A genetically engineered fish that glows green from the inside out is helping illuminate what pollutants do inside the body.

Endocrine disruptors aresubstances found in a wide range of industrial products, including plastics, as well as in many femalecontraceptives.

The chemicals mimic the actions of sexual hormones, resulting in various reproductive problems in both people and animals. Previous research has shown the chemicals cause fish to change gender, and in people, endocrine disruptors have been associated with lower sperm counts and breast and testicular cancers.

Yet scientists have had difficulty tracking what endocrine disruptors do inside a person or an animal's body. So a team genetically engineered zebrafish to glow in places where an endocrine-disrupting chemical is presentand thus show where it may be harming the body.

"We've essentially put genetic elements within the fish, over time, that are specifically designed to identify where the chemicals penetrate and act within the body," said study leader Charles Tyler at the U.K.'s University of Exeter.

"This genetic machinery produces proteins which don't interfere with the way these chemicals act in the body, but they fluoresce green under a fluorescent microscope, providing a reporting system to identify which body tissues are being affected.

"This, in turn provides a more 'intelligent' way of identifying where the [pollutants'] potential health impacts might be" in people.

(See "Glowing Animals: Beasts Shining for Science.")

Glowing Fish Confirm Past Findings

Tyler and team exposed the zebrafish to varying levels of chemicals known to affect the hormone estrogen, including ethinyloestradiol, found in contraceptive pills; nonylphenol, present in paints and industrial detergents; and bisphenol A (BPA), a component of many plastics.

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Fish Glow Green After Genetic Engineering