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…     

线粒体体外代谢热动力学研究

线粒体是细胞重要的细胞器之一，有细胞的“能源工厂”之称．因为线粒体内有许多酶，是特殊的酶催化氧化反应的场所山；所有动、植物细胞的线粒体都能通过各种营养物的氧化而产生“富能”物质ATP．采用一定的技术可将线粒体从细胞中分离出来，分离出来的线粒体中的酶系统还有一定的活性，而且线粒体内也有一定的营养物质，这样酶系统就能利用这些营养物进行代谢，从而释放出一定的能量．我们用微量热法对两种鱼肝脏线粒体进行了测量，发现线粒体代谢过程分四个阶段：停滞期、活性恢复期、稳定期、活性衰减期．在活性恢复期和活性衰减期，…     

大鼠肝细胞微粒体及线粒体的脂肪酸组成分析

线粒体(mitochondria)是一种重要的细胞器,除成熟红细胞外,普遍存在于各种细胞中,肝细胞内尤为丰富。线粒体是细胞能量代谢的中心,是细胞有氧呼吸的基地和供能的场所,细胞生命活动中需要的能量,约有95％由线粒体供应。微粒体(microsome)主要是细胞质内一些微细的内质网多能性结构,它与肝脏的解毒功能有关。     

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…     

线粒体特异性检测与调控

线粒体(mitochondria)是一种由双层膜包被的细胞器,存在于大多数细胞中,能够通过位于线粒体内膜上的呼吸链产生能量,被称为细胞的"能量工厂"。此外,线粒体参与到细胞分化、信息传递和细胞凋亡等过程,并调控细胞周期和细胞生长。线粒体的功能障碍与多种人类疾病相关,如帕金森氏病、阿尔兹海默氏病、心血管疾病和某些癌症等。鉴于其在生物体中的重要作用,线粒体一直是科学家们的研究重点。本文就线粒体特异性检测和调控研究的最新进展进行了综述。     

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.     

线粒体中无机物种的探测与线粒体功能的干预

线粒体是细胞内微小的细胞器,它通过产生ATP为细胞运转提供几乎全部所需的能量.线粒体广泛参与信号传导、能量代谢、自噬凋亡等细胞过程,对维持生物体正常生理功能至关重要.同时,其功能损伤也与癌症、阿尔兹海默症等多种疾病的发生和发展密切相关.线粒体功能需要在多种蛋白质和无机物种共同参与下才能完成,所以及时了解这些物种的分布和变化情况对维护线粒体生理功能非常重要.线粒体功能又可利用金属配合物的独特理化性质来进行干预或调控,从而实现预防或治疗疾病的目的.本文以探测线粒体无机物种和调控线粒体功能为主题,综述了近年来我国研究者在该领域取得的一些代表性研究成果,同时提出了发展中存在的问题和面临的挑战.     

有机分子荧光探针成像检测线粒体内ROS的研究进展

线粒体是细胞的"能量工厂",它利用氧气进行氧化磷酸化产生三磷酸腺苷(ATP),为细胞及生命体提供能量.同时,伴随着呼吸链中电子的泄漏,多种活性氧物种(ROS)在线粒体内快速产生.线粒体ROS在维持氧化还原平衡、参与调控细胞的增殖、分化、凋亡等行为方面发挥重要作用.当ROS水平超过机体抗氧化防御能力时,会导致疾病的发生.因此,发展准确检测线粒体ROS的方法,对深入探究ROS的细胞功能调控及相关疾病的发生发展意义重大.由于ROS存在浓度低、寿命短、反应活性高等特点,对其进行精准检测是化学、生物学及医学领域的一大挑战.荧光成像技术具有时空分辨率高、生物相容性好、灵敏度高等显著优势,成为实时检测细胞及活体内ROS的有力工具.近年来,相继发展了诸多荧光探针,实现了线粒体ROS的成像分析.本文着重总结与评述了近年来发展靶向线粒体、荧光可视化多种ROS有机分子探针工作的研究进展,并在构建新型线粒体荧光探针、进一步利用荧光成像方法深入剖析线粒体ROS的细胞学功能等方面进行了探讨与展望.     

线粒体热化学研究──Ⅳ．鱼类肝脏线粒体代谢的微量热学研究

线粒体热化学研究──Ⅳ．鱼类肝脏线粒体代谢的微量热学研究谭安民，刘义，谢昌礼，屈松生，顾贫，邓凤姣（武汉大学化学系武汉４３００７２）（武汉大学生命科学院武汉）关键词鱼肝脏，线粒体，微量热学，热化学线粒体在能量代谢的过程中，除一部分能量用于合成ＡＴＰ外...     

