基因药物的前沿技术

基因药物的直接体内基因治疗发展迅速,新型基因药物不断产生。本文讨论了效果比较肯定的基因疫苗、反义ＲＮＡ药物、三链ＤＮＡ药物这三种新型基因药物技术的基本方法。分析了它们各自存在的优点和问题,并介绍了它们的应用范围及应用研究进展。     

Gene transfer into mammalian somatic cells in vivo.

Direct gene transfer into mammalian somatic tissues in vivo is a developing technology with potential application for human gene therapy. During the past 2 years, extensive progress and numerous breakthroughs have been made in this area of research. Genetically engineered retroviral vectors have been used successfully to infect live animals, effecting foreign gene expression in liver, blood vessels, and mammary tissues. Recombinant adenovirus and herpes simplex virus vectors have been utilized effectively for in vivo gene transfer into lung and brain tissues, respectively. Direct injection or particle bombardment of DNA has been demonstrated to provide a physical means for in situ gene transfer, while carrier-mediated DNA delivery techniques have been extended to target specific organs for gene expression. These technological developments in conjunction with the initiation of the NIH human gene therapy trials have marked a milestone in developing new medical treatments for various genetic diseases and cancer. Various in vivo gene transfer techniques should also provide new tools for basic research in molecular and developmental genetics.     

转基因植物转录后基因沉默的特点、机理及应用

自在转基因植物中发现转基因沉默现象以来 ,很多学者对该现象进行了广泛的研究 ,认为其作用机制有三种 :位置依赖性基因沉默、转录水平基因沉默、转录后水平基因沉默。目前主要集中于转录后水平基因沉默的研究 ,通过研究发现它具有广泛性、可传导性及特异性的特点 ,并对其机制提出了一些假说。最近 ,人们还发现转录后水平基因沉默与植物抗病毒能力有联系。本文对转基因植物转录后基因沉默的特点、机理及应用方面的进展作了综述     

Perspectives of gene combinations in phenotype presentation

Cells exhibit a variety of phenotypes in different stages and diseases. Although several markers for cellular phenotypes have been identified, gene combinations denoting cellular phenotypes have not been completely elucidated. Recent advances in gene analysis have revealed that various gene expression patterns are observed in each cell species and status. In this review, the perspectives of gene combinations in cellular phenotype presentation are discussed. Gene expression profiles change during cellular processes, such as cell proliferation, cell differentiation, and cell death. In addition, epigenetic regulation increases the complexity of the gene expression profile. The role of gene combinations and panels of gene combinations in each cellular condition are also discussed.     

DNA organisation in the chicken lysozyme gene region

DNA sequences surrounding the lysozyme gene of the chicken have been cloned in several recombinants which define a region of 40 Kb. We have detected no other gene with a sequence related to that of the lysozyme gene, nor any gene expressed in the oviduct in these recombinants. This situation contrasts with that of the ovalbumin gene, in the vicinity of which lie two other genes of related structure expressed in the oviduct under hormonal control. The lysozyme gene region, however contains a complex array of repeated sequences, which have been resolved into at least five classes. An inverted repeat overlaps the lysozyme gene itself.     

Lectin functionalized nanocarriers for gene delivery

Gene therapy has emerged as one of the most promising therapeutic methods to treat various diseases. However, inadequate gene transfection efficacy during gene therapy demands further development of more efficient gene delivery strategies. Targeting genetic material to specific sites of action endows numerous advantages over non-targeted delivery. An ample variety of non-viral gene delivery vectors have been developed in recent years owing to the safety issues raised by viral vectors. Non-viral gene delivery vectors containing specific targeting ligands on their surfaces have been reported to enhance the gene transfection efficiency via receptor-mediated endocytosis for gene delivery. Among various targeting moieties investigated, carbohydrates and lectins (carbohydrate-binding proteins) played an essential role in gene delivery via either direct or reverse lectin targeting strategies. Lectins have a specific carbohydrate binding domain that can bind specifically to the carbohydrates. This review sheds light on various gene delivery nanovectors conjugated with either lectins or carbohydrates for enhanced gene transfection.     

