The Fully Recovered Frog

For his research on genetic diseases, Michael Zasloff, an American scientist, operated on frogs to remove tissue samples that he would examine later. Usually, the operation was minor. Zasloff stitched up the frogs, returned them to the tank in a corner of his laboratory, and most of the time, the frogs recovered.

In the summer of 1986, Zasloff removed tissue from an African clawed frog. A few days later, he glanced into the murky waters of the tank to check on the frog’s condition. The waters teemed with bacteria, a condition that could lead to infection. Zasloff half expected the frog to be dead, or at the very least sick. Instead, it was surprisingly active.

At first, Zasloff wondered if he had the wrong frog. He looked for the surgical wound. There it was in the frog’s side, but instead of a red festering sore, the wound was small and almost healed.

Zasloff realized that he was observing a miracle. The frog had made a surprising recovery. Something must be protecting it from infection. But what?

Zasloff abandoned his earlier research and turned his attention to the frog. Eventually, he discovered the reason for the frog’s unexpected good health. Special infection-fighting chemicals known as magainins were produced in the frog’s skin glands.

Research is on-going, but we now know that the African clawed frog isn’t the only frog species to produce magainins. Each species of frog produces a slightly different form, and with 5400 different frog species in the world, a whole army of disease-fighting chemicals might be lurking in ponds and lakes around the globe.


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