(ORDO NEWS) — The opalescent coastal squid has superpowers. Not only can he change the color of his skin – which many cephalopods can do – he can also make parts of himself invisible. Scientists have managed to incorporate this ability into human cells.
Using special proteins found in squid cells, the researchers managed to bind them to human kidney cells. The results can help us better understand the various cellular mechanisms.
“Our project focuses on the development of cellular systems and tissues with controlled properties for the transmission, reflection and absorption of light,” explained biomolecular engineer Atruli Chatterjee of UCI.
Squids are not the only animals that can become transparent. While sliding lizards (Draco sumatranus) use their skin transparency to attract attention, opalescent coastal squids (Doryteuthis opalescens) use theirs to avoid unwanted attention.
Females of this type of squid can turn a white stripe along the back from opaque white to almost transparent. They do this using specialized cells called leukophores, which have membrane-bound particles made from reflector proteins.
Depending on how these proteins are located, they can change the way light is transmitted or reflected around them. And this is not an accidental process: squid can change the location of these highly refracting proteins in their cells using an organic chemical called acetylcholine.
To try this trick in human tissues, the research team genetically engineered human kidney cells to produce reflexes that stuck together as disordered particles in the cell cytoplasm.
“We were surprised to find that the cells not only express reflexin, but also pack the protein into spheroidal nanostructures and distribute them over the bodies of the cells,” said engineer Alon Gorodetsky.
Using quantitative phase microscopy, the researchers showed that these proteins changed the way light was scattered through engineered cells compared to kidney cells without reflexin.
They then exposed the expression-reflecting cells to various levels of sodium chloride and found that they can regulate the levels of light passing through them, as the salt causes the particles to grow in size and change their position.
The more salt, the more light is scattered and the more opaque the cells become. Kidney cells now had customizable light transmitting and reflective capabilities – essentially a kind of invisibility.
The salt reaction “resembles the acetylcholine-induced switching of opacity and broadband reflectivity for the leucophore-containing layers of female D. opalescens squids,” the researchers wrote in their article.
The team says their success lays the foundation for incorporating other squid features in mammalian cells, such as color change and iridescence.
It will also allow researchers to further study the mechanisms underlying these abilities, since so far culturing cephalopod mollusk skin cells in the laboratory has proven to be a very difficult task.
Possible future applications may include the ability to visualize entire living tissue with increased clarity, which allows us to find things that were not previously obvious. The team pointed out how similar studies of green fluorescent jellyfish proteins have led to their now popular use in fluorescence microscopy.
“Our results can provide many opportunities in biology, materials science and bioengineering,” the team concluded.
This study is published in Nature Communications.
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