水稻线粒体DNA的热变性及热力学研究

自从1963－1964年发现线粒体DNA（mtDN）以来，人们对线粒体DNA的结构、功能等方面进行了很多研究．高等植物线粒体DNA的研究也有不少报导．线粒体DNA之所以引起人们广泛兴趣决非偶然．线粒体具有独立复制的能力，它有自己独特的DNA、rRNA、tRNA、核糖体．它是细胞的动力站，生物氧化链上某些重要的酶的一部分亚基是由线粒体基因组编码的．对线粒体DNA的深入研究，肯定会对线粒体起源问题提供有价值的线索．此外，植物的雄性不育、真核细胞的抗药性等，也都可能与线粒体DNA有关．尽管如此，线粒体及线粒体DNA的某些功能至今仍…     

交河矿城古车师人的线粒体DNA分析

从距今2000－2500年左右的交河故城古代中提取古DNA，用4对重叠引物对线粒体基因组的调控区(363bp)进行了扩增及测序，线粒体基因组编码区的扩增片段用于限制性片段多样性分析。结果显示4个个体中具有3个DNA序列，其中来自不同墓穴的两个个体的序列相同，说明这两者间有密切的母系遗传关系。系统发育分析表明古车师的4个个体分散分布在现代新疆维吾尔人的序列之中。从这些结果可以初步得出结论，即古车师人群并不是一个同源群体，在早期铁器时代，欧亚人群的混合就已经存在了。     

交河故城古车师人的线粒体DNA分析

从距今2000～2500年左右的交河故城古代人骨中提取古DNA,用4对重叠引物对线粒体基因组的调控区(363bp)进行了扩增及测序.线粒体基因组编码区的扩增片段用于限制性片段多样性分析.结果显示4个个体中具有3个DNA序列,其中来自不同墓穴的两个个体的序列相同,说明这两者间有密切的母系遗传关系.系统发育分析表明古车师的这4个个体分散分布在现代新疆维吾尔人的序列之中.从这些结果可以初步得出结论,即古车师人群并不是一个同源群体,在早期铁器时代,欧亚人群的混合就已经存在了.     

北京鸭肝脏线粒体DNA的限制酶图谱

本文用五种限制性内切酶(EcoRⅠ,BamHⅠ,PstⅠ,BglⅠ和BglⅡ)建立了北京鸭肝脏线粒体DNA的内切酶图谱。这五种酶除BglⅡ不能切割鸭肝线粒体DNA外,EcoRⅠ,BamHⅠ,PstⅠ和BglⅠ在鸭肝线粒体DNA上分别有1,2,4和5个切割位点。应用电子显微镜及电泳法对鸭肝线粒体DNA的各种酶解片段进行测定后,推导出了此线粒体DNA的限制酶图谱。此外,还确定了D-环的位置及线粒体DNA复制的方向。     

基因编辑在线粒体疾病中的应用

线粒体作为细胞的能量工厂,在维持细胞能量代谢与人类生命活动中发挥着至关重要的作用.线粒体基因组的突变会导致一系列线粒体遗传代谢疾病的发生,严重威胁人类生命健康,发展靶向线粒体的基因编辑手段对于线粒体疾病的治疗具有重要意义.近年来,以限制性核酸酶、锌指核酸酶、转录激活因子样效应核酸酶、规律成簇的间隔短回文重复序列(CRISPR)以及碱基编辑器为代表的一系列基因编辑方法迅速发展.本文综合评述了基因编辑工具应用于哺乳动物细胞的线粒体DNA的研究进展、不足和发展方向,以期为线粒体疾病治疗技术的开发提供参考.     

缢蛏线粒体DNA提取方法的比较

分离缢蛏肌肉组织,液氮磨碎后,用3种方法提取线粒体DNA,紫外分光光度法定量．用琼脂糖凝胶电泳和线粒体COI基因PCR扩增产物鉴定所提取的线粒体DNA．结果显示OD260／OD280均在1．69-1．85之间．高盐沉淀法提取的线粒体DNA量最多．     

基于标记法的福白菊精油抗真菌机理研究

以福白菊为原料, 通过有机溶剂萃取和水蒸气蒸馏相结合制备福白菊精油. 分别采用健那绿、 细胞膜荧光探针DiI、 碘化丙啶、 罗丹明123以及溴化乙锭等染料标记酵母细胞、 酵母细胞膜、 酵母线粒体和质粒DNA, 研究福白菊精油对酵母细胞、 酵母细胞膜、 线粒体以及质粒DNA的破坏作用, 探讨福白菊精油的抗真菌机理. 研究结果表明, 福白菊精油不仅能破坏真菌的细胞膜, 使其细胞内含物外泄, 还能够穿过细胞膜, 破坏其线粒体膜和DNA, 最终导致真菌细胞死亡.     

