It's alive and glowing

New biosensors help track gene editing

Tatiana Matveeva, "Scientific Russia"

It is now possible to see the activity of CRISPR gene editing tools in organisms with the naked eye and with the help of an ultraviolet flashlight thanks to a new technology. The tool has successfully worked on plants, the press service of the Oak Ridge National Laboratory (USA) reports. The development is described in the journal ACS Synthetic Biology (Yuan et al., Plant-Based Biosensors for Detecting CRISPR-Mediated Genome Engineering).

Genetically modified poplar sprouts glow bright green in ultraviolet, and ordinary ones glow red.

Previously, to determine whether an organism was modified using the CRISPR tool, it was necessary to know what the original genome looked like before it was edited. The new development allows you to monitor the work of "genetic scissors" in real time. 

Typically, a CRISPR instrument is coupled to a short RNA sequence that directs to the corresponding DNA sequence. When the target DNA is detected, the Cas9 protein modifies it by acting like tiny molecular scissors, cutting one or both strands of DNA, depending on the type of CRISPR technology used.

To this algorithm, the scientists added two more elements: the biosensor guide RNA, which redirects the activity of Cas9, and a protein that signals the activity of "scissors". The researchers sew these two components into the body's DNA to enable a monitoring system.

The biosensor's guide RNA intercepts the CRISPR tool, preventing the array from connecting to the original gene target and redirecting the "scissors" to a specific DNA sequence that encodes a non-functioning green fluorescent protein, or GFP. When the sequence is edited, GFP is turned on – and a green glow appears, signaling the process of work. Only instead of GFP, the scientists used a similar signaling protein eYGFPuv, which is visible in ultraviolet light. 

"Now we can see whether CRISPR is active in real time, regardless of the size, shape and location of the studied organisms," the authors note. "This flexibility accelerates the bioengineering process and expands the possibilities of using biosensors in laboratory and field conditions."

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