Douet J, Tourmente S
Unité Mixte de Recherche CNRS 6547 BIOMOVE, Université Blaise Pascal, Aubière Cedex, France.
Heredity (Edinb). 2007 Jul;99(1):5-13. doi: 10.1038/sj.hdy.6800964. Epub 2007 May 9.
5S ribosomal DNA is a highly conserved tandemly repeated multigenic family. As suggested for a long time, we have shown that only a fraction of the 5S rRNA genes are expressed in Arabidopsis thaliana. In Xenopus laevis, there is a developmental control of the expression of the 5S rRNA genes with only one of the two 5S rDNA families expressed during oogenesis. For both Arabidopsis and Xenopus, the strongest transcription of 5S rRNA, respectively in the seed and during oogenesis is correlated with heterogeneity in the transcribed 5S rRNAs. Epigenetic mechanisms such as modification of the chromatin structure are involved in the transcriptional regulation of the 5S rRNA genes in both organisms. In Arabidopsis, two silencing pathways, methylation-dependent (RNAi) and methylation-independent (MOM pathway), are involved in the silencing of a 5S rDNA fraction.
5S核糖体DNA是一个高度保守的串联重复多基因家族。正如长期以来所表明的那样，我们已经证明，在拟南芥中只有一小部分5S rRNA基因会表达。在非洲爪蟾中，5S rRNA基因的表达存在发育调控，在卵子发生过程中，两个5S rDNA家族中只有一个会表达。对于拟南芥和非洲爪蟾而言，分别在种子和卵子发生过程中5S rRNA最强的转录与转录的5S rRNA中的异质性相关。染色质结构修饰等表观遗传机制参与了这两种生物中5S rRNA基因的转录调控。在拟南芥中，两条沉默途径，即依赖甲基化的（RNA干扰）和不依赖甲基化的（MOM途径），参与了一部分5S rDNA的沉默。
