电化学DNA传感器研究进展

电化学DNA传感器是一种新型的生物传感器，对其基本原理、组成及其在基因检测、基因疾病诊断药物机理研究等方面作了介绍，并对其发展趋势进行了展望．     

布氏轮藻肌动蛋白基因家族的全基因组鉴定及表达分析

为了解肌动蛋白actin在轮藻植物生长发育中的潜在功能，本研究利用生物信息学方法对布氏轮藻肌动蛋白基因家族进行了鉴定及表达分析.在布氏轮藻中共鉴定出16个肌动蛋白基因，将其重命名为CbACT1～CbACT16,其氨基酸长度为361～1182 AA,相对分子质量为39 886.71～117 256.72 Da,等电点介于4.68～8.93;亚细胞定位预测显示15个肌动蛋白基因位于细胞质中，1个位于叶绿体中；二级结构结果表明肌动蛋白基因主要以无规则卷曲和α螺旋为主；共线性分析中仅发现一对源自片段重复的旁系同源基因；系统发育结果表明轮藻肌动蛋白基因可以分为两个亚家族，结合基因结构及保守基序分析，同一亚家族倾向于具有相似的外显子分布，较多的共有基序；基于启动子顺势作用元件分析表明，16个肌动蛋白基因参与了许多与生物和非生物胁迫、激素调节和光反应有关的生命活动.组织表达分析显示，16个基因在四种不同组织中存在差异性表达，表明它们在不同组织的生长发育过程中具有不同的功能.因此，轮藻肌动蛋白基因家族可能参与了轮藻植物不同组织的发育过程及响应生物和非生物胁迫等的过程.     

广西六寨中泥盆世生物礁基底层内的Pseudomicroplasma—Cystiphylloides群落及其相关问题的探讨

分析记述的Ｐｓｅｕｄｏｍｉｃｒｏｐｌａｓｍａ—Ｃｙｓｔｉｐｈｙｌｌｏｉｄｅｓ群落，保存于广西六寨中泥盆统东岗岭组生物礁基底层内；至少由十一大门类的４９个居群组成；生物生活方式有六种；动物进食类型有四种；由三个营养级构成群落的营养结构；生物生活取食位置在垂向空间上具有四个层次；Ｐｓｅｕｄｏｍｉｃｒｏｐａｓｍａ、Ｃｙｓｔｉｐｈｙｌｌｏｉｄｅｓ是优势生物和特征生物；底栖固着、悬食、中位生活取食层次、初级消费者营养级等为群落的主要生态特征。该化石群落所代表的原生群落，生存于中泥盆世吉维特期的早期，发育于水流畅通地势较为平坦的浅海陆棚环境（风暴浪基面以上的潮下带）。该化石群落的特征反映的是其原生群落中底栖动物群的生态特征。原生群落的消亡与群落演替有关。     

鱼类中的多倍性及其在鱼类演化中的作用(续)

两性生殖多倍体的适应和演化能力 Stebbins曾提出,由于基因的大量重复,削弱了新突变和基因重组的作用,从而使多倍体很难真正产生出新适应的基因复合体,因此演化的主要趋势是二倍体种的演替。Ohno及其同事们的看法正与此相反。他们认为,只有由基因重复而造成的多余的、不负责任的DNA才能作为新基因位点出现,为过去不曾有也不可能有的新适应编码,从而实现远比宗的分化、远比一种刚形成的共同祖先所能产生的辐射适应大得多的进化改变,而基因重复的最好方式正是多倍化。     

简单并不代表原始：关于生物早期演化的一种新观点

１９７７年,Ｗｏｅｓｅ等［１］通过对细菌ｒＲＮＡ分析,提出了生物分类的三大界学说,即真核生物、古细菌和真细菌．Ｉｗａｂｅ等［２］对一种在生物三大界分岐之前就发生重复的ＡＴＰ酶基因分析,进一步推测古细菌与真核生物更为接近（图１ａ）．从图１ａ中还可以看出...     

三种原生动物蛋白质和同工酶电泳研究

由于蛋白质(酶)是基因的直接产物,因此,对蛋白质(酶)的分析可以反映出生物体的遗传本质.近年来,国外已应用凝胶电泳技术对原生生物的蛋白质与同工酶进行了广泛的研究.但是,有关原生动物的总蛋白质电泳分析尚未见有报导,另外,有关同工酶的研究也往往仅限于少数几种酶.本文以三种原生动物为材料,建立蛋白质凝胶浓度梯度电泳技术和多种同工酶电泳检测系统,为进一步研究这些单细胞真核生物打下一个基础.     

