A transcriptor is a

transistor upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch ...

-like device composed of DNA and

RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...

rather than a

semiconducting material A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. I ...

such as

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ...

. Prior to its invention in 2013, the transcriptor was considered an important component to build biological computers.

Background

To function, a modern computer needs three different capabilities: It must be able to store information, transmit information between components, and possess a basic

system of logic A formal system is an abstract structure used for inferring theorems from axioms according to a set of rules. These rules, which are used for carrying out the inference of theorems from axioms, are the logical calculus of the formal system. A form ...

. Prior to March 2013, scientists had successfully demonstrated the ability to store and transmit data using biological components made of proteins and DNA. Simple two-terminal

logic gate A logic gate is an idealized or physical device implementing a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. Depending on the context, the term may refer to an ideal logic ga ...

s had been demonstrated, but required multiple layers of inputs and thus were impractical due to scaling difficulties.

Invention and description

On March 28, 2013, a team of bioengineers from Stanford University led by Drew Endy announced that they had created the biological equivalent of a transistor, which they named a "transcriptor". That is, they created a three-terminal device with a logic system that can control other components. The transcriptor regulates the flow of

RNA polymerase In molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that synthesizes RNA from a DNA template. Using the enzyme helicase, RNAP locally opens the ...

across a strand of DNA using special combinations of enzymes to control movement. According to project member Jerome Bonnet, "The choice of enzymes is important. 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." Transcriptors can replicate traditional AND, OR, NOR, NAND,

XOR Exclusive or or exclusive disjunction is a logical operation that is true if and only if its arguments differ (one is true, the other is false). It is symbolized by the prefix operator J and by the infix operators XOR ( or ), EOR, EXOR, , , ...

, and

XNOR gate The XNOR gate (sometimes XORN'T, ENOR, EXNOR or NXOR and pronounced as Exclusive NOR. Alternatively XAND, pronounced Exclusive AND) is a digital logic gate whose function is the logical complement of the Exclusive OR (XOR) gate. It is equivalen ...

s with equivalents, which Endy dubbed "Boolean Integrase Logic (BIL) gates", in a single-layer process (i.e., without requiring multiple instances of the simpler gates to build up more complex ones). Like a traditional transistor, a transcriptor can amplify an input signal. A group of transcriptors can do almost any type of computing, including counting and comparison.

Impact

Stanford dedicated the BIL gate's design to the

public domain The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because those rights have expired, ...

, which may speed its adoption. According to Endy, other researchers were already using the gates to reprogram

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...

when the Stanford team published its research. Computing by transcriptor is still very slow; it can take a few hours between receiving an input signal and generating an output. Endy doubted that biocomputers would ever be as fast as traditional computers, but added that is not the goal of his research. "We're building computers that will operate in a place where your cellphone isn't going to work", he said. Medical devices with built-in biological computers could monitor, or even alter, cell behavior from inside a patient's body. ''

ExtremeTech ExtremeTech is a technology weblog, launched in June 2001, which focuses on hardware, computer software, science and other technologies. Between 2003 and 2005, ExtremeTech was also a print magazine and the publisher of a popular series of how-t ...

'' writes:

UC Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public university, public land-grant university, land-grant research university in Berkeley, California. Established in 1868 as the University of Californi ...

biochemical engineer

Jay Keasling Jay D. Keasling is a professor of chemical engineering and bioengineering at the University of California, Berkeley. He is also associate laboratory director for biosciences at the Lawrence Berkeley National Laboratory and chief executive officer ...

said the transcriptor "clearly demonstrates the power of synthetic biology and could revolutionize how we compute in the future".

References

External links

*{{cite journal, title=Amplifying Genetic Logic Gates, author=Jerome Bonnet, author2=Peter Yin, author3=Monica E. Ortiz, author4=Pakpoom Subsoontorn, author5=Drew Endy, journal=Science, date=March 28, 2013, doi= 10.1126/science.1232758, pmid=23539178, volume=340, issue=6132, pages=599–603, bibcode=2013Sci...340..599B, s2cid=206546590 - original journal article, published in ''

Science Science is a systematic endeavor that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earli ...

''
Explanatory video
created by Drew Endy
NPR article
with series of moving pictures that explain how the transcriptor works
Public domain release
of the BIL gates technology American inventions DNA nanotechnology Molecular biology Theoretical computer science