Some pieces of DNA have the ability to copy-and-paste themselves throughout a host animal, including in humans. If we could understand how this works, we might be able to harness this ability to correct disease-causing mutations. This image depicts the DNA (called a retrotransposon) caught in the act of copying itself into a new piece of DNA, which tells us how it knows where to go.

The image revealed that the DNA target site and RNA cargo of a LINE retrotransposon can be altered, paving the way to a programmable gene insertion tool.