一种研究和鉴别悬浮培养红豆杉细胞凋亡与坏死的新方法

将在动物细胞凋亡研究中应用的Hoechst-PI双重荧光染色法与琥珀酸脱氢酶（SDH）染色法相结合,建立了一种更加完善、能同时鉴别和研究悬浮培养的植物细胞凋亡及坏死的新方法－Hoechst-PI-SDH三重染色法（H－P－S法）。该方法可直接用于红豆杉悬浮培养细胞,无需对细胞进行去壁、固定及切片等其它方法所必需的步骤,在荧光显微镜下可鉴别活细胞、死细胞及凋亡细胞,并可同时观测细胞凋亡的全部过程。该方法简单、快速、准确,而且克服了因细胞膜通透性差异引起的对死、活细胞判断的困难,可在植物细胞凋亡的研究中广泛应用。     

Ce(NH4)2(NO3)6对蔓茎堇菜悬浮细胞凋亡和总黄酮含量的影响

用DNA Laddering和DAPI荧光检测法对Ce(NH4)2(NO3)6诱导的蔓茎堇菜(Viola diffusa Ging.)悬浮细胞的凋亡情况进行研究,同时还测定了诱导过程中悬浮细胞的生长量和总黄酮含量。结果表明,Ce(NH4)2(NO3)6可诱导蔓茎堇菜悬浮细胞发生凋亡,1.0 mmol.L-1Ce(NH4)2(NO3)6胁迫诱导培养8 d时,细胞凋亡率最高(55.7%);总黄酮含量显著增加,达2.820%。表明Ce(NH4)2(NO3)6在诱导蔓茎堇菜悬浮细胞凋亡并抑制其生长的同时,还能促进黄酮类化合物的合成。     

介绍一种观察凋亡细胞形态学特征的染色方法--苏木素-伊红染色法(HE染色法)

就苏木素-伊红染色法用于观察与鉴别细胞凋亡与细胞坏死作了较详细的介绍。此染色法对凋亡细胞的形态学特征检测,既方便又可靠,在一般普通光学显微镜下就可进行观察与检测。此法不失于研究细胞凋亡的一种检测观察凋亡细胞形态学特征的简便方法。     

DMSO 对悬浮培养的东北红豆杉细胞凋亡和紫杉醇合成的影响

研究了不同浓度的DMSO对悬浮培养的东北红豆杉(Taxus cuspidata)细胞的增殖能力、细胞活性以及紫杉醇合成和释放等方面的影响,同时应用荧光指示剂双染法检测了细胞凋亡的发生情况.结果显示2%的DMSO处理能显著降低细胞活性,抑制细胞的增殖能力,使细胞核内DNA含量减少,培养中、后期在荧光显微镜下可见部分细胞核出现典型的凋亡形态,同时伴有紫杉醇产量的明显增加;对照组及1%以下浓度组未出现上述改变.结果表明一定浓度的DMSO能诱导细胞凋亡,促进细胞紫杉醇合成能力的提高.     

热疗通过上调基因PUMA表达诱导胃癌MKN45凋亡

目的探讨热疗诱导胃癌MKN45细胞凋亡及其对胃癌细胞促凋亡蛋白PUMA表达的影响。方法体外复苏与培养人胃癌MKN45细胞。对照组常温(37℃)下培养,实验组按不同时间分组43℃水浴加热胃癌MKN45后培养24h,采用倒置显微镜和透射电镜观察热疗后胃癌细胞的形态结构变化。四甲基偶氮唑盐比色法(MMT)检测细胞增殖抑制。AO/EB荧光双染色法及Annexin-V/PI双染色法流式检测细胞凋亡。Western blot检测促凋亡蛋白PUMA蛋白表达。结果光镜观察发现热疗后MKN45细胞明显皱缩、变圆及细胞漂浮,3h多数细胞漂浮。电镜下可见热疗后MKN45细胞核仁增多,胞核及胞浆出现大小不等的空泡和凋亡小体。MTT实验提示,热疗可明显抑制MKN45细胞生长(P0.01)。AO/EB荧光双染色显示,热疗后细胞呈淡黄或橘红色,胞核呈现致密斑状。热疗0.5h、1h、2h和3h后,AO/EB荧光双染色法及Annexin-V/PI双染色法流式检测细胞凋亡率基本一致。热疗0.5h后细胞凋亡率明显增高,1h略低于0.5h,2h达最高峰。Western blot显示,MKN45细胞各热疗时间的PUMA蛋白表达明显升高,热疗0.5h开始升高,热疗2h达最高峰,1h略低于0.5h,3h有所回落(P0.05)。结论热疗2h诱导胃癌细胞凋亡的效果最佳,并且可通过上调基因PUMA表达诱导胃癌MKN45凋亡。     

