CRISPR used to convert bacteria into microscopic tape recorders


Tape recorders convert temporary signals, such as badog audio, into recordable data written to the tape as they pbad through a recorder at a set speed. The researchers tried to develop a similar biological system, which they call temporal registration in matrices by means of the CRISPR expansion (TRACE). "When you think about recording signals that change temporarily with electronics, or an audio recording … that's a very powerful technology, but we were thinking how you can scale this to living cells." notes Ravi Sheth, a graduate student in Wang's laboratory.

CRISPR has previously been used to record and store poems, books and even an experimental film in DNA, but this is the first time that CRISPR has been used to Record cellular activity and the timing of those events. The authors report that "… the engineering of the CRISPR-Cas adaptation system to directly record the biological signals and their temporal context, and not simply the exogenous DNA information sequence, has not been achieved to date … In this frame, a biological input signal is first transformed into a change in the abundance of a set of DNA triggering within living cells.The CRISPR-Cas spacer acquisition machinery is used to record the amount of DNA triggering in CRISPR matrices in a unidirectional way ".

To generate their bacterial registration system, the researchers designed two different plasmids in a laboratory strain of Escherichia coli. The first plasmid created more copies of itself in response to an external signal. A second recording plasmid effectively marked the time and expressed the necessary CRISPR / Cas system components. When there was no external signal, the recording plasmid continued inserting copies of a spacer sequence into the CRISPR locus. However, when an external signal was detected, the self-replicating plasmid was activated, which led to the insertion of signal sequences. What you get is a background of spacing sequences that follow time, interspersed with sequences of signals that were inserted as a result of changes in the cell's environment. The CRISPR locus can be read using computational tools. Initial tests with the TRACE system showed that the recorded information was stable within the cell populations for eight days.

After generating its prototype system, the team demonstrated how it could be multiplexed, allowing the simultaneous registration of three different signals, in this case availability of copper, trehalose and fucose metabolites in the cell population environment for three days . "This work allows the temporal measurement of dynamic cell states and environmental changes and suggests new applications for chronic large-scale biological events," the authors conclude. "Our work allows new applications in the biological record, TRACE could be used to record the fluctuations of metabolites, changes in genetic expression and information badociated with the lineage in cell populations in difficult-to-study habitats, such as the mammalian gut or in open environments, such as the soil or the marine environment. "

Dr. Wang says the next team plans to use the TRACE platform to investigate markers that indicate changes in normal or diseased states in the gastrointestinal tract and other body systems.

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