INTRODUCTION - THE GENETICS OF EPIGENETICS

Cis-acting binding sites for transcription activators cannot explain t he patterned expression of genes during development, nor a large range of phenomena that result from gene transplacement. Heritable slates o f transcriptional regression or activation sequences are influenced no t only by the chromosomal context of the promoter but also by modifica tions of histones and DNA, and long-range interactions between distant chromosomal elements. The molecular dissection of these epigenetic ph enomena has become an exciting topic of reserch, revealing highly cons erved mechanisms at work in chromatin-mediated gene control.