Evolutionary coorigin of the RNA polymerase sigma factor and the lambda repressor inferred from gene nucleotide sequence homologies

The lambda phage cI gene and E. coli rpoD gene encoding the lambda repressor and sigma factor, respectively, were aligned with each other based on the internal homologies found in the rpoD gene. Statistical evaluations for these intragenic and intergenic base sequence homologies in the corresponding alignments have conclusively demonstrated that the rpoD gene must have evolved by repeated gene duplications from a primitive gene closely similar to and co-ancestral to the cI gene.     

Contribution of horizontal gene transfer to the evolution of Saccharomyces cerevisiae

The genomes of the hemiascomycetes Saccharomyces cerevisiae and Ashbya gossypii have been completely sequenced, allowing a comparative analysis of these two genomes, which reveals that a small number of genes appear to have entered these genomes as a result of horizontal gene transfer from bacterial sources. One potential case of horizontal gene transfer in A. gossypii and 10 potential cases in S. cerevisiae were identified, of which two were investigated further. One gene, encoding the enzyme dihydroorotate dehydrogenase (DHOD), is potentially a case of horizontal gene transfer, as shown by sequencing of this gene from additional bacterial and fungal species to generate sufficient data to construct a well-supported phylogeny. The DHOD-encoding gene found in S. cerevisiae, URA1 (YKL216W), appears to have entered the Saccharomycetaceae after the divergence of the S. cerevisiae lineage from the Candida albicans lineage and possibly since the divergence from the A. gossypii lineage. This gene appears to have come from the Lactobacillales, and following its acquisition the endogenous eukaryotic DHOD gene was lost. It was also shown that the bacterially derived horizontally transferred DHOD is required for anaerobic synthesis of uracil in S. cerevisiae. The other gene discussed in detail is BDS1, an aryl- and alkyl-sulfatase gene of bacterial origin that we have shown allows utilization of sulfate from several organic sources. Among the eukaryotes, this gene is found in S. cerevisiae and Saccharomyces bayanus and appears to derive from the alpha-proteobacteria.     

自杀行为的生物遗传因素研究

自杀是我国15-34岁人群首位重要的死亡原因。自杀行为的发生与生物学、心理学、社会学等多种因素有关。研究表明自杀行为确有一定的遗传学基础,近年来自杀行为的生物遗传因素研究发现5-HT系统相关基因、儿茶酚胺氧位甲基转移酶基因、精胺/精脒乙酰转移酶基因等候选基因单核甘酸多态性与自杀行为有明显关联。有学者认为,自杀行为的遗传学基础可能是附加于精神疾病的遗传或家庭环境诱导所致。本文就近年来国内外有关自杀的主要相关基因研究发现作一综述。     

Characterization of REC104, a gene required for early meiotic recombination in the yeast Saccharomyces cerevisiae.

The REC104 gene was initially defined by mutations that rescued the inviability of a rad52 spo 13 haploid strain in meiosis. We have observed that rec104 mutant strains undergo essentially no induction of meiotic gene conversion, and we have not been able to detect any meiotic crossing over in such strains. The REC104 gene has no apparent role in mitosis, since mutations have no observable effect on growth, mitotic recombination, or DNA repair. The DNA sequence of REC104 reveals that it is a previously unknown gene with a coding region of 549-bp, and genetic mapping has localized the gene to chromosome VIII near FUR1. Expression of the REC104 gene is induced in meiosis, and it appears that the gene is not transcribed in mitotic cells. Possible roles for the REC104 gene product in meiosis are discussed.     

蓝藻基因转移系统的选择与建立

蓝藻是一类进行光合放氧的原核生物 ,因其结构的特殊性 ,已成为表达外源基因的理想宿主之一。然而外源基因转化系统的选择与建立一直影响着蓝藻基因工程的快速发展。总结了各类蓝藻基因转移系统的特点、影响因素、各系统间的优缺点、以及不同蓝藻株系最适基因转移系统的选择等 ,为利用蓝藻进行遗传操作提供可能 ,为蓝藻基因工程发展提供信息。     

Structure and mapping of the fosB gene. FosB downregulates the activity of the fosB promoter.

We have determined the genomic structure of the fosB gene and shown that it consists of 4 exons and 3 introns at positions also found in the c-fos gene. By deletion analysis we have characterized a region upstream of the TATA box which is the promoter region of the gene. Several consensus sequences have been identified, including an SRE and AP-1 binding site whose relative positions are identical to those in the 5' upstream region of the c-fos gene. We have also shown that FosB and c-Fos can downregulate the activity of the fosB promoter to a similar extent. The fosB gene is located in the [A1-B1] region of mouse chromosome 7.     

