tailieunhanh - Báo cáo y học: "Silencing of transposons in plant genomes: kick them when they’re down"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học quốc tế cung cấp cho các bạn kiến thức về ngành y đề tài: Silencing of transposons in plant genomes: kick them when they’re down. | Review Silencing of transposons in plant genomes kick them when they re down Daniel Zilberman and Steven Henikoff Address Howard Hughes Medical Institute Basic Sciences Division Fred Hutchinson Cancer Research Center 1100 Fairview Avenue North Seattle WA 98109 USA. Correspondence Steven Henikoff. E-mail steveh@ 5 Published 16 November 2004 Genome Biology 2004 5 249 The electronic version of this article is the complete one and can be found online at http 2004 5 l2 249 2004 BioMed Central Ltd Abstract Recent progress in understanding the silencing of transposable elements in the model plant Arabidopsis has revealed an interplay between DNA methylation histone methylation and small interfering RNAs. DNA and histone methylation are not always sufficient to maintain silencing and RNA-based reinforcement can be needed to maintain as well as initiate it. Throughout evolution genomes have been invaded by selfish DNA elements that use them as vehicles for selfpropagation. In order to defend themselves against these genomic parasites genomes need something akin to an immune system - a mechanism that can distinguish self from non-self at the nucleic-acid level and inactivate the non-self sequences. In the last few years studies of DNA methylation post-translational histone modifications and RNA silencing in the plant Arabidopsis thaliana and other organisms have begun to reveal what appears to be just such an integrated genome defense system. An essential property of eukaryotic cells is the ability to establish heritable patterns of gene silencing without alterations in DNA sequence. Methylation of cytosine nucleotides usually within CG dinucleotides is the most common form of covalent DNA modification in the eukaryotic kingdom and most eukaryotes use it to propagate epigenetic control 1 . For example DNA methylation plays an important role in imprinting silencing of genes specifically on the basis of their origin in one or other parent and in .