Résumé
In eukaryotes, chromatin is essential for heredity. Chromatin architecture is sometimes ‘epistatic’ over the DNA and imparts a different heritable state to the same DNA sequence or the same functional state to unrelated DNA sequences. This has been documented recently in a wide variety of studies focused on regulation of the yeast mating type, the function of
Polycomb and
trithorax group proteins, the specification of eukaryotic centromeres and neocentromeres, and genomic imprinting.
Part of the eukaryotic genetic information is not encoded in the primary sequence of DNA, but rather in heritable DNA modifications and chromatin components.