Alchemist Fish

Genetically modified fish (and fruit flies) could pull dangerous mercury from the environment

- Cody Cottier

FOR DECADES MERCURY has been settling into lakes and oceans, where it builds up relentlessly in fish and everything that eats them—humans included. This pollution, which exposes millions of people to a toxic substance that can damage neural and reproductive health, “always seemed like such an intractable thing,” says Kate Tepper, a postdoctoral researcher at Australia’s Macquarie University.

Seeking ways to make a dent in this problem, Tepper and her colleagues genetically engineered zebra fish and fruit flies so that they convert methylmercury—the kind that “bioaccumulates,” binding to muscle tissue and becoming more concentrated as it moves up the food chain—into the less harmful elemental mercury, which evaporates from the body as gas.

The researchers injected fish and fly embryos with Escherichia coli genes to produce an enzyme that catalyzes the conversion process. As reported in