Speeding Up Dietary Evolution with Fecal Transplants
In an earlier study, the Utah researchers showed that the creosote-eating woodrats from the Sonoran and Mojave deserts had higher proportions of gut microbes that might detoxify creosote, while juniper-eating woodrats from the Great Basin had a different set of gut bacteria.
In the new study, Dearing and colleagues performed three experiments using two kinds of woodrats -- juniper eaters from the Great Basin desert and creosote eaters from the Mojave Desert. They were captured and kept in the lab on a diet of rabbit chow.
In the first experiment, the scientists studied the relative abundances of gut-microbe genes in two groups of the creosote-eating Mojave woodrats. One group was fed rabbit chow containing 1 percent of creosote resin for two days, followed by rabbit chow with 2 percent of creosote resin for three days. The control group was fed only rabbit chow. Gut microbes were removed from the foreguts of both woodrat groups. DNA was isolated from the microbes to identify genes involved in detoxification.
The scientists found that a woodrat's diet determines the composition of its gut microbes. "Mammals are adapted to the plant toxins they eat," Kohl says. The guts of creosote-fed woodrats were teeming with microbes that may degrade creosote, while the guts of creosote-free woodrats had only one-fourth the levels of the same gut microbes.
In the second experiment, the researchers experimentally removed gut microbes to highlight their dietary role in woodrats. Antibiotics kill about 90 percent of the gut microbes in animals, severely impairing their ability to consume toxic foods.
Two groups of woodrats were pretreated with the antibiotic neomycin in their drinking water. One group was placed on a diet of rabbit chow and creosote resin. With their gut microbes killed by th
|Contact: Lee J. Siegel|
University of Utah