黄瓜线粒体DNA类质粒pC1的性质和核酸序列研究

津研四号黄瓜线粒体中除主环ＤＮＡ外,还有４种ＤＮＡ类质粒：ｐＣ１、ｐＣ２、ｐＣ３、ｐＣ４。将环形类质粒ｐＣ１ｌｐｋ ｇｃ ｐＵＣ１９的ＥｃｏＲⅠ位点上,克隆至Ｅ．ｃｏｌｉ ＪＭ１０９中。以克隆的ｐＣ１为探针,进行同源性检测,ｐＣ１与津研四号黄瓜的核基因组、叶绿体基因组、线粒体基因组和线粒体中其他类质粒不同源。对ｐＣ１进行序列测定和分析,ｐＣ１长度２ ８８９ｂｐ,含有多个正向和反向重复序列,有３个８     

低温诱导的黄瓜ccr18基因的cDNA克隆及其表达特性分析

采用mRNA差异显示银染技术克隆得到在黄瓜（Cucumis sativus L.)冷敏型品种“津研4号”低温锻炼中特异表达基因的cDNA克隆（ccr18),其大小为639bp。在基因组中以单拷贝或低拷贝形式存在。Northern blot分析显示ccr18基因在12、24、48和72h低温处理的黄瓜中表达,在6h低温处理及对照中没有表达。这表明ccr18基因与黄瓜低温锻炼相关,序列同源性比较表明,它与拟南芥(Arabidopsis thaliana)染色体ⅢBAC库中的F14P3基因组序列具有88％的同源性。     

南美斑潜蝇对不同黄瓜品种的寄主选择性

采用自由选择法测定了南美斑潜蝇Liriomyza huidobrensis对黄瓜不同品种的寄主选择性。结果表明,南美斑潜蝇成虫产卵和取食选择性最强的黄瓜品种为冬棚王,其对冬棚王的选择性与对光和地黄瓜、新四号黄瓜、津优2号、双杂一号、津杂2号、冬雪王、早春王、神农春四号、津春4号等品种的选择性存在显著差异,而与山东密刺、津优1号、春四号黄瓜、津杂4号、鲁优二号、津优4号、唐山秋瓜、神农春五号、津绿4号等品种差异不显著。测定结果表明,黄瓜不同品种间的叶毛数、可溶性蛋白质及可溶性糖含量存在显著差异。相关分析表明,南美斑潜蝇对不同黄瓜品种的寄主选择性与其叶毛数存在显著的负相关,相关系数r=-0.475 5(P=0.039 5<0.05),而与叶片的可溶性蛋白质及可溶性糖含量关系不显著。     

植物线粒体DNA质料研究进展

本文列出了已发现的高等植物中的线粒体ＤＮＡ质粒,按分子形状分为线粒体环状ＤＮＡ质粒和线粒体线状ＤＮＡ质粒,环状线粒体ＤＮＡ质粒的特征是分子较小,序列中有正向／反向重复序列,ＯＲＦ一般较小。线状线粒体ＤＮＡ质粒的特征是分子较大,末端有重复序列,５’端与蛋白质共价结合,有较长的ＯＲＦ。还分别介绍了它们的复制机制、转录和起源。质粒间及质粒及核基因组、线粒体基因组、叶绿体基因组的同源性也作了介绍。最后,综     

一种检测线粒体核酸酶靶向剪切活性的新方法北大核心CSCD

旨在建立一种简便检测线粒体DNA(mt DNA)核酸酶靶向剪切活性的方法。利用转基因技术,将一段含有两个靶向目标序列(T1、T2)的线粒体DNA序列随机整合到宿主基因组中,通过实时荧光定量PCR筛选单拷贝或低拷贝的单克隆转基因细胞株。将含有T1、T2的CRISPR(clustered regularly interspaced short palindromic repeats)/Cas9质粒分别瞬时转染到所选细胞株中,靶向剪切核基因组,在靶向目标序列处造成DNA双链断裂,引发非同源末端连接修复机制,引入插入或缺失突变。观察测序峰图,证明两个靶向目标序列T1、T2均有剪切效率,且T1高于T2。建立了一种高效快速检测线粒体核酸酶靶向剪切活性的新方法。     