可固定性荧光探针:线粒体成像的可靠工具

线粒体是一种具有双层膜结构的细胞器,参与细胞新陈代谢过程的能量循环以及离子平衡过程,在细胞生理过程中具有极其重要的意义。一些小分子荧光染料/探针结构中带有正电荷,因受到线粒体内膜负电势的牵引而标记在线粒体上,为研究线粒体的形态或功能提供了重要的可视化成像工具。然而,大多数线粒体染料/探针对线粒体的靶向标记稳定性仍不够理想,因为线粒体电势处于不断的动态变化中,当电势降低时,对染料的亲和力相应降低。尤其在病理条件下(比如细胞凋亡)细胞代谢受到阻滞时,线粒体膜电势显著降低,阳离子染料将扩散离开线粒体,造成非特异性荧光。最近,Kim团队和本人课题组提出可固定线粒体探针的新概念,用活性基团将荧光分子探针通过共价键固定在线粒体中,开发了稳定靶向线粒体中的定量探测微环境p H值、粘度、膜电势荧光探针。我们认为,对于追踪和探测具有高度动态变化特性的线粒体而言,开发可固定的线粒体荧光分子探针是必然趋势,因此本文进行评述和展望。     

Calorimetric and DSC studies of mitochondria isolated from cytoplasmic male sterile line of rice

In this paper, the thermogenesis and differential scanning calorimetry (DSC) curves of energy release of the mitochondria isolated from variant strains of cytoplasmic male sterile lines of rices have been determined by using an LKB2277 Bioactivity Monitor and a DuPont 910 differential scanning calorimeter. The regularity and characteristics of the energy release of the mitochondria at constant and changing temperature were investigated, the differences in shape of the curves and the thermodynamic and kinetic characteristics of the thermogenesis of the mitochondria were compared, the thermodynamic and kinetic parameters of energy release of the mitochondria in the thermogenesis increasing stage were calculated, and the experimental thermokinetic equations describing the different thermogenesis processes were established. This revised version was published online in July 2006 with corrections to the Cover Date.     

Differential thermal analysis of low-rank coals

Differential thermal analysis (DTA) of low-rank coals of high lignite to subbituminous rank from coal mines of Pakistan is reported. The studies carried out in dynamic oxygen atmosphere indicate that the exothermic reactions occur between 300 and 650°C and that the samples undergo stepwise oxidation of the organic matter rather than a continuous process as indicated by the pattern of shoulders from 250 to 350°C accompanying the main peak around 450°C. The effect of heating rate, particle size and volatile content was also studied in relation to oxidation. The results show that the increase in heating rate from 10 to 80 deg min⁻¹ results in a marked shift in all the events in the DTA curve towards higher temperatures. As for the effect of particle size, the DTA records of 100–75, 150–100, 250–150 μm and greater than 250 μm fractions show that the magnitude and position of shoulder peaks are more sensitive to changes in particle sizes compared to the main peak. The curves recorded to study the effect of changing volatile content of samples between 30–40% indicate a complex pattern of shoulders accompanying the main peak. In general, the number of shoulder peaks increases with increasing volatile content of samples but their positions do not follow any trend. The DTA curves recorded in nitrogen contain ill-de-fined oxothermic effects over the 300–750°C temperature range. These curves consist of an endothermic peak around 150°C, two exothermic shoulders in the temperature region 300–400°C and a large broad exothermic whip between 500 and 700°C. The heating rates have similar effects as in oxygen while the particle size do not influence the results. It has been concluded that the organic matter in the coals studied here is extremely heterogeneous with different burning characteristics; as a result it is very difficult to quantify energy changes associated with poorly resolved exothermic events along the DTA curve. The effects also dominate in N₂ atmosphere thus making identification of mineral matter difficult. The overall pattern of DTA events in oxygen can be correlated with the heating rate, particle size and volatile content of samples.     

