In organizing the symposium, Epel and Clegg hope to stimulate more scientists to focus on the adaptations made by embryos under stress. Research in this new field may shed light on a range of biological questions, including how drug resistance evolves, and which species are most likely to be vulnerable to global change, Epel said. For example, Joseph Kiesecker, a postdoctoral fellow at Yale, described how DNA damage to developing frogs' eggs, caused by a dose of ultraviolet-B light, can make the eggs vulnerable to a deadly fungus. Kiesecker has been working with Andrew Blaustein, professor of zoology at Oregon State University, to study a rescue mechanism that frog embryos evolved eons ago to repair DNA damage. The gene repair work is done by an enzyme called photolyase, and Kiesecker and Blaustein have found that frog eggs from species with the greatest photolyase activity are most likely to survive a blast of UV-B light and less likely to succumb to later assaults by the fungus.
Mammals also have DNA repair mechanisms, and even in the womb damage can occur to embryos.
In his own research, Epel has found a coping mechanism that embryos use to prevent damage before it has to be repaired an essential protection for a species like the fat innkeeper worm, which survives in coastal mudflats, resisting natural and man-made toxins washed off the land by streams. The innkeeper worm's embryo detects toxins as soon as they touch a cell wall and spits them out of the cell. To do this, Epel found, the embryo relies on a protein woven into the walls of some of its cells that forces toxins out. Recently, Epel and others have found MDR pumps in many organisms, from bacteria to mammals. This defense against toxins almost certainly has been around for millions of years.