DNA is pretty amazing. It is a chemical code that stores all the information needed to make every life form on earth. In my novel Thirty, memories are encoded into DNA sequences to be stored. Recently scientists did just that in bacterial cells.
Synthetic biologists at MIT in Boston borrowed retrons from bacteria to create a DNA based memory system inside cells called SCRIBE (Synthetic Cellular Recorders Integrating Biological Events). Retrons are a tool that bacteria use to edit the DNA of their hosts. In the SCRIBE system retrons were used to cause a mutation in a particular gene only if cells were exposed to a specific stimulus – either light or a chemical.
The scientists grew large colonies of bacteria containing these artificial retrons. The bacteria were then exposed to either light or a chemical for varying amounts of time. This caused a mutation in an antibiotic resistance gene, so the treated cells wouldn’t grow in the presence of an antibiotic. This was an easy readout of which cells had the mutation. The bacteria were also sequenced to see how many contained the expected mutation. The percentage of cells with the mutation correlated with the time of exposure or the amount of exposure to the stimulus. So if more chemical was used or the chemical or light was on the cells for longer, more cells had the mutation.
So now these cells had a ‘memory’ of their environment encoded in their DNA.
Cellular memory isn’t new. Mammalian cells use epigenetic marks on DNA to transmit memory of environmental factors like diet from parent to offspring. But SCRIBE is the first system to easily manipulate cellular memory to produce a usable readout. This system can be used to target any gene for mutation and can be coupled with many different types of stimulus. So it can be tailor made to different purposes.
SCRIBE could be used to create cells that can test water or other environments for toxic chemicals or pollutants. Hopefully it could one day be adapted to human cells. Then it could be used to study the signals that control how embryos develop. Or perhaps to detect cancerous cells.
I’ll be eagerly watching to see how this tool is used in the near future.
The Scientific Papers: