Ribodysgenesis: sudden genome instability in the yeast Saccharomyces cerevisiae arising from RNase H2 cleavage at genomic-embedded ribonucleotides.

Ribonucleotides can be incorporated into DNA during replication by the replicative DNA polymerases. These aberrant DNA subunits are efficiently recognized and removed by Ribonucleotide Excision Repair, which is initiated by the heterotrimeric enzyme RNase H2. While RNase H2 is essential in higher eukaryotes, the yeast Saccharomyces cerevisiae can survive without RNase H2 enzyme, although the genome undergoes mutation, recombination and other genome instability events at an increased rate.

Methods to study mitotic homologous recombination and genome stability.

Spontaneous mitotic recombination occurs in response to DNA damage incurred during DNA replication or from lesions that do not block replication but leave recombinogenic substrates such as single-stranded DNA gaps. Other types of damages result in general genome instability such as chromosome loss, chromosome fragmentation, and chromosome rearrangements. The genome is kept intact through recombination, repair, replication, checkpoints, and chromosome organization functions.