When Bruce Branchini was a kid, he would catch fireflies in a jar in his backyard and wonder how that flicker worked. For 30 years, he’s been trying to answer that question. Today, Branchini is a biochemistry professor at Connecticut College in New London. He’s studied fireflies from Tennessee to Italy to understand more about the process that causes the flicker. He describes that process kind of like a recipe.
"We've known about the ingredients for a long time," he said. "We've even known about several of the steps needed in the recipe."
The most important ingredients are a glowing protein in the firefly’s body called luciferin, and the oxygen in the air of a summer night. But they didn't know the final step that turns those ingredients a little flash of light. Now, Branchini and his team have found the answer. They published their findings last month in the Journal of the American Chemical Society. They found out that when those ingredients meet inside the firefly, they produce a secret ingredient. A dash of something called superoxide ion, a very reactive form of oxygen with an extra electron.
Branchini says this discovery could have real-world uses, too. Luciferin is used to test drugs that fight cancer and other diseases. As a bioluminescent chemical, it allows scientists and medical experts to easily see inside the human body, and this discovery allows scientists to change the color of a firefly's glow by changing the color of luciferin.
"We can make changes in its amino acid structure- so, make mutants," Branchini said. "And by doing that, we can change the normal color of yellow-green to make it more lime-green or we can make it all the way out to red."
He says it's not certain yet- that'll take more research. But it's possible this discovery might do a lot more than just answer a childhood question.
