黑线仓鼠与大仓鼠线粒体DNA控制区全序列SNPs分析

以华北地区大仓鼠和黑线仓鼠为研究对象,运用第三代DNA分子标记SNPs(single nucleotide polymorphisms)技术,研究了其线粒体DNA控制区(mtDNA D-loop)全序列的单核苷酸多态性.结果表明:在黑线仓鼠和大仓鼠种群中共检测到11个单倍型,22个多态位点,其中只有2个是颠换,其余都是转换.不同种群的核苷酸多态性不同,种群内的核苷酸多态性小于种群间的核苷酸多态性.线粒体DNA D-loop全序列适合作黑线仓鼠和大仓鼠的核苷酸多态性和遗传进化关系的分析.     

DNA分子标记在猫科动物系统发生关系研究中的应用

DNA分子标记的广泛应用,使得系统进化、生物地理、群体遗传及人类学等领域的研究得到前所未有的发展.猫科动物分子系统发育关系的重建是目前猫科动物DNA研究的主要方向,进而可以从DNA分子水平上研究猫科动物的进化过程及系统发育关系的本质.本文对DNA分子标记在猫科动物分子系统学中的部分研究成果做了概括.     

动物线粒体DNA

线粒全DNA作为分子标记已被广泛应用于家畜育种、生物进化、发病机理、临床诊断等方面的研究，并取得了许多有价值的结果．综述了动物线粒体DNA的结构特征、遗传特征，并阐明了线粒体DNA多态性研究方法、研究进展以及线粒体DNA多态性在动物遗传育种中的应用．     

基于线粒体ND5基因的昆虫分子系统学研究进展

ND5基因位于mtDNA上,其进化速率较快,是昆虫分子系统学研究中理想的分子标记之一.目前,已经利用该基因从各个分类水平对昆虫系统发育关系、物种形成与分化、种群遗传与变异及生物地理等方面做了广泛的研究.对ND5基因的分子特点及其在昆虫系统学研究中的应用进行综述.     

石斑鱼类的分子系统学研究进展

石斑鱼类是世界上最重要的海洋经济鱼类之一，其种类繁多，大部分营定居性生活．由于种间缺乏明显的外部形态区别特征．石斑鱼的分类一直是鱼类系统分类学中的一个难题，存在着很多争议和混淆．通过DNA序列分析在分子水平重建物种的系统进化关系是当前系统学研究的一个新热点，是传统系统学研究的重要补充和佐证．本文简要综述了石斑鱼类传统分类研究状况、存在问题及当前石斑鱼类的分子系统学研究进展，并对石斑鱼类的系统学研究发展作了展望．     

DNA遗传标记与绵山羊遗传育种

综述了分子遗传标记限制性片段长度多态、随机扩增多态DNA、DNA指纹、微卫星DNA、线粒体DNA限制性片段长度多态、扩增片段长度多态DNA等技术的原理、遗传特点，及其在绵羊和山羊遗传育种中的研究现状，并对其在绵羊和山羊育种中的应用前景作了展望。     

分子标记技术在真菌上的应用(综述)

对分子标记在真菌分离菌株的分子鉴定、基因定位克隆、遗传图谱构建、遗传多样性分析、遗传亲子分析及线粒体DNA遗传研究等方面的应用进行了综述。     

核基因在鱼类分子系统学研究中的应用 (运筹学与控制论)

