Reading and writing in DNA is slower than in other media, however, which makes it better suited for archival storage of massive amounts of data, rather than for quick retrieval or data processing. "Imagine that you had really cheap video recorders everywhere," Church said. "Just paint walls with video recorders. And for the most part they just record and no one ever goes to them. But if something really good or really bad happens you want to go and scrape the wall and see what you got. So something that's molecular is so much more energy efficient and compact that you can consider applications that were impossible before."
About four grams of DNA theoretically could store the digital data humankind creates in one year.
Although other projects have encoded data in the DNA of living bacteria, the Church team used commercial DNA microchips to create standalone DNA. "We purposefully avoided living cells," Church said. "In an organism, your message is a tiny fraction of the whole cell, so there's a lot of wasted space. But more importantly, almost as soon as a DNA goes into a cell, if that DNA doesn't earn its keep, if it isn't evolutionarily advantageous, the cell will start mutating it, and eventually the cell will completely delete it."
In another departure, the team rejected so-called "shotgun sequencing," which reassembles long DNA sequences by identifying overlaps in short strands. Instead, they took their cue from information technology, and encoded the book in 96-bit data blocks, each with a 19-bit address to guide reassembly. Including jpeg images and HTML formatting, the code for the book required 54,898 of these data blocks, each a unique DNA sequence. "We wanted to illustrate how the modern world is really full of zeroes and ones, not As through Zs alone," Kosuri said.
The team discussed including a DNA copy with each print edition of Regenesis. But in the book, Church and his co-autho
|Contact: David Cameron|
Harvard Medical School