Epigenomic communication systems in humans and honey bees: from molecules to behavior

Abstract

A 2010 Nature editorial entitled "Time for the Epigenome" trumpets the appearance of the International Human Epigenome Consortium and likens it to Biology's equivalent of the Large Hadron Collider. It strongly endorses the viewpoint that selective modifications of "marks" on DNA and histones constitute the crucial codes of life, a proposition which is hotly contested (Ptashne et al., in 2010). This proposition reflects the current mindset that DNA and histone modifications are the prime movers in gene regulation during evolution. This claim is perplexing, since the well characterized organisms, Drosophila melanogaster and Caenorhabditis elegans, lack methylated DNA "marks" and the DNA methytransferase enzymology. Despite their complete absence, D. melanogaster nevertheless has extensive gene regulatory networks which drive sophisticated development, gastrulation, migration of germ cells and yield a nervous system with significant neural attributes. In stark contrast, the honey bee Apis mellifera deploys its human-type DNA methyltransferase enzymology to "mark" its DNA and it too has sophisticated development. What roles therefore is DNA methylation playing in different animals? The honey bee brings a fresh perspective to this question. Its combinatorial chemistry of pheromones, tergal and cuticular exudates provide an exquisite communication system between thousands of individuals. The development of queen and worker is strictly controlled by differential feeding of royal jelly and their adult behaviors are accompanied by epigenomic changes. Their interfaces with different "environments" are extensive, allowing an evaluation of the roles of epigenomes in behavior in a natural environment, in the space of a few weeks, and at requisite levels of experimental rigor.