By recreating the firefly’s glow in the lab, scientists continue to tease out the secrets behind how the insects light up, the American Chemical Society announced in a new video. Scientists had known that a compound called luciferase produced the firefly’s glow. Now, a new study published in the Journal of the American Chemical Societydescribes how a molecule toxic to most animals, called a superoxide ion, plays a key role in the reactions that cause luciferase to produce light. Superoxide, which can cause inflammation and cell damage in humans and other animals, doesn’t appear to harm the bug because the reactions are contained and happen quickly, the scientists say. The finding could lead to important applications in medicine, especially in cancer research where luciferase’s light can be used to track how a tumor spreads through an organism.