MFN1介导的线粒体融合在心肌细胞凋亡中的作用研究

目的:探讨线粒体融合关键蛋白MFN1介导的线粒体融合在调控心肌细胞凋亡中的作用。方法:通过si RNA降低体外培养H9C2心肌细胞中MFN1的表达后,采用Western blot检测线粒体细胞色素c(Cyto c)释放及其下游凋亡效应分子Caspase9与Caspase3活性,流式细胞术检测细胞内活性氧(ROS)的产生情况,流式细胞术检测细胞凋亡的情况。结果:干扰MFN1可显著促进H9C2心肌细胞内细胞色素c由线粒体释放至胞浆,促进Caspase9与Caspase3的激活,增加细胞内活性氧ROS产生并提高细胞凋亡率(均P0.05)。结论:MFN1介导的线粒体融合可保护心肌细胞凋亡,其机制可能与抑制ROS产生与细胞色素C释放有关。     

Bcl-2家族蛋白调控线粒体膜通透性和细胞色素C释放的新机制

Bcl-2家族蛋白在调控线粒体功能和细胞色素C释放中起重要作用。最近发现Bcl-2分子通过与其他促凋亡分子相互作用调控线粒体外膜通透性,其具体分子机制尚不完全清楚。本课题组采用化学生物学方法,在研究Bax/Bak非依赖的细胞凋亡途径中,发现了一些小分子化合物能够诱导Bim表达量急剧升高,Bim能转位到线粒体上,与Bcl-2相互作用增强,并直接促进Bcl-2构象变化。有意义的是,Bim可以诱导Bcl-2功能发生转换并能够形成大的复合体通道来介导细胞色素C释放。研究结果提示Bcl-2分子可变成促凋亡分子,参与Bax/Bak非依赖的细胞色素C释放和细胞凋亡。     

荧光定量PCR精确检测人胚胎干细胞线粒体DNA拷贝数方法的建立

建立一种精确定量人胚胎干细胞线粒体DNA拷贝数的方法。构建包含线粒体DNANDl和核单拷贝基β-globin基因序列的重组质粒作为标准品;收集无饲养层培养体系下人胚胎干细胞DNA样本,结合2个单独的Taqman探针实时荧光定量PCR对待测样本中线粒体NDl和核β-globin基因分别进行定量,从而对人胚胎干细胞线粒体DNA的含量进行了精确定量。结果提示,人胚胎干细胞线粒体DNA的平均拷贝数／细胞为1321±228。研究表明,该技术可对人胚胎干细胞线粒体DNA拷贝数进行准确的测定,为研究培养条件对人胚胎干细胞线粒体DNA拷贝数的影响及优化体外培养条件奠定了基础。     

肝细胞线粒体凋亡途径及保护机制研究进展

线粒体在能量代谢、自由基产生、衰老、细胞凋亡中起重要作用。线粒体的基因突变,呼吸链缺陷,线粒体膜的改变等因素均会影响整个细胞的正常功能,从而导致病变。凋亡发生时,线粒体通透性转换孔开放,使得线粒体膜电位降低,呼吸链电子传递障碍,细胞ATP合成障碍,生成大量活性氧簇,线粒体发生水肿,线粒体外膜破裂,膜间隙释放大量促凋亡因子如细胞色素C。Bcl-2家族对线粒体的功能有调控作用,介导细胞色素C的释放,Caspase酶原的激活等。病毒性肝炎、酒精性肝病,梗阻性黄疸、肝癌、毒素和药物介导的肝损伤等疾病中都伴随着肝细胞凋亡的发生,目前保肝药物对肝细胞线粒体功能的保护机制主要体现在稳定线粒体膜功能,减轻氧化损伤等方面,针对临床疾病的治疗有很好的指导作用。     

肝细胞线粒体凋亡途径及保护机制研究进展

线粒体在能量代谢、自由基产生、衰老、细胞凋亡中起重要作用。线粒体的基因突变,呼吸链缺陷,线粒体膜的改变等因素均会影响整个细胞的正常功能,从而导致病变。凋亡发生时,线粒体通透性转换孔开放,使得线粒体膜电位降低,呼吸链电子传递障碍,细胞ATP合成障碍,生成大量活性氧簇,线粒体发生水肿,线粒体外膜破裂,膜间隙释放大量促凋亡因子如细胞色素C。Bcl-2家族对线粒体的功能有调控作用,介导细胞色素C的释放,Caspase酶原的激活等。病毒性肝炎、酒精性肝病,梗阻陛黄疸、肝癌、毒素和药物介导的肝损伤等疾病中都伴随着肝细胞凋亡的发生,目前保肝药物对肝细胞线粒体功能的保护机制主要体现在稳定线粒体膜功能,减轻氧化损伤等方面,针对临床疾病的治疗有很好的指导作用。     

