因组学的最新研究进展,深入探讨了花生EST数据资源在基因克隆、分子标记开发及表达谱研究等方面的利用价值,并在分析花生EST数据库特点的基础上,展望了新一代测序技术在花生中的应用前景。为更好的利用花生EST数据库提供参考。     

一种新的EST聚类方法

该研究发展了一种EST（expressed sequence tag）聚类方法（ESTClustering）,用于分析大规模EST测序中所产生的大量数据,以获得高质量,非重复表达序列,该方法在聚类过程中采用MEGABLAST工具对一致序列进行序列同源比较,并用phrap程序对每一EST簇进行拼接检验。这一聚类策略能降低测序错误带来的影响,有效识别基因家族成员,并避免选择性剪接的干扰,与NCB（National Center for Biotechnology Information）的UniGene clustering）方法相比,ESTClustering的聚类结果可以更好地反映表达序列的多样性,用ESTClustering对112256条拟南芥EST聚类测试,产生23581个EST簇,其中13597个EST簇有对应拟南芥基因组编码序列,与该基因组中有EST作为依据的预测基因数目接近。应用该方法对收集的147191条水稻EST序列进行聚类,形成33896个EST簇。     

EST分子标记开发及在比较基因组学中的应用

数量迅速增加的EST(expressed sequence tags)为分子标记的开发提供了宝贵的资源。与来自于基因组DNA开发的传统标记相比,以EST为基础的分子标记是一种新型分子标记,具有其显著的优势,如开发简便、信息量高和通用性好等,在多方面都有重要的利用价值。本文详细地介绍了目前基于EST开发的5类分子标记以及基于生物信息学方法的开发策略,这些标记包括EST-PCR、EST-SSR、EST-SNP、EST-RFLP和EST-AFLP。此外,对这些标记在比较基因组学研究中的应用进行了评述,包括比较作图、遗传多样性评价及系统发育研究等。     

充分利用EST数据库资源

表达序列标签(EST）数据库作为一种重要的基因组数据库,已成为新基因的发现、基因表达及重组蛋白表达等研究的有力分子生物学工具.介绍了如何充分利用EST数据库.     

Reconstructing the evolution of genes along the species tree

A model and algorithm are proposed to infer the evolution of a gene family described by the corresponding gene tree, with respect to the species evolution described by the corresponding species tree. The model describes the evolution using the new concept of a nested tree. The algorithm performance is illustrated by the example of several orthologous protein groups. The considered evolutionary events are speciation, gene duplication and loss, and horizontal gene transfer retaining the original gene copy. The transfer event with the loss of the original gene copy is considered as a combination of gene transfer and loss. The model maps each evolutionary event onto the species phylogeny.     

Myogenin基因的分子生物学综述

对肌细胞生成素(myogenin,MyoG)的作用机制及其基因的定位、结构、遗传变异及其与经济性状的关系等进行了综述。     

The HP1 protein family: getting a grip on chromatin

HP1 was first described in Drosophila as a heterochromatin-associated protein with dosage-dependent effects on heterochromatin-induced gene silencing. Recently, membership of the HP1 protein family has expanded tremendously. A number of intriguing interactions between HP1 and other proteins have been described, implicating HP1 in gene regulation, DNA replication, and nuclear architecture.     

野生稻优异基因分子标记定位与利用研究进展

对野生稻中抗(耐)生物胁迫和非生物胁迫等许多有用的遗传性状,抗病虫、耐非生物胁迫环境、高产和细胞质雄性不育恢复等优异基因的分子标记定位研究进行了综述,评价了野生稻中的这些优异基因的利用现状及其应用前景。     

Mutation in Escherichia coli K-12 Mediating Spherelike Envelopes and Changed Tolerance to Ultraviolet Irradiation and Some Antibiotics

In a mutation experiment with a rough, ampicillin-resistant strain of Escherichia coli K-12, two smooth ampicillin-sensitive mutants were isolated. One of the mutants (with the envA gene) was recently described. The second mutant (strain D23) with the envB gene which has been mapped to a position close to streptomycin resistance (strA) at 64 min is described. The envB gene gives rise to spherelike cells. Electron microscopy revealed an abnormal septum formation and a circular distribution of the nuclear material. Strain D23 (with envB) showed a changed resistance to several antibiotics as well as an increased tolerance to ultraviolet irradiation. The envB gene decreased the ampicillin resistance mediated by the ampA gene (at 82 min), but no effect was found on episomally mediated penicillin resistance.     

