拟南芥不同dcl突变体中tsRNA的表达分析

为了解拟南芥中Dicer-like蛋白对tRNA衍生的小RNA(tRNA-derived small RNAs,tsRNAs)的产生有何影响,对拟南芥野生型和不同Dicer-like(DCL)基因突变体进行tRNA-seq测序,并分析tsRNA和tRNA的表达量.结果显示,DCL4基因突变后tsRNA的表达量明显降低,说明DCL4可能参与tsRNA的产生.拟南芥tRC1位点(Chr1:21268000-21310000)具有大量串联分布的tRNA序列,通过对RNA介导的甲基化(RdDM)途径相关基因CLSY1突变体中tRC1位点的24 nt siRNA和tsRNA进行分析,推断tRC1位点的tsRNA受RdDM途径负调控.综上,本研究鉴定到DCL4在tsRNA生成中的潜在作用,部分tsRNA的生成与RdDM途径有关.

T4病毒研究进展

T4病毒科由一类单股正链RNA病毒组成,分为松天蛾β样病毒属和松天蛾ω样病毒属.这2个属的病毒具有不同的基因组结构,β样病毒含单组分基因组,其结构蛋白由一亚基因组RNA表达;而ω样病毒含双组分基因组,2个RNA分子分别编码复制酶蛋白和结构蛋白.在T4病毒基因组RNA 3′端有类似tRNA的二级结构.ω样病毒壳蛋白的氨基酸序列一致性高达66%～86%,而β样病毒壳蛋白的氨基酸同源性则要低得多.在昆虫细胞中表达壳蛋白基因时都能形成病毒类似粒子.该文还介绍了T4病毒复制机理以及T4病毒与其他病毒的进化关系.

单股正链RNA病毒基因组3′非编码区的高级结构与功能研究进展

单股正链RNA病毒种类繁多 ,其宿主涉及人、动物、植物 ,对人畜健康和农业经济生产都有重大的影响 .病毒基因组 3′UTR内的序列形成茎环、假结、TLS等高级结构 ,既可以作为顺式元件 ,又可以结合蛋白质反式因子 ,对病毒的转录、复制、翻译都有调控作用 .简要介绍了单股正链RNA病毒代表种属的 3′UTR内高级结构与功能的研究方法、主要进展和存在的问题 .

Mitochondrial transport of catalytic RNAs and targeting of the organellar transcriptome in human cells

Mutations in the small genome present in mitochondria often result in severe pathologies.Different genetic strategies have been explored,aiming to rescue such mutations.A number of these strategies were based on the capacity of human mitochondria to import RNAs from the cytosol and designed to repress the replication of the mutated genomes or to provide the organelles with wild-type versions of mutant transcripts.However,the mutant RNAs present in mitochondria turned out to be an obstacle to therapy and little attention has been devoted so far to their elimination.Here,we present the development of a strategy to knockdown mitochondrial RNAs in human cells using the transfer RNA-like structure of Brome mosaic virus or Tobacco mosaic virus as a shuttle to drive trans-cleaving ribozymes into the organelles in human cell lines.We obtained a specific knockdown of the targeted mitochondrial ATP6 mRNA,followed by a deep drop in ATP6 protein and a functional impairment of the oxidative phosphorylation chain.Our strategy provides a powerful approach to eliminate mutant organellar transcripts and to analyse the control and communication of the human organellar genetic system.

The complete mitochondrial genome of Oreta fuscopurpurea(Lepidoptera: Drepanidae) and its phylogenetic implications

In this study, the first complete mitochondrial genome（mitogenome） of lepidopteran family Drepanidae（superfamily Drepanoidea） was reported with the notes about its phylogenetic implications. The Oreta fuscopurpurea mitogenome is 15,564 bp in length, including 13 protein-coding genes, two ribosomal RNAs（lrRNA and srRNA）, 22 transfer RNAs and a non-coding control region（AT-rich region）, with a 79.6% A＋T content. The gene orientation and arrangement of the mitogenome are the same as other sequenced lepidopterans. All protein-coding genes usually start with the common ATN codon except for COI gene, which used CGA as the initial codon; eight PCGs use a typical stop codon of TAA, whereas the remaining PCGs use incomplete stop codon of T or TA. All tRNAs have the typical clover-leaf structure with the exception of t RNA^（Ser）（AGN）. The lrRNA and sr RNA genes are 1,409 bp and 778 bp in size respectively, with the former harboring one（TA）_（13） microsatellite-like repeat and an 17 bp insertion. The 20 intergenic spacers totaling of 184 bp and 8 overlapping sequences totaling of 25 bp are scattered throughout the whole mitogenome. The 526 bp AT-rich region contains some structures characteristic of lepidopterans, such as the motif ATAGA preceded by an 19 bp poly-T stretch, a tRNA-like and a sterm-loop structures. Phylogenetic analysis of the Oreta fuscopurpurea with other 47 insect species covering 20 lepidopteran families were conducted based on the sequence data of the 13 mitogenomic protein coding genes with maximum likelihood（ML） and Bayesian inference（BI） methods, and the results showed distinctly that the superfamily Drepanoidea was sister to the clade of（Bombycoidea, Lasiocampoidea） ＋（Noctuoidea, Geometroidea）.

Complete Sequence of pABTJ2, A Plasmid from Acinetobacter baumannii MDR-TJ, Carrying Many Phage-like Elements

Acinetobacter baumannii is an important opportunistic pathogeq in hospital, and tile multidrug-resistant isolates of A. haumannii have been increasingly reported i,a recent years. A num- ber of different mechanisms of resistance have been reported, some of which are associated with plasmid-mediated acquisition of genes. Therefore, studies on plasmids in A. haumannii have been a hot issue lately. We have performed complete genome sequencing of A. haumannii MDR-TJ, which is a multidrug-resistant isolate. Finalizing the remaining large scaffold of the previous assem- bly, we found a new plasmid pABTJ2, which carries many phage-like elements. The plasmid pAB- TJ2 is a circular double-stranded DNA molecule, which is 110,967 bp in length. We annotated 125 CDSs from pABTJ2 using IMG ER and ZCURVE_V, accounting lbr 88.28% of the whole plasmid sequence. Many phage-like elements and a tRNA-coding gene were detected in pABTJ2, which is rarely reported among A. haumannii. The tRNA gene is specific for asparagine codon GTT, which may be a small chromosomal sequence picked up through incorrect excision during plasmid forma- tion. The phage-like elements may have been acquired during the integration process, as the GC content of the region carrying phage-like elements was higher than that of the adjacent regions. The finding of phage-like elements and tRNA-coding gene in pABTJ2 may provide a novel insight into the study of A. haumannii pan-plasmidome.