脉冲场凝胶电泳技术及应用

脉冲场凝胶电泳(PFGE)是一种重要的用于分离大分子量线状DNA的电泳技术。介绍了PFGE的基本原理、方法、影响因素,并对其在微生物分子分型、DNA辐射损伤修复、细胞凋亡和转基因技术等研究方面的应用作了简要的综述。     

Chromosome-sized DNA molecules of Plasmodium falciparum

At least seven chromosome-sized DNA molecules (750 to 2000 kilobases in length and one fraction of undetermined molecular weight) from cultured clones and isolates of Plasmodium falciparum have been separated by pulsed-field gradient gel electrophoresis. Whereas asexual blood stages and sexual stages of the same line have identical molecular karyotypes, the length of chromosome-sized DNA molecules among different geographical isolates and several clones derived from a single patient is different. These length alterations of chromosomes are the result of DNA rearrangements that must occur unrelated to sexual differentiation.     

Volatilization of high molecular weight DNA by pulsed laser ablation of frozen aqueous solutions

DNA has been volatilized by pulsed laser ablation of a thin film of a frozen aqueous DNA solution. The target film was irradiated in vacuum by a pulsed laser at power densities sufficient to ablate the ice matrix. The expanding ablated water vapor entrained embedded DNA molecules and expelled them into the gas phase. Ejection of DNA molecules as large as 410 kilodaltons was verified by collection of the ablation products and subsequent mass analysis by polyacrylamide gel electrophoresis with autoradiographic detection.     

Understanding the anomalous electrophoresis of bent DNA molecules: a reptation model

In polyacrylamide gel electrophoresis, the retardation of DNA molecules containing regions of intrinsic curvature can be explained by a novel reptation model that includes the elastic free energy of the DNA chain. Computer simulations based on this model give results that reproduce the dependence of anomalous mobility on gel concentration, which is quantified by new experimental data on the mobilities of circularly permuted isomers of kinetoplast DNA fragments. Fitting of the data required allowing for the elasticity of the gel.     

Erratum

Figure 5 (p. 205) of the report "Observation of individual DNA molecules undergoing gel electrophoresis" by Steven B. Smith et al. (13 Jan., p. 203) was printed upside-down.     

两种检测扁桃基因组RAPD扩增产物方法的比较分析

通过2;(w/v)的琼脂糖凝胶和8;(w/v)的聚丙烯酰胺凝胶电泳对扁桃品种基因组DNA的RAPD检测.结果表明:8;(w/v)聚丙烯酰胺凝胶优于2;(w/v)琼脂糖凝胶,主要表现在,8;聚丙烯酰胺凝胶对长度相差100 bp以下的DNA分子的分离较2;的琼脂糖凝胶电泳效果好;且8;聚丙烯酰胺凝胶的分辨范围广,在线性DNA分子(0.1～2.0 kb)范围内也能得到很好的分离效果;用8;的聚丙烯酰胺凝胶分离扁桃品种基因组DNA的RAPD扩增结果,表现出在扁桃品种间DNA水平上差异大,运用此方法提高了扁桃品种的鉴别能力.     

银染聚丙烯酰胺凝胶电泳技术体系的优化

【目的】针对银染PAGE实验中常出现的背景颜色深、条带弥散、凝胶变形及条带不整齐等问题进行归纳总结并提出优化方法。【方法】以甘蓝型油菜基因组DNA为研究对象,通过PAGE电泳后银染并调整试剂配方、实验条件,筛选出适合实验的技术体系。【结果】甲醇浓度、电压稳定性、电泳温度、气泡等显著影响实验结果。甲醛浓度过高(1.25%)时,虽所需染色时间短,但凝胶背景深;甲醛浓度过低(0.001 25%)时,背景浅但条带淡,需要长时间染色;电压不稳定会造成条带弥散;电泳温度过高,导致凝胶变形,条带弯曲;凝胶中的气泡会扰乱DNA条带的形状;NaOH浓度在0.875%~1.375%,染色结果无明显差异。【结论】甲醛用量4 mL(1%)、保持稳定电压、在冰浴中电泳、制胶时及时赶走所有气泡,可得到凝胶背景浅、条带清晰且正常的结果。     

感染叶锈菌的小麦细胞间隙液对小麦悬浮细胞程序性死亡的诱导

以小麦悬浮细胞为材料,分别用感染叶锈菌小种165的小麦细胞间隙液(IWF165)和未接菌的小麦细胞间隙液(IWFck)对其进行处理,处理后不同时间点取样进行形态学观察和DNA电泳。结果表明,用IWF165处理后的悬浮细胞可观察到明显的染色质凝聚化、边缘化和细胞核解体等现象;同时DNA电泳结果显示IWF165处理后的细胞基因组DNA发生降解并形成明显的DNA梯状条带。而用IWFck处理的悬浮细胞,其细胞核结构完整,染色质分布均匀;DNA电泳没有出现DNA梯状条带。在感染叶锈菌的小麦细胞间隙液中存在着激发子,它能够诱导小麦悬浮细胞发生程序性死亡。     

