Within bacterial cells, specialized immune systems known as retrons fend off viral attacks. But that’s not all they can do. Scientists, including Seth Shipman, Ph.D., at Gladstone Institutes, have shown that retrons also serve an important purpose in the lab: precise DNA editing. In fact, retrons can be combined with CRISPR—the far more famous bacterial-defense-system-turned-gene-editor—to better edit human cells.