利用植物悬浮培养细胞进行蛋白质快速定位分析的方法

稳定遗传表达分析是一种植物中常用的整体解析基因的方式。有多种转化方式可供选择,也可根据所需要的获得的转基因植物材料选择受体材料。但是由于稳定遗传转化周期较长且大部分材料不适合于进行荧光观察,所以在一些基因的研究中逐渐被瞬时表达分析系统。虽然瞬时表达分析用时短,但是转化效率受到多方面的限制,转化材料无法保存。目前由于植物悬浮培养细胞材料均一,增殖迅速并且可以满足大批量研究需求逐渐成为植物研究中的热点材料。以此同时,在亚细胞定位方面,悬浮培养细胞还是良好的应用材料。采用农杆菌介导法进行植物悬浮培养细胞的转化中方法较为成熟,但是获得纯净的转基因细胞系的转化周期较长。在本研究中针对上述问题我们建立了一种转化时间短,转化效率高的植物悬浮培养细胞稳定遗传转化体系。同时将这个体系应用到基因的亚细胞定位当中进行蛋白质快速定位分析。     

Annexin V-FITC/DAPI细胞凋亡检测法

[目的]建立新的荧光染料DAPI与FITC标记Annexin V联合的细胞凋亡流式细胞术检测方法,以用于具有橙红色荧光的药物处理细胞的流式细胞术凋亡检测。[方法]以倒置荧光显微镜成像和流式细胞仪分别检测不同浓度DAPI对活和死细胞的标记作用。以荧光酶标仪检测不同浓度DAPI处理细胞的荧光信号,并进行相关性分析。以流式细胞术比较Annexin V-FITC/DAPI双染法与Annexin V-FITC/PI双染法对无色和含红/橙色荧光药物导致的细胞凋亡。[结果]DAPI标记可用于区分死细胞和活细胞,DAPI标记死细胞的荧光信号和DAPI的浓度呈线性正相关。Annexin V-FITC/DAPI双染法与Annexin V-FITC/PI双染法相比,二者对不含红橙色荧光药物诱导的多种肿瘤细胞的凋亡检测结果无显著差异。与Annexin V-FITC/PI双染法相比,Annexin V-FITC/DAPI双染法可有效避免药物自身荧光与PI通道重合导致的流式检测干扰。[结论]成功建立了新的Annexin V-FITC/DAPI双染法用于细胞凋亡的流式细胞术检测,该方法能够避免具有红、橙色荧光基团的药物对的干扰检测凋亡。     

Calcofluor White M2R与Sytox Green双重染色法鉴别蜜蜂微孢子虫

东方蜜蜂微孢子虫(Nosema ceranae)是一种广泛寄生于东方蜜蜂Apis cerana,西方蜜蜂Apis mellifera和熊蜂Bombus Latreille上的寄生虫,对蜜蜂和熊蜂的危害较大,进而影响养蜂业的发展。本实验采用荧光染色试剂Calcofluor White M2R与核酸染料Sytox Green双重染法来鉴别蜜蜂或熊蜂体内的N.ceranae及孢子的存活状态。结果得出,在荧光显微镜下可见死孢子被染上黄绿色荧光,活的呈现蓝白色荧光,而寄主细胞、细菌、病毒等不被染色。这是一种快速有效鉴别N.ceranae及其死活的方法,从而判定蜜蜂或熊蜂体内的微孢子虫在是否具有侵染活性,对微孢子虫的研究及药物防治具有重要作用。     

