Adventures in Synthetic Biology. Story by Drew Endy and Isadora Deese and the MIT Synthetic Biology Working Group. Art by Chuck Wadey. Originally published in 2005. Available for free, PDF

Reviewed by Carl Zimmer

In the early 1970s, three scientists ran a simple experiment. They cut genes out of the DNA of a frog and inserted them into E. coli. The frog genes functioned in their new home. The microbe was able to make RNA from them, the first step in translating the information in genes into proteins. And when the microbe divided in two, it made new copies of the frog genes along with its own. It was, to some extent, a microbe-frog hybrid.

The experiment was simple only in its concept, though. It had taken the scientists–Herbert Boyer, Stanley Cohen, and John Morrow–years of research to find the tools to do the job, such as enzymes that bacteria use slice up the DNA of invading viruses. And because it had been the first time that anyone had achieved such a feat, it shook the world.

On the one hand, many scientists and pharmaceutical companies saw a huge potential future for gene pasting. Imagine E. coli carrying the gene for human insulin, for example. Instead of harvesting insulin from cow pancreases, it would be possible to brew insulin the same way people brew beer. One company that sprang up in the wake of the frog-microbe experiment, Cetus, promised that by 2000, virtually all diseases would be cured with proteins made through the genetic engineering that Boyer and his colleagues had invented. 

On the other hand, critics saw the apocalypse. Some feared that insulin-pumping E. coli would run amok and spread an epidemic of diabetic comas. If the world embraced genetic engineering, the eminent biologist Erwin Chargaff warned, "the future will curse us."

Forty years after Boyer and his colleagues created their frog-microbe hybrid, the extreme predictions at either end of the prophecy spectrum have failed to come true. No diabetic coma epidemic. (E. coli burdened with human insulin genes can't compete with their lean, wild relatives.) Instead, millions of diabetics get a reliable supply of insulin from the microbes. On the other hand, just having a microbial factory doesn't automatically mean you can cure all diseases. Or even many of them. (I write more about how E. coli launched the biotech industry in my book Microcosm.)

Now, however, genetic engineering is morphing into something new. In the late 1990s, a group of engineers and biologists came together to try to manipulate cells the way they might manipulate the circuits in computer. The analogy between computers and cells is far from perfect, because our bodies are the product of evolution rather than a computer factory. Nevertheless, we have genes that switch other genes on and off, and some genes require inputs from several other genes before they make their own proteins. Cells use this genetic circuitry to detect signals, to process information, and to make decisions. The engineers and biologists set out to rewire that circuitry, inserting many different genes in combinations that would produce new behaviors. They called their project synthetic biology.

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