H3K27me and PRC2 transmit a memory of repression across generations and during development

Establishing memory of gene repression Although cells in the body contain the same DNA content, they can display widely varying form and function among tissues. This comes about by differential gene regulation and by establishing a type of gene expression memory that is passed down during cell division to daughter cells. Gaydos et al. report that in nematodes, both sperm and oocytes transmit a memory of chromatin repression to embryos in the form of modified histones. During DNA replication, modified histones are passed to daughter chromatids to provide chromatin memory for a few cell divisions. Histone-modifying enzymes replenish histone modifications and provide long-term chromatin memory. Science , this issue p. 1515