高等动物细胞核膜和核纤层结构、功能及动态变化调控机制

细胞核是真核细胞中最大的细胞器．高等动物细胞核主要由双层核膜、核孔复合体、核纤层、染色质和核仁等组成．在细胞有丝分裂期,细胞核呈现去装配和再装配等动态变化．在细胞分裂间期,核膜、核孔复合体和核纤层构成细胞核的外周结构,为遗传物质在染色质和核仁中的代谢提供了一个相对稳定的环境,同时调控细胞核内外的物质转运,在细胞增殖、分化、个体发育和细胞衰老等许多方面发挥着重要作用．本文主要对高等动物细胞核膜和核纤层结构、功能及动态变化调控机制等方面的研究进展进行简要综述．     

体外细胞核组装中核纤层与核膜的关系

采用非洲爪蟾卵提取物非细胞体系,以外源Lambda DNA诱导细胞核的体外组装,以此实验模式为基础,研究了细胞核体外组装过程中核纤层的组装,结果表明核纤层蛋白参与细胞核的体外组装过程,核内骨架的组装与核纤层的组装在时间上是有序的,核内骨架的组装可能为核纤层的装配提供了先决条件.在非洲爪蟾卵提取物非细胞体系中加入抗核纤层蛋白抗体,抑制核纤层的正常装配过程,核膜组装发生异常.结果提示核纤层的组装与核膜的组装是密切相关的.     

核纤层蛋白与核纤层病的研究进展

核纤层蛋白(lamin)是中间纤维蛋白家族的重要成员,其多聚体组成的网格状结构紧贴于核膜内侧,在维持细胞核的正常及有丝分裂过程中发挥着重要的作用。近年来,大量研究表明编码核纤层蛋白的基因尤其是lamin A编码基因(LMNA)突变会引起一系列的疾病,即核纤层病(lami-nopathy)。该文就核纤层蛋白和核纤层病的关系进行综述,有助于读者了解核纤层蛋白的重要性,也为核纤层病的治疗提供线索。     

核纤层蛋白的研究进展

核纤层普遍存在于高等真核细胞的细胞核中,向外与内层核膜上的蛋白结合,向内与染色质的特定区段结合,其主要成分是核纤层蛋白。核纤层蛋白主要参与细胞核的形状和大小的维持、核膜的组织、DNA的复制及有丝分裂。近年来的研究表明,核纤层蛋白与许多人类疾病密切相关。目前,核纤层蛋白在人类的各种组织和细胞中已有比较系统的研究,并且呈组织特异性及发育时序性表达。本文将就核纤层的最新研究进展做一综述。     

A型核纤层蛋白的研究进展

A型核纤层蛋白由LMNA基因编码,为核纤层的主要成分,呈动态网状结构,位于核膜下层,起重要的机械支持作用,直接或间接与染色质相互作用,在维持染色质结构、转录、DNA复制和细胞凋亡等方面发挥重要作用.LMNA基因及其编码蛋白lamin A/C异常能引起一组人类遗传病,称为核纤层蛋白病.为深入了解A型核纤层蛋白的正常生理功能及其在相关核纤层蛋白病中的作用,本文就A型核纤层蛋白的结构分类、修饰组装、动力学、相互作用蛋白及相关核纤层蛋白病等方面进行综述.     

真核细胞的核纤层及其相关结构的研究

核纤层由A和B两种核纤层蛋白及核纤层蛋白结合蛋白组成。越来越多的证据显示：A、B两种核纤层蛋白与内核膜蛋白在细胞完成各项生理功能过程中发挥着重要的作用,如：细胞核的装配、遗传物质的复制、转录以及维持细胞结构和功能的完整性等。本综述了近几年的最新研究成果,其中包括：对新发现的大量的内核膜蛋白的鉴定,核纤层蛋白和内核膜蛋白在细胞核的装配和间期细胞中的独特作用,同时从细胞生物学角度探讨了核纤层蛋白的突变与疾病的关系,为真核细胞核纤层及其相关结构的进一步研究提供了重要线索。     

A型核纤层蛋白在氧化应激和DNA损伤反应中的作用

核纤层蛋白是一种存在于真核细胞核膜下的中间丝纤维蛋白,是细胞核中重要的骨架蛋白,对维持细胞核的结构和功能具有重要作用。其基因突变会引起一系列的遗传性疾病,称为核纤层蛋白病。这些疾病在细胞水平表现出氧化应激和DNA损伤的特征,提示核纤层蛋白在氧化应激和DNA损伤反应中具有重要作用。本文主要就A型核纤层蛋白在氧化应激、DNA损伤反应中的作用机制进行综述。     

6-DMAP诱导PM胚胎形成过程中核纤层蛋白B的动力学变化

我们的前期研究发现:被微管抑制剂nocodazole抑制在第一次有丝分裂中期的小鼠受精卵在加入6-DMAP处理后核膜重新出现,并且父、母本的基因组未发生融合,分别形成了类似雌、雄原核的两个细胞核,它们共存于卵细胞质中,我们把这种特殊的胚胎称之为PM胚胎(post-mitoticembryo)。本研究表明:在去除抑制剂3h后未能形成核膜的胚胎进一步卵裂,而形成核膜的PM胚胎培养24h未见进一步发育。此外,我们采用免疫荧光染色观察PM胚胎核膜重现过程中核纤层蛋白B的动力学变化,结果显示:在加入6-DMAP后核纤层蛋白B在染色体周围逐渐聚集,约3h后核膜完全形成,此时核纤层蛋白B在染色体周围的聚集达到最高峰。文中还对6-DMAP诱导核膜形成的机制进行了探讨。     

核纤层蛋白B1的功能及其在神经系统疾病和肿瘤中的研究新进展

核纤层蛋白B1 (Lamin B1)是核纤层蛋白家族重要成员之一,其主要功能在于维持细胞核骨架完整性,并通过影响染色体分布、基因表达及DNA损伤修复等参与细胞的增殖和衰老。其表达异常与多种疾病有关,如神经系统疾病(神经管畸形,ADLD)及肿瘤(胰腺癌)等,是潜在的药物靶点和肿瘤标志物。对Lamin B1功能的深入研究,将有助于对相关神经系统疾病和肿瘤发生发展的分子机制的了解并为治疗靶点研究提供新方向。     

核膜血影重复蛋白研究进展

核膜血影重复蛋白(Nesprins)连接细胞核与多种细胞骨架和(/或)细胞器,在细胞核与细胞骨架定位、质-核间物质运输和动力传导、核膜构建、细胞迁移、锚定和极性建立等过程中发挥重要作用.本文综述核膜血影重复蛋白的发现、编码基因、结构、功能以及与相关疾病的关系研究现状,并展望潜在的未来研究动向.     

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.