Pass the disruption

Courtesy of Michael Skinner

The paper:

The finding:
A group led by Michael Skinner from Washington State University briefly exposed pregnant female rats to endocrine disruptors and found sperm defects in the F1 generation of male rats, which were passed through the male germ line to the F4 generation. Offspring of treated rats also had DNA methylation differences. "Potentially this transgenerational epigenetic mechanism could be how the environment is influencing disease," says Skinner.

The significance:
The study provided clear evidence of multigenerational effects of environmental exposure, says Andrea Gore, from University of Texas, Austin, who has since collaborated with Skinner's group.

The catch:
Doses used in the study were higher than those seen in the environment, the authors note. "All bets are off when you extrapolate the findings" to humans or other animals, says Randy Jirtle from Duke University. Skinner's group is now working to study the effects of dose on sperm viability.

The progress:
Skinner and colleagues allowed male offspring of treated rats to age six months to a year and found that a number of other conditions, such as kidney disease and breast tumors, were passed across generations (Endocrinol, 147: 5515-23, 2006). Jirtle says it will be important to identify the precise methylation effects that give rise to the phenotypes, "because epigenomes vary greatly [among] species."