微小RNA在心肌重塑中的作用

微小RNA (microRNA, miRNA)是一类含有约22个核苷酸的内源性非编码RNA, 通过与靶mRNA的3′非翻译区(3′ UTR)互补配对, 抑制翻译或促进靶mRNA的降解介导转录后基因调控,涉及多种生物学过程.目前研究表明,miRNA参与了心脏的发育、病理性心肌肥大等过程,表明miRNA可作为新的治疗心肌肥大的靶向分子.本文就新近有关miRNA在心肌重塑中的研究进展予以综述.     

微小RNA对人类免疫缺陷病毒感染的影响: 飞向入侵者的子弹?

微小RNA(miRNA)是一类内源性小RNA,通过结合mRNA的3′非翻译区对基因进行转录后的调节,具有广泛的生物学功能.已有研究表明,宿主miRNA能调节人类免疫缺陷病毒(HIV)的基因表达,影响HIV的复制能力、感染性,并可能与HIV的潜伏有关.与此同时,HIV来源的病毒miRNA同样在病毒的生活史以及病毒与宿主的...     

微小RNA与免疫调节

微小RNA(miRNA)是一类22核苷酸的高度保守的小分子非编码RNA,主要通过与靶mRNA的3′非编码区碱基互补配对结合而引起靶RNA降解或翻译抑制.越来越多的研究显示,miRNA在免疫反应中具有新型调节作用,包括调节免疫细胞的发育和分化、B细胞抗体的产生、炎性介质的释放、细胞信号转导等.miRNA在维持机体免疫系统...     

非编码RNA作为ceRNA在人癌症中的功能及机制

非编码RNA(non-coding RNA, ncRNA),即无编码蛋白质潜力的RNA,包括短非编码RNA,例如微RNA(microRNA, miRNA),长非编码RNA(long coding RNA, lncRNA)和环状RNA(circular RNA, circRNA)等,已被证明可以在RNA水平上调节细胞中多种生理及病理过程。miRNA是约18～22个核苷酸大小的内源性非编码RNA分子,可以通过MRE与靶基因的3′非翻译区(untranslated region,UTR)中的互补序列结合,抑制蛋白质编码基因的表达,并导致mRNA转录物的更新、转换或降解。2011年,Salmena等提出,非编码RNA与具有编码蛋白质能力的RNA(mRNA)之间存在一种被称为竞争性内源RNA(competing endogenous RNA, ceRNA)的相互作用机制假说,即含有miRNA反应元件(MRE)的ncRNA通过与miRNA结合,解除miRNA对靶基因的抑制作用。这一假说对基因表达调控的传统认知进行了补充,在RNA水平上将多种ncRNA的作用补充到经典的miRNA调控mRNA翻译的过程,将其延伸为ceRNA-miRNA-mRNA的网络调控模式。近年来研究发现,ceRNA机制广泛存在于胃癌、结肠癌和膀胱癌等各类癌症中,并且在肿瘤的基因调控及肿瘤细胞的增殖、侵袭、转移、凋亡、细胞周期等生物过程中发挥作用。本文将介绍ceRNA及其网络的机制与分子基础,并且结合两类非编码RNA——lncRNA及circRNA作为ceRNA分别在人类不同癌症类型中的近期研究进展作一综述,讨论该机制在肿瘤中的角色及作用,以期拓宽对肿瘤发生发展机制的视野,为癌症治疗提供新思路。     

miRNA和lncRNA在动物脂肪沉积中的研究进展

微小RNA(MicroRNA,miRNA)是一类由18–25个核苷酸组成的高度保守的核苷酸序列,它可以特异性结合信使RNA (mRNA)的3′-非编码区域,进而发挥降解mRNA或阻遏mRNA翻译的负调控作用。长链非编码RNA (Long non-coding RNA,lncRNA)是一类长度超过200个核苷酸、不能编码蛋白质或只能编码蛋白质微肽的核苷酸序列,它可以在表观遗传、转录水平和转录后水平调控基因表达。脂肪作为一种重要的储能物质,在调节动物体能量平衡过程中发挥着重要的作用,并与动物产肉量、肉品质等产肉性状密切相关。而脂肪功能的紊乱可导致高血脂、Ⅱ型糖尿病以及一系列心血管疾病发生,因此动物脂肪沉积的分子调控机制备受人们关注。近年来,越来越多的研究发现miRNA和lncRNA在动物脂肪沉积中发挥重要作用。文中就现阶段miRNA和lncRNA在动物脂肪沉积中的研究进展进行综述,以期为进一步揭示动物脂肪沉积的分子调控机制提供理论指导和新思路。     

