A couple of years ago I bought a 30GB iPod classic for Christmas. At that time I couldn’t imagine what I would do with all that storage capacity, but it was the same price as an 8GB iPod nano, so I bought it nonetheless. Less than a year later, I ran out of space on my iPod. This year for my birthday my wife gave me a 160GB iPod. And in less than three months, I’ve already used about a third of the available storage space.
Data proliferation is not just a problem for me. It’s a widespread concern as more and more information technology applications demand more compact data processing and storage circuitry. Some technologists think that DNA represents a possible solution to these issues. One gram of this biomolecule can harbor as much information as 1 trillion compact discs!1
DNA can serve as a storage medium because, in essence, this molecule is an information-based system. In fact, DNA’s chief function is data storage—housing the information necessary to make all the proteins used by the cell.
The cell’s machinery forms the polynucleotide chains of DNA (which twirl around each other to form a double helix) by linking together four different nucleotides, abbreviated A, G, C, and T. The sequence of nucleotides in the DNA strands represents information. (For example, the nucleotide sequence that specifies the production of a single protein chain is called a gene.)
In his book Information and the Origin of Life, information theorist Bernd-Olaf Küppers points out that the structure of DNA’s information closely resembles the hierarchical organization of human language. Think of nucleotides functioning as alphabet letters, genes like words, and so on.
Technologists hope to take advantage of the information-housing properties of DNA for data storage applications. One recent proof-of-principle study conducted by a team from Japan demonstrated that the genome (entire genetic makeup) of a living organism (the bacterium, Bacillus subtilis) could be used to maintain data.2 When stored within an organism’s genome, data exists in a more robust format than when housed in magnetic media and silicon chips. These two nonliving systems can be readily destroyed and their contents lost without constant maintenance. In contrast, living organisms can reproduce. As they do, the information harbored in their genomes will be passed on to the next generation. This inheritance makes it possible to maintain information over extensive periods of time, perhaps up to hundreds of thousands of years.
The Japanese researchers treated sequences of nucleotides as strings of data. Using combinations of two nucleotides to represent the numbers of a hexadecimal system (42=16), they employed DNA sequences to represent all the characters on a keyboard and, consequently, encoded a message within a DNA sequence. Using these representations, they were able to prepare a synthetic piece of DNA that contained the message: “E=mcΛ2 1905!” The team then incorporated the laboratory-made DNA into the B. subtilis genome in multiple locations. This redundancy insured that mutations to the genome would not degrade or destroy the message. The repeated sequences also allowed them to recover the message in a fairly straightforward manner. The scientists showed that the message could be readily retrieved by sequencing the organism’s genome and performing multiple alignments of the sequence. Since the message was encoded within the genome multiple times, it can be easily distinguished from the “noninformation” within the genome.
Practical applications for DNA storage remain for the future. But, as this study illustrates, the advances needed to matriculate this technology are happening at a fast pace. And the payoffs could be huge. In the meantime, the use of DNA as a digital storage medium carries more immediate significance—not technological, however, but theological.
Data storage capacity within the structure of DNA underscores the notion that information is housed in this biomolecule. DNA data storage makes it clear that biochemical information is truly information. And information serves as a potent marker for intelligent design. Human experience consistently teaches that information emanates from intelligence. Messages come from a mind. Information, in whatever form it takes, is not limited to communicating ideas, needs, and desires between human minds. As this discovery shows, information has become—more than ever—an integral part of modern technology.
The information content of DNA, therefore, makes it rational to believe that life must have come from an intelligent agent, a Creator. It also makes it realistic for me to hope for a really juiced up iPod in the not-so-distant future.
- Gheorghe Păun, Grzegorz Rozenberg, and Arto Salomaa, DNA Computing: New Computing Paradigms (Berlin, Germany: Springer-Verlag Berlin Heidelberg, 1998), 19–41.
- Nozomu Yachie et al., “Alignment-Based Approach for Durable Data Storage into Living Organisms,” Biotechnology Progress 23 (2007): 501–05.