基因诱捕技术及基因诱捕数据库

基因诱捕（gene trap）是基于小鼠胚胎干细胞、报道载体（诱捕载体）建立的一种基因突变方法。诱捕载体在整合位点利用内源基因调控元件模仿内源基因表达,使其表达终止,从而可以阐明内源基因的功能。由于诱捕载体及其报道基因的特点,基因诱捕技术可用于高通量生产,便于小鼠基因功能的大规模研究．为各类疾病动物模型的建立奠定良好基础。     

基因打靶突变小鼠与基因功能研究

ES细胞是建立基因打靶突变小鼠的必要条件 ,也可用于制备转基因动物 .基因敲除、精细突变和条件性基因打靶技术建立的基因打靶突变小鼠在人类遗传病机理研究、基因治疗和基因功能研究方面都有着重要作用 .     

类胡萝卜素合成的相关基因及其基因工程

类胡萝卜素具有多种生物功能,尤其在保护人类健康方面起着重要的作用,如它们是合成维生素A的前体,能够增强人体免疫力和具有防癌抗癌的功效。人体自身不能合成类胡萝卜素,必须通过外界摄入;但类胡萝卜素在许多植物中含量较低,并且很难用化学方法合成。随着类胡萝卜素生物合成途径的阐明及其相关基因的克隆,运用基因工程手段调控类胡萝卜素的生物合成已成为可能。本文综述了微生物和高等植物类胡萝卜素生物合成途径中相关基因的克隆,以及运用这些基因通过异源微生物生产类胡萝卜素和提高作物类胡萝卜素含量的基因工程研究进展。     

杆状病毒p74基因具有种属特异性

选用苜蓿丫纹夜蛾核多角体病毒杆粒 (AcMNPVbacmid)为材料 ,通过在大肠杆菌中利用RecA基因介导的同源重组 ,将其p74基因剔除 ,并精确地用斜纹夜蛾核多角体病毒 (SpltMNPV)的p74基因进行了替换。所构建的重组AcMNPV杆粒在修饰后的p74基因位点中未留下任何有可能影响该基因表达及功能的选择标记 ,SpltMNPV的p74基因直接位于AcMNPVp74基因的启动子控制下。RT PCR显示替换后的p74基因得到了表达。生物测定结果显示 ,重组病毒AcMNPV杆粒 polhSL74无法通过口服方式感染银纹夜蛾幼虫 ,表明杆状病毒p74基因具有种属特异性。     

益生菌的功能基因导入和基因编辑

益生菌已经在临床和食品领域应用多年,其安全性和有效性已经获得人们的认可。随着分子生物学技术的发展,采用益生菌作为载体进行基因导入或基因编辑,这些遗传改造的益生菌一部分已经作为新的药品或疫苗进入到临床应用阶段。携带功能基因的益生菌定殖于肠道进行表达和缓慢释放,这类益生菌作为活体药物获得益生菌和功能基因的双重功效,可用于治疗某些疑难病症。携带蛋白质抗原基因的益生菌定殖于肠道进行表达,可诱导肠道黏膜免疫、细胞免疫和体液免疫,这是一条更安全的口服疫苗途径。成簇的规则间隔短回文重复序列(clustered regularly interspaced short palindromic repeats,CRISPR)及其相关蛋白(CRISPR-associated protein,Cas)以其高效与便捷性推动了益生菌基因编辑的发展。这篇综述介绍了CRISPR-Cas9操作系统在益生菌方面的应用。对传统遗传操作较难的益生菌采用CRISPR-Cas9技术进行基因编辑,使其基因敲除和基因突变,基因敲入和基因调控等更为简单、高效和易操作。这些CRISPR/Cas9、CRISPRa和CRISPRi技术在益生菌的基因表达调控和代谢工程等领域具有巨大的应用潜力,例如医药、食品以及工业等相关重要产品的获得。本文总结了益生菌基因导入和基因编辑在生物制品生产中的相关应用,最后对其未来的研究方向进行展望。     

