Researchers have discovered a new gene, called agrp2 that helps in fish change color depending on its surroundings.

The gene is the third in a family called agouti that has been identified in humans. The first gene helps in determining skin and hair color, while the other gives clue on obesity and diabetes.

A student at the Vanderbilt Institute of Obesity and Metabolism discovered the gene that allows background adaptation in bony fish. These include zebrafish, trout and salmon and they can change color in minutes as against mammals that need to grow a new coat depending on the environment.

“When my graduate student, Youngsup Song, discovered a third agouti protein in the fish pineal gland, an organ that regulates daily rhythms in response to light, we initially thought we had found the pathway that regulates hunger diurnally,” said Cone, chair of the Department of Molecular Physiology & Biophysics and director of the Vanderbilt Institute for Obesity and Metabolism.

“That is the mechanism that makes you hungry during the day, but not at night,” he continued. “However, Chao Zhang, a graduate student who followed up the study, ultimately discovered that this agouti protein … is involved in the rapid pigment changes that allow fish to adapt to their environment.”

A study on the new gene is being reported this week in the early edition of the Proceedings of the National Academy of Sciences (PNAS).

The researchers find the new protein regulates the expression of some genes to get the pigment-lightening effect.

“Together, the versatile agouti proteins and melanocortin receptors are responsible for regulation of body weight, the banded patterns of mammalian coats, and even red hair in most people,” Cone said. The current work shows that agouti proteins are also involved in the camouflage mechanisms used in thousands of fish species.