In the foreseeable future, humans might carry microscopic natural computers inside their cells that could guard against disease and warn of toxic threats based on a Stanford research achievement. A team of engineers there has invented genetic transistors, completing a simple computer within a living cell, a major step forward in the emerging field of synthetic biology. The startling achievement, to be unveiled in Friday’s issue of the journal Science, presages the day when “living computers’ inside the human body could screen for cancer, detect toxic chemicals or even turn cell reproduction on and off. The computers could deliver true-false answers to virtually any biological question that might be posed within a cell. For instance: Is toxic mercury present? It could detect it. Also: They can count. This would be a useful tool when treating diseases like cancer, where cells divide uncontrollably. Suppose a liver cell carries a counter that records how many times it divides. Once the counter hits 500, for instance, the cell could be programmed to die. These cell-based computers will be a different kind of computer, Endy said. “We’re not going to replace the silicon computers. We’re not going to replace your phone or your laptop. But we’re going to get computing working in places where silicon would never work. “Any place you want a little bit of logic, a little bit of computation, a little bit of memory — we’re going to be able to do that,’ said Endy. Conceptually, it’s like electronics, where a transistor controls the flow of electrons along a circuit. But biology is the basis for what the team calls a “transcriptor,’ which controls the flow of an important protein as it travels along a strand of DNA. Transcriptors are a biological version of electrical engineers’ “logic gates’ — the building blocks of digital circuits that send and receive signals. The gates could derive true-false answers to virtually any biological question that might be posed within a cell. For instance: Is toxic mercury present? It could detect it. Also: They can count. This would be a useful tool when treating diseases like cancer, where cells divide uncontrollably. Suppose a liver cell carries a counter that records how many times it divides. Once the counter hits 500, for instance, the cell could be programmed to die. Endy’s work “clearly demonstrates the power of synthetic biology and could revolutionize how we compute in the future,’ said UC Berkeley biochemical engineer Jay Keasling. He is director of the Synthetic Biology EngineeringResearch Center that helped support research at Stanford. Endy, recruited to Stanford from the Massachusetts Institute of Technology, is a builder — a civil engineer who started with boyhood Erector Sets and Legos, later working on bridge repair projects for Amtrak. Now he’s building with the stuff of life to use it as a technology platform. “Biology is not just a science of discovery, but also a technology for making things,’ he said.
