Study Shows Effects Of Toxin Exposure Passed To Offspring, Demonstrates New Mechanism For Inheritance Of Traits

Work By WSU Research Team Chosen As One Of The Top 100 Science Stories Of 2005 By Discover Magazine

By Cherie Winner

Molecular biologist Michael K. Skinner and his co-workers found that exposing fetal rats to environmental toxins can affect their sexual development in a way that shows up in subsequent generations as well. They showed that the toxins did not cause mutations or changes in the DNA sequences. Rather, the toxins caused changes in chemicals attached to the DNA. Such changes are called "epigenetic," meaning "around the genes."

"I think this concept that epigenetics is going to play a really important role in biology is just now being appreciated," said Skinner in June, when his team's results were published in the journal Science. "It probably is a big piece of the puzzle which we didn't really have before."

Their work joins a growing body of evidence that genes–DNA sequences–are not the only source of heritable traits. Instead, changes in small chemicals attached to the DNA can turn genes on or off, affecting a wide range of processes, including normal development and susceptibility to disease. Over the past several years, epigenetic changes have been implicated in several kinds of leukemia and in the premature aging of cloned animals, such as Dolly the sheep.

Skinner's group showed that epigenetic changes can be even more stable in a population than changes to the DNA itself. Its work raises the possibility that events in a person's lifetime, such as exposure to toxins, stress or disease, could affect that person's descendents several generations later.

The list of top science stories was published in Discover magazine's special issue, "Year in Science."

Skinner is a professor in the WSU School of Molecular Biosciences and directs the Center for Reproductive Biology and the Center for Integrated Biotechnology.

Cherie Winner works in the Washington State University News Service, Pullman.