Fig. 3.

Two examples of molecular studies of epigenetic phenomena in ciliates. A) DNA elimination: in Oligohymenophorea, the entire micronuclear genome is transcribed into small scnRNAs. These transcripts are transported to the old macronucleus where they bind to regions of homology (MDSs indicated in light blue) and are degraded. The scnRNAs that did not bind to any region of the old macronucleus are transported into the new macronucleus and mark homologous regions (orange) for deletion. B) Alternative processing: MDSs from divergent paralogs are combined in varying orders to create gene variants. In the micronucleus (top) the MDSs labeled 1–4 are in a scrambled order. MDSs are reassembled and may be used in multiple macronuclear genes in alternative processing, which allows for the creation of several genes from two paralogs.