Hypomethylation and hypermethylation of the tandem repetitive 5S rRNA genes in Arabidopsis
Abstract
5S ribosomal DNA (5S rDNA) is organized in tandem repeats on chromosomes 3, 4 and 5 in Arabidopsis thaliana. One part of the 5S rDNA is located within the heterochromatic chromocenters, and the other fraction forms loops with euchromatic features that emanate from the chromocenters. We investigated whether the A. thaliana heterochromatin, and particularly the 5S rDNA, is modified when changing the culture conditions (cultivation in growth chamber versus greenhouse). Nuclei from challenged tissues displayed larger total, as well as 5S rDNA, heterochromatic fractions, and the DNA methyltransferase mutants met1 and cmt3 had different impacts in Arabidopsis. The enlarged fraction of heterochromatic 5S rDNA was observed, together with the reversal of the silencing of some 5S rRNA genes known as minor genes. We observed hypermethylation at CATG sites, and a concomitant DNA hypomethylation at CG/CXG sites in 5S rDNA. Our results show that the asymmetrical hypermethylation is correlated with the ageing of the plants, whereas hypomethylation results from the growth chamber/culture conditions. In spite of severely reduced DNA methylation, the met1 mutant revealed no increase in minor 5S rRNA transcripts in these conditions. The increasin...Continue Reading
References
DNA methylation controls histone H3 lysine 9 methylation and heterochromatin assembly in Arabidopsis
Citations
The histone variant H2A.W defines heterochromatin and promotes chromatin condensation in Arabidopsis
Related Concepts
Related Feeds
Aging Genetics (Keystone)
This feed focuses on aging epidemiology and genetic, epigenetic, and proteomic aspects underlying aging, as well as aging- associated biomarkers. Here the latest research in this domain.
Cell Aging (Keystone)
This feed focuses on cellular aging with emphasis on the mitochondria, autophagy, and metabolic processes associated with aging and longevity. Here is the latest research on cell aging.
Genetics & Epigenetics of Aging
Dozens of genes are implicated in lifespan, and epigenetic changes during aging affect cell function. This feed focuses on the genetics and epigenetics of aging.
Cell Aging
This feed focuses on cellular aging with emphasis on mitochondria, autophagy, and metabolic processes associated with aging and longevity. Here is the latest research on cell aging.