So That's What You've Been Doing All This Time

Following a recent meeting at Cold Spring Harbor Laboratory, a perspectives piece by a group of researchers appearing it this month's Genes and Development gives a definition for epigenetics, saying that "an epigenetic trait is a stably heritable phenotype resulting from changes in a chromosome without alterations in the DNA sequence." They also postulate that there are three types of signals that work in concert to establish an epigenetic state: the "epigenator" signal from the environment, the "epigenetic initiator" that responds to the epigenator and find the proper chromatin region, and the "epigenetic maintainer" that upholds the chromatin environment.