一种检测线粒体核酸酶靶向剪切活性的新方法

旨在建立一种简便检测线粒体DNA(mt DNA)核酸酶靶向剪切活性的方法。利用转基因技术,将一段含有两个靶向目标序列(T1、T2)的线粒体DNA序列随机整合到宿主基因组中,通过实时荧光定量PCR筛选单拷贝或低拷贝的单克隆转基因细胞株。将含有T1、T2的CRISPR(clustered regularly interspaced short palindromic repeats)/Cas9质粒分别瞬时转染到所选细胞株中,靶向剪切核基因组,在靶向目标序列处造成DNA双链断裂,引发非同源末端连接修复机制,引入插入或缺失突变。观察测序峰图,证明两个靶向目标序列T1、T2均有剪切效率,且T1高于T2。建立了一种高效快速检测线粒体核酸酶靶向剪切活性的新方法。     

植物线粒体DNA质粒研究进展

本文列出了已发现的高等植物中的线粒体DNA质粒,按分子形状分为线粒体环状DNA质粒和线粒体线状DNA质粒,环状线粒体DNA质粒的特征是分子较小, 序列中有正向/反向重复序列,ORF一般较小。线状线粒体DNA质粒的特征是分子较大,末端有重复序列,5'端与蛋白质共价结合,有较长的ORF。还分别介绍了它们的复制机制、转录和起源。质粒间及质粒与核基因组、线粒体基因组、叶绿体基因组的同源性也作了介绍。最后,综述了植物线粒体DNA质粒与植物的细胞质雄性不育（CMS）之间的关系。     

两个不同抗性黄瓜品种和云南黑籽南瓜根系分泌物对黄瓜枯萎病发生的影响

研究了黄瓜品种津研4号（感枯萎病）、津春4号（抗枯萎病）和云南黑籽南瓜根系分泌物对津研4号黄瓜枯萎病发生的影响及其原因.结果表明:感病品种根系分泌物处理的黄瓜枯萎病发病早,接种后第15天病株率显著高于对照,至第20天时病株率与对照相近;而抗病品种根系分泌物处理的病株率一直显著小于对照.感病品种根系分泌物浇灌的植株株高、鲜质量降低,根系活力下降、电导度（伤害度）增加,而抗病品种和云南黑籽南瓜根系分泌物处理对植株影响较小.感病品种根系分泌物促进了黄瓜枯萎病菌的生长,而抗病品种和云南黑籽南瓜根系分泌物则抑制了病菌生长.     

大豆GmC4H基因的克隆及同源基因的生物信息学分析

本研究分别在大豆品种中豆27和九农20中克隆大豆肉桂酸-4-羟化酶基因(Glyma.20G114200),得到长度为1 797 bp的C4H基因c DNA序列。比对两者c DNA序列发现4个碱基差异位点。通过对二者氨基酸序列进行理化性质及结构与功能分析发现,C4H基因编码蛋白的5~24位氨基酸之间和32~55位氨基酸之间存在跨膜区域;C4H蛋白含有细胞色素P450结构域。大豆C4H基因的四个拷贝分别分布于第2、第10、第14和第20号染色体上,Glyma.20G114200与Glyma.10G275600的蛋白质同源性高,而另外两个同源基因Glyma.02G236500和Glyma.14G205200的蛋白质同源性高。结果表明,可能大豆4个C4H同源基因在进化过程中发生了功能的较大分化。     

宁夏枸杞与茄科其他植物线粒体基因组的比较与系统进化分析

本研究以宁夏枸杞(Lycium barbarum)的主栽品种‘宁杞1号’为参照,分别从基因构成、内含子分布、同源共线性、保守基因簇、重复序列,以及系统进化等方面与目前已报道的辣椒(Capsicum annuum)、茄子(Solanum melongena)、马铃薯(S.tuberosum)、番茄(S.lycopersicum)、天仙子(Hyoscyamus niger)和烟草(Nicotiana tabacum)等六种茄科(Solanaceae)植物的线粒体基因组进行比较分析,以进一步了解它们的线粒体基因组在结构组成上的异同和亲缘关系。结果表明,茄科不同植物的线粒体基因组大小差异较大,从413 881 bp(宁夏枸杞)到688 698 bp(马铃薯)不等,基因数量在61～71个,其中的蛋白质编码基因除在宁夏枸杞和辣椒中为单拷贝以外,在茄科其他植物中均出现不同程度的多拷贝现象。宁夏枸杞分别与茄子(16个)、马铃薯(16个)和天仙子(15个)共有较多数量的保守基因簇。通过线粒体基因组重复序列分析发现,宁夏枸杞与辣椒的重复序列数量接近,但宁夏枸杞中的简单重复序列(simple sequenc...     

