GLOWING TADPOLE: This tiny tadpole serves as a chemical sentinel, fluorescing when in contact with contaminants and more brightly with increasing exposure. Thanks to its small size, which can be used in an automated read-out system, the tadpoles can be used to test large number of water samples. Image: © Anthony Sébillot

Unhealthy Glow: Fluorescent Tadpoles Expose Chemical Contamination

Transgenic fish fry and larval frogs light up when exposed to hormone-disrupting compounds in water

By Erica Gies

In cartoons glowing goo signals that there is bad stuff in the water. Now life imitates art: A French biotechnology company has created a transgenic tadpole that fluoresces when it encounters chemical contaminants in water that disrupt thyroid functioning. The test promises to shine a light on a class of endocrine-disrupting pollutants, which pollution regulators have in their crosshairs.

This month France-based WatchFrog begins its first high-profile trial to test effluent from a hospital near Paris under the auspices of the ministries of environment and industry. The Organization for Economic Cooperation and Development (OECD) is also evaluating the thyroid test, and the U.S. Environmental Protection Agency (EPA) is already using it.

Tests on living organisms—in vivo—are more revealing than traditional chemical analyses. Instead of targeting specific compounds, they can highlight any toxic chemical or mixture that disrupts a key organ or life system. Until recently, however, in vivo testing for endocrine disruptors has been conducted on full-grown animals, which means the process is slow, taking years to develop and weeks to execute. It is also expensive—each run costs 60,000 to 100,000 euros.

These impediments have let WatchFrog hop ahead. The company’s innovation is to combine the best of two worlds: “in vivo testing at the scale of in vitro,” says CEO Gregory Lemkine. WatchFrog’s three-millimeter-long Xenopus tadpoles, a common species in physiology labs, are small enough to fit in standard lab equipment. “Our tests cost between 10 and 20 times less,” Lemkine says, and they offer results in 24 to 48 hours.

Read more: Unhealthy Glow: Fluorescent Tadpoles Expose Chemical Contamination: Scientific American.

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