Gene function

The problem of gene function--of the relationships between hereditary material and the characteristics of organisms--preceded the rediscovery of Mendel's laws and accompanied the development of genetics in the XXth century. Molecular biologists replaced the simple gene-character relationship by two relationships: the first, between genes and proteins, was well defined, whereas the second between proteins and the complex structural and functional characteristics of organisms remained unknown. I will describe in this article the experimental approaches which helped to characterize during the last twenty years the relationships between proteins and characters. Four principles of macromolecular organization emerged from these studies: conservation of the elementary components during evolution, existence of pathways and networks, pleiotropy and redundancy. These principles are the explanation of the surprising experimental observations that have been made in recent years. The existence of these principles makes problematic any prediction on the consequences of gene modification. It both sounds the death-knell of the simplistic reductionist approach of many biologists, whereby genes were considered as responsible for specific functions, and definitely prevents the distribution of genes in separate, well defined categories.     

Gene dispensability

Genome-wide mutagenesis studies indicate that up to about 90% of genes in bacteria and 80% in eukaryotes can be inactivated individually leaving an organism viable, often seemingly unaffected. Several strategies are used to learn what these apparently dispensable genes contribute to fitness. Assays of growth under hundreds of physical and chemical stresses are among the most effective experimental approaches. Comparative studies of genomic DNA sequences continue to be valuable in discriminating between the core bacterial genome and the more variable niche-specific genes. The concept of the core genome appears currently unfeasible for eukaryotes but progress has been made in understanding why they contain numerous gene duplicates.     

基因沉默

基因沉默 (ｇｅｎｅｓｉｌｅｎｃｉｎｇ)是指生物体中特定基因由于种种原因不表达。一方面 ,基因沉默是遗传修饰生物 (ｇｅｎｅｔｉｃａｌｌｙｍｏｄｉｆｉｅｄｏｒｇａｎｉｓｍｓ)实用化和商品化的巨大障碍 ,另一方面 ,基因沉默是植物抗病毒的一个本能反应 ,为用抗病毒基因植物工程育种提供了具有较大潜在实用价值的策略———ＲＮＡ介导的病毒抗性 (ＲＮＡ ｍｅｄｉａｔｅｄｖｉｒｕｓｒｅｓｉｓｔａｎｃｅ ,ＲＭＶＲ) [1～ 3] 。基因沉默现象首先在转基因植物中发现 ,接着在线虫、真菌、昆虫、原生动物以及老鼠中陆续发现。大量的研究表…     

Dicer基因

Dicer编码RNaseⅢ家族,是一进化保守基因。它包含四个ORF框架：DExH/DEAH盒解旋酶,PAZ,两个RNaseⅢ催化区与双链RNA结合区DS－RBD。目前发现Dicer在RNA干扰以及异时发育中起重要作用,它可以切割长的双链RNA成长度为22nt左右的小干扰RNA－siRNA,异时基因stRNA的成熟也与需要Dicer的参与。Dicer行使切割功能需要RDE－1或其同源基因ALG1／ALG2的协同。随着研究的深入,Dicer的其它生物功能将进一步被发现。     

壳聚糖作为基因治疗载体的研究

本文从壳聚糖－DNA复合物／微球的形成方法和机理,稳定性,转染细胞效率等方面综述了壳聚糖在基因治疗领域目前的研究现状。     

Identifying Gene Interaction Enrichment for Gene Expression Data

Gene set analysis allows the inclusion of knowledge from established gene sets, such as gene pathways, and potentially improves the power of detecting differentially expressed genes. However, conventional methods of gene set analysis focus on gene marginal effects in a gene set, and ignore gene interactions which may contribute to complex human diseases. In this study, we propose a method of gene interaction enrichment analysis, which incorporates knowledge of predefined gene sets (e.g. gene pathways) to identify enriched gene interaction effects on a phenotype of interest. In our proposed method, we also discuss the reduction of irrelevant genes and the extraction of a core set of gene interactions for an identified gene set, which contribute to the statistical variation of a phenotype of interest. The utility of our method is demonstrated through analyses on two publicly available microarray datasets. The results show that our method can identify gene sets that show strong gene interaction enrichments. The enriched gene interactions identified by our method may provide clues to new gene regulation mechanisms related to the studied phenotypes. In summary, our method offers a powerful tool for researchers to exhaustively examine the large numbers of gene interactions associated with complex human diseases, and can be a useful complement to classical gene set analyses which only considers single genes in a gene set.