Properties of the Circular Plasmid-like DNA Bl from Mitochondria of Cytoplasmic Male-sterile Rice

Mitochondrial DNA from suspension-cultured cells of the cytoplasmicmale-sterile rice line, A-58 CMS, was shown to contain fourminicircular DNAs. We chose for further examination the largestminicircular DNA, designated Bl. A molecular clone containingthe complete sequence of Bl was constructed and used to probemitochondrial and nuclear genomes by Southern hybridization.No evidence was found for the existence of integrated copiesof Bl in the main mitochondrial genomes of either male-sterileor fertile rice. Sequences homologous to Bl, however, were foundin nuclear genomes of both the male-sterile and the fertilerice. The complete nudeotide sequence of Bl (2,135 bp) was determined,and found to contain sequences homologous to those in the 1,913bp plasmid-like DNA of maize. (Received May 15, 1987; Accepted July 20, 1987)     

Plasmid-like DNAs associated with mitochondria of cytoplasmic male-sterile Sorghum

Summary Plasmid-like, linear DNAs were detected in preparations of mitochondrial DNA from cytoplasmic male-sterile sorghum. Designated N-1 and N-2, the DNAs exhibited molecular sizes of ca. 5,700 and 5,300 bp, respectively. The DNAs occurred in only the IS1112C entry among 24 entries examined. Electron microscopy of the DNAs indicated that the molecules were linear as isolated. Nick translation of N-1 and N-2 followed by membrane hybridization indicated substantial homology between the two DNAs, and some homology to the S-1 and S-2 maize plasmid-like DNAs. At least four additional DNA species, ranging from ca. 1,000–4,000 bp if linear, were also detected in sorghum mitochondrial DNA. The detection of plasmid-like DNAs in sorghum, with homology to the plasmid-like DNAs of maize, suggests an etiological relationship of the molecules to the inheritance and expression of cytoplasmic male sterility in sorghum, perhaps in a manner analogous to the postulated role of these elements in maize.Cooperative Investigations of Agricultural Research Service, U.S. Department of Agriculture, Institute of Food and Agricultural Sciences, University of Florida, Texas Agricultural Experiment Station, and Department of Genetics, North Carolina State University. Florida Experiment Stations Journal Series No. 3578     

Two linear plasmid-like DNA elements simultaneously maintained in Pleurotus ostreatus

Two linear plasmid-like DNA elements, designated pLP01 and pLP02, have been isolated from a strain of Pleurotus ostreatus, an edible basidiomycete. pLP01 (10.0 kb) and pLP02 (9.4 kb) were found in mitochondrial preparations of the fungus and appear to have 5' ends blocked by association of a protein. Proteinase K cleavability of the 5'-terminal protein of pLP01 was higher than that of pLP02, indicating that the terminal proteins of both plasmid-like elements are distinct from one another. pLP01 and pLP02 were estimated to be present to the extent of 1-2 copies each per mitochondrial genome equivalent. The two plasmid-like elements had no homology between them and also were not homologous with the mitochondrial and nuclear genomic DNAs of the fungus.     

Linkage analysis of the nuclear homologues of mitochondrial plasmid-like DNAs in rice.

A genetical study on the nucleotide sequences of the nuclear DNAs which share homology with rice mitochondrial plasmid-like DNAs, B1, B2, B3 and B4 was carried out. Restriction fragments of the nuclear DNAs hybridized with these plasmid-like DNAs showed polymorphisms in their length between Indica and Japonica rice cultivars. The hybridized signals found specifically in Indica or Japonica cultivars segregated in the F2 population derived from a cross between these two subspecies. The observed ratio of the nuclear homologues in the F2 population demonstrated that they were transmitted according to the Mendelian inheritance. The co-segregation of homologues was examined and the linkage was detected between the B1-nuclear homologue of Japonica and the B4-nuclear homologue of Indica, and also between the nuclear homologues of B2 and B3 of Indica. The linkage between the B1-nuclear homologue of Japonica and the B4-nuclear homologue of Indica was conserved in the different rice cultivars.     

