促肾上腺皮质激素释放因子和促肾上腺皮质激素

神经肽类激素的发现扩大了激素生理、生化研究范畴。1955年Schally和Gillemine同时发现下丘脑存在促肾上腺皮质激素释放因子(CRT)。在此发现的启示下,下丘脑九种肽类激素被发现和神经内分泌器官得到确认。然而由于它的纯化和化学结构的鉴定相当困难,有一个时期关于它的研究几乎处于停滞状态。1981年纯化的促肾上腺皮质激素释放因子的化学结构的发现为研究它的性质、功能起了巨大的推动作用。促肾上腺皮质激素释放因子和促肾上腺皮质激素(ACTH)二者之间的研究密切相关,本文试对二者的研究、进展作一综述。     

促黄体生成素释放激素的酶促降解

本文着重阐明促黄体生成素释放激素(LH-RH)的酶促降解机制以及影响酶促降解的因素;简要介绍了几种降解酶的物理化学和生物化学性质;并讨论了LH-RH 酶促降解的生理功能。     

基底膜促细胞分化

个体发育取决于细胞分化。在细胞分化中,基因按一定的时间和空间次序选择地表达,通过基因的开启或关闭,最终表达特定的蛋白质。细胞分化受多种因素的影响,其中,基底膜是细胞分化的影响因素之一。基底膜中的主要成分有胶原、层黏连蛋白、蛋白聚糖,它们分别在细胞分化中起到一定作用。该文主要阐述基底膜及其主要成分在促细胞分化的作用和参与细胞分化的机制,为研究细胞分化提供新的思路。     

酶促RNA

阻止活体基因表达的反义RNA已普遍成为当今生物技术公司最热门的研究领域之一。然而,却面临着许多技术障碍.一旦反义RNA位于细胞内部就被酶所破坏,这意味着RNA不具有重复使用性.解决此问题的诸多办法是化学改变反义物质以阻止上述降解发生,或者控制其过量投入.但是,澳大利亚联邦科学与工业研究组织(CSIRO)的研究人员设计出了另一种不同方法.他们试图遗传加工微生物以获得一些RNA片段,在RNA合成蛋白之前切断人们希望“静止”的基因的RNA.     

促肾上腺皮质激素释放因子

促肾上腺皮质激素释放因子(CRF)是第一个被提出来的释放因子,长时间得不到提纯和鉴定。1981年以来,有关这方面的研究,迅猛发展,研究报道也较多,主要表现在以下几个方面。一、CRF 的化学结构早期研究发现,牛下丘脑提取物注入大鼠体内,可使大鼠垂体ACTH 分泌增加。1955年,Saffran 等将能够刺激垂体分泌ACTH 的体液物质命名为促肾上腺皮质释放因子     

人类胎盘促肾上腺皮质激素释放因子促进局部促肾上腺皮质激素分泌

胎盘含有生物活性促肾上腺皮质激素释放因子(CRF)和促肾上腺皮质激素(ACTH)。有人曾提出,二者在妊娠时都能由胎盘生成。利用间接免疫荧光染色法发现,CRF 定位于足月胎盘的细胞滋养层细胞。利用人类胎盘细胞的单层培养,作者还发现,CRF 能促进胎盘中含有 ACTH 顺序(11-24)的肽分泌。CRF 促进胎盘内 ACTH 分泌的 EC_(50)约为35.5nM,高于 CRF 促进离体培养脑下垂体前叶细胞 ACTH 分泌的 EC_(50)此活性可被 CRF 拮抗剂所逆转,也可被二丁酰 cAMP 和 fosrkolin(能促进腺苷酸环化酶的一种     

乳酸菌促生长因子的研究

乳酸菌属于肠道内的有益菌,对调节人体健康有益,其生长能力和活性受外界条件的影响.促生长因子是一类对微生物生长繁殖具有促进作用的物质,可用于有效提高乳酸菌数量和活性.围绕乳酸菌促生长因子与益生元的关系及其来源、类别和作用机理等方面,综述其在乳酸菌上的研究与应用,并对未来发展方向进行了展望,以期为促生长因子在乳酸菌产业中的...     

BMF促细胞凋亡研究进展

BMF(Bcl-2-modifying factor)是一种具有促凋亡作用的Bcl-2家族成员.在正常生理状态下,内源性的BMF持续锚定在胞浆中的细胞骨架上,时刻感受细胞内的变化.一旦损伤刺激作用于细胞,BMF从胞浆转移至线粒体,触发线粒体凋亡途径,造成细胞损伤.BMF的促凋亡作用受到转录、翻译和翻译后修饰的调控,过表达或者转录上调的BMF主要定位于线粒体,诱导细胞凋亡.由此可见,BMF具有强大的促凋亡功能.     

AMPK促凋亡机制研究进展

腺苷酸活化蛋白激酶(AMP-activated protein kinase,AMPK)是调节细胞能量代谢的关键酶。近年来研究还发现AMPK可通过抑制p53降解、上调Bim表达、抑制m TOR活性及升高活性氧(ROS)水平等途径促进细胞凋亡。本文综述了近年来关于AMPK促细胞凋亡机制的研究进展。     

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.