RNA干扰技术在哺乳动物中的应用

RNA干扰(RNAi)是生物界普遍存在的一种抵御外来基因和病毒感染的进化保守机制.RNAi是由双链RNA触发的转录后基因沉默机制,具有序列特异性,在哺乳动物细胞中,RNAi由21～23个核苷酸组成的双链RNA引发.小干扰RNA(siRNA)可以在体外合成或通过表达载体在哺乳动物细胞内合成.由于RNAi技术具有快速、简单和特异性强等特点,在基因功能研究、抗病毒治疗和抗肿瘤治疗等方面有广泛的应用前景.     

RNA干扰与技术

RNA干扰(RNA interference,RNAi)是由双链RNA诱导的、序列特异的基因沉默机制。它是自然存在于植物、线虫和果蝇中抵抗外来基因(包括病毒、转座子)入侵的方式。在哺乳动物细胞中,能够人工诱导RNA干扰,沉默有同源序列基因表达。这一新技术具有特异性、高效性。因此,正被用来研究人类基因组的功能、肿瘤和抗病毒感染等。     

RNAi及其抑制口蹄疫病毒复制的研究进展

RNA干扰(RNA interference,RNAi)是指由双链RNA(double strand RNA,dsRNA)介导的序列特异的RNA降解过程。已经证明,在植物和昆虫细胞中RNAi是其主要的抗病毒免疫机制,至今为止几乎没有发现在病毒感染哺乳动物细胞过程中诱发有效的抗病毒RNAi反应。因此,人们希望能够利用人工方法在哺乳动物细胞中建立有效的抗病毒RNAi防御策略。迄今为止,对多种哺乳动物病毒的研究结果令人振奋。主要围绕RNAi的分子基础、基本策略及其在抑制口蹄疫病毒复制中的研究现状作了综述。     

RNAi在药物研究中的应用

RNA干扰是双链RNA分子在mRNA水平上诱发的序列特异性的转录后基因表达沉默。在哺乳动物细胞里,RNAi可以由21-25个核苷酸长度的小干扰RNA（siRNA）触发,在后基因组时代的基因功能研究和药物开发中具有广阔的应用前景。现针对近年RNAi在药物研究中的应用包括应用RNAi发现新药靶、辅助确认药靶、RNAi药物、RNAi与耐药性等方面作一综述。     

RNA干扰的研究进展及应用

RNA干扰(RNAi)是生物体的一种在进化上保持高度保守的,能抵御外源基因或外来病毒侵犯的重要防御机制,是一种序列特异性的转录后基因沉默现象。它由双链RNA引发,广泛存在于动、植物等各种生物体内。我们简要综述了RNAi发生的机制、特点、哺乳动物与RNAi现象,以及RNAi的应用等。     

小鼠XBP1基因RNA干扰慢病毒载体的构建及筛选

目的:构建小鼠XBP1基因RNA干扰(RNA interference,RNAi)慢病毒载体,筛选具有较好干扰效率的小鼠XBP1 siRNA靶序列.方法:针对小鼠XBP1基因特异性序列,设计4个RNAi靶序列及1个阴性对照序列,合成含有正义和反义Oligo DNA的互补DNA序列,退火形成双链DNA,并克隆到经Age Ⅰ和EcoR Ⅰ酶切后的pGCL-GFP载体连接产生短发卡RNA(shRNA)慢病毒载体,PCR筛选阳性克隆,DNA测序鉴定.由病毒包装系统进行包装,经滴度测定后感染NIH3T3细胞,应用Real-time PCR鉴定干扰效率.结果:PCR鉴定与DNA测序证实合成的寡核苷酸链插入正确,293T细胞测定病毒滴度为1×108TU/ml.Real-timePCR证实XBP1-siRNA-3靶点的干扰效率最高,其干扰效率达到95%以上.结论:成功构建并筛选了小鼠XBP1基因RNAi慢病毒载体,为研究XBP1在巨噬细胞免疫功能调控中的作用奠定了基础.     

RNAi技术的医疗应用潜力

RNA干扰是指双链RNA在细胞内特异性地诱导同源互补的mRNA降解,从而阻断相应基因表达的现象。RNAi发展成为一种新型的基因治疗方式的进程取决于哺乳动物砌RNAi的研究进展。在大多数哺乳动物细胞中,直接导入长dsRNA引发的非特异性基因沉默掩盖了RNAi效应,而多种有效的双链RNA导入方式在一定程度上解决了这一问题。初步的实验结果表明,用RNAi治疗癌症、病毒感染等疾病的设想有可能变成现实。     

RNAi及其在家禽病毒病治疗上的应用

双链小RNA介导的RNA干扰(RNA interference,RNAi)是近年发现的一项以序列特异方式诱导同源mRNA降解的新技术。由于RNAi精巧的特异性和有效性,已被认为是特异性基因治疗的重要工具。其中作为抑制病毒复制的潜在工具更为引人注目。因此,将RNAi的作用机制和其在家禽病毒病治疗上的应用做以综述。     

RNA干扰作用研究进展

RNA干扰 (RNAinterference ,RNAi)是指与内源性mRNA编码区某段序列同源的双链RNA分子 (double strandedRNA ,dsRNA)导入细胞时 ,该mRNA发生特异性的降解 ,导致基因表达的沉默。本文介绍RNAi作用的发现、机制和目前使用的产生RNAi的方法     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

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.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

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