PKCδ在细胞凋亡中的作用

PKCδ是nPKC家族成员,参与细胞凋亡调控,其激活机制与特异性位点的磷酸化和半胱天冬酶3(caspase-3)的剪切密切联系.PKCδ激活后可通过多种途径介导细胞凋亡:激活多种蛋白激酶级联启动细胞凋亡信号,转位至线粒体诱导细胞色素C等凋亡因子的释放,核转位启动核内凋亡通路诱导细胞凋亡.本文综述了PKCδ的分子结构、激活机制以及调控细胞凋亡的最新研究进展.     

AIF及AIF依赖的细胞凋亡

AIF是一种线粒体蛋白,具有氧化还原酶和诱导细胞凋亡两种活性。AIF从线粒体到细胞核的转位足以介导体外细胞凋亡的发生,而且是以非caspases依赖的方式进行的。AIF的诱导凋亡活性是小鼠胚胎形态发生过程中类胚体成腔所必需的,也参与了神经细胞的细胞凋亡。真菌、线虫等的细胞凋亡也有AIF同源分子的参与。因此,AIF介导的细胞凋亡代表了独立于caspase信号通路之外的另一条更原始、更保守、更普遍的凋亡途径。     

不同饲养层对鸡胚胎干细胞培养效果的影响

目的:为探索鸡胚胎干细胞培养的优化条件,比较不同饲养层对鸡胚胎干细胞离体培养的效果。方法:用传至第2代的鸡胚成纤维细胞与鸭胚成纤维细胞,经丝裂霉素处理后制作饲养层,比较这2种饲养层以及不用饲养层对鸡胚胎干细胞离体培养效果的影响。结果:在以鸡胚成纤维细胞和鸭胚成纤维细胞作为饲养层的培养体系中,鸡胚胎干细胞均可保持良好的生长状态,而且2种饲养层对鸡胚胎干细胞克隆形成的影响差异不显著(P0.05)。结论:鸡胚成纤维细胞和鸭胚成纤维细胞均可作为较好的饲养层细胞用于鸡胚胎干细胞的离体培养。     

人脐带间充质干细胞作为维持人胚胎干细胞生长饲养层细胞的研究

目的寻找可以维持人胚胎干细胞未分化生长的人源性细胞作为饲养层细胞,从而解决使用鼠源性细胞作为饲养层带来的安全问题。方法尝试以人脐带间充质干细胞作为饲养层细胞来培养人胚胎干细胞,检验其是否可以维持人胚胎干细胞的未分化生长状态。用胶原酶消化法分离人脐带间充质干细胞,光镜下观察细胞形态;流式细胞仪检测其表面标志;诱导人脐带间充质干细胞向成骨细胞和脂肪细胞进行分化。将人胚胎干细胞系H1接种于丝裂霉素C灭活后的人脐带间充质干细胞上,每隔5d进行一次传代。培养20代后,对人胚胎干细胞特性进行相关检测,包括细胞形态、碱性磷酸酶染色、相关多能性基因的表达、分化能力。结果从人脐带中分离出的间充质干细胞为梭形,呈平行排列生长或漩涡状生长;细胞高表达CD44、CD29、CD73、CD105、CD90、CD86、CD147、CD117,不表达CD14、CD38、CD133、CD34、CD45、HLA-DR;具有分化成脂肪细胞和成骨细胞的潜能。人胚胎干细胞在人脐带间充质干细胞饲养层上培养20代后,继续保持人胚胎干细胞的典型形态,碱性磷酸酶染色为阳性,免疫荧光染色显示OCT4、Nanog、SSEA4、TRA-1-81、TRA-1-60的表达为阳性,SSEA1表达为阴性,体外悬浮培养可以形成拟胚体。结论人脐带间充质干细胞可以作为人胚胎干细胞的饲养层细胞,支持其生长,并维持其未分化生长状态。     

饲养层及细胞因子对胚胎干细胞的影响

不同动物胚胎干细胞的生长条件不同,因此筛选合适的饲养层细胞建立适宜的培养体系是胚胎干细胞培养中的关键环节。本文就不同的饲养层细胞及各种外源细胞因子的作用做了简要论述。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.