Thursday, December 17, 2009

The Cecil B. DeMille of Our DNA

“DNA is an abbreviation for deoxyribonucleicantidisestablishmentarianism, a complex string of syllables.”
  ~ Dave Barry

All human life starts with a single cell that then copies itself some 10 trillion times over. Since all cells start out the same, how does one group know to become a nose and another that most wonderfully named body part, the Islets of Langerhans? The epigenome, that's how.

If I understand things correctly*, the epigenome is the Cecil B. DeMille of our DNA, directing the complexity of cellular assignments on a spectacular scale. Here is what the European Union's Epigenome Network of Excellence says about it: "The field of epigenetics has emerged to bridge the gap between nature and nurture. In the 21st century you will most commonly find epigenetics defined as 'the study of heritable changes in genome function that occur without a change in DNA sequence.'"

Scientists believe the epigenome influences what individual cells become and continues to influence development throughout life. Identical twins are a favorite research subject, since they start life with identical genes that gradually change and diverge, sometimes radically. The environment, diet and aging all may play a role in producing the changes the epigenome makes to DNA. And, yes, those changes can be passed on to the next generation.

Earlier this year, PBS's Nova aired a wonderful introduction to epigenetics called "The Ghost in Our Genes" — excerpts and a wealth of related information are available on the PBS Web site; it's well worth a visit.

The New York Times has also been on the case for some time. In late 2008 the Times published this massive partial map of a single chromosome; then, in February 2009, came this substantial but user-friendly explanation of what all the shouting is about.

Now, a publication called Genetics Times reports a significant breakthrough in the field: researchers at the Salk Institute have identified "the first detailed map of the human epigenome." Even though it's just one chromosome, this is a really big deal.

Joseph Ecker, Ph.D., professor and director of the Genomic Analysis Laboratory at the Salk Institute and a member of the San Diego Epigenome Center, led the research. As Genetics Times explains, "Ecker's group will now begin to examine how the epigenome changes during normal development as well as examining a variety of disease states." Researchers foresee potential applications for problems as diverse as cancer and mental disorders.

Another promising area: tissue regeneration. The December 13, 2009 edition of 60 Minutes on CBS had a fascinating segment on efforts to grow new body parts in the lab and, in some cases, in our own bodies. (You can see excerpts here.) Imagine what could be done with more knowledge of the epigenome — transplant waiting lists could eventually become a thing of the past.

Even if you're not sure what to make of the epigenome, take a listen to a little ditty scientist Matt Barnett has written about it — "The Epigenome Song."  As the man sings, "Eating for your epigenes will make you strong and lean and mean." 

“The capacity to blunder slightly is the real marvel of DNA. Without this special attribute, we would still be anaerobic bacteria and there would be no music.”
~ Lewis Thomas

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* Note to readers: Divinipotent Daily is no scientist — math anxiety saw to that long ago. I'm just a chronically curious person who is drawn like a bee to wildflowers to explanations of how and why. As a result, I subscribe to science blogs and consumer science magazines, follow scientists on Twitter, read the occasional science book, develop related enthusiasms and become increasingly incomprehensible to my loved ones.

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