Adsorption of Hazardous Azorhodanine Dye from an Aqueous Solution Using Rice Straw Fly Ash

The potential of using rice straw fly ash (RSFA) as low-cost adsorbents for the removal of hazardous azorhodanine (AR) dye from aqueous solution was investigated. The effects of different variables in the batch method as a function of solution pH, contact time, concentration of adsorbate, adsorbent dosage, and temperature were investigated, and optimal experimental conditions were ascertained: 0.05 g for initial dye concentration of 20–100 mg/L at pH 2. The experimental equilibrium data were tested by the isotherm models, namely the Langmuir and Freundlich adsorption and the isotherm constants were determined. The kinetic models, pseudo-first-order and pseudo-second-order, were employed to analyze the kinetic data. The activation energy of adsorption was also evaluated and found to be +10.89 kJ.mol^?1, indicating that the adsorption is physisorption. Various thermodynamic parameters, such as Gibbs free energy, entropy, and enthalpy of the ongoing adsorption process, have been calculated and found to be spontaneous and exothermic, respectively.     

Effect of heating rate on the separation of various phenomena in the DSC technique

The value chosen for the heating rate plays an important role in the DSC technique. For example, the use of a low heating rate is of great help in determining the kinetic parameters of reactions more clearly. In this paper, the separation of peaks corresponding to heat flux-time curves of two various phenomena is especially studied. These peaks are shown in a typical cure reaction of epoxy resins. After determination of the kinetic parameters, DSC curves are simulated and a good agreement is found between theoretical and experimental curves. The effect of the heating rate on the separation factor of these peaks is studied, as well as its effect on the sensitivity of heat-flux measurement.     

Thermal analysis of eucalptus camaldulensis and cotton stalks at different heating rates

The thermal decomposition of Eucalptus Camaldulensis and Cotton Stalks at different heating rates showed three exothermic peaks. The heating rate is the factor that affects their sharpness and position. The peaks are sharp at low heating rates. IR spectra of pyrolized residue at different temperature were also studied.     

壳聚糖液晶溶液的性能

制备了聚糖液晶溶液,并采用偏光显微镜(POM)、流变仪、差示扫描量热仪(DSC)等分别对液晶织构、黏度、相转变性能进行了研究.结果表明:壳聚糖呈现典型的胆甾相液晶织构;其溶液黏度随浓度及剪切力的变化规律符合高分子液晶溶液的变化规律;在DSC升、降温曲线上分别存在吸热峰和放热峰.     

聚氯乙烯燃烧特性及HCl的生成机理

采用热重法对聚氯乙烯（ＰＶＣ）的燃烧过程进行了研究,探讨阳聚氯乙烯燃烧科技司,并由它们的微分热重曲线计算出的反应动力学参数及影响反应常数的因素进行了研究。同时,考察了恒速升温和快速升温过程ＨＣＩ的生成特性。结果表明,ＰＶＣ的燃烧机理是由三个过程决定的,可用三个一级反应表示。ＰＶＣ的燃烧过程的第一阶段为脱氯阶段。第二阶段的活化能和指前因子明显低于第一和一阶段。此阶段为挥发分释放阶段。升温速率的增加导     

Thermoanalytical study of inner and outer residue of coffee harvest

The better use of agricultural residues is expected, when they are mostly disposed of improperly and it is often burned in the natural environment. This study of the thermal decomposition of residues was performed from the coffee crop for energy purposes and in this case was used thermal analysis techniques for such assessment. The TG/DTG and DSC curves showed that the thermal decomposition occurs in four consecutive events and it is predominantly exothermic. The first mass loss evidenced in TG/DTG curves has an endothermic peak in DSC curve, which it can be associated with the water liberation of the material. This first thermal event also can be related to the liberation of volatile compounds present in the sample, which is also corroborated by the endothermic peak. The other events of mass loss are related with the thermal decomposition of the material. This decomposition has an exothermic behavior, which is positively applied to the main aim of this scientific research: the coffee straw use like biomass energy font. The thermoanalytical techniques were satisfactory in the characterization of this material.     

Thermal behavior of holo- and hemicellulose obtained from rice straw and bagasse

Thermal gravimetric analysis, and differential thermal behavior of holo- and hemicelluloses obtained from rice straw and bagasse were investigated. Degradation was found to be of first order reaction. The activation energy values and the rate constants were calculated from the kinetic of weight loss. Hemicellulose was found to be less stable than holocellulose, and the stability of the samples was arranged in the order, rice straw holo- > bagasse holo- > rice straw hemi- > bagasse hemicellulose. Degradation of rice straw (holo- as well as hemicellulose) was performed via two exothermic processes, whereas bagasse hemicellulose combustion was completed through three exothermic processes. The magnitude and the shape of the exotherms depend, mainly, on the chemical composition of the sample.