食物或食物原材料中特定属的植物的定量PCR检测方法

一种根据PCR技术测定食物或食物原材料中的特定属的植物量的方法，包括：（1）提供修正样品，其中来自作为检测靶的特定属的植物样品和标准植物样品的混合比率预先确定，并从该样品中提取基因组DNA；（2）通过向作为试验受试者的食物或食物原材料中添加已知量的标准植物样品来制成测试样品，并从该样品提取基因组DNA；（3）用引物和这些基因组DNA实施定量。     

液相色谱-串联质谱法同时测定生物组织全基因组DNA甲基化和羟甲基化水平

测定全基因组DNA甲基化和羟甲基化水平对于研究环境污染物暴露的影响及致病机理具有重要的作用。本文建立了液相色谱-串联质谱（LC-MS/MS）同时测定动物组织中全基因组DNA甲基化和羟甲基化水平的方法。从动物组织样品中提取DNA,并将其酶解成单核苷,利用液相色谱-串联质谱法测定5-甲基胞嘧啶核苷、5-羟甲基胞嘧啶核苷和鸟嘌呤核苷的含量,计算全基因组DNA甲基化率和羟甲基化率。利用该方法研究了砷暴露对大鼠肝脏和小脑全基因组DNA甲基化和羟甲基化水平的影响,得到了砷影响DNA甲基化及羟甲基化的初步数据。该方法具有良好的重现性、灵敏度和稳定性,可以同时检测差异较大的DNA甲基化和羟甲基化水平。为同时研究DNA甲基化和羟甲基化水平提供了有力的支持。     

中科院微生物所DNA芯片分析平台投入使用

不久前，中国科学院微生物所基因组联合中心DNA芯片分析平台正式投入使用。DNA芯片技术是近十年来发展起来的一项进行基因组学研究的新技术，主要应用于微生物比较基因组学，人类癌症基因组学、人类基因组单体型图、动物基因组学、植物基因组学、疾病诊断和治疗、药物筛选、农作物优育优选、司法鉴定、食品卫生监督、环境检测等领域。其主要特点是可以对生物样品进行快速、高通量的比较基因组学研究，是进行生物个体及群体基因组学研究必不可少的工具。此次微生物所构建的DNA芯片平台采用美国NimbleGen公司的先进技术，配以Genpix 400B芯片扫描仪、MAUI杂交炉等先进仪器设备。     

量热法研究线粒体代谢的热力学和动力学行为

线粒体是细胞中极为重要的细胞器，是产生细胞所必需的“富能”物质ATP的重要场所，为细胞活动提供所需化学能．在生命体能量代谢过程中除一部分能量用于合成ATP外，其余则以热的形式释出．用精密热量计测出线粒体代谢过程中的热量输出对了解线粒体的功能和代谢机制具有十分重要的意义．用微量热法研究线粒体体外代谢已有一些报导［‘，’］．本工作用精密热量计和差式扫描量热仪侧定了水稻线粒体体外代谢热谱和DSC曲线，计算了水稻线粒体活性增长速率常数，比较了不同保藏时间的水稻线粒体体外代谢的差异，并初步探讨了水稻线粒体在变…     

Non-isothermal kinetic analysis of the thermal denaturation of type I collagen in solution using isoconversional and multivariate non-linear regression methods

To further understand the kinetics of the thermal denaturation of type I collagen, the 16 and 8 mg/mL bovine hide collagen solutions were studied by differential scanning calorimetry at different heating rates. The activation energy of the denaturation process was examined utilizing the differential (Friedman) and the integral (Ozawa-Flynn-Wall) isoconversional methods, and several kinetic models were evaluated using the method of multivariate non-linear regression. Besides, the denaturation behavior was simulated under different temperature conditions. Results showed that the activation energy decreased in a different way at lower and higher degrees of conversion, respectively. A three-state model, in which a reversible step was followed by an irreversible one, was the best of the estimated models to describe the denaturation process, which could be approximated by single-step or two-consecutive-step in terms of temperature conditions.     

Properties of DNA + Dipropylsulfoxide or Dibutylsulfoxide + Water Ternary Solutions

Aqueous solutions of DNA in the presence of dipropylsulfoxide (DPSO) and of dibutylsulfoxide (DBSO) have been studied using UV-vis spectroscopy and density measurements. It has been shown that significant thermal denaturation of DNA occurs when DPSO or DBSO are present. The results obtained were compared with those obtained previously with dimethylsulfoxide (DMSO) and diethylsulfoxide (DESO). It is suggested that the lowering of the transition enthalpy with increasing length of the carbon chain of the dialkylsulfoxides is due to significance contribution from hydrophobic interactions.     