三种原生动物蛋白质和同工酶电泳研究

由于蛋白质(酶)是基因的直接产物,因此,对蛋白质(酶)的分析可以反映出生物体的遗传本质。近年来,国外已应用凝胶电泳技术对原生生物的蛋白质与同工酶进行了广泛的研究。但是,有关原生动物的总蛋白质电泳分析尚未见有报导,另外,有关同工酶的研究也往往仅限于少数几种酶。本文以三种原生动物为材料,建立蛋白质凝胶浓度梯度电泳技术和多种同工酶电泳检测系统,为进一步研究这些单细胞真核生物打下一个基础。     

抗虫转Bt基因植物的环境安全研究进展

抗虫性状转Bt基因植物是目前世界上商业化种植规模仅次于耐除草剂性状的第二大类转基因植物.本文从对非靶标生物的影响、基因漂移、靶标生物的抗性和杂草化演化4个方面简介了抗虫转Bt基因植物环境安全研究的主要进展,并就今后应该继续研究的问题提出了建议.     

英语诗歌语篇中的重复

运用G.利奇等现代语言学家提供的理论框架, 对英语诗歌语篇中的重复现象进行分析,认为重复是英语诗歌最重要的创作手段.论文阐述了三种常见的重复手段及其表现形式, 认为英诗的韵律是以重复为特征的,词语重复和平行结构是诗歌特有的语言组合方式; 重复是诗歌语篇的一种衔接手段.论述诗歌语篇的重复与诗歌前景化的关系,强调诗歌中的重复是对常规语言的偏离,是诗歌前景化十分重要的表现形式,而偏离的手段就是运用违背日常语言的诗意化的词语、诗意化的音韵和诗意化的结构,认为重复的手段总是与诗歌语篇的整体意义有着直接的关系,每一种重复都会传达作者的某种动机,因此,研究诗歌中那些频繁出现的音素、词语和语言结构的重复模式具有十分重要的意义.本文还着重分析了现代诗人在运用重复时反传统的一些基本特征及表现形式.     

牛蛙标准Ag-NOR_s形态的初步观察

银染核仁组织者(Ag-NORs)是1975年由Goodpasture和Bloom所做的开创性工作.后来,通过原位杂交的方法证明银染核仁组织者区就是18S 28S 5.8SrRNA基因所在的位点.由此,银染为各类生物rRNA基因的研究提供了一种简单、快速的方法.按Schmid的报道,无尾类中有68％个体的NOR异形是由NOR串接重复造成的.其     

Widespread horizontal transfer of mitochondrial genes in flowering plants

Horizontal gene transfer--the exchange of genes across mating barriers--is recognized as a major force in bacterial evolution. However, in eukaryotes it is prevalent only in certain phagotrophic protists and limited largely to the ancient acquisition of bacterial genes. Although the human genome was initially reported to contain over 100 genes acquired during vertebrate evolution from bacteria, this claim was immediately and repeatedly rebutted. Moreover, horizontal transfer is unknown within the evolution of animals, plants and fungi except in the special context of mobile genetic elements. Here we show, however, that standard mitochondrial genes, encoding ribosomal and respiratory proteins, are subject to evolutionarily frequent horizontal transfer between distantly related flowering plants. These transfers have created a variety of genomic outcomes, including gene duplication, recapture of genes lost through transfer to the nucleus, and chimaeric, half-monocot, half-dicot genes. These results imply the existence of mechanisms for the delivery of DNA between unrelated plants, indicate that horizontal transfer is also a force in plant nuclear genomes, and are discussed in the contexts of plant molecular phylogeny and genetically modified plants.     

Global trends of whole-genome duplications revealed by the ciliate Paramecium tetraurelia

The duplication of entire genomes has long been recognized as having great potential for evolutionary novelties, but the mechanisms underlying their resolution through gene loss are poorly understood. Here we show that in the unicellular eukaryote Paramecium tetraurelia, a ciliate, most of the nearly 40,000 genes arose through at least three successive whole-genome duplications. Phylogenetic analysis indicates that the most recent duplication coincides with an explosion of speciation events that gave rise to the P. aurelia complex of 15 sibling species. We observed that gene loss occurs over a long timescale, not as an initial massive event. Genes from the same metabolic pathway or protein complex have common patterns of gene loss, and highly expressed genes are over-retained after all duplications. The conclusion of this analysis is that many genes are maintained after whole-genome duplication not because of functional innovation but because of gene dosage constraints.     

拟南芥基因倍增及基因流失分析

基因倍增指基因组中含有基因的DNA片段复制出一个或更多拷贝的过程，是进化出新物种的主要原因。采用新的数据和方法研究拟南芥基因组的基因倍增过程，通过分析串联基因倍增和大规模基因倍增的存在比例和同义置换率分布，并估计大规模倍增后基因流失的比例，揭示了拟南芥基因组一次非常明显的全基因组倍增，采用科学的方法估计这次倍增发生在约8000万年前。比较该结果与之前的研究，提出了一种解释拟南芥基因倍增过程更合理的模型。     

拟南芥基因倍增及基因流失分析

基因倍增指基因组中含有基因的DNA片段复制出一个或更多拷贝的过程,是进化出新物种的主要原因。采用新的数据和方法研究拟南芥基因组的基因倍增过程,通过分析串联基因倍增和大规模基因倍增的存在比例和同义置换率分布,并估计大规模倍增后基因流失的比例,揭示了拟南芥基因组一次非常明显的全基因组倍增,采用科学的方法估计这次倍增发生在约8000万年前。比较该结果与之前的研究,提出了一种解释拟南芥基因倍增过程更合理的模型。     

