TAIL TATS When researchers tattooed mouse tails, the only cells found with ink inside were macrophages. The tattoo appeared the same before (left) and after (right) ink-holding macrophages were killed, because it was recaptured by new macrophages.
A. Baranska et al/J. Expt. Med. 2018
SKIN WINStaphylococcus epidermidis, a species of bacteria that lives on human skin, grows here in a dish. Strains of this bacteria make a cancer-fighting compound that stops DNA synthesis.
R. Gallo and Teruaki Nakatsuji/UC San Diego
MARKING MICROBES When tuberculosis bacteria, seen in this scanning electron micrograph, gobble up a new synthetic molecule, they glow under a microscope — making them easy to spot in tests.