MicroRNA在脂肪细胞分化中的调节作用

MicroRNA(miRNA)是一类内源性、短小、大小为～22核苷酸的单链非编码RNA.miRNA广泛分布于真核细胞内,能够通过与靶mRNA3'末端非翻译区(3'-untranslated region,3'UTR)特异性结合来降解或抑制靶mRNA的翻译,从而对基因进行转录后基因表达的调控.miRNA不仅调控生物体的生长和发育过程,而且参与调控多种生理学和病理学过程,如细胞分化、细胞增殖、胰岛素的分泌、脂肪代谢以及肿瘤的形成.研究表明miRNA在肿瘤、糖尿病、代谢等多种疾病中发挥着重要的作用.本文对miRNA在脂肪细胞分化及脂类代谢中的调节作用进行综述.     

辐射相关microRNA研究进展

microRNA(miRNA)是一类由内源基因编码的长度约22核苷酸的非编码单链RNA分子,主要以碱基互补方式与靶基因mRNA的3'非翻译区特异性结合,通过降解mRNA或抑制蛋白翻译合成而实现对靶基因的转录后调控。研究发现,miRNA在电离辐射诱导的生物学反应中发挥重要作用。我们从以下层面概述辐射相关miRNA的研究进展,即辐射调节miRNA表达、miRNA对辐射后DNA损伤的调节、miRNA参与的辐射生物学效应。     

MicroRNA与肺癌发生、诊断及治疗

微小RNA(miRNAs)是一大类小的非编码RNA,它通过与靶mRNA 3′非翻译区部分互补配对来调节特定基因的表达。近来研究表明,miRNA可作为癌基因或抑癌基因在肺癌发生发展过程中起重要作用。比较癌组织和非癌组织中miRNA表达谱的差异可筛选出部分miRNA分子作为肺癌诊断和预后判断的潜在生物标记。调节具有致癌或抑癌功能的miRNA表达可能成为肺癌治疗新方法,而结合传统放化疗及其敏感性miRNA标志也为肺癌治疗研究提供了新的策略。该文对miRNA在肺癌发生与发展、基因诊断和治疗中的作用做一综述。     

microRNA多态性与肿瘤发生和药物反应相关

microRNA(miRNA)是进化保守的、非编码单链小RNA,长度约为18-25个核苷酸.作为基因表达的微观管理者,miRNA通过结合在mRNA的3′-UTR抑制翻译过程或使其降解.miRNA多态性是指一类能够干扰miRNA功能的新多态性或单核苷酸的多态性.这种多态性不仅出现在pri-miRNA、pre-miRNA和成熟的miRNA序列中;也可以出现在靶基因3′-UTR;还可以呈现在miRNA基因表观遗传学的改变.miRNA多态性可能导致疾病的产生,也可以判断临床用药疗效及预后监测.目前miRNA多态性正在作为疾病（尤其是肿瘤）生物学研究的强有力工具,而且已应用于疾病的诊断和预后.     

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.     

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.     

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.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Chemical constituents from the fruits of Rhus typhina L. and their chemotaxonomic significance

This work describes the isolation and characterization of twenty-nine compounds from the fruits of Rhus typhina L., including eleven flavonoids (1–11), eleven phenols (12–22), two pentacyclic triterpenes (23–24), two organic acids (25–26), one lumichrome (27), one courmarin (28) and one pyrimidine (29) on the basis of their spectroscopic data. Compounds apigenin (1), daidzein (4), orobol (5), 3′, 5, 5′, 7-tetrahydroxyflavanone (6), naringenin (7), butein (8), (-)-catechin (9), quercetin-3-O-α-L-(3″-O-galloyl)-rhamnoside (11), 2-hydroxybenzoic acid (13), 4-hydroxybenzaldehyde (14), vanillin (15), methyl 3,4-dihydroxybenzoate (16), 3,5-dihydroxybenzamide (18), tyrosol (19), caffeic acid (20), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (21), phlorizin (22), friedelin (23), oleanolic acid (24), 4,4-dimethyl-heptanedioic acid (25), anthranilic acid (26), lumichrome (27), scoparone (28) and uracil (29) have not been recorded before in this plant. This is the first report on the occurrence of compounds 4–7, 9, 11, 13–14, 16, 18–21, 25–29 from the genus Rhus. Moreover, the chemotaxonomic significance of these isolated compounds was also summarized.