Genomic imprinting in microorganisms

Genomic imprinting is an epigenetic mark introduced on a DNA molecule without alteration of the base sequence. Upon replication, the primary mark is propagated to the daughter DNA molecules. Epigenetic DNA modification often serves as a regulatory signal and may play a crucial role in many developmental processes. Although this mode of gene regulation was first discovered in multicellular eukaryotes, cases of imprinting have been recently found in lower eukaryotes, bacteria and phage. Thus it may be reasonable to list DNA modification among the major mechanisms that regulate gene expression.