小果野蕉microRNAs及其靶基因的生物信息学预测

通过基于表达序列标签（EST）、基因组勘测序列（GSS）和高通量测序基因组序列（HTGS）的同源序列比对搜索,以及一系列的标准筛选,最终预测到属于8个家族的10条小果野蕉miRNAs。在线软件psRNATarget预测到24对miRNAs与靶基因的互作,这些靶基因主要参与小果野蕉的新陈代谢、生长发育以及胁迫响应等过程。     

mgr-mir-9 implicates Meloidogyne graminicola infection in rice by targeting the effector MgPDI

MicroRNAs (miRNAs), a class of small non-coding RNAs, are crucial endogenous gene regulators in a range of animals, including plant-parasitic nematodes. Meloidogyne graminicola is an obligate sedentary endoparasite of rice and causes significant yield losses. A number of studies focused on the roles of M. graminicola effectors during the parasitic process; however, how nematode miRNAs regulate its effectors needs elucidating. In this research, we analyzed a cluster of M. graminicola miRNAs obtained at the second-stage juveniles (J2s) stage that are closely linked to the regulation of M. graminicola effectors. There are 49 767 105 total clean reads obtained from three libraries. A total of 233 known miRNAs and 21 novel miRNAs were identified. Among the known miRNAs, mgr-lin-4, mgr-mir-1, mgr-mir-100, mgr-mir-86, mgr-mir-279, mgr-mir-87, mgr-mir-71, mgr-mir-9, mgr-mir-50, mgr-mir-72, and mgr-mir-34 are the most abundant 11 miRNAs families. Moreover, the expression levels of selected miRNAs were validated by real-time quantitative PCR. We hypothesized that these miRNAs might regulate the expression of secreted effectors during the J2s stage to facilitate its infection. Consistent with this, we found that mgr-mir-9 targets MgPDI, an important M. graminicola effector mRNA. In addition to that, J2s treated with mgr-mir-9 mimics showed down-regulation of MgPDI expression and reduced reproductive ability, alluding mgr-mir-9 is involved in nematode infection. These results provide novel insight into the regulatory functions of M. graminicola miRNAs during the infection and identify miRNAs and their effector targets as potential key management targets to limit parasite survival during the early stages of infection.     

葡萄microRNA156b和microRNA172c及其靶基因在冬芽二次成花过程中的表达特性研究

利用半定量RT-PCR与实时荧光定量RT-PCR(qRT-PCR)技术检测‘藤稔’葡萄microRNA156b(Vv-miR156b)和microRNA172c(Vv-miR172c)及其靶基因(Vv-SPL9和Vv-AP2)在摘心处理(5月14日、5月20日、5月28日)后不同发育时期冬芽中的表达情况,并利用RLM-5’-RACE验证了miRNAs作用其靶基因的方式。结果表明:仅5月28日摘心处理的冬芽能够进行花芽分化并形成花序,而其他处理及对照未能花芽分化。2种RT-PCR检测结果基本一致,5月28日摘心处理的2条miRNAs表达水平明显下降,且花序中有最低表达。相应的靶基因在冬芽二次成花过程中的表达水平呈现出与其miRNAs相反的变化趋势。RLM-5’-RACE结果显示,2条miRNAs介导靶基因裂解,裂解位点均在miRNAs 5’端的第10和11位碱基之间。表明microRNA156b和microRNA172c通过介导相应靶基因的裂解调控其靶基因的表达,从而影响葡萄冬芽的二次成花。     

植物microRNA及其作用靶位的研究进展

microRNA(miRNA)是指真核生物中长度约21～25个核苷酸的小型内生的非编码RNA家族.它们能识别体内特定的mRNA,并在转录及转录后水平有调控基因的表现.microRNA在植物生长发育、代谢平衡、信号传导等很多方面具有必不可少的调节功能.主要对植物microRNA的特点、作用机制及其作用靶位的研究进展进行了综述.     

海鞘(Ciona intestinalis)新microRNA基因的识别及其靶标预测

microRNAs(miRNAs)是一类长度约22 nt的非编码小RNA,通过碱基互补配对的方式调控靶基因的表达.本文采用同源搜索的方法,以线虫、果蝇、文昌鱼和人类的miRNA为探针,与海鞘的基因组序列进行比对,同时结合miRNA二级结构特征及SVM假阳性分析共发现10个新的miRNA基因.通过靶基因预测,共找出225个潜在靶基因,这些靶基因主要参与细胞代谢、转录调节、结合活性等功能.新miRNA基因的识别为海鞘miRNA功能研究奠定了基础,并为更进一步揭示脊椎动物miRNA的起源与进化提供了理论依据.     

拟南芥miRNA及其靶序列配对特征分析

microRNAs(miRNAs)是真核生物中一类长度约为22 nt的非编码小分子RNA,miRNA与AGO等蛋白形成RISC沉默复合体,通过剪切或翻译抑制对靶基因起负调控作用。对拟南芥miRNA序列及其配对的靶序列间的特征进行了统计分析,结果表明miRNA序列5′端富含A、U,第1、第19碱基位对U、C具有较强的倾向性;miRNA与靶序列间常有1~4个碱基错配,错配碱基常出现在第1,第2和第21位,而第3~第6,第9~第10,第16~第17碱基配对较为保守,为人工合成miRNA的设计及miRNA靶基因的预测以提供了依据。     

陆地棉胚珠及纤维发育过程中miRNA分离与鉴定

microRNA(miRNA)是生物中一类起负调控作用的非编码的小分子RNA,主要在转录后水平上调节生物体的生长与发育。直接克隆法是鉴定植物中miRNA最常用也是最有效的方法之一。利用直接克隆法分离了陆地棉开花后0~10 d(days post anthesis, DPA)胚珠中总RNA,从中筛选17~24 nt小分子RNA构建cDNA文库,对初筛得到的阳性克隆进行测序。通过与miRNA数据库比对,最终获得4个保守的miRNA。进一步对他们的转录表达进行分析,发现所有miRNA在棉花胚珠纤维不同发育时期均能表达。其中miR167a、miR172c和miR394b在棉花幼苗的根茎叶中有不同程度的表达。预测得到55个miRNA的靶基因,多数靶基因编码转录因子、代谢酶类以及发育相关蛋白,进一步证明miRNA参与调控棉花纤维的形态建成、发育等各项生理活动。     

A microRNA in a multiple-turnover RNAi enzyme complex

In animals, the double-stranded RNA-specific endonuclease Dicer produces two classes of functionally distinct, tiny RNAs: microRNAs (miRNAs) and small interfering RNAs (siRNAs). miRNAs regulate mRNA translation, whereas siRNAs direct RNA destruction via the RNA interference (RNAi) pathway. Here we show that, in human cell extracts, the miRNA let-7 naturally enters the RNAi pathway, which suggests that only the degree of complementarity between a miRNA and its RNA target determines its function. Human let-7 is a component of a previously identified, miRNA-containing ribonucleoprotein particle, which we show is an RNAi enzyme complex. Each let-7-containing complex directs multiple rounds of RNA cleavage, which explains the remarkable efficiency of the RNAi pathway in human cells.     

新奇的调控分子——microRNA

microRNA(miRNA)是一类内源性表达的在转录后基因调控中发挥重要作用的小分子非编码RNA。在动植物细胞中,miRNA通过翻译抑制和靶mRNA去稳定性来调控靶基因,从而调控生长、发育、分化、死亡等生物过程。综述了miRNA的发现、形成、特点及调控机制。