Identification of mitochondrial plasmid-like DNAs in Picea abies (L.) Karst.

The Norway spruce (Picea abies (L.) Karst.) mitochondrial DNA has been extracted from embryonal suspensor masses. In addition to a master chromosome, a family of plasmid-like DNAs were identified. These latter shared cross homologies but had no evident sequence homology with the master chromosome. The occurrence of mitochondrial plasmid-like DNAs was investigated in trees from different provenances. A vast majority of trees displayed extrachromosomal DNA elements of variable stoechiometry. For some trees, the sequences homologous to the extrachromosomal DNA elements were found associated with high molecular weight DNA. Received: 9 July 1997 / Revision received: 29 January 1998 / Accepted: 29 November 1998     

Two linear plasmids in mitochondria of Fusarium solani f. sp. cucurbitae

Two linear plasmid-like DNAs designated pFSC1 (9.2 kbp) and pFSC2 (8.3 kbp) were found in an isolate of the plant pathogenic fungus Fusarium solani f. sp. cucurbitae race 1. The plasmids were maternally inherited and copurified with mitochondrial DNA obtained from a mitochondria-enriched cell fraction suggesting that they are located in mitochondria. The plasmids did not share extensive sequence similarity. No homology was detected between either plasmid and the nuclear or mitochondrial genome when cloned plasmids were used as probes in Southern hybridization analyses. The fungus was cured of plasmids by ethidium bromide treatment. Compared to the plasmid-containing isolate, plasmid-cured derivatives had reduced pathogenicity on a susceptible plant host, Cucurbita maxima "Pink Banana."     

Small, repetitive DNAs contribute significantly to the expanded mitochondrial genome of cucumber

Closely related cucurbit species possess eightfold differences in the sizes of their mitochondrial genomes. We cloned mitochondrial DNA (mtDNA) fragments showing strong hybridization signals to cucumber mtDNA and little or no signal to watermelon mtDNA. The cucumber mtDNA clones carried short (30-53 bp), repetitive DNA motifs that were often degenerate, overlapping, and showed no homology to any sequences currently in the databases. On the basis of dot-blot hybridizations, seven repetitive DNA motifs accounted for >13% (194 kb) of the cucumber mitochondrial genome, equaling >50% of the size of the Arabidopsis mitochondrial genome. Sequence analysis of 136 kb of cucumber mtDNA revealed only 11.2% with significant homology to previously characterized mitochondrial sequences, 2.4% to chloroplast DNA, and 15% to the seven repetitive DNA motifs. The remaining 71.4% of the sequence was unique to the cucumber mitochondrial genome. There was <4% sequence colinearity surrounding the watermelon and cucumber atp9 coding regions, and the much smaller watermelon mitochondrial genome possessed no significant amounts of cucumber repetitive DNAs. Our results demonstrate that the expanded cucumber mitochondrial genome is in part due to extensive duplication of short repetitive sequences, possibly by recombination and/or replication slippage.     

Comparative electrophoretical analysis of plasmid-like mitochondrial DNAs in Vicia faba and in some other legumes

Minicircular DNAs found in mitochondria of 6-d-old etiolated seedlings of Vicia faba L. were also present in mitochondria isolated from cell suspension cultures and from green leaves of this plant. These results support the suggestion that the plasmid-like molecules found in mitochondria of V. faba are an essential component of the mitochondrial genome. The minicircular DNAs were, apparently, peculiar for the species V. faba since they were found in all three cultivars of this species which were studied. The distribution pattern of plasmid-like DNAs in Vicia villosa L. was completely different and mitochondria from Medicago sativa L. also contained specific minicircular DNAs. Thus, minicircular DNAs are typical for the mitochondrial genomes of several legumes and different plant species have their specific mitochondrial plasmid-like DNAs