Mitochondrial and nuclear DNA complementation in the respiratory chain function and defects

The 16569 base pairs of the mitochondrial DNA encode with a specific genetic code 13 proteins involved in the respiratory chain complex formation. Nuclear gene products also contribute to the formation of these complexes. In the first point, the organization and expression of the mtDNA are described with the main characteristics of the enzymatic complexes as well as nuclear gene expression. New information concerned with mitochondrial DNA deletions and mutations are described particularly with respect to Kearns-Sayre Syndrome.     

Molecular Characterization of Acanthamoeba spp. Occurring in Water Bodies and Patients in Poland and Redefinition of Polish T16 Genotype

Acanthamoeba genus is divided into 20 genotypes (T1–T20) on the basis of the gene encoding 18S rRNA sequence. Using of at least 2 kbp gene fragments is strongly recommended to identify new genotypes and 5% difference is commonly used as a criterion of new genotypes, however, this value is questionable. In this paper, Polish Acanthamoeba strains described earlier on the basis of ~850 bp Ami fragment of 18S rRNA gene as T4, T11 and a new T16 genotype, have been analyzed using near‐complete sequence of the gene. This analysis was needed because the Ami fragment does not reveal full variability within 18S rRNA gene. Phylogenetic analysis based on Ami fragment is biased by artifacts in the construction of the tree, so the fragment should not be used for identification of new putative Acanthamoeba genotypes. The analysis confirmed that the Polish sequences represent T4 and T11 genotypes and that the strains described earlier as T16 genotype are in fact a new subgroup of the T20 genotype and that this genotype should be divided into two subgroups: T20a (two strains described by [J. Eukaryot. Microbiol. 62 (2015) 69]) and T20b (11 Polish strains described in this study). The T20b subgroup was isolated from both clinical samples and water bodies used by people as bathing places and there is a risk of infection for humans during contact with water.     

Regulation of aspartokinase III synthesis in Escherichia coli: isolation of mutants containing lysC-lac fusions.

Mutants containing fusions of the lac gene to the lysC gene were isolated. In these, the expression of beta-galactosidase was regulated by lysine (and arginine), as previously described for aspartokinase III.     

Hybrid genes in the analysis of transformation conditions: II. Transient expression vs stable transformation—analysis of parameters influencing gene expression levels and transformation efficiency

Reports on direct gene transfer have dealt with either the obtention of stable transformants and transgenic plants, or described the use of reporter genes to analyse different aspects of gene expression in plant protoplasts and conditions for their use in transient gene expression assays.
In this paper we present comparisons between several transformation techniques, show species-specific differences in efficiencies of stable transformants and in the levels of transient gene expression, and report on the identification of major parameters responsible for DNA uptake as judged from transient chloramphenicol acetyl transferase (CAT) expression levels and from efficiencies of transformation based on kanamycin-resistance. The described procedures have been simplified, optimized and standardized and should allow routine use with a great variety of plant species.     

Recent progress in the development of RNA interference for plant parasitic nematodes

RNA interference (RNAi), first described for Caenorhabditis elegans , has emerged as a powerful gene silencing tool for investigating gene function in a range of organisms. Recent studies have described its application to plant parasitic nematodes. Genes expressed in a range of cell types are silenced when preparasitic juvenile nematodes take up double-stranded (ds)RNA that elicits a systemic RNAi response. Important developments over the last year have shown that in planta expression of a dsRNA targeting a nematode gene can successfully induce silencing in parasitizing nematodes. When the targeted gene has an essential function, a resistance effect is observed paving the way for the potential use of RNAi technology to control plant parasitic nematodes.