You might not think a lone E. coli bacterium has much in the way of memory. But now, researchers have hacked their DNA so that they can store memories of their environment—working much like an old tape recorder.
New Scientist reports that chunks o DNA code in E. Coli called retrons carry the genetic code for enzymes that generate new strands of DNA that are inserted into the genome. Now, they've been engineered so that they produce DNA that corresponds to detection of certain ambient conditions in the surrounding environment—the presence of a certain chemical, say, or bright light. That new chunk of DNA chunk is then effectively a memory of what's happened around them. The results are published in Science.
What's interesting, though, is that the sensing and recording is only partially efficient. New Scientist explains:
As time goes by, more of the cells will respond to the input and record the memory. By calculating at a certain point how many of the cells carry the memory, it's possible to work out either the input's strength, or the length of exposure... It's a signal that accumulates over time rather than an all-or-nothing switch... In other words, its analogue rather than digital.
Which may sound like a step back, but the researchers claim it could be used to great effect in the human body, sensing and recording events and exposures that cause damage to our cells, in the long-run providing the inside story of health inside our body. [Science via New Scientist]
Image by Sanofi Pasteur