乙肝病毒样颗粒在初始树突细胞进入Ⅰ类和Ⅱ类MHC抗原提呈通路

<正>病毒样颗粒(VLPs)代表了有效地引发机体免疫的病毒蛋白的高密度展示方式,由乙肝病毒外膜蛋白组成的病毒样颗粒可以诱导机体的细胞免疫和体液免疫应答。然而,研究表明乙肝病毒外膜蛋白VLPs可以破坏树突细胞的功能。作者研究了乙肝病毒外膜蛋白VLPs和树突细胞亚类的相互作用及抗原在树突细胞中通过主要组织相容性I类和II类抗原呈递途径的提呈状况。在体外试验针对CpG的应答中,乙肝病毒外膜蛋白VLPs降低了浆细胞样树突细胞的α-干扰素的产生,但是在体内给予     

大肠杆菌周质和外膜蛋白的定位

大肠杆菌周质和外膜蛋白发挥功能必须首先到达其特定亚细胞分区.大肠杆菌通过一系列与蛋白质分泌有关的蛋白（Sec蛋白）将周质和外膜蛋白转运至内膜.在切除了信号肽后,与周质蛋白的定位不同的是,外膜蛋白的最终定位还需要其他因子的协助.外膜蛋白的定位近来认为是以周质作为中介的.     

脉冲电场下肿瘤细胞的窗口效应（英文）

基于多层电介质模型,对于适应于球形生物细胞的脉冲电场,提出了一种等效电路模型,在相同频域下,内膜和外膜的变化趋势相同,频域分析表明,不同频谱场将引起不同的生物医学效应.我们针对癌症细胞计算了跨膜电压,并讨论了脉冲和跨膜电压以及阻抗的关系.结果表明不同的频域和不同的持续时间对细胞的内膜和外膜有选择性的影响,时域和频域的分析显示,在细胞上有一个窗口,当持续时间在10~(-8)~10~(-6)s之间,细胞内膜的电压将高于细胞外膜的电压.窗口效应为解释生物细胞的脉冲电学效应提供了一种参考思路.     

脉冲电场下肿瘤细胞的窗口效应

基于多层电介质模型,对于适应于球形生物细胞的脉冲电场,提出了一种等效电路模型,在相同频域下,内膜和外膜的变化趋势相同,频域分析表明,不同频谱场将引起不同的生物医学效应．我们针对癌症细胞计算了跨膜电压,并讨论了脉冲和跨膜电压以及阻抗的关系．结果表明不同的频域和不同的持续时间对细胞的内膜和外膜有选择性的影响,时域和频域的分析显示,在细胞上有一个窗口,当持续时间在10^-8～10^-6 s之间,细胞内膜的电压将高于细胞外膜的电压．窗口效应为解释生物细胞的脉冲电学效应提供了一种参考思路．     

压力负荷性心衰小鼠左心室跨壁L-型钙电流的变化

为了观察正常和心衰时心内膜下和心外膜下心肌细胞L-型钙电流(ICa-L)的差别,我们采用主动脉弓狭窄的方法建立小鼠压力超负荷性心衰模型,采用全细胞膜片钳技术记录了正常、主动脉狭窄(band)及假手术对照(sham)组动物左心室游离壁内、外膜下心肌细胞的动作电位时程(action potential duration,APD)和ICa-L。结果显示:(1)与sham组同龄的正常小鼠左心室心内膜下细胞动作电位复极达90％的时程(APD90)为(38．2±6．44)ms,较心外膜下细胞的APD90(15.67±5.31)ms明显延长,二者的比值约为2．5:1;内膜下细胞和外膜下细胞ICa-L密度没有差异,峰电流密度分别为(-2.7±0.49)pA/pF和(-2.54±0．53)pA/pF;(2)Band组内、外膜下细胞的动作电位复极达50％的时程(APD50)、APD90均较sham组显著延长,尤以内膜下细胞延长突出,分别较sham组延长了400％和360％,内、外膜下细胞APD90的比值约为4.2:1;(3)与sham组相比, band组内膜下细胞ICa-L密度显著减小,在+10 mV～+40 mV的4个电压下分别降低了20．2％、21．4％、21.6％和25.7％(P< 0．01),但其激活电位、峰电位和翻转电位没有改变;band组外膜下细胞的ICa-L密度与同期sham组相比无明显变化;band组钙通道激活、失活及复活的动力学特征与sham组相比没有改变。以上结果提示,生理状态下小鼠左心室内、外膜下细胞ICa-L密度不存在明显差别,提示ICa-L与APD跨壁异质性的产生无关;心衰时左心室内、外膜下细胞APD明显延长,以内膜下细胞延长尤为突出,内膜下细胞ICa-L密度明显减少,而外膜下细胞ICa-L密度无明显改变,这种ICa-L的非同步变化在心衰时可能起到对抗APD延长、减少复极离散度的有益作用。     

