Squid are incredible creatures, with abilities we humans think of as ‘superpowers.’ When you picture a superhero, you might imagine them to have healing or invisible powers, well, squids have both.
Previously, scientists from Massachusetts found squid could potentially cure human disease with their gene-editing skills. Now, researchers from the UCI (University of California, Irvine) have discovered that squid also have the ability to turn invisible and they have managed to recreate that in human cells, to turn those cells transparent.
Active camouflage is camouflage that rapidly adapts to the surroundings of an object. It is a survival strategy used by squids, octopuses, cuttlefish, and is also applied to military vehicles or gear.
How do these animals turn invisible? They have cells that change how light scatters off of them, enabling them to change color or become transparent. While researchers have previously copied this ability onto camouflage materials, such as squid-skin-inspired invisibility cloaks, they wanted to take it even further and see if it could be transferred directly to our cells.
For the study, the UCI scientists focused on a species of squid known as Doryteuthis opalescens, which has a stripe along its body that can change from white to transparent. This stripe contains reflective cells called leucophores, which are made up of particles called leucosomes that contain proteins called reflectins. All these features are what allows the squid to scatter light, creating iridescent camouflage.
To apply this ability to human cells, the UCI team genetically engineered human embryonic kidney cells to express reflectin, and it worked. The proteins successfully gathered into particles inside the cells, changing how they scattered light.
Alon Gorodetsky, the study co-author, said:
We were amazed to find that the cells not only expressed reflectin but also packaged the protein in spheroidal nanostructures and distributed them throughout the cells’ bodies. Through quantitative phase microscopy, we were able to determine that the protein structures had different optical characteristics when compared to the cytoplasm inside the cells; in other words, they optically behaved almost as they do in their native cephalopod leucophores.
The researchers wanted to check how this ability could be controlled, so they placed the cells between a pair of coated glass plates and exposed them to sodium chloride. They found that cells exposed to higher sodium levels appeared to scatter more light from their surroundings better than those under lower sodium levels.
This project showed that it’s possible to develop human cells with stimuli-responsive optical properties inspired by leucophores in cephalopods, and it shows that these amazing reflectin proteins can maintain their properties in foreign cellular environments.
The UCI team published the research on June 2 in the journal Nature Communications.