应用引物延预扩增提高微量DNA拷贝数

采用引物延伸预扩增方法,可普遍提高微量模板ＤＮＡ的考贝数,便于进行基因分析时克服标本时少、来源困难的制约,采用常规扩增、检测２４８ｂｐ的ＤＹＺ１片段体系为观察对象,其最小模板量需１．５ｎｇ／２０μｌ体系。以１５个碱基随机寡核苷酸为引物,对最小模板量进行预扩增,再以其产和１／１０为模板,特异扩增ＤＹＺ１片段。进行了相对定量分析,判断源模板ＤＮＡ拷贝数增加的程度。结果１．５ｎｇ男性ＤＮＡ,经随机扩增后     

小麦随机扩增多态性DNA的反应体系探索

随机扩增多态性DNA(RAPD)是近年来发展起来的一种DNA多态性检测技术。通过以小麦基因组DNA为模板 ,对RAPD反应程序中的一些重要参数进行摸索和优化试验 ,建立了随机扩增多态性DNA分析应用反应体系。即反应体积为 2 5μ1,Mg2 浓度为 2 0mM ,dNTP浓度为 150 μM ,模板DNA量 5ng～2 5ng ,随机引物量 30ng～ 4 5ng ,Tap酶 1单位 ;反应过程为 90℃变性 30s ,38℃结合 1min ,72℃延伸 2min(最后一个循环 10min) ,共 4 0个循环。该体系可有效地应用在小麦遗传育种研究中 ,重复性好 ,可靠性高。     

广东野百合DNA提取和RAPD条件的优化

以野百合(Lilium brownii)新鲜叶片、硅胶干燥叶片及鳞片为材料,研究了DNA的提取方法,并对影响随机扩增多态DNA(RAPD)反应的各因素进行了优化。建立了野百合RAPD的优化反应体系及程序,即在20μl反应体系中,含20 ng模板DNA,2.0 mmol/L Mg2 、0.2 mmol/L dNTPs、1.5 U Taq DNA聚合酶、0.3μmol/L随机引物S1519;扩增程序为:94℃预变性5 min,然后94℃30 s,38℃50 s,72℃1 min,35个循环,最后72℃延伸10 min,4℃保存。     

石榴叶片SRAP体系优化及其在白花芽变鉴定中的应用

采用优化的SRAP-PCR反应体系,对红花石榴母株上的白花变异枝进行鉴定和分析.结果表明,适宜石榴的SRAP-PCR反应体系中含dNTP 0.2 mmol/L、Mg2+ 2 mmol/L、引物0.4 μmol/L、DNA模板0.8 mg/L、Taq聚合酶50 000 U/L.600对SRAP随机引物组合中有580对引物组合有较好的扩增效果,其中Me30/Em7引物组合在母株和变异枝条间扩增出1条长度为78 bp的稳定差异条带.根据该差异片段序列设计的特异引物在母株中有68 bp扩增条带,在变异枝条中没有扩增条带.表明白花变异枝条的产生可能与母株DNA片段缺失有关.     

永瓣藤ISSR—PCR反应体系的建立与优化

以永瓣藤基因组DNA为模板,通过单因子、双因子实验研究了ISSR反应体系中主要成分(Mg2 、dNTP、引物、模板DNA、TaqDNA聚合酶)以及热循环参数(退火温度、循环数、变性时间、退火时间、延伸时间)对扩增结果的影响,并找出各自的最适条件,建立了适合永瓣藤ISSR分析的反应体系和扩增程序,即在25 μL反应体系中,内含1×PCR buffer、1.5 mmol/L Mg2 、200 μmol/L dNTP、0.5 μmol/L引物、50 ng 模板、2 U TaqDNA聚合酶.扩增程序为94 ℃预变性5 min,然后进行35个循环:94 ℃变性30 s,复性1 min,72 ℃延伸1 min,循环结束后72 ℃延伸7 min.这一优化系统的建立为今后利用ISSR标记技术进行永瓣藤鉴定及种质遗传多样性分析提供了一个标准化程序.     