利用分子标记探讨鱼类的系统发育和分子进化已经逐渐成为现代鱼类系统学研究的热点之一。本文综述了核基因在鱼类分子系统发育和分子进化研究中的应用现状及其存在的优缺点。常用的核基因主要有核糖体基因,其中保守的18SrDNA及28SrDNA主要用于研究高级分类阶元;在研究亲缘关系较近的物种以及不同地理种群时,比较常用到的则是ITSs以及SINEs;而RAGs及S7性质独特,也常被用于鱼类的分子系统学研究中。以往的研究主要利用线粒体基因(如Cytb等)研究鱼类的分类和进化,但多年来的研究发现,线粒体基因在研究鲤形目(Cypriniformes)、鲈形目(Perci-formes)等鱼类系统发育时并不能成为最佳的选择。最近的研究表明,核基因能够弥补线粒体基因的缺陷,并可广泛应用于鱼类系统发育研究。然而,核基因的应用也面临着如下问题:1)因核基因重组导致数据分析难度较大;2)鉴定不同类群时存在一定误差;3)单倍性核基因片段较难获得;4)对某些进化时间短的群体的系统发育研究效果较差。随着上述问题的逐步解决,核基因的应用将会更加广泛。     

鸟类线粒体基因组及系统发育的研究进展

相对于核基因组而言,线粒体基因组具有结构简单、分子量小、基因排列紧密、严格母系遗传、进化速率较快和无组织特异性等特点。近年来,线粒体DNA已被作为重要的分子标记,应用于推断很多分类等级的系统发育关系。本文综述了脊椎动物线粒体基因组、鸟类线粒体基因组以及Mt DNA在鸟类系统发育研究中的应用等方面的研究现状,并对今后研究前景进行了展望。     

安徽省毫州地区黄牛群体遗传多样性研究

利用随机扩增多态DNA技术对安徽省毫州地区黄牛种群进行了DNA多态性检测,以期了解该地区黄牛群体的遗传变异,进而探讨分子遗传标记在家畜小群体保种方案中的应用.计算了多态性引物在个体间的平均带纹等位片段频率、平均带纹等位片段杂合度和遗传多样性指数,并作分子亲缘关系聚类分析.该地区黄牛种群扩增等位基因片段的遗传杂合度比较高.     

Complete replacement of mitochondrial DNA in Drosophila

The introduction of foreign mitochondria or mitochondrial DNA into a cell is a useful technique for clarifying the molecular mechanisms responsible for the maintenance of mitochondria. Novel combinations of mitochondrial and nuclear genomes have been studied in mammalian cells in culture and in yeast. In Drosophila, we have recently constructed heteroplasmic flies possessing both endogenous mitochondrial DNA and foreign mitochondrial DNA by intra- and interspecific transplantation of germ plasm. During the maintenance of these heteroplasmic lines, flies of D. melanogaster are produced that no longer possess their own mitochondrial DNA but retain the foreign mitochondrial DNA from D. mauritiana. .These flies are fertile and the foreign mitochondrial DNA is stably maintained in their offspring. Here we report the complete replacement of endogenous mitochondrial DNA with that from another multicellular species. Molecular and genetic analysis of this replacement in Drosophila should provide new insight into the functional interaction between nuclear and organelle genomes.     

Mitochondrial DNA repairs double-strand breaks in yeast chromosomes

The endosymbiotic theory for the origin of eukaryotic cells proposes that genetic information can be transferred from mitochondria to the nucleus of a cell, and genes that are probably of mitochondrial origin have been found in nuclear chromosomes. Occasionally, short or rearranged sequences homologous to mitochondrial DNA are seen in the chromosomes of different organisms including yeast, plants and humans. Here we report a mechanism by which fragments of mitochondrial DNA, in single or tandem array, are transferred to yeast chromosomes under natural conditions during the repair of double-strand breaks in haploid mitotic cells. These repair insertions originate from noncontiguous regions of the mitochondrial genome. Our analysis of the Saccharomyces cerevisiae mitochondrial genome indicates that the yeast nuclear genome does indeed contain several short sequences of mitochondrial origin which are similar in size and composition to those that repair double-strand breaks. These sequences are located predominantly in non-coding regions of the chromosomes, frequently in the vicinity of retrotransposon long terminal repeats, and appear as recent integration events. Thus, colonization of the yeast genome by mitochondrial DNA is an ongoing process.     

