Adding Letters to the DNA Alphabet

semi-synthetic bacterium

Credit: William B. Kiosses

The recipes for life, going back billions of years to the earliest single-celled organisms, are encoded in a DNA alphabet of just four letters. But is four as high as the DNA code can go? Or, as researchers have long wondered, is it chemically and biologically possible to expand the DNA code by a couple of letters?

A team of NIH-funded researchers is now answering these provocative questions. The researchers recently engineered a semi-synthetic bacterium containing DNA with six letters, including two extra nucleotides [1, 2]. Now, in a report published in Nature, they’ve taken the next critical step [3]. They show that bacteria, like those in the photo, are not only capable of reliably passing on to the next generation a DNA code of six letters, they can use that expanded genetic information to produce novel proteins unlike any found in nature.

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Summer Reading Suggestions from Scientists: Harold Varmus

Summer ReadingSummertime! Long weekends, a vacation, the threat of boredom. Time for uninterrupted reading—on beaches or in air-conditioned bedrooms. A chance to look beyond the best-seller lists or the daily news to dive, with full concentration, into one or two books that some friend has argued might be a life-changing experience. In that spirit, here are two for which I would make that argument to almost any friend.

In the sphere of science: The Age of Wonder: The Romantic Generation and the Discovery of the Beauty and Terror of Science, by Richard Holmes (HarperCollins, 2008). Holmes is primarily a literary biographer (of Coleridge and other Romantic poets), but also an art historian and a science junkie, who has written about ballooning and women scientists. Of the many books I’ve read about the growth of the scientific enterprise, The Age of Wonder stands out for several reasons: its deep engagement with the full range of cultural and political currents in which science arises; its focus on the excitement about discovery—geographical, astronomical, chemical, biological—that permeated the late 18th and early 19th centuries; and its absorption with personal histories of people who made those discoveries. Holmes is a superb storyteller and drawn to the complexities of life (especially in Britain) that influenced the talented people—Joseph Banks, Humphry Davy, several members of the Herschel family—who made novel observations that changed our perceptions of the world and solidified the place of science.

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Genome Exhibit Opens at Smithsonian

Photo of one of the interacive touch screen exhibits

Credit: Sasan Azami-Soheily, National Human Genome Research Institute, NIH

To celebrate the 10th anniversary of the completion of the Human Genome Project—a 13-year endeavor that I had the privilege of leading—the Smithsonian’s National Museum of Natural History in Washington, DC is launching an absolutely fantastic exhibit called “Genome: Unlocking Life’s Code.”

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