Deconstructing ribosomal DNA: from the sequence to the chromosome across the Tree-of-Life (rDNA-LIFE)

rDNA-Life aims to explore the evolutionary dynamism of ribosomal RNA genes (rDNA), a dynamism that is surprisingly high given their crucial role in the synthesis of ribosomes and thus for life-on-Earth. There are four main rDNAs: the 18S, 5.8S, and 26S rRNA genes, which are coded in a single operon, and the 5S rRNA gene usually coded outside that operon. These rDNAs are present in high numbers, from 50 to 13,000 copies per cell, and typically tandemly arranged. However, despite their importance and abundance, several aspects of the biology of these critical molecules for life remain enigmatic, particularly their mode of molecular evolution, genomic arrangements and epigenetic regulation. rDNA-Life aims to deconstruct ribosomal DNA with the purposes of: (1) defining the model of evolution that best explains rDNAs high dynamism and the differences depending on the rDNA type, (2) assessing the impact of epigenetic processes, like methylation, on rDNA evolution and (3) establishing the landscape of rDNA arrangements across the Tree-of-Life.