棉花MicroRNA研究进展

概述了miRNA的结构特点、生物合成、作用机理、功能以及棉花miRNAs研究等方面的研究进展。     

Multidimensional analysis of an evolving lineage

To identify the forces directing organismal evolution, a general analytical system is developed to synthesize structuralist and Darwinian traditions in an explicitly historical framework. Morphological features of lungless salamanders are examined to identify hierarchical systems of developmental and functional constraint on evolution and their interactions with processes at the genic and populational levels. Characteristic patterns of change occur repeatedly in the evolutionary history of this group.     

Positive natural selection in the human lineage

Positive natural selection is the force that drives the increase in prevalence of advantageous traits, and it has played a central role in our development as a species. Until recently, the study of natural selection in humans has largely been restricted to comparing individual candidate genes to theoretical expectations. The advent of genome-wide sequence and polymorphism data brings fundamental new tools to the study of natural selection. It is now possible to identify new candidates for selection and to reevaluate previous claims by comparison with empirical distributions of DNA sequence variation across the human genome and among populations. The flood of data and analytical methods, however, raises many new challenges. Here, we review approaches to detect positive natural selection, describe results from recent analyses of genome-wide data, and discuss the prospects and challenges ahead as we expand our understanding of the role of natural selection in shaping the human genome.     

microRNA参与调控植物抵御病原微生物的研究进展

在自然界中植物会不断遭受各种病原微生物的侵袭,严重影响植物的生长与作物的产量。经过长期互作影响,植物进化出复杂的抵御病原微生物的机制。microRNAs(microRNA)作为一类长度在21~24nt、内源、非编码小RNA,能通过降解靶基因的m RNA或者抑制其翻译在转录后水平调节靶基因,进而参与植物的生长发育、非生物胁迫等众多生物过程。近年的研究显示,mi RNA在植物抵御病原微生物的过程中扮演重要角色。本文从植物抵御细菌、病毒、真菌等方面综述了近年来miRNA参与的植物抵御病原微生物的研究进展,为揭示植物抵御生物胁迫机制提供理论基础。     

miRNA调控植物花芽分化的研究进展

综述了miR156、miR172、miR159/319等microRNA家族在花芽分化调控中的研究进展,并展望了microRNA在果树花芽分化过程中的研究前景.     

植物miRNA的生物学特性及在环境胁迫中的作用

MicroRNA(miRNA)是一类在生物体内普遍存在的非编码、长度约为21 nt的小RNA分子,一般由内源基因编码,RNA聚合酶Ⅱ转录后,经过Dicer-Like酶等一系列的蛋白复合物将pre-miRNA(precursor miRNA)剪切成成熟miRNA,在转录及转录后水平介导靶mRNA转录沉默、降解或翻译抑制来调控基因的表达,是真核细胞基因表达的重要调控因子。第一个miRNA是在秀丽隐杆线虫(C.elegans)中发现的lin-4,与lin-14 mRNA 3′UTR的碱基序列部分互补,降解lin-14,从而抑制lin-14的表达。lin-4对靶基因lin-14的调控与线虫的生长发育密切相关。而第一个发现的植物miRNA是拟南芥mi R171,它靶向剪切编码基因Scarecrow-Like(SCL)家族的mRNA,调控其基因的表达,进而影响植物的生长发育。植物部分miRNA,如mi R156—mi R408在各植物物种中相对保守,而mi R408以后的miRNA具有物种特异性。植物在生长过程中会遭遇诸多不可预知(如同盐碱、干旱、重金属以及害虫和病原菌的侵扰等)的环境胁迫。固着生长的特性使得植物不能像动物那样通过移动来避免不利环境的影响,因此,需要自身特殊机制来应对这些环境胁迫。植物在长期逆境中已进化出极为精细复杂的生理和分子机制。miRNA与它作用的靶基因是响应环境胁迫的主要调控因子。miRNA参与了植物的生长发育、信号转导、蛋白质降解、营养胁迫、抗病原菌的入侵以及适应高盐和干旱等逆境胁迫过程,对于调节内源抗性基因表达具有一定意义。目前通过高通量测序、实时定量PCR检测和转基因等技术已经发现了很多与环境胁迫相关的miRNA,它们在逆境胁迫下的表达呈现显著差异性;miRNA的过表达植株经逆境胁迫处理可能表现出一定的抗逆或敏感性。同一家族的miRNA不同成员在响应环境胁迫时具有物种特异性。新疆地区是典型的大陆性干旱气候,降水量少,盐碱荒漠化地区多。在这样严酷的环境中顽强生存着许多盐生旱生类植物,这些植物的miRNA如何在逆境中发挥调控作用,依然需要更深入的探索。本文主要综述了现阶段植物miRNA生物合成、与靶基因作用方式、生物功能以及不同环境胁迫下对miRNA和作用的靶基因影响等方面的研究进展,以便更好地利用miRNA依据的生物技术开展研究和应用转化。     

