二甲基亚砜对生物膜的作用机理

二甲基亚砜被广泛应用于生物、化学和药学领域,这些应用大多与其增加生物膜的通透性、促进活性分子跨膜传输的作用密切相关。本文对二甲基亚砜增加生物膜通透性的理论及实验研究做简要综述,主要强调二甲基亚砜在生物膜中诱导水性孔道形成的分子动力学模拟及其相关的实验研究。     

环糊精葡萄糖基转移酶高效异源表达研究进展

环糊精葡萄糖基转移酶(cyclodextringlycosyltransferase,CGTase)酶法合成环糊精是目前生产环糊精的主要方法。本文介绍了用于生产环糊精葡萄糖基转移酶的几种工程菌株:大肠杆菌、枯草芽孢杆菌以及毕赤酵母,其中大肠杆菌是目前应用最广泛的用于表达CGTase的表达系统。除此之外,本文还总结了高效表达环糊精葡萄糖基转移酶的有效策略:选择合适的表达载体、启动子以及信号肽,以及密码子优化和分子伴侣共表达,以期为在相关CGTase研究领域开展研究提供参考。     

环状RNA:一种基因调控RNA

环状RNA是一种通过共价结合线性RNA分子的3′端和其上游5′形成的闭合环状结构RNA,广泛存在于真核生物系统内,其结构具有稳定性,序列具有保守性,表达具有时空特异性。目前研究发现环状RNA的形成是受多个因素调控的,并可通过吸附miRNA分子,在pre-mRNA的剪切过程中与线性RNA形成竞争或促进其来源的基因表达,对基因的表达具有调控作用,同时在组织的分化发育和肿瘤、心肌肥厚、动脉粥样硬化、神经系统等多种疾病的发生发展过程中具有重要作用。     

环糊精在上市医药产品中的应用研究进展

环糊精是一类重要的药用高分子材料,通过与药物形成包合物结构而实现提高难溶性药物溶解性、增强药物稳定性、改善药物生 物利用度等目的。结合天然及改性环糊精的性质特点、体内代谢及生物安全性等信息,归纳了环糊精在已上市医药产品中的研究及应用, 为环糊精领域相关制剂的临床研究及产业化提供一定的参考。     

利用环状糊精纯化淀粉水解酶类

环状糊精是由环状糊精葡萄糖基转移酶作用于淀粉所产生的一组非还原性环状低聚糖 ,最常见的有α,β和γ型 ,它们分别是由 6、7或 8个葡萄糖单元以α 1,4糖苷键联结而成的。由于其特殊的“内疏水外亲水”分子结构 ,使得环状糊精能与多种有机分子形成特殊结构的包合物 ;同时环状糊精还能与酶的活性 /非活性部位相互作用 ,所以以环状糊精为配体 ,利用亲和层析纯化水解淀粉的酶类     

作为非病毒基因载体的环糊精及其衍生物

环糊精由于自身的生物相容性和结构易裁剪性,通过结构修饰、聚合或超分子组合等设计被逐渐应用于非病毒基因载体系统。本文将分别从环糊精、其小分子衍生物、含环糊精聚合物以及超分子结构综述国内外近几年的设计思路和研究进展,并探讨含环糊精及其衍生物的非病毒基因载体的"结构-安全性-基因转染效率"关系。     

纳米粒药物载体在抗癌领域的研究进展

抗癌药物载体是合成化学在药学领域的新发展,其中纳米粒药物载体材料以独特的结构特点、较大的载药量等优势受到国内外广泛关注。经亲水聚合物修饰后的纳米粒药物载体有较高的生物相溶性,且药物分子能靶向作用于癌细胞,延长药物半衰期,提高生物利用度,具有生物可降解性,消除毒副作用。在抗癌领域显示出研究意义和应用价值。本文就纳米粒药物载体研究进展进行综述述。     

β-环糊精主客体识别抗菌剂及抗菌性能研究进展

细菌污染与人类的生存息息相关,随着多重耐药细菌的增加,提高抗菌剂抗菌性能、抑制细菌传播和感染成为抗菌剂研究领域的热点问题。利用β-环糊精的包结作用与抗菌剂主客体识别改善抗菌剂的理化性质,增强抗菌剂的抗菌性能引起了广泛关注。环糊精具有内疏水外亲水的特殊结构,疏水内腔可选择性地与空腔大小相匹配的疏水客体分子进行主客体识别,将抗菌剂包合,从而改善抗菌剂理化性质,提高抗菌剂抗菌性能。本文综述了β-环糊精及其衍生物与有机抗菌剂、天然抗菌剂主客体识别对抗菌剂理化性质及抗菌性能的影响,分析了主客体识别的包合机理及主客体之间的作用,系统地归纳总结了环糊精主客体识别抗菌剂对不同细菌的抗菌作用及在医药、纺织、食品等领域的应用研究现状,以期为环糊精主客体识别抗菌剂的深入研究及应用提供参考。     

质谱成像及其在植物内源性分子原位表征中的应用进展

质谱成像作为一种新型分子影像技术,可在组织或细胞水平上同时获得样本表面多种分子组成、丰度及原位空间分布信息.近年来,随着该技术的不断发展与完善,质谱成像正逐渐成为质谱分析领域的研究前沿与热点.目前,该技术已被广泛应用于诸多领域:如基础医学、药学、微生物学、动物学等.值得注意的是,在植物学研究领域,质谱成像技术也正逐渐受到重视并被广泛应用.本文基于多种质谱成像方法及相关技术流程,综述了该技术在植物内源性分子原位表征中的应用进展,尤其是在药用植物有效成分成像表征中的应用,并对质谱成像技术现有缺点与不足、潜在价值与应用前景进行了总结与展望.     

微卫星DNA标记技术及其在昆虫学上的应用

微卫星DNA标记作为一种多态性和稳定性高、重复性好、呈共显性的分子遗传标记技术,目前已被广泛应用于昆虫学的研究中。本文介绍了微卫星DNA标记的基本原理和特点,并综述了近年来该技术在昆虫种群遗传结构及分化、生物学特性与习性、遗传图谱的构建、基因定位以及系统发生等领域中的应用。     

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.