No matter how loving a couple may seem, their genes are waging a molecular battle in the developing embryo: "his" genes do what they can to promote their own propagation, and "her" genes fight back to make sure they are not overrun.

This genetic battle of the sexes, called parental imprinting, flies in the face of an accepted biological tenet, that a gene plays the same role in an offspring no matter which parent contributes it. Recently biologists have learned that parents have ways to stack the deck in their favor: They can mark particular genes in the set each one contributes, a process called imprinting, so that later–in the germ cells or the new embryo–these genes get special treatment. And by selectively silencing the mother’s or father’s copy of a gene, embryos can further that parent’s genetic interests.

But imprinting presents a genetic conundrum: Why should an organism choose to silence a perfectly functional copy of a gene in a parent-specific manner? Some researchers think that when it comes to the growth of offspring, each parent has different interests, particularly in species where the male mates with multiple females and each female invests a great deal of energy in her children. The male’s goal is to get the female to invest as much as possible in his offspring–to make each offspring large. She, on the other hand, would rather ration her resources to ensure that she can produce additional offspring–likely with different fathers. Thus paternally derived genes would foster large offspring, while maternally derived genes would moderate growth to safeguard the mother.

First discovered in insects, parental imprinting has recently been shown to be at work in mammals, including humans. On June 1, Dr. Shirley Tilghman–who discovered one of the first known imprinted genes in mammals–will explain how imprinted genes play key roles in development and why, when their expression goes awry, they can cause cancer and genetic disease.

Dr. Tilghman, a trustee of The Rockefeller University, is the Howard A. Prior Professor of the Life Sciences at Princeton University, where she directs the new Institute for Integrative Genomics.

For additional information, please call Ms. Gloria Phipps at (212) 327-8967