"The Mojave is huge, and there aren't many things that eat creosote," she says.
Dearing conducted the study with Jael Malenke, a postdoctoral fellow in biology at the University of Utah, and Elodie Magnanou, who held the same position until March 2008 and now is at Pierre and Marie Curie University in France.
The study was funded by the National Science Foundation.
'A Tale of Two Poisons'
Human plant consumption is healthy, thanks to agriculture, which breeds toxins out of plants we eat, Dearing says. People also adapted genetically like the woodrats to certain changes in their diets. There are extra genes for starch-digesting enzymes in people with high-starch diets (potatoes, rice, grains), such as Japanese and Europeans.
"Eating for [non-human] herbivores is really dangerous," Dearing says. "Most plants make toxins to prevent from being eaten."
She says little is known about how plant-eating vertebrate animals disarm plant defenses. Until the advent of genetic techniques to scan an animal's genome, or genetic blueprint, "we could only look at one, two or three enzymes at a time. Much more work has been done on insects because they are pests and eat a lot of the plants we eat."
Wood creosote is a resin that comes from creosote bushes or high-temperature treatment of certain other woods, and once was used in laxatives, cough medicine and disinfectants. It is different than the more commonly known coal tar creosote, which is made of petrochemicals and is the world's most widely used wood preservative, applied to power poles, railroad ties and bridge timbers.
Even with detoxification genes, creosote bush is so toxic the packrats can eat only so much. When they eat it exclusively, in winter, they actually lose weight. They gain weight in the spring when they also eat annual plants and grasses, yucca and other plants. Juniper also is toxic, bu
|Contact: Lee Siegel|
University of Utah