Silencing of transposons in the Drosophila ovary relies on three Piwi family proteins--Piwi, Aubergine (Aub), and Ago3--acting in concert with their small RNA guides, the Piwi-interacting RNAs (piRNAs). Aub and Ago3 are found in the germ cell cytoplasm, where they function in the ping-pong cycle to consume transposon mRNAs. The nuclear Piwi protein is required for transposon silencing in both g...

In some mammalian systems small interfering RNAs (siRNA) targeting homologous sequences in promoter regions of genes induce transcriptional gene silencing (TGS). We have previously reported the induction of TGS by an siRNA (prom-A siRNA) targeting the tandem NF-kappaB-binding motifs within the human immunodeficiency virus, type 1 (HIV-1), promoter region. Here we report that induction of TGS by...

Argonautes are highly conserved proteins found in almost all eukaryotes and some bacteria and archaea. In humans, there are eight argonaute proteins evenly distributed across two clades, the Ago clade (AGO1-4) and the Piwi clade (PIWIL1-4). The function of Ago proteins is best characterized by their role in RNA interference (RNAi) and cytoplasmic post-transcriptional gene silencing (PTGS) - whi...

1 1 Distribution of this document in any form violates the copyrights of the publisher. Cosuppression, post-transcriptional gene silencing (PTGS), and virus-induced gene silencing (VIGS) all describe homology-dependent gene silencing phenomena in plants that involve what is more broadly known as RNA interference (RNAi). The study of these phenomena in plants has provided numerous key discoverie...

In recent decades, availability of ample information of various plant genomes has reached the hand of plant researchers through genome sequencing and expressed sequence tag (EST) analysis that eventually facilitate the functional study of wide range of genes. The previous work on plant functional genomics were exclusively based on forward genetics; that is, identification of a mutant and subseq...

A fundamental aspect of Post-transcriptional gene silencing (PTGS) is the requirement of homology between the transgene sequence and the virus or mRNA sequence being silenced. For example, virus-resistant plants are resistant only to viruses that are very closely related to the virus from which the transgene was derived. One idea is to devise an artificial sequence that is at least 90 – 95% hom...

BACKGROUND Endogenous microRNAs (miRNAs) are potent negative regulators of gene expression in plants and animals. Artificial miRNAs (amiRNAs)-designed to target one or several genes of interest-provide a new and highly specific approach for effective post-transcriptional gene silencing (PTGS) in plants. METHODOLOGY We devised an amiRNA-based strategy for both japonica and indica type strains ...

Background RNA interference (RNAi) has emerged as a powerful genetic tool for scientific research over the past several years. RNAi is known as a conserved integral part of the gene regulation processes present in all eukaryotes that utilizes small RNAs (sRNAs) to direct the silencing of gene expression at i.a. the post-transcriptional level. Posttranscriptional gene silencing (PTGS) starts wit...

The discovery of the mechanism of RNA interference by ds RNA by Prof. Andrew Fire and Prof. Craig Mello in 1998, gave them the Nobel Prize in 2006. This discovery revealed a new mechanism for gene regulation through "gene silencing" at the transcriptional level (TGS) or at the post-transcriptional level (PTGS), which play a key role in many essential cellular processes. Today dsRNA is used as a...

Background and Aims: Virus-Induced Gene Silencing (VIGS) is a virus vector technology that exploits antiviral defense mechanism. By infecting plants with recombinant viruses containing host genes inserted in the viral genome, VIGS achieves the RNA silencing process. The purpose of this study was to investigate the possibility of tomato (Lycopersicon esculentum Mill.) and tobacco (Nicotiana be...