A genome-wide comparison of recent chimpanzee and human segmental duplications

We present a global comparison of differences in content of segmental duplication between human and chimpanzee, and determine that 33% of human duplications (> 94% sequence identity) are not duplicated in chimpanzee, including some human disease-causing duplications. Combining experimental and computational approaches, we estimate a genomic duplication rate of 4-5 megabases per million years since divergence. These changes have resulted in gene expression differences between the species. In terms of numbers of base pairs affected, we determine that de novo duplication has contributed most significantly to differences between the species, followed by deletion of ancestral duplications. Post-speciation gene conversion accounts for less than 10% of recent segmental duplication. Chimpanzee-specific hyperexpansion (> 100 copies) of particular segments of DNA have resulted in marked quantitative differences and alterations in the genome landscape between chimpanzee and human. Almost all of the most extreme differences relate to changes in chromosome structure, including the emergence of African great ape subterminal heterochromatin. Nevertheless, base per base, large segmental duplication events have had a greater impact (2.7%) in altering the genomic landscape of these two species than single-base-pair substitution (1.2%).     

Unravelling angiosperm genome evolution by phylogenetic analysis of chromosomal duplication events

Conservation of gene order in vertebrates is evident after hundreds of millions of years of divergence, but comparisons of the Arabidopsis thaliana sequence to partial gene orders of other angiosperms (flowering plants) sharing common ancestry approximately 170-235 million years ago yield conflicting results. This difference may be largely due to the propensity of angiosperms to undergo chromosomal duplication ('polyploidization') and subsequent gene loss ('diploidization'); these evolutionary mechanisms have profound consequences for comparative biology. Here we integrate a phylogenetic approach (relating chromosomal duplications to the tree of life) with a genomic approach (mitigating information lost to diploidization) to show that a genome-wide duplication post-dates the divergence of Arabidopsis from most dicots. We also show that an inferred ancestral gene order for Arabidopsis reveals more synteny with other dicots (exemplified by cotton), and that additional, more ancient duplication events affect more distant taxonomic comparisons. By using partial sequence data for many diverse taxa to better relate the evolutionary history of completely sequenced genomes to the tree of life, we foster comparative approaches to the study of genome organization, consequences of polyploidy, and the molecular basis of quantitative traits.     

Stability of expression-linked surface antigen gene in Trypanosoma equiperdum

African trypanosomes evade clearance in immune-competent hosts by periodically replacing their major surface glycoprotein with an antigenically different glycoprotein. Expression of many of these variant surface glycoproteins (VSGs) is associated with the duplication and transposition of silent basic copy genes (BCs) into unlinked genomic expression sites. The new expression-linked VSG gene copies (ELCs) are oriented with their 3' ends proximal to chromosome telomeres. Other VSG genes are activated without the production of an ELC. The 3' ends of these VSG genes are near chromosome telomeres both when they are active and when they are inactive. Recently, we have shown that activation of the VSG-1 gene in the BoTaR (Bordeaux trypanozoon antigen repertoire) serodeme of Trypanosoma equiperdum involves the duplication and transposition of a telomeric BC gene into one of at least three unlinked telomeric sites. Here we show that the VSG-1 ELC is inactivated but not eliminated in some antigenic variants derived from a VSG-1 expressor. In addition, a subsequent variant that again expresses VSG-1 has not reactivated the residual VSG-1 ELC (R-ELC), but instead contains a new, active VSG-1 ELC in an unlinked telomeric site. These results show that the simple presence of an ELC in a potential expression site is not sufficient for its expression.     

甘蓝型油菜BnHY5基因的表达模式及非生物胁迫响应分析

为探究甘蓝型油菜中HY5的表达情况,首先通过甘蓝型油菜基因组数据分析预测HY5及其同源基因HYH(HY5-Homologous),克隆获得了四个HY5(命名为BnHY5)以及三个HYH(命名为BnHYH)重复基因全长cDNA序列.其次,对BnHY5进行了蛋白结构预测、理化性质分析,研究结果表明:BnHY5蛋白为不稳定、亲水性蛋白,主要结构域为亮氨酸拉链.最后,探究了甘蓝型油菜中该基因的表达情况,用荧光定量PCR分析了BnHY5重复基因表达模式和响应非生物胁迫的情况,BnHY5四个基因中,BnHY5-2的表达水平最高,BnHY5-1、BnHY5-2不存在组织表达差异且表达水平高于BnHY5-3、BnHY5-4.BnHY5基因不仅响应高温、低温、镉、高盐非生物胁迫,而且参与ABA和GA_3激素信号响应,说明BnHY5在逆境胁迫中有重要作用.此外BnHY5重复基因在非生物胁迫下的表达模式发生改变,BnHY5四个基因的表达占比与不同类型胁迫处理相关,存在表达差异.