DNA element with a murky past is borrowing cell's repair machinery

Like their viral cousins, retrotransposons have been found borrowing the cell's own machinery to achieve their goals. They hijack a little-known piece of the cell's DNA repair function to close themselves into a ring-like shape and then create a matching double strand. The finding upends 40 years of conventional wisdom and may offer new insights into cancer, viral infections and immune responses. It could also offer a new way to insert sequences into the genome.