黄瓜SSR-PCR反应体系的优化

采用L9(34)正交试验设计,研究了黄瓜SSR-PCR反应体系的主要成分对扩增结果的影响,并比较了变性聚丙烯酰胺凝胶电泳和琼脂糖凝胶电泳检测扩增产物多态性的差异。结果表明,最适反应体系为:在20μL体系中包括dNTP 200μmol.L-1、Primer 0.4μmol.L-1、Mg2+2.5μmol.L-1、Taq酶0.5μmol和模板DNA60 ng。用变性聚丙烯酰胺凝胶电泳检测SSR扩增产物结果更准确。     

基于微流控芯片电泳的番茄黄化曲叶病毒快速检测

【目的】探索微流控芯片电泳方法在PCR产物检测方面的效果,并建立针对番茄黄化曲叶病毒（Tomato yellow leaf curl virus,TYLCV）的微流控芯片电泳检测方法,弥补琼脂糖凝胶电泳方法在试剂消耗、所用时间、安全性方面的缺陷。【方法】通过对TYLCV的基因组进行分析后,在该基因组中相对稳定的位置设计引物,同时兼顾引用已被研究者研究过的引物,对这些选择的引物进行特异性、稳定性、灵敏度等方面的验证,筛选出用于后续试验的引物。选择DNA标准物φX174/BsuR I(Hae Ⅲ) marker,分别进行琼脂糖凝胶电泳和微流控芯片电泳,对二者在耗材、耗时和灵敏度方面进行比较,确定微流控芯片电泳在核酸检测方面的应用价值。利用筛选出的其中1对引物对番茄叶片的实际样品进行PCR扩增,随后通过微流控芯片电泳对其进行检测,以此探讨微流控芯片电泳在病毒检测方面的检测效果。【结果】共筛选出14对TYLCV备用引物,其中2对引自文献,12对为本文设计,每对引物均可满足微流控芯片检测要求。选择其中1对引物TYLCV-T作为随后的研究对象。利用琼脂糖凝胶电泳和微流控芯片电泳对DNA标准物检测,结果表明微流控芯片电泳在耗时方面不足琼脂糖凝胶电泳的1/10,约为13 min,试剂消耗为琼脂糖凝胶电泳的1/8,检测灵敏度方面至少比琼脂糖凝胶电泳高103倍,根据DNA标准物原液浓度计算可知,微流控芯片电泳至少可准确检测到浓度为5×10-6 μg?μL-1的核酸样品。利用微流控芯片电泳对TYLCV-T扩增的TYLCV PCR产物进行检测,将检测峰值图与DNA标准物的峰值图时间比较,就可判断出产物峰的大小范围。【结论】筛选出的关于TYLCV的备用引物可作为进一步研究微流控芯片技术在该病毒检测方面的基础;通过将琼脂糖凝胶电泳和微流控芯片电泳进行比较,确立了后者在核酸检测方面的应用价值;通过微流控芯片电泳对TYLCV PCR产物的检测,建立了基于微流控芯片电泳的TYLCV快速检测方法,为TYLCV的快速检测提供新的技术支持。     

Cloning of large segments of exogenous DNA into yeast by means of artificial chromosome vectors

Fragments of exogenous DNA that range in size up to several hundred kilobase pairs have been cloned into yeast by ligating them to vector sequences that allow their propagation as linear artificial chromosomes. Individual clones of yeast and human DNA that have been analyzed by pulsed-field gel electrophoresis appear to represent faithful replicas of the source DNA. The efficiency with which clones can be generated is high enough to allow the construction of comprehensive libraries from the genomes of higher organisms. By offering a tenfold increase in the size of the DNA molecules that can be cloned into a microbial host, this system addresses a major gap in existing experimental methods for analyzing complex DNA sources.     

Separation of large DNA molecules by contour-clamped homogeneous electric fields

Electric fields can be manipulated by a method in which multiple electrodes are arranged along a closed contour and clamped to predetermined electric potentials. This method may be applied to a broad range of problems in the separation of macromolecules by gel electrophoresis. DNA molecules as large as 2 megabases can be well separated with a contour-clamped homogeneous electric field alternating between two orientations 120 degrees apart. The pattern of separation is independent of position in the gel, which is an advantage over previous methods. DNA less than 50 kilobases can be separated without distortion even at high voltage with a nonalternating contour-clamped homogeneous field. Decreased band broadening in DNA less than 200 bases can be achieved with a contour-clamped inhomogeneous field.     

