Stanford creates biological transistors, the final step towards computers inside living cells04/04/2013 23:10
Bioengineers at Stanford University have created the first biological transistor made from genetic materials: DNA and RNA. Dubbed the “transcriptor,” this biological transistor is the final component required to build biological computers that operate inside living cells. We are now tantalizingly close to biological computers that can detect changes in a cell’s environment, store a record of that change in memory made of DNA, and then trigger some kind of response — say, commanding a cell to stop producing insulin, or to self-destruct if cancer is detected.
Stanford’s transcriptor is essentially the biological analog of the digital transistor. Where transistors control the flow of electricity, transcriptors control the flow of RNA polymerase as it travels along a strand of DNA. The transcriptors do this by using special combinations of enzymes (integrases) that control the RNA’s movement along the strand of DNA. “The choice of enzymes is important,” says Jerome Bonnet, who worked on the project. “We have been careful to select enzymes that function in bacteria, fungi, plants and animals, so that bio-computers can be engineered within a variety of organisms.”
Like a transistor, which enables a small current to turn on a larger one, one of the key functions of transcriptors is signal amplification. A tiny change in the enzyme’s activity (the transcriptor’s gate) can cause a very large change in the two connected genes (the channel). By combining multiple transcriptors, the Stanford researchers have created a full suite of Boolean Integrase Logic (BIL) gates — the biological equivalent of AND, NAND, OR, XOR, NOR, and XNOR logic gates. With these BIL gates (pun possibly intended), a biological computer could perform almost computation inside a living cell.