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What is the essence of life? Scientists say they're a step closer to finding out. They've created an organism with what appears to be the minimum number of genes to sustain the life form. As NPR's Rae Ellen Bichell reports, the discovery could lead to new manufacturing methods.
RAE ELLEN BICHELL, BYLINE: In the mid-1990s, a few top biologists set out on a quest to make an organism that would have only the genes that are absolutely essential for survival.
J. CRAIG VENTER: We were asking basic fundamental questions of life. What did we think might comprise the most primitive cell?
BICHELL: That's J. Craig Venter, a genome scientist and founder and CEO of a research institute in his name. He says it was mostly philosophical curiosity.
VENTER: We decided it gave us a chance to ask unique questions about fundamental biology and origins of life.
BICHELL: This week, two decades later, Venter and colleagues published one possible answer in the journal Science. They've created a single-celled organism with only 473 genes. That gives it the smallest genome of any known living thing that can reproduce on its own. For comparison, humans have about 20,000 genes.
They started with an already very simple bacterium. If a gene could be removed without disrupting the cell's ability to live, grow and reproduce, it was. Out it went. And here's the interesting part. They had to keep a lot more genes than they expected. There are about 150 of them, a third of the cell's genome, that it can't live without. But no one knows what they're for. Venter says that's the next goal, to figure out what the heck all those mysterious genes actually do.
VENTER: This is essential for understanding all of life, to understand the basic components.
BICHELL: But not just for the pure knowledge. He and his colleagues have bigger goals. They eventually want to be able to design cells that would produce whatever chemical they want them to. And that sense, the minimal cell could be like the frame of car, a starting point on which to build.
VENTER: So it's sort of a basic component that we can add things to.
BICHELL: For example, Venter says, you might add in a gene from some odd deep-sea creature and be able to engineer it to eat carbon dioxide and spit out fuel.
VENTER: If you just have a cassette of those genes that you can just plug in, that will enable design to go much faster
BICHELL: One of Venter's companies, Synthetic Genomics Inc., already applied to patent the process of making this minimal genome. But, says George Church, the process is nowhere near grand industrial applications. He's a professor of genetics at Harvard Medical School.
GEORGE CHURCH: I think the main reason it should be celebrated is that it is achievement of a 20-year goal.
BICHELL: After all, he says, people are already manipulating individual genes using other, faster methods. The process of changing an entire genome would have to be speedy, cost effective and widely applicable for it to get to a point where it's useful in producing something like biofuel. Church, who does this kind of work too, says people should be thinking about worst-case scenarios.
CHURCH: Most of the organisms we manipulate in the laboratory are so weak that they wouldn't survive outside the laboratory.
BICHELL: But it is a possibility.
CHURCH: So anything that has a chance - even a remote chance - of spreading through the wild should be something where we're very cautious and have mechanisms in place to limit it and/or reverse it.
BICHELL: And right now, there aren't really any. Rae Ellen Bichell, NPR News.
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