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About this Article
Written by: Trevor Nelson
Written on: May 7th, 2013
Tags: biomedical engineering, computer science, health & medicine
Thumbnail by: Bonnet/Endy/ Stanford University School of Engineering
About the Author
Current sophomore studying mechanical engineering at Viterbi. Very passionate about running, with six marathons under his belt. Believes the smallest things in life have the biggest impact.
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Volume XVII Issue I > Cellular Computing: Pushing the Boundaries of Computation
Dr. Endy and his team have developed a cellular logic gate, dubbed a transcriptor, which was the last of three things necessary to making cellular computing a reality: a way to store information, a method of transporting information, and something to perform basic logic operations. Storage has been achieved through recoding DNA into storing massive amounts of data. By re-configuring a harmless virus, data is able to be transferred between different cells and components in a cell. Lastly Endy’s transcriptor is able to process basic logic. Though in the infant stages of research, the possibilities of these breakthroughs include combating diseases and making livestock and crops safer.

Introduction

Thirty miles outside of Shanghai,China, a railway manufacturing plant spills a highly dangerous chemical that seeps into a river that local farmers depend on to irrigate their crops. In a couple days these crops turn an iridescent blue, alerting the farmers to the contamination. Halfway around the world, an absent minded man looks down at his phone at a notice that popped up, alerting him of low glucose levels, and averting what could have been a life threatening event.
What do these two seemingly disparate events have in common? They’re both scenarios that can be made possible with biological computing, utilizing an organism's cells to perform many of the same tasks that modern day computers can. Transcriptors in the crops (the direct parallel being transistors in most modern day electronics) detect the chemical inside the plant and when it reaches a threshold limit, releases RNA Polymerase along strands of DNA, causing the gene that controls the color to express itself as blue rather than its standard color. Similarly for the example with the man, transcriptors monitor the flow of glucose molecules in the blood stream. This information can be stored in strands of DNA, whose sole purpose is the storage of data, and then accessed by a computing device that’s built to be integrated with these new synthetically engineered computing systems, allowing the collection of data so that corrections can be made upon the results. Theoretically these systems could even eliminate the need human correction; going off of the example of the man with low glucose levels, the cellular computer could then deliver specific amounts of insulin into the bloodstream.

Background

Electronic devices that perform computations, “computers”, consist of three main things: a way to store information , a way to transfer information between different parts, and the ability to process a basic system of logic [1]. Likewise if a biological system wants to act as a computational device it would have to have these same three things. Relatively early on it has been demonstrated that it is easy to store information by encoding DNA in a certain way [2], and the transferring of information has been done by re-configuring certain non-harmful viruses [3]. The missing link was a transistor like operator that could process basic logic, which has eluded researchers for a while.
Recently, biological engineers led by Drew Endy at Stanford University have made that final breakthrough, developing a “transistor” (that they have named transcriptor) made of DNA and RNA that is capable of acting as logic gates, such as AND and XOR (shown in Fig. 1) [4]. Now with all three components in place, further proof of concept and initial research should start to emerge, paving the way for many future possibilities.
Bonnet/Endy/ Stanford University School of Engineering
Figure 1: Cellular L
Bonnet/Endy/ Stanford University School of Engineering
Figure #: caption.
ogic Gate.