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Meet the Epigenome The answer lies beyond both nature and nurture. Bygren's data - along with those of many other scientists working separately over the past 20 years - have given birth to a new science called epigenetics. At its most basic, epigenetics is the study of changes in gene activity that do not involve alterations to the genetic code but still get passed down to at least one successive generation. These patterns of gene expression are governed by the cellular material - the epigenome - that sits on top of the genome, just outside it (hence the prefix epi-, which means above...
...evolve, but researchers have found that it takes only the addition of a methyl group to change an epigenome. A methyl group is a basic unit in organic chemistry: one carbon atom attached to three hydrogen atoms. When a methyl group attaches to a specific spot on a gene - a process called DNA methylation - it can change the gene's expression, turning it off or on, dampening it or making it louder. (See more about...
...proposed in the 1970s, yet it wasn't until 2003 that anyone experimented with DNA methylation quite as dramatically as Duke University oncologist Randy Jirtle and one of his postdoctoral students, Robert Waterland, did. That year, they conducted an elegant experiment on mice with a uniquely regulated agouti gene - a gene that gives mice yellow coats and a propensity for obesity and diabetes when expressed continuously. Jirtle's team fed one group of pregnant agouti mice a diet rich in B vitamins (folic acid and vitamin B12). Another group of genetically identical pregnant agouti mice got no such prenatal nutrition...
...most of human evolution, a stressful world would have been marked by famines or periods of starvation, and that environment might have resulted in a particular pattern of gene expression that would have prompted the body to store more fat in preparation for the next bout of scarcity. Today, of course, the same response to stress would result in obesity. This theory of a thrifty fat-storing system that kicks in under high levels of early stress was originally proposed by British physician David Barker. (See pictures from an X-ray studio...
...researchers, who had already used this same process in studies of HIV and the hepatitis C virus, hoped to find that some of the treated cells could not be infected with the influenza virus, which would suggest that the virus needed the deactivated gene to function. Instead, the researchers were surprised to find that the rate of infection increased dramatically when certain genes were deactivated...