利用荧光共振能量转移技术在活细胞内研究顺铂诱导的凋亡信号通路

为在活细胞内探讨顺铂诱导的凋亡通路．实验样品经顺铂处理后,应用基于荧光共振能量转移(FRET)原理设计的荧光探针pFRET-Bid和pSCAT-3来检测Bid切割和Capase-3活化的动态变化,同时,利用荧光成像在亚细胞水平对Bid转位线粒体的动力学特征进行了实时分析．结果表明：在顺铂诱导的细胞凋亡过程中,Bid切割发生在药物刺激后4～5 h, 历时(120±20) min．Bid切割活化后即从胞浆内转位到线粒体,历时(90±15) min．在凋亡后期,可以明显检测到Caspase-3 的激活．研究表明,应用FRET及荧光成像技术,可以在活细胞内实时、直观、可视地研究顺铂诱导的细胞凋亡过程,从而客观地反映了Bid、Caspase-3等蛋白质分子在该凋亡信号通路中的动态行为及时空传递特性．     

地塞米松诱导培养的大鼠大脑皮质星形胶质细胞凋亡

目的　研究地塞米松诱导纯化培养的大鼠大脑皮质星形胶质细胞凋亡的作用。方法　不同浓度的地塞米松(浓度为 10 -3 、 10 -4、 10 -5mol/L)与纯化培养的大鼠大脑皮质星形胶质细胞共同孵育 18小时后 ,吖啶橙染色荧光显微镜观察细胞凋亡形态学改变 ,流式细胞仪检测细胞凋亡和结晶紫比色法酶标仪测定活细胞数。结果　 (1)吖啶橙染色荧光显微镜观察 :10 -4组偶见细胞凋亡 ,10 -3 组可见许多细胞有典型的凋亡形态学改变核固缩 ,深染 ,或肿胀 ,碎裂 ,并可见凋亡小体。 (2 )流式细胞仪检测细胞凋亡 :10 -3 组细胞凋亡率为 15 99% ,与其它三组相比明显增高 ,有显著性差异 (P <0 0 1)。 (3)结晶紫法酶标仪测定活细胞数 :10 -3 组OD值为 0 . 185与其它三组相比明显下降 ,有显著性差异 (P <0 0 1) ,表明活细胞数明显减少。结论　大剂量地塞米松可诱导体外的星形胶质细胞凋亡。     

Ultrastructural identification of apoptotic nuclei using the TUNEL technique

Summary We describe an ultrastructural adaptation of the method of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL) for the identification of DNA fragmentation. Thin sections of tissue embedded in hydrophilic resin were nick end labelled with biotinylated dUTP which was subsequently labelled with avidin conjugated to gold particles. The technique was validated by labelling the nuclei of L929-8 cells treated with tumour necrosis factor α. These cells are known to respond to treatment with the factor by undergoing apoptosis. The method was then used on tissue from the chick embryo which is known to be undergoing programmed cell death. This tissue was from the neural tube and the posterior necrotic zone of the limb bud, where cells can be identified as undergoing apoptosis based on the morphology of their nuclei. The method specifically labelled heterochromatin adjacent to the nuclear envelope as well as the associated with the nucleolus of cells from regions of the embryo where programmed cell death was expected. In addition to labelling the nuclei of cells that were clearly undergoing apoptosis, the method also identified nuclei of apparently normal cells. This method, used in conjunction with corroborating techniques, provides a means for the early detection of cells undergoing DNA fragmentation, before the onset of gross apoptotic morphology, and in cells that do not show classical apoptotic characteristics.     

Immunogenic cell death modalities and their impact on cancer treatment

It is still enigmatic under which circumstances cellular demise induces an immune response or rather remains immunologically silent. Moreover, the question remains open under which circumstances apoptotic, autophagic or necrotic cells are immunogenic or tolerogenic. Although apoptosis appears to be morphologically homogenous, recent evidence suggests that the pre-apoptotic surface-exposure of calreticulin may dictate the immune response to tumor cells that succumb to anticancer treatments. Moreover, the release of high-mobility group box 1 (HMGB1) during late apoptosis and secondary necrosis contributes to efficient antigen presentation and cytotoxic T-cell activation because HMGB1 can bind to Toll like receptor 4 on dendritic cells, thereby stimulating optimal antigen processing. Cell death accompanied by autophagy also may facilitate cross priming events. Apoptosis, necrosis and autophagy are closely intertwined processes. Often, cells manifest autophagy before they undergo apoptosis or necrosis, and apoptosis is generally followed by secondary necrosis. Whereas apoptosis and necrosis irreversibly lead to cell death, autophagy can clear cells from stress factors and thus facilitate cellular survival. We surmise that the response to cellular stress like chemotherapy or ionizing irradiation, dictates the immunological response to dying cells and that this immune response in turn determines the clinical outcome of anticancer therapies. The purpose of this review is to summarize recent insights into the immunogenicity of dying tumor cells as a function of the cell death modality.     

Increased cell surface exposure of phosphatidylserine on propidium iodide negative thymocytes undergoing death by necrosis.

Phosphatidylserine (PS) exposure on propidium iodide negative cells using FITC labelled annexin-V has been used to quantify apoptosis in vitro and in vivo. Detection of PS within cells undergoing necrosis is also possible if labelled annexin-V specific for PS enters the cell following early membrane damage. Necrotic or late apoptotic cells can be excluded from flow cytometric analysis using propidium iodide which enters and stains cells with compromised membrane integrity. Here we show that thymocytes undergoing death exclusively by necrosis show early exposure of PS prior to loss of membrane integrity. This early exposure of PS occurs in cells treated with agents which both raise intracellular calcium levels and are also capable of interacting with protein thiol groups. We also demonstrate that PS exposure in thymocytes induced to undergo apoptosis by three different agents does not correlate with calcium rises but correlates with and precedes DNA fragmentation.     

Early ultrastructural injuries in the thyroid of the normal rat radioinduced by diagnostic and/or therapeutic amounts of iodine-131.

After irradiation, two principal mechanisms of cytolytic cell death can be involved: apoptosis and necrosis. By using morphological criteria, cells undergoing apoptosis can be distinguished from cells dying by necrosis. In nuclear medicine 131I is used to ablate thyroid remnants or to treat well differentiated thyroid carcinoma. The aim of study was to describe the progressive morphological thyroid changes induced by a diagnostic and/or therapeutic amounts of 131I in the rat using electron microscopy, in an attempt to determine which is the cell death pathway and to analyse "stunned" thyroid tissue to elucidate this effect. Tissular and ultrastructural examinations show that damages induced by 131I irradiation of the normal thyroid gland are heterogeneous. Thyroid cells die by necrosis after this metabolic irradiation, and no signs of apoptosis were observed by electron microscopy. In the other hand, stunning effect did not seem to impair the effectiveness of 131I treatment.     

Isolation and characterization of mammalian cells that are undergoing apoptosis by a bovine serum albumin density gradient

When cells are treated with cytotoxic agents, they enter apoptosis asynchronously to yield cells at various stages of cellular deterioration. This mixture makes it difficult to study the biochemical pathways leading to cell death. We have fractionated apoptotic mammalian cells in a simple discontinuous bovine serum albumin (BSA) density gradient centrifugation into five layers, each containing cells at different stages of apoptosis, (1) nonapoptotic, (2) undergoing apoptosis, and (3) mature apoptotic cells, as judged by light and electron microscopy of chromatin condensation and by the extent of DNA fragmentation. Modifications of apoptosis markers including c-Jun N-terminal kinase/stress-activated protein kinase and procaspase 3 cleavage were apparent in those cells that are undergoing apoptosis. Apoptosis-specific histone H2B phosphorylation was highly elevated and DNA fragmentation activity in the cytoplasm was observed in those cells that are undergoing apoptosis, but not much was observed in the cells of other fractions. Results show that apoptotic cells can be fractionated easily by the BSA gradient method, and this method will be invaluable for studying the biochemical processes that drive apoptosis.     

Cleavage of plasma membrane calcium pumps by caspases: a link between apoptosis and necrosis

Neuronal death, which follows ischemic injury or is triggered by excitotoxins, can occur by both apoptosis and necrosis. Caspases, which are not directly required for necrotic cell death, are central mediators of the apoptotic program. Here we demonstrate that caspases cleave and inactivate the plasma membrane Ca(2+) pump (PMCA) in neurons and non-neuronal cells undergoing apoptosis. PMCA cleavage impairs intracellular Ca(2+) handling, which results in Ca(2+) overload. Expression of non-cleavable PMCA mutants prevents the disturbance in Ca(2+) handling, slows down the kinetics of apoptosis, and markedly delays secondary cell lysis (necrosis). These findings suggest that caspase-mediated cleavage and inactivation of PMCAs can lead to necrosis, an event that is reduced by caspase inhibitors in brain ischemia.     

