Alchemist Fish

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

- Cody Cottier

FOR DECADES MERCURY has been set- tling into lakes and oceans, where it builds up relentlessly in fish and every- thing that eats them—humans includ- ed. This pollution, which exposes mil- lions of people to a toxic substance that can damage neural and reproductive health, “always seemed like such an in- tractable 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 ge- netically engineered zebra fish and fruit flies so that they convert methylmer- cury—the kind that “bioaccumulates,” binding to muscle tissue and becoming more concentrated as it moves up the food chain—into the less harmful ele- mental 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