仿火箭电泳应用于单细胞凝胶电泳技术的优势(摘要)(英文)

[目的]研究仿火箭电泳应用于单细胞凝胶电泳技术,为单细胞凝胶电泳技术寻求另一种可行的电泳方法提供参考。[方法]将仿火箭电泳方法应用于单细胞凝胶电泳技术,检验单细胞水平上的DNA损伤,并与传统的电泳方法比较,分析其优劣势。[结果]在细胞DNA未受损状态下,2种电泳方法所得的结果一致;而在细胞DNA受到损伤时,传统的电泳方法下一些细胞的慧尾发散出现漂移,仿火箭电泳方法得到的慧尾图像集中且未发生偏移。[结论]仿火箭电泳方法较传统的电泳方法存在一定优势。     

仿火箭电泳应用于单细胞凝胶电泳技术的优势

[目的]研究仿火箭电泳应用于单细胞凝胶电泳技术,为单细胞凝胶电泳技术寻求另一种可行的电泳方法提供参考。[方法]将仿火箭电泳方法应用于单细胞凝胶电泳技术,检验单细胞水平上的DNA损伤,并与传统的电泳方法比较,分析其优劣势。[结果]在细胞DNA未受损状态下,2种电泳方法所得的结果一致;而在细胞DNA受到损伤时,传统的电泳方法下一些细胞的慧尾发散出现漂移,仿火箭电泳方法得到的慧尾图像集中且未发生偏移。[结论]仿火箭电泳方法较传统的电泳方法存在一定优势。     

棉酚对多浪羊淋巴细胞凋亡及其对核酸降解的研究

 主要通过使用RPMI 1640培养基培养淋巴细胞、瑞氏—吉姆萨染色、DNA和RNA电泳等方法来研究棉酚对多浪羊淋巴细胞的凋亡效应和对淋巴细胞核酸影响。研究结果表明,经瑞氏—吉姆萨染色4h淋巴细胞出现凋亡小体;DNA和RNA通过琼脂糖凝胶电泳检测在4h分别出现梯状条带和18S降解。可见,当细胞培养液中棉酚浓度为1.35μmol/L,培养淋巴细胞4h后,可抑制多浪羊淋巴细胞的增殖,并且促进凋亡及其核酸的降解。     

用SSR标记建立玉米黄早四DNA标准指纹图谱的方法研究

DNA标准指纹图谱是分子检测技术用于玉米新品种选育及其DUS辅助评价的重要基础。通过玉米对黄早四DNA的SSR标准指纹图谱构建方法的研究,筛选出20对可以用于玉米DNA标准图谱构建的核心引物,它们的平均PIC值为0.8554,检测出的等位基因数是6~15个,平均8.55个,Bnlg125和Bnlg2162检测到了玉米黄早四的DNA特有谱带;8%的聚丙烯酰胺电泳体系可以将亲缘关系很近的玉米品种区分开来。对玉米DNA标准指纹图谱的建立方法和DNA取样方法进行了深入探讨。     

SOD对紫外辐射受损的苏云金芽孢杆菌作用的研究

探讨了超氧化物歧化酶 (SOD)等自由基清除剂对苏云金芽孢杆菌紫外辐射的影响。结果表明 ,SOD、绞股蓝皂甙等自由基清除剂能够明显地提高紫外辐射损伤细胞的存活率 ,并且SOD的保护作用表现为防护与恢复两种不同的作用。又通过细胞电泳与琼脂糖凝胶电泳发现紫外辐射后其细胞膜及质粒DNA均受到了明显的损伤 ;SOD对细胞膜损伤有一定的恢复作用 ,而对DNA不表现恢复效应。由此认为 :紫外线对细胞膜及DNA均有损伤 ,SOD恢复作用的主要部位在细胞膜而不是DNA分子。为进一步确定SOD的作用以及利用自由基清除剂制备高效的Bt农药提供了理论基础。     

单粒微米珠-单根DNA复合物的微流控分离初步研究

定点单分子DNA芯片有重要用途,但其制备极具挑战性,用光镊、磁镊及原子力显微镜等方法分离单分子DNA,为此建立的平台设备昂贵,且分离效率太低,难以满足实验要求。本研究采用微流控技术,在层流基础上电泳分离与富集单粒微米珠-单根DNA的复合物,旨在为基于微米孔阵列承载这种复合物的定点单分子DNA芯片的制备提供样本。此技术的完善将为单分子DNA芯片制作开辟新的途径。     

Method for Isolating Mitochondrial DNA from Etiolated Tissue of Cabbage

Isolation of high-quality mitochondrial DNA（mtDNA） is an important premise for researching molecular mechanisms in cytoplasmic male sterility of cabbage（Brassica oleracea L.var.capitata）. An efficient protocol for separation and purification of mitochondria and extraction of mitochondrial DNA（mtDNA） from etiolated tissues of cabbage was developed. We took a method combined mannitol density gradient with differential centrifugation, selected appropriate rotational speed, extended DNase I treating time and changed mitochondria cracking condition. The results showed that the extracted mitochondria in this protocol had complete structure, appeared to ellipsoid and had not been contaminated with other impurities under the Jannus Green B staining. The isolated mitochondrial DNA had high purity and yield through detecting the optical density, nuclear specific primer PCR and agarose gel electrophoresis. The results indicated that mitochondrial DNA extracted by this protocol had high quality and enabled to be used in futher genetic studies.     

咖啡叶片DNA提取方法的比较研究

以咖啡成熟叶片为材料,进行多种DNA提取方法比较研究,并通过琼脂糖凝胶电泳和紫外分光光度计检测所提的DNA样品。结果表明,CTAB改良Ⅰ和CTAB改良Ⅱ均可用于咖啡叶片的DNA提取,尤其是CTAB改良Ⅱ法,提取的DNA产量较CTAB改良Ⅰ高,能满足后续分子生物学研究的要求。