条纹斑竹鲨基因组的RAPD分析初报

采用11种随机引物对4 条条纹斑竹鲨基因组进行了RAPD检测.结果表明,11种引物在每条个体上扩增的 DNA片段总数在77～84之间,单个随机引物扩增的DNA片段数目由1至11条不等,平均为7.5条 DNA 片段,片段的大小在 300～2 800bp之间.个体之间的相似率在90%以上.     

濒危药用植物厚朴ISSR引物筛选及反应条件的优化

以厚朴DNA为模板,利用正交试验分别对影响厚朴ISSR-PCR反应的Taq酶浓度、dNTP浓度、引物浓度、Mg~(2+)浓度、模板DNA浓度进行了优化,并通过梯度PCR确定不同引物的最佳退火温度和循环次数,最终确定厚朴最佳反应体系及扩增条件为:25μl 体系,其中包括1.5 mmol·L~(-1) MgCl_2,0.3 μmol·L~(-1)引物,0.04 U·μl~(-1)Taq 酶,0.2 mmol·L~(-1) dNTP,4 ng·μl~(-1)模板DNA,1 × Buffer;扩增程序:94℃预变性5 min,94℃变性30 s,50℃～60℃(退火温度随引物不同而定)退火45 s,72℃延伸90 s,共40个循环,然后72℃延伸8 min,4℃终止反应.此外,还利用优化的反应体系成功筛选出21条ISSR引物,并利用部分引物对厚朴个体进行了遗传多样性分析.     

cDNA-AFLP比较当归早薹基因转录差异反应体系的建立

建立了利用cDNA-AFLP技术对当归早薹相关的差异表达基因进行筛选的方法,优化了影响cDNA-AFLP试验结果的关键因子,包括选择性扩增模板量、酶离子浓度、dNTP浓度。结果表明,以1μL稀释10倍的预扩增产物作为模板、1.5 mmol/LMgCl2、0.6 mmol/L dNTP,进行的选择性扩增反应获得DNA片段分子量范围较广,在100-1 000 bp长度范围中均有扩增片段,是较为理想的选择性扩增的结果。聚丙烯酰胺凝胶电泳验证了试验结果,在优化条件下利用部分引物组合可以较好地比较早薹当归在基因转录水平发生的差异。     

长距离反向PCR技术高效扩增已知DNA片断的侧翼序列

为解决传统反向PCR技术扩增片段短、假阳性多的不足,建立了长距离反向PCR(LD I-PCR)扩增技术:0.5μg DNA/mL的反应体系使DNA酶解片段充分自身环化连接,其产物用25 nt~30 nt的序列特异引物进行长距离PCR。结果表明该方法能特异地扩增出长达16 kb的序列,在已知DNA片段的侧翼序列克隆方面具有高效、简便、特异的优点。     

杨梅RAPD-PCR体系的正交优化研究

以杨梅DNA为模板,对影响杨梅RAPD-PCR扩增的重要参数进行了优化试验,以期建立杨梅RAPD反应的最佳体系。通过采用正交试验设计的方法,对杨梅RAPD-PCR条件进行了优化,结果表明最佳的杨梅RAPD-PCR的反应体系(20μl)中含有1×buffer,1.0U TaqDNA聚合酶,3.0mmol/L MgCl2,0.30mmol/L dNTPs,1.5μmol/L引物和模板DNA 30-40ng。适宜的扩增条件为94℃预变性3min,再进入38个PCR循环(94℃变性30s,38℃退火30s,72℃延伸90s),72℃延伸7min,4℃保存。     

Organizational variation of DYZ1 repeat sequences on the human Y chromosome and its diagnostic potentials

The long arm of the human Y chromosome is flecked with various fractions of repetitive DNA. DYZ1 is one such fraction, which is organized tandemly as an array of a 3.4-kb repeat ranging from 2000-4000 copies in normal males. We have studied the organizational variation of the DYZ1 fraction on the human Y chromosome using DNA samples from CEPH family members and the random population employing the RFLP approach, fluorescence in situ hybridization (FISH), and conducted a similarity search with GenBank sequences. Typing of genomic DNA using DYZ1 as a probe showed an allele length and copy number variations even between two male siblings. Hybridization of DNA from monochromosome hybrids with this probe showed its presence on chromosome 15 in addition to the Y chromosome. Fluorescence in situ hybridization of metaphase chromosomes from an apparently normal male showed DYZ1 sequences in the proximal region of chromosome 11 in addition to the long arm of the Y chromosome. Typing of sets of semen and blood DNA samples from the same human individuals showed discernible allelic variation between the two samples, indicating tissue-specific programmed sequence modulation. DYZ1 seems to be the first probe having the unique potential to discriminate unequivocally the difference between the DNA originating from semen and blood samples, and may be exploited in forensic cases. This probe may also be used as a diagnostic tool to ascertain Y chromosome mosaicism in patients (e.g., Turner), its aberrant status in somatic cells, and possible sequence modulation/rearrangement in the germline samples. Additionally, this can be used to uncover sequence polymorphism in the human population.     

