Scientists pioneer a new revolution in biology by embedding film on DNA

If cells can be made to store information, the applications are vast — microbes could monitor environmental pollution and neurons could be programmed to record how the brain develops.

world Updated: Jul 13, 2017 15:30 IST
The Guardian
The Guardian
London
Eadweard Muybridge,Harvard Medical School,Seth Shipman
To build the prototype molecular recorder, the Harvard team hacked the immune defences that protect bacteria from invading viruses. (Reuters File)

His groundbreaking photos showed life in motion, from cantering bison to leapfrogging boys, and settled an argument that had long divided trainers and riders: do all four hooves of a racehorse ever leave the floor at once?

Now, more than a century later, the stills and animations of Eadweard Muybridge , the eccentric Englishman and father of the motion picture, have had a modern makeover. Where Muybridge captured his pictures on photographic plates, Harvard scientists have set them in DNA.

There is more to the feat than showing off. If cells can be made to store information, the applications are vast. Microbes could be turned into living sentinels to monitor environmental pollution. Meanwhile, neurons could be programmed to record how the brain develops in a living animal.

“We encoded images and a movie into DNA in a living cell which is fun, but it’s not really the point of the system,” said Seth Shipman, a geneticist at Harvard Medical School. “What we’re trying to develop is a molecular recorder that can sit inside living cells and collect data over time.”

To build the prototype molecular recorder, the Harvard team hacked the immune defences that protect bacteria from invading viruses. When a bacterium is breached by an intruding virus, it releases enzymes to chop up the virus’s genetic code. To make sure it is prepared for future attacks, the bacterium remembers the invader by adding a chunk of the virus’s genetic code to its own genome.

Shipman and his colleagues created strands of synthetic DNA in the lab that encoded in the letters G, T, C and A, the positions and shades of pixels found in an image of a hand and five pictures of a galloping horse taken by Muybridge in the 1880s. The scientists then fed the strands of DNA to E coli bacteria. The bugs treated the strips of DNA like invading viruses and dutifully added them to their own genomes.

The researchers left the bugs in a dish for a week during which time they grew and divided into new bacterial cells. Shipman then collected some of the bacteria and read out their genomes. He found that the synthetic strands of DNA, which carried all the information needed to reconstruct either the hand image or the pictures of the galloping horse, had been spliced into the bugs’ genetic code.

“We delivered the material that encoded the horse images one frame at a time,” Shipman said. “Then, when we sequence the bacteria, we looked at where the frames were in the genome. That told us the order in which the frames should then appear.” Even though the bugs had grown and divided over the week, they had retained the synthetic strands of DNA which Shipman used to reconstruct the images with 90% accuracy.

“What this shows us is that we can get the information in, we can get the information out, and we can understand how the timing works too,” he said. Details of the work are reported in Nature .

First Published: Jul 13, 2017 15:30 IST