When you think of DNA, odds are, you picture the famous double helix, a ladder-like structure elegantly twisted like a corkscrew.
But DNA doesn't always assume this form. The existence of one shape of DNA in humans, in particular — a four-stranded knot of genetic code — has been controversial among scientists for years. Because this so-called i-motif loves acidic environments (a condition that scientists can create in the lab but doesn't naturally occur in the body), many scientists thought that it couldn't possibly exist in human cells.
But in recent years, studies have pointed to the possibility that this bizarre form of DNA could, in fact, exist in living humans. Now, a new study published today (April 23) in the journal Nature Chemistry provides the first direct evidence that it does exist and that it may play an important role in regulating our genes. [Unraveling the Human Genome: 6 Molecular Milestones]
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