Mechanisms of heritable gene repression during development of Drosophila.

During development, patterns of differential gene expression, defining determined states of cells, need to be maintained over many cell generations. In Drosophila, genetic and molecular analyses led to the discovery of a set of proteins which seem to exert such a memory function by using epigenetic mechanisms. Recent experiments demonstrate that, in particular, the heritable inactivation of regulatory genes relies on stable changes in the higher-order constitution of chromatin.