The widespread impact of mammalian MicroRNAs on mRNA repression and evolution

Thousands of mammalian messenger RNAs are under selective pressure to maintain 7-nucleotide sites matching microRNAs (miRNAs). We found that these conserved targets are often highly expressed at developmental stages before miRNA expression and that their levels tend to fall as the miRNA that targets them begins to accumulate. Nonconserved sites, which outnumber the conserved sites 10 to 1, also mediate repression. As a consequence, genes preferentially expressed at the same time and place as a miRNA have evolved to selectively avoid sites matching the miRNA. This phenomenon of selective avoidance extends to thousands of genes and enables spatial and temporal specificities of miRNAs to be revealed by finding tissues and developmental stages in which messages with corresponding sites are expressed at lower levels.     

Transplantation of fetal hematopoietic stem cells in utero: the creation of hematopoietic chimeras

Transplantation of normal, immature, fetal hematopoietic cells into a preimmune fetal recipient with a congenital hemoglobinopathy may allow partial reconstitution of normal hemoglobin production without the complications associated with postnatal bone marrow transplantation (immunosuppression and the occurrence of graft versus host disease). In order to test this hypothesis the naturally occurring polymorphism at the beta-hemoglobin locus of the sheep was used as a marker for engraftment and hematopoietic chimerism. Intraperitoneal injection of allogeneic fetal stem cells into normal fetal lambs resulted in hematopoietic chimerism in three of four surviving recipients. This chimerism has been sustained for 6 months after birth and 9 months after engraftment, without evidence of graft versus host disease, and without the use of immunosuppressive therapy.     

动物病毒microRNA的研究进展

MicroRNAs(miRNAs)是一种含有约22～25个核苷酸的非编码单链RNA分子,广泛存在于人类及其他各种生物中。它通过与靶mRNA特异性的碱基互补配对,引起靶mRNA降解或者抑制其翻译,从而调节基因的转录后表达水平。病毒microRNA是新发现的一类miRNA,综述了近年来病毒microRNA的产生、作用机制、生物学功能及其在动物上的研究进展。     

靶向猪内质网应激通路的microRNAs预测与验证

【目的】预测并验证靶向猪内质网应激通路中关键基因的microRNAs(miRNAs),为进一步研究miRNAs对猪内质网应激信号通路调控提供理论基础。【方法】首先利用伪狂犬病毒(PRV)感染猪肾上皮(PK15)细胞,高通量测序检测差异表达的miRNAs。然后通过TargetScan预测靶向内质网应激通路关键基因ATF6、IRE1、PERK、GRP78、XBP1的miRNAs。构建含有候选miRNAs作用位点的双荧光素酶报告基因重组载体,并分别与miRNA-mimics共转染幼仓鼠肾(BHK-21)细胞,通过测定荧光素酶活性来验证内质网应激通路关键基因与候选miRNAs的靶标关系。然后在PK15细胞中分别过表达候选miRNAs,利用qRT-PCR和Western blot检测候选miRNAs对内质网应激通路关键基因mRNA和蛋白表达的影响。【结果】miRNA测序结果显示,PRV感染后共引起35条miRNAs差异表达。TargetScan预测显示,靶向ATF6、IRE1、PERK、GRP78、XBP1的交集miRNAs为miR-142-5p、miR-145-5p、miR-150和miR-1...