Transistors Made of DNA and RNA: Stanford's Newly Created Biological Computer

Computers have continuously evolved since their first creation. They've gone from being made out of vacuum tubes and electricity to transistors made from semiconducting materials. Now, scientists propose another step on this evolutionary path--using DNA and RNA in the place of gears and electrons.

A team of bioengineers from Stanford University have created a biological transistor, which they've named the transcriptor, made from DNA and RNA. The transcriptor essentially allows engineers to compute inside living cells. This could help record when the cells have been exposed to certain stimuli or environment factors, aiding in future research. It could even turn cell reproduction on and off as needed--something that could have huge implications in the field of medicine.

"Transcriptors are the key component behind amplifying genetic logic--akin to the transistor and electronics," said Jerome Bonnet, one of the researchers, in a news release.

In electronics, a transistor controls the flow of electrons along a circuit. The transcriptor, similarly, controls the flow of a specific protein known as RNA polymerase as it travels along a strand of DNA. In this particular transcriptor, the researchers were able to repurpose a group of natural proteins called integrases in order to realize digital control over the flow of the RNA polymerase. This allowed them to engineer amplifying genetic logic.

The researchers can perform some amazing feats with these trascriptors. Using them, the scientists have created what are known as logic gates, which can derive true-false answers to virtually any biochemical question that might be posed within a cell. They refer to these gates as "Boolean Intergras Logic" gates or BIL gates. While these gates don't necessarily make a biological computer by themselves, they are a crucial component.

How did they manage it? In order to create the transcriptors and logic gates, the researchers calibrated combinations of enzymes--the integrases--that control the flow of RNA polymerase. The selection of theses enzymes was crucial for success; in the end, the researchers chose ones that function in bacteria, fungi, plants and animals so that in the future, bio-computers could be engineered within a variety of organisms.

"The potential applications are limited only by the imagination of the researcher," said co-author Monica Ortiz in a news release.

The biological computer may not have been created just yet, but it holds enormous potential. It could be inserted into human cells to halt or start cell reproduction, and could have numerous applications in research. In order to speed the creation of this computer, the researchers have contributed all of BIL gates to the public domain so that others can immediately harness and improve the tools.

"Most of biotechnology has not yet been imagined, let along made true. By freely sharing important basic tools, everyone can work better together," said Bonnet in a news release.

The details of these findings are published in the journal Science.