Structural instability of human tandemly repeated DNA sequences cloned in yeast artificial chromosome vectors.

The suitability of yeast artificial chromosome vectors (YACs) for cloning human Y chromosome tandemly repeated DNA sequences has been investigated. Clones containing DYZ3 or DYZ5 sequences were found in libraries at about the frequency anticipated on the basis of their abundance in the genome, but clones containing DYZ1 sequences were under-represented and the three clones examined contained junctions between DYZ1 and DYZ2. One DYZ3 clone was quite stable and had a long-range structure corresponding to genomic DNA. All other clones had long-range structures which either did not correspond to genomic DNA, or were too unstable to allow a simple comparison. The effects of the transformation process and host genotype on YAC structural stability were investigated. Gross structural rearrangements were often associated with re-transformation of yeast by a YAC. rad1-deficient yeast strains showed levels of instability similar to wild-type for all YAC clones tested. In rad52-deficient strains, DYZ5 containing YACs were as unstable as in the wild-type host, but DYZ1/DYZ2 or DYZ3 containing YACs were more stable. Thus the use of rad52 hosts for future library construction is recommended, but some sequences will still be unstable.     

A repeating unit of the DYZ1 family on the human Y chromosome consists of segments with partial male-specificity

An average-sized human Y chromosome contains about 3,000 copies of the repeating DNA family DYZ1. A major repeating unit of the family, pHY10, has been cloned and an entire 3,564-bp sequence has already been determined by Nakahori et al. (1986). In the present study, pHY10 was divided into six consecutive segments, A to F, which were independently amplified by the PCR technique to see if they were strictly male-specific. pHY10 appears to consist of segments of various male-specificity. The B segment was apparently male-specific; however, the use of additional techniques (Southern-blot analysis or second PCR amplification in combination with the standard PCR) revealed homologous sequences in some females. None of the six segments of pHY10 may be male-specific in a strict sense. Different segments appear to be conserved during evolution to different extents. The 323-bp E segment appears to be the least conserved and to be responsible for the generation of most variations within the DYZ1 family.     

Rapid detection of genetically modified organisms on a continuous-flow polymerase chain reaction microfluidics

The ability to perform DNA amplification on a microfluidic device is very appealing. In this study, a compact continuous-flow polymerase chain reaction (PCR) microfluidics was developed for rapid analysis of genetically modified organisms (GMOs) in genetically modified soybeans. The device consists of three pieces of copper and a transparent polytetrafluoroethylene capillary tube embedded in the spiral channel fabricated on the copper. On this device, the P35S and Tnos sequences were successfully amplified within 9 min, and the limit of detection of the DNA sample was estimated to be 0.005 ng μl⁻¹. Furthermore, a duplex continuous-flow PCR was also reported for the detection of the P35S and Tnos sequences in GMOs simultaneously. This method was coupled with the intercalating dye SYBR Green I and the melting curve analysis of the amplified products. Using this method, temperature differences were identified by the specific melting temperature values of two sequences, and the limit of detection of the DNA sample was assessed to be 0.01 ng μl⁻¹. Therefore, our results demonstrated that the continuous-flow PCR assay could discriminate the GMOs in a cost-saving and less time-consuming way.     

