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英文原稿
Some bacteria have evolved a powerful system, called CRISPR, to fight viral infections.
When a virus strikes, a bacterium captures and stores a short, identifying sequence of the virus’s DNA—a sort of genetic “memory card.”
If the same virus attacks future generations of the bacteria, they use the memory card to guide a killer enzyme to the identical sequence in the new invader and cut it away.
Scientists have co-opted this natural molecular machinery not only to turn off the action of a gene but also to insert new genetic code into living organisms, including humans.
CRISPR has sparked an explosion of research—and a heated ethical debate.
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