A rat genome gene chip is shown in the Molecular Toxicology lab at the U.S. Food and Drug Administration (FDA) headquarters in Silver Spring, Maryland, November 5, 2009. Reuters Pictures logo Reuters Pictures 27 months ago

A rat genome gene chip is shown in the Molecular Toxicology lab at the U.S. Food and Drug Administration (FDA) headquarters in Silver Spring, Maryland, November 5, 2009.