Scientists have been able to store 2.2 petabytes in one gram of DNA
Since time immemorial, mankind has wanted to share and use
information for later use. First, it was through the caveman paintings and
symbols. Then we invented the alphabets, ideograms, numbers and other symbols.
Using these, books were written and stored for future generations, in palm
leaves, papyrus sheets or paper. The invention of printing brought the
Gutenberg revolution, making multiple copies easily and spreading education to
millions of people.
Printed books occupy space. Libraries and archives are bursting
at the seams. Enter the computer age and digitization using the binary code of
combining zeros and ones (0,1) for alphabets and other such symbols, and
reading them using the on-off electrical signals, which has made electronic
storage possible, cutting down the size and space for ‘hard copies’. Integrated
circuits, processors and related electronic wizardry have shrunk the size of computers
and storage devices from room-size to finger nail size.
But even so, the amount of information storable in a given ‘hard
drive’ is growing exponentially. “That means the cost of storage is rising but
our budgets are not”, as Dr. Nick Goldman of the European Bioinformatics
Institute at Hinxton, UK told The Economist he together with 4
colleagues at Hinxton and 2 from Agilent Technologies, California, U.S decided
to use DNA as the information storage
device, rather than electronics. Their paper titled “Towards practical,
high-capacity, low maintenance information storage in synthesized DNA” has just
been published in the journal Nature .
Why DNA? Indeed the question should be ‘why not DNA”. It is a
long chain, consisting of 4 alphabets (chemical units called bases and referred
to as A, G, C and T) put together in a string of sequence — similar to what the
English language does with its 26 alphabets and punctuation marks, or digital
computers with the combination of zeros and ones in chosen sequences. DNA has
been used since life was born over 2 billion years ago to store and transfer
information right through evolution. It is small in size — the entire
information content of a human is stored in a 3 billion long sequence of A, G,
C and T, and packed into the nucleus of a cell smaller than a micron
(thousandth of a millimetre). It is stable and has an admirable shelf life.
People have isolated DNA from the bones of dinosaurs dead about 65 millions
ago, read the sequence of bases in it and understood much information about the
animal. The animal (shall we say the ‘host’ of the DNA) is long since dead but
the information lives on.
DNA is thus a long-lived, stable and easily synthesized storage
hard drive. While the current electronic storage devices require active and continued
maintenance and regular transferring between storage media (punched cards to
magnetic tapes to floppy disks to CD...), DNA based storage needs no active
maintenance. Just store in a cool, dark and dry place!
In the Hinxton method , they moved away from the conventional
binary (0 and 1) code and used a ternary code system (three numerals 0, 1 and 2
using combinations of the bases A, G, C and T) and encode the information into
DNA. This novelty avoids any reading errors, particularly when encountering
repetitive base sequences. Also, rather than synthesize one long string of DNA
to code for an entire item of information, they broke the file down to smaller
chunks, so that no errors occur during synthesis or read-out. These chunks are
then read in an appropriate manner or protocol, providing for 100 per cent
accuracy.
How much information can be stored in DNA?
Goldman and co have been able to store 2.2 petabytes (a peta is a
million billion or 10 raised to power 15) in one gram of DNA.
What about the speed? And how does one read the files?
Today, the speed is slow and the reading using DNA sequencers is
expensive, but in time both the speed will improve and the cost come down
considerably.
What did Goldman and group store in DNA?
For starters, they stored all 154 sonnets of Shakespeare (in
ASCII text), the 1953 Watson-Crick paper on the DNA double helix (in PDF
format), a colour photograph of Hinxton (in JPEG) and a clip from the “I have a
Dream” speech of Martin Luther King (in MP3 format).
Natural selection and evolution have used DNA to store and read
out to make our bodies. And we are now using DNA to store and archive the
products of our brains. What a twist!
Posted By
Linda.R
HOS-LP2
BIS
[Source: The Hindu News Paper]
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