Synthetic Life Seeks Work

Aug 25, 2015

By Brian Alexander

In the May 15, 2014, edition of the journal Nature, Floyd Romesberg’s chemistry lab at San Diego’s Scripps Research Institute published a paper titled “A Semi-Synthetic Organism with an Expanded Genetic Alphabet.” Romesberg and his colleagues had created a bacterium incorporating chemical building blocks that, as far as anybody knows, have never been part of any earthly life form.

There had been previous claims to “creating life.” Genome pioneer Craig Venter led a team that manufactured a genome for a germ that causes pneumonia in cows, but their effort used the familiar chemical bases of DNA, known by the letters A, G, C, and T. Romesberg’s group, on the other hand, added two additional letters, dubbed X and Y. When the bacteria successfully replicated X and Y in succeeding generations, Romesberg’s lab could claim to have made the first living thing with an expanded genetic code.

“People would ask what the big deal is, and I said, ‘Imagine you had a language with only four letters,’” Romesberg says. “‘It would be clumsy and would really curtail the kinds of stories you could tell. So imagine two more letters. Now you could write more interesting stories.’”


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3 comments on “Synthetic Life Seeks Work

  • @OP link – This sort of “kill switch” is meant to assuage anyone who wonders what happens if the bacteria escape. But it isn’t foolproof. Both Romesberg and Church reported a tiny fraction of the bacteria managed to slip the genetic handcuffs via mutation. That means if they were released outside the lab, an artificial organism might somehow scavenge up a substitute chemical from the environment to replace the critical one fed to it in the labs. Or it might exchange genes with other organisms it runs into outside a lab dish. Such an event could allow modified germs to live and reproduce.

    So with 2 extra letters, care needs to be taken about the possibility of producing and accidentally releasing, new life forms with an extended genetic code.



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  • Hi Alan. Did you see the program on 4 last night with Jim Al-Khalili explaining quantum physics? I was especially interested in the last part of the program on quantum tunnelling and quantum evolution. He showed an experiment they are carrying out in his college that uses heavy water which seems to stop the mutation of bacteria. Do you know if this is a first?



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  • Olgun
    Aug 28, 2015 at 7:06 am

    Hi Alan. Did you see the program on 4 last night with Jim Al-Khalili explaining quantum physics? I was especially interested in the last part of the program on quantum tunnelling and quantum evolution.

    Yes! I thought the tunnelling points about substituting Deuterium for Hydrogen quite interesting.



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