骨桥蛋白增强自发性高血压大鼠血管外膜成纤维细胞的迁移活性

血管外膜成纤维细胞迁移参与形成新生内膜是一些血管疾病的共同发病过程。研究高血压动物模型的外膜成纤维细胞是否与对照组不同将有利于阐述高血压血管重塑的机制。本实验比较自发性高血压大鼠(spontaneously hy-pertensive rats,SHR)与正常对照大鼠(Wistar-Kyoto rats,WKY)的血管外膜成纤维细胞在体外培养条件下迁移能力的差别,并对其机制进行了探讨。采用大鼠胸主动脉的培养血管外膜成纤维细胞,用Transwell技术测定培养细胞的迁移能力。用实时定量PCR技术检测mRNA表达。结果表明,在血清和bFGF趋化作用下,SHR培养血管外膜成纤维细胞的迁移活性显著强于WKY(每个视野平均迁移细胞数目,血清:35.20±5.26 vs 22.2±3.27,P<0.05;bFGF:30.23±4.54vs 19.20±4.47,P<0.05)。进一步研究发现,SHR培养血管外膜成纤维细胞中的骨桥蛋白(osteopontin,OPN)mRNA水平显著高于WKY(1863.23±43.91 vs 326.24±68.29,P<0.01)。反义OPN(100 μmol/L)对血清诱导的SHR血管外膜成纤维细胞迁移有抑制作用(每个视野平均迁移细胞数目 38.60±5.98 vs 26.61±3.84,P<0.05)。而正义及错配义OPN组均无此效应。反义OPN对SHR细胞迁移的抑制作用呈浓度依赖性。上述结果证实SHR培养血管外膜成纤维细胞的迁移能力强于WKY,OPN在细胞迁移中     

疫苗

960592 脑膜炎奈瑟氏球菌5C外膜蛋白的克隆和表达[英]/Guillen, G.…∥Acta Biotechnol.-1995,15(1).-97～106[译自DBA,1995,14(12),95-06948] 脑膜炎奈瑟氏球菌5类蛋白之一的5C外膜蛋     

鲍曼不动杆菌Omp34经线粒体途径诱导HeLa细胞凋亡

[目的]构建鲍曼不动杆菌(Acinetobacter baumannii)外膜蛋白34(outer membrane protein 34,Omp34)的表达载体pcDNA3.1/myc-His-Omp34,研究Omp34引起HeLa细胞凋亡的机制。[方法]PCR扩增目的基因Omp34,将其克隆至载体pcDNA3.1/myc-His;菌液PCR和测序筛选阳性克隆;将pcDNA3.1/myc-His-Omp34转染HeLa细胞;反转录PCR和Western Blot检测Omp34在HeLa细胞中的表达;CCK8实验检测细胞增殖抑制率;JC-1探针检测线粒体跨膜电位;透射电镜观察HeLa细胞线粒体结构,Western Blot鉴定HeLa细胞线粒体凋亡相关蛋白。[结果]成功构建pcDNA3.1/myc-His-Omp34真核表达载体;并且Omp34可抑制HeLa细胞增殖,引起线粒体损伤及跨膜电位崩溃,导致促凋亡蛋白Bax和Bad表达升高,抗凋亡蛋白Bcl-2和Bcl-XL表达降低。[结论]成功构建pcDNA3.1/mycHis-Omp34表达载体,并证明Omp34可经线粒体途径导致HeLa细胞凋亡。     

牦牛多杀性巴氏杆菌外膜蛋白OmpH的扩增与生物信息学分析

旨在扩增牦牛多杀性巴氏杆菌外膜蛋白OmpH的编码基因,并预测OmpH蛋白二级结构和B细胞抗原表位,从而探讨牦牛多杀性巴氏杆菌外膜蛋白OmpH在免疫保护中所起的作用。对牦牛多杀性巴氏杆菌的外膜蛋白OmpH基因进行PCR扩增及序列测定。应用生物信息学相关软件和方法,对牦牛多杀性巴氏杆菌OmpH蛋白的二级结构和B细胞抗原表位进行预测。牦牛多杀性巴氏杆菌OmpH基因全长1 478 bp,ORF包含1 002 bp编码333个氨基酸。二级结构以无规卷曲为主,有少量的α-螺旋和延伸带;推测OmpH蛋白有1个细胞黏附位点、2个糖基化位点。     

革兰氏阴性细菌β-桶状结构外膜蛋白折叠与组装的研究进展

β-桶状结构外膜蛋白是革兰氏阴性细菌细胞外膜层的主要组成部分,在营养吸收、维持外膜完整性、病原菌致病性及多重耐药性等方面发挥着重要的作用,对细菌的存活至关重要。详细了解这些蛋白的合成、折叠与组装到外膜的过程在增加筛选抗病原菌药物靶位、增强有益菌的生物活性等方面具有重要意义。本文对近年来革兰氏阴性细菌β-桶状结构外膜蛋白的合成、转运、折叠及组装到外膜过程的研究结果进行了综合论述,重点叙述了β-桶状结构外膜蛋白组装复合体的研究进展,并在此基础对这一类蛋白的折叠与膜整合过程提出一些新的见解,便于读者快速、全面了解该领域的最新发现和发展。     

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.