Img/2012/5/25/dnai.jpgWashington: It may sound like the stuff of a sci-fi thriller, but scientists claim to have developed a way to turn living cells into rewritable digital data storages -- like "living hard drives".
After numerous attempts, a team of researchers from the Stanford University`s Schools of Engineering and Medicine finally found a method for repeatedly encoding, storing, and erasing the digital information within the DNA.
Keeping data in cells could have widespread applications in future studies, the researchers said. "It`s a tool to study processes where you need to track history of cells," lead study researcher Jerome Bonnet said.
"Most of the questions in biology are questions about history," said Ton Subsoontorn, who was part of the research. "You ask, `Why does this cell become a cancer cell?` and `Why does this cell stay a normal cell?`"
According to the team, just as a computer chip stores data by flipping an electrical bit or magnetic field on or off, the DNA system flips the orientation of a section of DNA to indicate an on-or-off bit, The Stanford Daily reported.
The research involved establishing precise control over two enzymes -- integrase and excisionase -- that work in opposition to manipulate proteins within bacterial cells. The team already showed in previous research how to irreversibly flip a stretch of DNA about 500 base pairs in length.
"We needed to reliably flip the sequence back and forth, over and over, in order to create a fully reusable binary data register," Bonnet said. "So we needed something different."
The team had lots of early success flipping the sequence in either direction independently, but struggled to make both systems work within the same cell to create re-writable data.
The challenge took 750 trials over three years before the team succeeded. "We now have enzymes which can bind to the sequence, cut it, flip it and paste it in new orientation," Bonnet said.
The enzyme system that Bonnet`s team produced was adapted from the behaviour of a virus, said Subsoontorn. Some viruses attack bacteria by splicing their own DNA into the genome of the bacteria. The research team`s work used enzymes from those viruses for its manipulations.
According to Subsoontorn, the DNA region being flipped is a promoter, meaning it signals for the expression of another genetic region. In one example, they placed a gene that makes the bacteria glow pink and another that make the bacteria glow blue on either side of the promoter.
Flipping the promoter then allowed the team to change the bacteria`s colour. Long-term applications for the idea are far more practical than just colour change, the team said.
For example, if the system is expanded to have more bits, a cell could record data about its own life cycle, which would be crucial for research on ageing and cancerous cells.
Keeping data could help bioengineers because they could use the data to learn the behaviours of cells in a system, the researchers said.
The DNA system also represents an advance because silicon computer chips are not yet small enough to fit within cells to take data. However, the DNA system still has advantages in the long term, Bonnet said.
Subsoontorn said some cells grow and divide so rapidly that silicon chips would not function, anyway. DNA, however, can grow and multiply along with its cell, he said.
Next, the team hopes to expand the capability of the data storage to a multi-bit system, progressing toward a scale where it can store practical amounts of data for real use.
First Published: Friday, May 25, 2012, 19:41