Rearranged mitochondrial genes in the yeast nuclear genome

We have found a contiguous DNA sequence in the yeast nuclear genome with extensive homology to non-contiguous yeast mitochondrial DNA sequences. Closely linked to this nuclear sequence in some, but not all, yeast strains is a tandem pair of transposable (Ty) elements. Certain features of the content and organization of this nuclear DNA sequence suggest that it may have originated from petite mitochondrial DNA which integrated into the nuclear genome.     

A mutation in the tRNA(Leu)(UUR) gene associated with the MELAS subgroup of mitochondrial encephalomyopathies

Mitochondrial encephalomyopathies are usually divided into three distinct clinical subgroups: (1) mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS); (2) myoclonus epilepsy associated with ragged-red fibres (MERRF); and (3) chronic progressive external ophthalmoplegia (CPEO) including Kearns-Sayre syndrome. Large deletions of human mitochondrial DNA and a transition mutation at the mitochondrial transfer RNALys gene give rise to CPEO including Kearns-Sayre syndrome and MERRF, respectively. Here we report an A-to-G transition mutation at nucleotide pair 3,243 in the dihydrouridine loop of mitochondrial tRNA(Leu)(UUR) that is specific to patients with MELAS. Because this mutation creates an ApaI restriction site, we could perform a simple molecular diagnostic test for the disease. The mutation was present in 26 out of 31 independent MELAS patients and 1 out of 29 CPEO patients, but absent in the 5 MERRF and 50 controls tested. Southern blot analysis confirmed that the mutant DNA always coexists with the wild-type DNA (heteroplasmy).     

白菜hau CMS不育系特异分子标记的开发与应用

以不同胞质的白菜和芥菜为材料,将hau CMS胞质的线粒体基因组与芸薹属植物中其他的细胞质雄性不育系的线粒体基因组进行比较,再经生物信息学分析,筛选得到hau CMS线粒体基因组上特异的序列,并根据该序列信息开发出用于鉴定白菜hau CMS类型的分子标记hau CMS-Specific.同时,通过序列对比分析发现hau CMS线粒体基因组缺失但其他胞质共有的线粒体基因组序列.根据该序列信息,开发了互补检测的分子标记hau CMS-Deletion.最后利用hau CMS、ogu CMS、pol CMS、oxa CMS、orf220CMS等不同胞质类型材料的DNA成功验证了这两对标记.     

胍基丁胺对谷氨酸诱导PC12细胞DNA损伤的影响

探讨了胍基丁胺对谷氨酸诱导PC12细胞DNA损伤的影响。在用一定浓度的谷氨酸诱导PC12细胞DNA断裂的同时，观察胍基丁胺对其DNA断裂和线粒体功能的影响，发现胍基丁胺能明显减轻谷氨酸诱导PC12细胞DNA断裂并能改善线粒体功能。这说明胍基丁胺具有抑制PC12细胞DNA损伤的作用，其机制可能与其拮抗NMDA受体，改善线粒体功能和减轻谷氨酸的氧化毒性有关。     

DNA ligase III is critical for mtDNA integrity but not Xrcc1-mediated nuclear DNA repair

DNA replication and repair in mammalian cells involves three distinct DNA ligases: ligase I (Lig1), ligase III (Lig3) and ligase IV (Lig4). Lig3 is considered a key ligase during base excision repair because its stability depends upon its nuclear binding partner Xrcc1, a critical factor for this DNA repair pathway. Lig3 is also present in the mitochondria, where its role in mitochondrial DNA (mtDNA) maintenance is independent of Xrcc1 (ref. 4). However, the biological role of Lig3 is unclear as inactivation of murine Lig3 results in early embryonic lethality. Here we report that Lig3 is essential for mtDNA integrity but dispensable for nuclear DNA repair. Inactivation of Lig3 in the mouse nervous system resulted in mtDNA loss leading to profound mitochondrial dysfunction, disruption of cellular homeostasis and incapacitating ataxia. Similarly, inactivation of Lig3 in cardiac muscle resulted in mitochondrial dysfunction and defective heart-pump function leading to heart failure. However, Lig3 inactivation did not result in nuclear DNA repair deficiency, indicating essential DNA repair functions of Xrcc1 can occur in the absence of Lig3. Instead, we found that Lig1 was critical for DNA repair, but acted in a cooperative manner with Lig3. Additionally, Lig3 deficiency did not recapitulate the hallmark features of neural Xrcc1 inactivation such as DNA damage-induced cerebellar interneuron loss, further underscoring functional separation of these DNA repair factors. Therefore, our data reveal that the critical biological role of Lig3 is to maintain mtDNA integrity and not Xrcc1-dependent DNA repair.     

