Scientists have genetically engineered a hummingbird bobtail squid to remove its pigment, creating an almost completely transparent animal with only its three hearts and brain showing when light hits it at the right angle. According to NPR, “The see-through squid are offering scientists a new way to study the biology of a creature that is intact and moving freely.” From the report: The see-through version is made possible by a gene editing technology called CRISPR, which became popular nearly a decade ago. [Scientists Caroline Albertin and Joshua Rosenthal at the Marine Biological Laboratory in Woods Hole, Mass.] thought they might be able to use CRISPR to create a special squid for research. They focused on the hummingbird bobtail squid because it is small, a prodigious breeder, and thrives in lab aquariums, including one at the lab in Woods Hole. Albertin and Rosenthal wanted to use CRISPR to create a bobtail squid without any pigment, an albino. And they knew that in other squid, pigment depends on the presence of a gene called TDO.
“So we tried to knock out TDO,” Albertin says, “and nothing happened.” It turned out that bobtail squid have a second gene that also affects pigment. “When we targeted that gene, lo and behold we were able to get albinos,” Albertin says. Because even unaltered squid have clear blood, thin skin, and no bones, the albinos are all but transparent unless light hits them at just the right angle. Early on, Albertin and Rosenthal realized these animals would be of interest to brain scientists. So they contacted Ivan Soltesz at Stanford and Cristopher Niell at the University of Oregon. “We said, ‘Hey, you guys, we have this incredible animal, want to look at its brain,” Rosenthal says. “They jumped on it.”
Soltesz and Niell inserted a fluorescent dye into an area of the brain that processes visual information. The dye glows when it’s near brain cells that are active. Then the scientists projected images onto a screen in front of the squid. And the brain areas involved in vision began to glow, something that would have been impossible to see in a squid with pigment. Because it suggests that her see-through squid will help scientists understand not only cephalopods, but all living creatures. The findings have been published in the journal Current Biology.