Calorimetric and dynamic light-scattering investigation of cationic surfactant--DNA complexes

By means of combined calorimetric and dynamic light-scattering measurements, we have investigated the conformational behavior of DNA chains after thermal melting in the presence of a cationic surfactant at different concentrations, up to a surfactant-to-phosphate group molar ratio close to unity. Both the specific heat capacity, C(ex)(p) and the hydrodynamic radius R of the DNA chains provide support for the existence of two structural arrangements with different thermal stabilities, coexisting in the bulk solution. Although a component remains an elongated unfolded DNA chain originated in the thermal denaturation, the second component, consisting of DNA-surfactant complexes, assumes a compact structure with an average size of about 80 nm, whose thermal denaturation occurs at temperatures higher than 100 degrees C.     

Thermal,spectral, and thermodynamic studies for evaluation of calf thymus DNA interaction activity of some copper(II) complexes

The square-pyramidal copper(II) complexes with ciprofloxacin in the presence of bipyridine derivatives have been synthesized and characterized using elemental analysis, magnetic moment measurement, thermal analysis (TG), IR, mass and reflectance spectra. The thermal denaturation study has been used for evaluating calf thymus DNA interaction activity. Spectral and hydrodynamic measurements have been used for validating the DNA interaction study. The thermodynamic profile was established for proper understanding of DNA binding Gibbs free energy.     

A differential scanning calorimetric study on the irreversible thermal unfolding of concanavalin A

A differential scanning calorimetry study on the thermal denaturation of concanavalin A at pH 5.2 where it exists in the dimeric form was carried out. The calorimetric transitions were observed to be irreversible and the transition temperature of the protein increased with increasing scan rate, indicating that the thermal denaturation process is under kinetic control. The thermal unfolding, and its scan rate dependence could be explained according to the kinetic scheme with k as first-order kinetic constant whose change with temperature is given by the Arrhenius equation. Using this model, rate constant as a function of temperature and activation energy of the process have been calculated. The average activation energy of the kinetic process using different approaches is 129±10 kJ mol⁻¹. The differential scanning calorimetric results on transition temperatures and calorimetric enthalpies supported by intrinsic fluorescence indicate that the irreversibility in the calorimetric transitions of concanavalin A includes a combination of post-transition aggregation, chain separation and loss of cofactor.     

Thermomechanical analysis of merino wool yarns

Summary There is a difference in structure across the wool fibre which is usually referred to as bilateral. The endothermic denaturation doublet of keratins has been observed by different authors for a variety of keratins and measuring conditions and mainly interpreted by different theories. Merino wool yarns have been analyzed by the thermomechanical analysis and at low stress two thermal transitions before melting have been identified. These two thermal transitions are in accordance with the onset temperatures of the denaturation doublet shown by the DSC both at temperatures lower than the thermal degradation temperature determined by TG. The DSC of fibrillated fibres by abrasion showed not a denaturation doublet but just only a denaturation peak. The two transitions of the TMA and the modification of the DSC curve by abrasion seems to confirm that abrasion removes the component which denaturates at lower temperature.     

Use of Adsorptive Transfer Stripping Voltammetry for Analyzing Variations of Cytosine Methylation in DNA

The electrochemical behavior and thermal stability of double stranded oligonucleotides containing 5‐methyl‐cytosine and 7‐deaza‐guanosine as nucleotide analogues, as well as of Jurkat genomic DNAs methylated to different degree were studied by ACV and SWV and by thernal denaturation analysis. ACV and SWV combined with thermal denaturation analysis of the natural and modified oligonucleotides gave information regarding the presence of methylation and the concomitant conformational changes. ACV and SWV of Jurkat DNA mixtures methylated to different degrees revealed a decrease of the peak heights with increasing methylation, indicating an increase of structural rigidity, in agreement with the thermal denaturation data. These results verify the, possibly local, conformational changes introduced by DNA methylation. The results obtained in all cases were reproducible.     

Cationic modified nucleic acids for use in DNA hairpins and parallel triplexes

Non-nucleosidic DNA monomers comprising partially protonated amines at low pH have been designed and synthesized. The modifications were incorporated into DNA oligonucleotides via standard DNA phosphoramidite synthesis. The ability of cationic modifications to stabilize palindromic DNA hairpins and parallel triplexes were evaluated using gel electrophoresis, circular dichroism and thermal denaturation measurements. The non-nucleosidic modifications were found to increase the thermal stability of palindromic hairpins at pH 8.0 as compared with a nucleosidic tetraloop (TCTC). Incorporation of modifications at the 5'-end of a triplex forming oligonucleotide resulted in a significant increase in thermal stability at low pH when the modifications were placed as the 5'-dangling end.