植物细胞程序性死亡的分类和膜通透性调控蛋白研究进展

程序性细胞死亡是由基因调控的贯穿于真核细胞生理和发育过程的细胞自杀行为。动物细胞的程序性死亡分成3类凋亡、自噬和坏死;线粒体和溶酶体分别在前两个过程中起关键作用。关于植物细胞程序性死亡的分类还存在很多争议,焦点是植物是否有细胞凋亡这种形式,核心问题是植物细胞的线粒体外膜上没有Bcl-2家族的膜通透性调控蛋白。近年,程序性细胞死亡也在细菌中发现,LrgAB家族的膜通透性调控蛋白起着重要作用。最近的研究表明,植物叶绿体外被膜上也有LrgAB家族的同源蛋白,它们在控制叶绿体发育和程序性细胞死亡方面起重要作用。因此,叶绿体在植物细胞死亡调控中的作用应该更加受到关注。     

Salmonella induces macrophage death by caspase-1-dependent necrosis

We provide evidence that Salmonella typhimurium kills phagocytes by an unusual proinflammatory mechanism of necrosis that is distinguishable from apoptosis. Infection stimulated a distinctly diffuse pattern of DNA fragmentation in macrophages, which contrasted with the marked nuclear condensation displayed by control cells undergoing chemically induced apoptosis. In apoptotic cells, DNA fragmentation and nuclear condensation result from caspase-3-mediated proteolysis; caspases also subvert necrotic cell death by cleaving and inactivating poly ADP-ribose polymerase (PARP). Caspase-3 was not activated during Salmonella infection, and PARP remained in its active, uncleaved state. Another hallmark of apoptosis is sustained membrane integrity during cell death; yet, infected macrophages rapidly lost membrane integrity, as indicated by simultaneous exposure of phosphatidylserine with the uptake of vital dye and the release of the cytoplasmic enzyme lactate dehydrogenase. During experimentally induced necrosis, lethal ion fluxes through the plasma membrane can be prevented by exogenous glycine; similarly, glycine completely blocked Salmonella-induced cytotoxicity. Finally, inhibition of the interleukin (IL)-1-converting enzyme caspase-1 blocked the death of infected macrophages, but not control cells induced to undergo apoptosis or necrosis. Thus, Salmonella-infected macrophages are killed by an unusual caspase-1-dependent mechanism of necrosis.     

Silica phagocytosis causes apoptosis and necrosis by different temporal and molecular pathways in alveolar macrophages

Chronic inhalation of crystalline silica is an occupational hazard that results in silicosis due to the toxicity of silica particles to lung cells. Alveolar macrophages play an important role in clearance of these particles, and exposure of macrophages to silica particles causes cell death and induction of markers of apoptosis. Using time-lapse imaging of MH-S alveolar macrophages, a temporal sequence was established for key molecular events mediating cell death. The results demonstrate that 80 % of macrophages die by apoptosis and 20 % by necrosis by clearly distinguishable pathways. The earliest detectable cellular event is phago-lysosomal leakage, which occurs between 30 and 120 min after particle uptake in both modes of death. Between 3 and 6 h later, cells undergoing apoptosis showed a dramatic increase in mitochondrial transmembrane potential, closely correlated with activation of both caspase-3 and 9 and cell blebbing. Externalization of phosphatidyl serine and nuclear condensation occurred 30 min–2 h after the initiation of cell blebbing. Cells undergoing necrosis demonstrated mitochondrial membrane depolarization but not hyperpolarization and no caspase activation. Cell swelling followed the decrease in mitochondrial membrane potential, distinguishing necrosis from apoptosis. All cells undergoing apoptosis followed the same temporal sequence, but the time lag between phago-lysosomal leakage and the other events was highly variable from cell to cell. These results demonstrate that crystalline silica exposure can result in either apoptosis or necrosis and each occurs in a well-defined but temporally variable order. The long time gap between phago-lysosomal leakage and hyperpolarization is not consistent with a simple scenario of phago-lysosomal leakage leading directly to cell death. The results highlight the importance of using a cell by cell time-lapse analysis to investigate a complex pathway such as silica induced cell death.