Behind the study: Life as we know it
All living things are made up of cells -- tiny factories that power everything an organism does. Cells are the smallest things that can be alive. Cellular factories are built and operated by thousands of proteins, which are governed by a dictatorial manager known as DNA.
Like a chemical instruction manual for life, DNA tells the factory which of 20 amino acids to use when building a particular protein.
DNA has a remarkably limited vocabulary, one that is the same in the cells of bacteria as it is in humans. This genetic language is designed using four basic chemicals, which biologists represent with four letters. Each necessary instruction is spelled out in a series of single words, each using just three of these four letters.
Error in editing
Like an endlessly re-released instruction manual, DNA's directives are constantly edited for clarity and brevity with each issue. Schimmel's group messed with this cellular editing function, he explains, "invading the genetic code and making it less accurate."
This caused the factory to make mistakes. And one of those errors was to incorporate an amino acid that occurs naturally but is never normally seen in proteins.
Using a different approach, the other research group, an international team led by Lei Wang who also works out of the Scripps Institute, changed the meaning of one of the three-letter words, instructing the factory to insert a 21st amino acid into a protein.
Another dark force?
While cloning and other forms of genetic engineering have been viewed as potentially dangerous by some, researchers said there is little need to fear takeover by a laboratory ET. But NASA's Meyer pointed out the obvious long-term concern:
"One might create an organism with a selective advantage that could supplant native organisms with the potential of serious unintended consequences," he said.
But August Böck, of der Universitat, Institut fur Genetik und Mikrobiologie in Munich, said the procedure is so complicated and, for now at least, totally dependent on a laboratory setting, that there is no danger.
In an accompanying analysis in Science, Böck called the work's evolutionary implications fascinating and said it would be "hugely beneficial" to biotechnology. But he added that it is unknown whether the organisms can be made dependent on the unnatural amino acid for their survival and growth. Only if this happens can a true alternate life form be declared, one that can evolve based on different rules of biology.
"This is not a new life form which has been created," Böck said in an e-mail interview. "It is a change of some basic principles with which the genetic information is faithfully translated into proteins."
Jason Dworkin, a SETI Institute biochemist who currently studies astrophysics at NASA's Ames Research Center, said because the work provides tools to manipulate the mechanisms of biology, it could be "a step toward artificial life."
But Dworkin said, "That goal, and the moral questions it raises, is very difficult. As with any powerful tool, there will be dangers [and other issues] to resolve."
Either way, Schimmel said the benefits of advancing understanding of living systems, with the possibility of having useful applications in medicine, technology and astrobiology, "far outweigh any dangers that I can imagine."
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