Epigenomics is the study of the effects of chromatin structure on the function of the included genes.
http://www.newyorker.com/magazine/2016/05/02/breakthroughs-in-epigenetics?mbid=nl_TNY%20Template%20-%20With%20Photo%20%2833%29&CNDID=31046461&spMailingID=8841059&spUserID=MTI3MTgyNTI1NDcwS0&spJobID=902696804&spReportId=OTAyNjk2ODA0S0Here are some quotes that I think captures much about the core nature of these fields.
“The remarkable thing about workers and gamergates,” Yan told me, “is that they are almost genetically identical.” The gene sequence before and after the transition is the same. Yet, as DNA methyl groups or histone modifications get shifted around those gene sequences, the worker transforms into a gamergate, and virtually everything about the insect’s physiology and behavior changes. “We’re going to solve how the change can have such a dramatic effect on longevity,” Reinberg said. “It’s like one twin that lives three times longer than the other”—all by virtue of a change in epigenetic information.
The medical impact of epigenetics remains to be established, but its biological influence has been evident for nearly a decade. Diffuse, mysterious observations, inexplicable by classical genetics, have epigenetic explanations at their core. When a female horse and a male donkey mate, they produce a longer-eared, thin-maned mule; a male horse and a female donkey typically generate a smaller, shorter-eared hinny. That a hybrid’s features depend on the precise configuration of male versus female parentage is impossible to explain unless the genes can “remember” whether they came from the mother or the father—a phenomenon called “genomic imprinting.” We now know that epigenetic notations etched in sperm and eggs underlie imprinted genes.
Perhaps the most startling demonstration of the power of epigenetics to set cellular memory and identity arises from an experiment performed by the Japanese stem-cell biologist Shinya Yamanaka in 2006. Yamanaka was taken by the idea that chemical marks attached to genes in a cell might function as a record of cellular identity. What if he could erase these marks? Would the adult cell revert to an original state and turn into an embryonic cell? He began his experiments with a normal skin cell from an adult mouse. After a decades-long hunt for identity-switching factors, he and his colleagues figured out a way to erase a cell’s memory. The process, they found, involved a cascade of events. Circuits of genes were activated or repressed. The metabolism of the cell was reset. Most important, epigenetic marks were erased and rewritten, resetting the landscape of active and inactive genes. The cell changed shape and size. Its wrinkles unmarked, its stiffening joints made supple, its youth restored, the cell could now become any cell type in the body. Yamanaka had reversed not just cellular memory but the direction of biological time.A question occurred to me in reading the article.
Is there any evidence to support the idea that the mechanism of chromatin structure effecting the functioning of an organism's DNA was a necessary prerequisite for multi-cellular creatures to evolve?Since bacteria and archaea never evolved into multi-cell organisms, do they have any protein wrappers on their DNA that effect their gene expression? Are there any primitive single-cell eukaryotes without such protein wrappers?