一母系遗传非综合征耳聋家系的线粒体DNA突变分析

在问卷调查及家系随访的基础上,在安徽省淮北市收集到一母系遗传非综合征耳聋家系,利用聚合酶链式反应-限制片段长度多态性分析(PCR-RFLP)和测序技术,检测了该家系成员线粒体DNA(mtDNA)上可导致非综合征耳聋的两个突变热点处(12S rRNA基因上的1 555位点和tRNASer(UCN)基因上的7 445位点)的碱基变化,发现该家系所有母系成员的mtDNA上都有A1555G同质型突变,但7 445位点无异常;进而对该家系两个表型明显不同母系成员(一例具有先天性耳聋表型,另一例听力正常)的mtDNA进行全长测序,结果未在mtDNA上发现除A1555G以外的其他位点突变,只发现了27处多态性序列变化,且两成员的mtDNA无序列差异.说明mtDNA上的A1555G同质型突变是该家系部分母系成员致聋的分子生物学基础之一;推测该家系A1555G突变携带者临床表型的差异可能与mtDNA多态性无关,而更可能是核修饰基因与A1555G突变协同作用的结果.     

Conservation and rearrangement of mitochondrial structural gene sequences

Mitochondria contain the simplest DNA molecules that are present in eukaryotes. Mitochondrial DNA (mtDNA) is easily purified, and is an important model system for studying eukaryote gene structure and basic molecular processes. The protein sequences of mitochondrial gene products have been shown to be conserved from yeast to man, and there are definite similarities at the DNA sequence level. In contrast, the overall organization of the mitochondrial genome is drastically different in these organisms. To understand this, we need to extend work on mtDNA to a wider range of species. We have chosen to study the mtDNA of Aspergillus nidulans because a particularly comprehensive analysis of this system can be achieved using genetics as well as biochemistry, and like most eukaryotes it is an obligate aerobe, whereas Saccharomyces cerevisiae is not. We have investigated whether defined pieces of particular yeast mitochondrial genes show enough homology to Aspergillus mtDNA fragments to enable the corresponding Aspergillus genes to be located on the physical map. The results reported here show that this is the case for all five genes tested, and present the first data on the physical organization of the structural genes in the mitochondrial genome of A. nidulans.     

Basal body movements as a mechanism for mitochondrial genome segregation in the trypanosome cell cycle

The mitochondrial genome of Trypanosoma brucei is organized in the form of a complex catenated network of circular DNA molecules. This mass of DNA, known as the kinetoplast, is present at a unique site in the single mitochondrion, and is replicated in a discrete, periodic S phase of the cell cycle. The single-copy nature of the kinetoplast suggests that there is a mechanism ensuring segregation fidelity of replicated copies to each daughter cell. Historically, speculation regarding the nature of this mechanism has often attributed significance to the close association between the kinetoplast and the flagellum basal body. We provide here direct evidence that this mitochondrial DNA complex is indeed linked to the basal body, and segregation of the kinetoplast DNA is dependent on a microtubule-mediated separation of the new and old flagellar basal bodies during the cell cycle. This unique system may represent the remnants of an evolutionarily archaic mechanism for genome segregation.