April 7, 2009

Biotransformation woodrat genes studied

U.S. biologists say they have narrowed their hunt for the genes that allow rodents to eat toxic creosote bushes in the southwestern United States.

As that region grew warmer 18,700 to 10,000 years ago, juniper trees vanished from what is now the Mojave Desert, robbing packrats of their favorite food, the scientists said. Instead, the rodents are consuming toxic creosote.

University of Utah Professor Denise Dearing and colleagues captured eight packrats -- also known as woodrats -- from each of two western regions: the Mojave Desert and the cooler Great Basin. Rats from both areas were fed rabbit chow mixed either with creosote or juniper.

The scientists said they then analyzed the rodents' DNA to look for active genes known as biotransformation genes that produce liver enzymes to detoxify the poisons in creosote and the less-toxic juniper.

We found 24 genes in woodrats from the Mojave Desert that could be key in allowing them to consume leaves from creosote bushes, said Dearing. We don't really understand how wild animals process their diets and how herbivores can feed on really toxic diets. If we can understand it, we may be able to understand how they will deal with climate change.

The study -- conducted with postdoctoral fellows Jael Malenke and Elodie Magnanou -- appears in the online edition of the journal Molecular Ecology.