Figure 1.

Sources and forms of rNMPs embedded in genomic DNA. Single ribonucleotides are primarily introduced in DNA by several DNA polymerases carrying out genome duplication and/or reparative DNA synthesis; their activity may also result in the direct incorporation of polyribonucleotide chains. Stretches of consecutive ribonucleotides embedded in chromosomal DNA may also derive from the aberrant processing of RNA:DNA hybrid structures, like RNA primers required for Okazaki fragments’ synthesis, R-loops, and hybrids at double-strand breaks (DSBs) sites.