© IKON IMAGES/CORBIS
Genomes are hotbeds of evolutionary conflict. Perhaps nothing speaks to this idea better than the war raging between retrotransposons and their host genomes. Retrotransposons, often referred to as jumping genes, are mobile genetic elements that parasitize host machinery to replicate themselves across the genome. Since their emergence more than 100 million years ago, retrotransposons have been enormously successful. Modern mammalian genomes, for example, are riddled with the scars of these copy-and-paste events, with retrotransposon-derived DNA now accounting for nearly 50 percent of the human genome.
The most dangerous retrotransposon in mammalian genomes is the long interspersed nuclear element-1 (LINE-1 or L1). L1 retrotransposons are a little more than 6 kilobases long and encode an RNA-binding protein and an endonuclease with reverse-transcriptase activity that allow the ...