A Genetic Analysis of the 63e-64a Genomic Region of Drosophila Melanogaster: Identification of Mutations in a Replication Factor C Subunit

We have performed and F(2) genetic screen to identify lethal mutations within the 63E-64A genomic region. We have isolated 122 mutations in 20 different complementation groups. Of these groups, 16 are represented by multiple alleles. We have also established that the Rop and Ras2 genes are located within the 63E-64A genomic domain at 64A10,11. We have sequenced 10.2 kb of DNA surrounding this gene pair and find that in addition to Rop and Ras2 there is another gene located within this DNA sequence. The gene product, which we have named Rfc40, shows 68% identity to the 40-kDa subunit of replication factor C. We find that the members of one complementation group (13 alleles) derived from our screen correspond to mutations in the Rop gene, whereas the members of another (five alleles) correspond to mutations in the Rfc40 gene. In addition we have isolated 11 new mutant alleles of the disembodied gene.     

Gene complexity and gene duplicability

Eukaryotic genes are on average more complex than prokaryotic genes in terms of expression regulation, protein length, and protein-domain structure [1-5]. Eukaryotes are also known to have a higher rate of gene duplication than prokaryotes do [6, 7]. Because gene duplication is the primary source of new genes [], the average gene complexity in a genome may have been increased by gene duplication if complex genes are preferentially duplicated. Here, we test this "gene complexity and gene duplicability" hypothesis with yeast genomic data. We show that, on average, duplicate genes from either whole-genome or individual-gene duplication have longer protein sequences, more functional domains, and more cis-regulatory motifs than singleton genes. This phenomenon is not a by-product of previously known mechanisms, such as protein function [10-13], evolutionary rate [14, 15], dosage [11], and dosage balance [16], that influence gene duplicability. Rather, it appears to have resulted from the sub-neo-functionalization process in duplicate-gene evolution [11]. Under this process, complex genes are more likely to be retained after duplication because they are prone to subfunctionalization, and gene complexity is regained via subsequent neofunctionalization. Thus, gene duplication increases both gene number and gene complexity, two important factors in the origin of genomic and organismal complexity.     

Characterization of the gene encoding human peroxisomal 3-oxoacyl-CoA thiolase (ACAA). No large DNA rearrangement in a thiolase-deficient patient.

We have characterized the gene encoding human peroxisomal 3-oxoacyl-CoA thiolase, an enzyme operative in the peroxisomal beta-oxidation system. We found one version of this gene (gene symbol ACAA) in the human genome, in contrast to the situation in rat where two versions have been described. The human gene shows a high structural similarity to the rat genes. It contains 12 exons and 11 introns and spans about 11 kb. We have determined the 5' end of the human thiolase mRNA by employing primer extension analysis and we have sequenced the region upstream of the gene. The putative promoter area displays some of the characteristics typical of promoters of other peroxisomal genes, in that it contains GC elements, but lacks TATA boxes. Finally, no large DNA rearrangement involving the thiolase gene could be observed in a patient suffering from pseudo-Zellweger syndrome (peroxisomal thiolase deficiency).     

腺病毒载体在生物治疗中的应用

腺病毒载体是目前重要的基因转移载体之一。腺病毒可作为真核基因表达载体,可制成灭活、重组或抗癌疫苗用于预防呼吸道疾病、癌症和肝炎等传染病。在癌症的基因治疗方面,Ａｄ 载体可运载肿瘤抑制基因,自身基因编码蛋白能诱导细胞调亡,可作为前药物感染细胞,还能利用Ａｄ 的一些特殊复制子,达到治疗肿瘤的目的     

大绿蛙Sox基因和Dmrt基因的序列分析

Sox基因家族与Dmrt基因家族在胚胎发育及性别分化中起着重要作用。采用PCR方法,扩增了大绿蛙Sox基因和Dmrt基因的保守区,分别获得长约220 bp和140 bp的片段。序列分析表明,大绿蛙雌雄个体之间Sox基因、Dmrt基因序列没有差异,与人和其它动物的Sox基因、Dmrt基因有非常高的相似性,显示了Sox基因及Dmrt基因在系统进化上的高度保守性。本研究为探讨大绿蛙的性别决定机制及Sox基因与Dmrt基因的进化提供了分子资料。