Figure 2. Model for RNA-templated genome rearrangements in Oxytricha [24].
Bidirectional RNA transcription of all DNA nanochromosomes in the old, maternal macronucleus (MAC) produces an RNA genome cache (A). Transport of these RNA transcripts to the newly developing macronucleus (B), where they may act as scaffolds to guide rearrangements (deletion, permutation and inversion) of corresponding micronuclear (MIC) DNA sequences (C). In this illustration, segments 2 and 3 are switched and segment 5 is inverted (number upside down) relative to the final macronuclear order.