Leaf-punch method to prepare a large number of PCR templates from plants for SNP analysis

DNA preparation is indispensable for genotyping by DNA polymorphism analysis, and that for a large number of plants is laborious. In the present study, a small leaf disk of rice, 1–2 mm in diameter, punched by a mini cork borer was found to be directly usable as a PCR template. DNA fragments <300 bp were amplified efficiently. Leaf disks of 1–1.5 mm in diameter were better than those of 2 mm for a small volume of reaction mixture. Multiplex PCR was possible with four or eight primer pairs using the small leaf disk as a template. Leaf disks of Arabidopsis, Lotus, wheat, soybean, tomato, Chinese cabbage, and melon were also good PCR templates. This method for preparation of PCR templates, named the leaf-punch method, was applicable to SNP analysis of a large number of plants by dot-blot-SNP analysis. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

RAPD技术在芦荟属植物分类研究中的应用

采用CTAB法提取11个芦荟材料的基因组DNA为模板,以50个随机引物进行RAPD分析。结果表明：大部分引物可以在不同模板上扩增出条带,但仅有6个引物可以同时在11个芦荟材料的DNA上扩增出条带,对11个芦荟种变种的RAPD结果进行聚类分析,结果表明基本符合传统分类观点。对RAPD技术在芦荟属植物分类研究中的问题进行了讨论。     

Selective protection of specific DNA sequences in the heterochromatin of C-banded human Y chromosomes.

The molecular basis of C-banding was investigated by in situ hybridization of human Y chromosome-derived repeated sequences, DYZ1 and DYZ2, to untreated or to alkaline-treated metaphases. Autoradiography of G-banded metaphases showed that both probes hybridized to the long arm of Y. Alkaline hydrolysis significantly reduced grain number for DYZ2 (58%-82%; P less than .05) but not for DYZ1 (P greater than .05). Similar results were observed for interphase nuclei. These findings demonstrated that the heterochromatin of the long arm contains at least two repetitive DNA fractions having two different sensitivities to alkaline hydrolysis. These observations support the notion that DYZ2 maps terminally on the Yq arm and may be nonheterochromatic.     

Evolution of DNA on Y-chromosome in hominoid primates as examined by PCR

Every species of non-human primates, especially those of hominoids, has a variety of reproductive structures and accompanying male traits, such as sexual dimorphism and relative size of testis to body weight, which may be at least partly triggered by DNA on the Y-chromosome. Recently, a panel of PCR (Polymerase Chain Reaction) primer sets were designed to amplify various DNA segments spread over the human Y-chromosome. We applied these primer sets for amplification of DNA segments on the Y-chromosome of hominoid species: chimpanzee, bonobo (Pygmy chimpanzee), gorilla, orangutan, whitehanded gibbon, agile gibbon, and Japanese monkey as an out group. The DNA segments including SRY, testis determining factor, and ZFX/ZFY could be amplified clearly in males of all species examined. These highly conserved genes may serve important biological functions. However, as the phylogenic distance from humans increased, some of the DNA segments could not be amplified. For example, DYZ1 (SY160) could be amplified only using human DNA as a template, and DYF60S1 (SY61), DYZ217 (SY126) and DYS233 (SY148) could be amplified only using human and African great ape DNA. It is interesting to note that locus DYS250 (SY17) could not be amplified in chimpanzee and bonobo but amplified in gorilla and orangutan. Locus DYS251 (SY18) was amplified in all species except the white-handed gibbon. These results indicate that a variety of evolutionary events including mutation, deletion, insertion, and rearrangement occurred in Y-chromosome DNA during primate evolution.     

Random priming PCR strategy to amplify and clone trace amounts of DNA

Here we report a new methodology to study trace amounts of DNA of unknown sequence using a two-step PCR strategy to amplify and clone target DNA. The first PCR is carried out with a partial random primer comprised of a specific 21-nucleotide 5' sequence, a random heptamer, and a 3' TGGC clamp. The second PCR is carried out with a single 19-nucleotide primer that matches the specific 5' sequence of the partial random primer. Using human and Mycoplasma genitalium DNA as examples, we demonstrated the efficiency of this approach by effectively cloning target DNA fragments from 1 pg DNA sample. The cloning sensitivity could reach 100 fg target DNA templates. Compared to the strategy of first adding adapter sequences to facilitate the PCR amplification of unknown sequences, this approach has the advantage of allowing for the amplification of DNA samples in both natural and denatured forms, which provides greater flexibility in sample preparation. This is an efficient strategy to retrieve sequences from trace DNA samples from various sources.