The Biology of Belief - Bruce H. Lipton [28]
Primacy of Environment. The new science reveals that the information that controls biology starts with environmental signals that, in turn, control the binding of regulatory proteins to the DNA. Regulatory proteins direct the activity of genes. The DNA, RNA, and protein functions are the same as described in the Primacy of DNA chart. Note: the flow of information is no longer unidirectional. In the 1960s, Howard Temin challenged the Central Dogma with experiments that revealed RNA could go against the predicted flow of information and rewrite the DNA. Originally ridiculed for his “heresy,” Temin later won a Nobel Prize for describing reverse transcriptase, the molecular mechanism by which RNA can rewrite the genetic code. Reverse transcriptase is now notorious, for it is used by the AIDS virus’ RNA to commandeer the infected cell’s DNA. It is also now known that changes in the DNA molecule, such as adding or removing methyl chemical groups, influence the binding of regulatory proteins. Proteins must also be able to buck the predicted flow of information, since protein antibodies in immune cells are involved with changing the DNA in the cells that synthesize them. The size of the arrows indicating information flow are not the same. There are tight restrictions on the reverse flow of information, a design that would prevent radical changes to the cell’s genome.
How do you get that sleeve off? You need an environmental signal to spur the “sleeve” protein to change shape, i.e., detach from the DNA’s double helix, allowing the gene to be read. Once the DNA is uncovered, the cell makes a copy of the exposed gene. As a result, the activity of the gene is “controlled” by the presence or absence of the ensleeving proteins, which are in turn controlled by environmental signals.
The story of epigenetic control is the story of how environmental signals control the activity of genes. It is now clear that the Primacy of DNA chart described earlier is outmoded. The revised scheme of information flow should now be called the “Primacy of the Environment.” The new, more sophisticated flow of information in biology starts with an environmental signal, then goes to a regulatory protein and only then goes to DNA, RNA, and the end result, a protein.
The science of epigenetics has also made it clear that there are two mechanisms by which organisms pass on hereditary information. Those two mechanisms provide a way for scientists to study both the contribution of nature (genes) and the contribution of nurture (epigenetic mechanisms) in human behavior. If you only focus on the blueprints, as scientists have been doing for decades, the influence of the environment is impossible to fathom. (Dennis 2003; Chakravarti and Little 2003)
Let’s present an analogy, which hopefully will make the relationship between epigenetic and genetic mechanisms clearer. Are you old enough to remember the days when television programming stopped after midnight? After the normal programming signed off, a “test pattern” would appear on the screen. Most test patterns looked like a dartboard with a bull’s eye in the middle, similar to the one pictured on the following page.
Think of the pattern of the test screen as the pattern encoded by a given gene, say the one for brown eyes. The dials and switches of the TV fine-tune the test screen by allowing you to turn it on and off and modulate a number of characteristics, including color, hue, contrast, brightness, and vertical and horizontal holds. By adjusting the dials, you can alter the appearance of the pattern on the screen, while not actually changing the original broadcast pattern. This is precisely the role of regulatory proteins. Studies of protein synthesis reveal that epigenetic “dials” can create 2,000 or more variations of proteins from the same gene blueprint.