A team of scientists at the University of Chicago has just announced the first-ever use of CRISPR in cephalopods. The scientists, working at the University’s Marine Biological Laboratory (MBL), were able to use the gene-editing method to remove the colorful spots from a species of squid. This is only a foray into genetically engineering cephalopods, however, as their physiology makes them ideal for this type of research.
OneZero picked up on the breakthrough, which the MBL scientists outlined in a paper recently published in Current Biology. The team, led by Joshua Rosenthal and Karen Crawford, says it achieved the first-ever “gene knockout” in a cephalopod; specifically, the squid species, Doryteuthis pealeii.
“CRISPR-Cas9 worked really well in Doryteuthis; it was surprisingly efficient,” Rosenthal said in an MBL press release. He added that delivering the CRISPR-Cas9 system into the squid’s single-celled embryo, however, was much harder.
In order to deliver the CRISPR-Cas9 system into the squid embryos, which have tough outer layers, the team developed “micro-scissors.” The team used the micro-scissors to clip the eggs’ outer layers, then used a needle to deliver the CRISPR-Cas9 reagents.
Using CRISPR-Cas9, the team was able to “knock out” the gene responsible for the squids’ pigmentation, as intended, turning their subjects almost completely transparent. There is a comparison of the two in the image up top; note the squid on the left has pigmented chromatophores (dots), while the CRISPR-edited squid on the right does not.
For those unfamiliar, CRISPR, or “Clustered Regularly Interspaced Short Palindromic Repeats,” is a family of DNA sequences found in the genomes of bacteria. Essentially, CRISPR is the defense mechanism bacteria use to guard against attacking viruses (bacteriophages). In the context of gene editing, scientists have adapted CRISPR to be programmable. This means the systems using the DNA sequences can be inserted into organisms, and in turn either “knock in” or “knock out” genes. (Cas9 is the enzyme that acts as the “molecular knife” for cutting strands of DNA.)
The special cells that control color on cephalopods (like the Woods Hole squid in this video) are called "chromatophores." The chromatophores of cephalopods are neuromuscular organs rather than cells and are not controlled hormonally, which is how many other animals change color. pic.twitter.com/UFkRdUgrZ9— Marine Biological Laboratory (MBL) (@MBLScience) August 13, 2020
“This is a critical first step toward the ability to knock out — and knock in — genes in cephalopods to address a host of biological questions,” Rosenthal said in the press release. Which is a bigger deal than it may seem, as cephalopods have sophisticated behaviors and a lot of nerve cells. In the future, Rosenthal says he wants to see how the firing of those nerve cells correlate with activity.
What do you think about this first-ever use of CRISPR in a cephalopod? Are you shocked at how efficient CRISPR already is at this point? Let us know your thoughts in the comments!
Feature image: Karen Crawford