Genome Defense

Hunter RNAs seek and destroy parasitic DNAs

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Science  17 Jul 2015:
Vol. 349, Issue 6245, pp. 280
DOI: 10.1126/science.349.6245.280-a

Tetrahymena uses small RNAs to fend off transposable elements

PHOTO: AARON J. BELL/SCIENCE SOURCE

Transposable elements (TEs) are parasitic DNA sequences. They present a serious threat to the host genomes in which they reside. Like other eukaryotes, the single-celled protist Tetrahymena uses small RNAs to control parasitic TEs. Noto et al. show that a subset of these small RNAs recognize the TEs they are synthesized from as foreign, as well as sequence-related TEs in other places in the genome. These RNAs stimulate the production of a second wave of small RNAs at these distant sites. The second-wave, or “late,” RNAs can bind to still further TE sequences, ensuring a robust and heritable defense of the entire genome.

Mol. Cell 59, 10.1016/j.molcel.2015.05.024 (2015).

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