粘细菌的多细胞形态发生及其分子调控

粘细菌的多细胞形态发生是粘细菌细胞社会性行为的主要表现.包括细胞有序聚集、细胞自溶、子实体发育和粘孢子的分化形成等.粘细菌的形态发生过程涉及复杂的信号系统和调控,与真核生物具有较大的相似性.是研究原核生物细胞分化发育以及生物进化的重要模式材料.     

粘细菌的种群生态及其生存策略

粘细菌是一类革兰氏阴性细菌,属于Delta变形菌纲,具有复杂的多细胞群体行为特性,并能够产生丰富的次级代谢产物,是重要的药源微生物和原核生物细胞间通讯、多细胞形态发生、生物进化等研究中的模式生物.在简要介绍粘细菌基本特性的基础上对粘细菌的生态多样性、生存策略及其在生态系统中功能进行了综述.     

原核生物的细胞分裂

自然界中所有的生物有机体都可以根据它们的细胞结构而明确地被划分为原核生物或真核生物。细菌和蓝藻和类菌质体属于原核生物,其它的有机体都属于真核生物。原核生物细胞一般比真核细胞小。细胞内的遗传物质 D N A 分散于细胞中央一个较大的区域,没有膜包围,故称这个区域为拟核。在细胞质中没有内质网、高尔基体、线粒体和     

细菌必需基因、最小基因组和合成细胞

单细胞原核生物是原始的细胞生命形式,确定细菌必需基因和最小基因组对理解生命的本质、细胞生命的起源和进化有非常重要的意义。文中简要介绍近年来有关细菌的必需基因、最小基因组和合成细胞的研究方法、理论和进展。还特别介绍人工建立最小细菌基因组的策略以及应用前景。     

黏细菌的分子生物学

黏细菌(myxobacterium)是一类具有复杂多细胞行为,并能产生大量新型活性物质的单细胞原核生物。黏细菌基因组较大,目前黄色黏球菌(Mycococcus xanthus)DK1622及纤维堆囊菌(Sorangium cellulosum)So ce56序列已经测定,这有助于从基因组水平对黏细菌进行深入的研究。本文对黏细菌细胞运动的分子机制、新发现的活性物质等方面进行了综述。     

黄色粘球菌的运动机制及其多细胞发育调控的研究进展

粘细菌是原核生物中的“高等生物”,具有特殊的运动能力以及类似真核生物的复杂的多细胞发育生活史,其多细胞发育过程的调控一直是粘细菌研究的热点。近年来,许多关于粘细菌研究的新理论、新学说不断涌现,给予粘细菌研究极大的启发。本文综述了模式菌株黄色粘球菌的运动类型、运动机制以及运动的调控系统,并对其多细胞发育过程的信号传递调控模式进行初步阐释,为更深一步的研究粘细菌复杂的生命调控过程奠定基础。     

光合细菌

光合细菌是地球上出现最早的具有原始光能合成体系的原核生物,是在厌氧条件下进行不放氧光合作用的细菌的总称,因具有细菌叶绿素和类胡萝卜素等光合色素,而呈现—定颜色。     

细菌来源的细胞外囊泡在病原微生物与宿主细胞相互作用中的研究

细胞外囊泡指所有类型的细胞包括免疫细胞通过不同的生物发生途径释放的具有双层膜结构,包含脂类、蛋白质、糖类、遗传物质的球形纳米级膜结合小泡,其也可以从许多生物液体中分离出来。细胞外囊泡在原核生物和真核生物中都被认为是细胞间通讯的有力载体,可以参与广泛的生物过程。该文从细胞外囊泡、细菌来源的细胞外囊泡、细菌来源的细胞外囊泡与宿主细胞相互作用等方面介绍了细胞外囊泡大小和组成,进一步阐述了细菌来源的细胞外囊泡的特点、功能、发生及其引发的炎症反应和细胞死亡,最后对细菌来源的细胞外囊泡作为疫苗和载体的应用进行了展望。     

原核生物细胞如何对环境因子作出响应、其信号传导路径及对逆境(非生物物质降解)的适应性

1原核生物细胞间存在信息交流早在30多年前,Reichenbach及其同事就采用照相的方式描述了粘细菌形成子实体的过程,各细胞之间表现出明显的群体行为,它们之间存在信息交流,这一事实是显而易见的。然而,原核生物细胞之间信息交流的物质基础,即决定信息交流的遗传物质是什么？其信号分子又是怎样？信号分子被什么受体接收？以怎样的路径在原核生物细胞内传导并怎样刺激细胞作出应答反应,以适应菌体细胞的需要和有利于在逆境条件下生存？等等问题,由于受到研究手段和技术的局限性,一直没有产生大的突破。2信息交流存在的广泛性及其研究…     

生物学特殊事例归纳

细菌是原核生物,细菌不一定全是分解者,如硝化细菌是生产者,根瘤菌是消费者。微生物的次级代谢产物有色素、抗生素、毒素和激素,而维生素却是初级代谢的产物。蓝藻和细菌是原核生物,它们结构简单,除了核糖体,一般无其他细胞器。     

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.