Scientists havesuccessfullycreated a pair of DNA nucleobases, which, likeadenine, guanine, cytosine, and thymine in natural DNA, can copy themselves nearly as well as the real thing.

The language of life is about to expand its vocabulary. An international team of researchers discovered that the body's copying machine for DNA works in the same way for manmade, artificial building blocks of DNA as it does for the natural kind.

If scientists find artificial DNA building blocks work well and are safe to use, the extra building materials could create DNA that codes for new molecules that the body can't make now. The artificial DNA could also form the basis of a partlysynthetic organism.

The DNA code in living things is made of four different molecules, called bases, that are nicknamed A, T, C and G. In a double row of DNA, the bases always link up to each other in a specific way, with A's matching with T's and C's matching with G's. In 2008, a team of researchers created a third, artificial pair of DNA molecules made to match with each other, named NaM and 5SICS. In this new study, some of the same researchers used a technique calledX-ray crystallographyto take pictures of A, T, C, G, NaM and 5SICS while they were getting copied in a test tube.

DNA is an important bodily process that happens often, so that cells can pass their genetic information on to new cells that are created all the time, such as skin or blood cells that develop to replace old, worn-out cells.

After NaM and 5SICS were made, several other groups of researchers found that a natural strand of DNA with NaM and 5SICS added to it will still copy itself nearly as well as all-natural DNA. Scientists didn't know why it worked so well. They worried they had somehow "tricked" the body's DNA copying machine, called DNA polymerase, said Floyd Romesberg, a chemist at the Scripps Research Institute in La Jolla, Calif. Romesberg was one of the principal inventors of NaM and 5SICS and was involved inthis new study, published online yesterday (June 3) in the journal Nature Chemical Biology.

The natural base pairs A, C, G and T have specific shapes and line up neatly with each other along their edges when they're inside a DNA helix. Scientists believe their shape and neat fit are important for DNA polymerase to work properly. On the other hand, NaM and 5SICS aren't shaped anything like the natural bases. They don't use the same chemical bonds as natural bases do and they don't line up edge-to-edge. [Move Over, DNA, and Meet the More Durable XNA]

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Scientists create artificial DNA molecule