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. Author manuscript; available in PMC: 2014 Dec 15.
Published in final edited form as: Nature. 2014 Jan 16;505(7483):353–359. doi: 10.1038/nature12987

Figure 3. Somatic genome rearrangement in ciliates.

Figure 3

Unicellular ciliates posses two nuclei: the germline micronucleus and the somatic macronucleus. After mating, the developing macronucleus is extensively edited to remove germline-specific sequences. The new mature somatic nucleus contains only genes needed for somatic (vegetative) growth. The rest of the germline-specific genome (red boxes) undergoes DNA elimination, an extraordinary method to purge the somatic genome of repetitive sequences and transposons. This process, called somatic genome rearrangement, differs between Tetrahymena and Oxytricha. a, Tetrahymena piRNAs (red lines) are generated by the germ line, and target germline-specific sequences of the developing somatic macronucleus for elimination. b, Oxytricha piRNAs (blue, orange and purple lines) are generated by the parent somatic macronucleus, and direct the retention of somatic genes in the mature somatic macronucleus (blue, orange and purple boxes).