In order to study the role played by cellular RNA pools produced by homologous genomic loci in defining the transcriptional state of a silenced gene, we tested the effect of non-functional alleles of the white gene in the presence of a functional copy of white, silenced by heterochromatin. We found that non-functional alleles of white, unable to produce a coding transcript, could reactivate in ...

Specific silencing of target genes can be induced in a variety of organisms by providing homologous double-stranded RNA molecules. In vivo, these molecules can be generated either by transcription of sequences having an inverted-repeat (IR) configuration or by simultaneous transcription of sense-antisense strands. Since IR constructs are difficult to prepare and can stimulate genomic rearrangem...

RNA silencing is a newly discovered mechanism of genetic regulation in eukaryotes. It is based on an immune system that protects eukaryotes against viruses and transposons and in some respects it is conceptually similar to classical humoral immunity. However RNA silencing is distinct from humoral immunity in that it only targets nucleic acids and has a specificity mechanism based on nucleic aci...

Small RNA-guided gene silencing is an evolutionarily conserved process that operates by a variety of molecular mechanisms. In multicellular eukaryotes, the core components of RNA-mediated silencing have significantly expanded and diversified, resulting in partly distinct pathways for the epigenetic control of gene expression and genomic parasites. In contrast, many unicellular organisms with sm...

DNA methylation and histone H3 lysine 9 methylation. Curr. Biol. 12, 1360 3 Richards, E.J. and Elgin, S.C. (2002) Epigenetic codes for heterochromatin formation and silencing: rounding up the usual suspects. Cell 108, 489–500 4 Bartee, L. et al. (2001) Arabidopsis cmt3 chromomethylase mutations block non-CG methylation and silencing of an endogenous gene. Genes Dev. 15, 1753–1758 5 Lindroth, A....

Given their sessile condition, land plants need to integrate environmental cues rapidly and send signal throughout the organism to modify their metabolism accordingly. Small RNA (sRNA) molecules are among the messengers that plant cells use to carry such signals. These molecules originate from fold-back stem-loops transcribed from endogenous loci or from perfect double-stranded RNA produced thr...