Ciliates, such as Pammecium and Tetrahymena, are single-celled eukaryotes that deal with the junk DNA infesting their genomes in a truly dramatic manner. They harbor complete copies of their genome within two separate nuclei. The micronucleus (or MIC) gives rise both to future progeny and to the macronucleus (or MAC), wherein the DNA is shredded, rearranged, and amplified, which allows the essential core of the genome-in some cases as little as 5% of it-to be expressed at high levels. The repetitive parasitic sequences that have been derived from transposable elements are trashed in the process.
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