Single-celled predator extends its ‘neck’ with the assistance of origami

Think about in case your neck was so extendible that your head might attain your native store whilst you sat on the couch. That will be the human equal of what one single-celled predator can do – and now the long-standing thriller of the way it can lengthen its “neck” greater than 30 occasions the size of its “body” has been solved.

The cell membrane of this organism is folded up right into a sequence of pleats that may solely unfold and refold in a technique, Eliott Flaum at Stanford College and her colleague Manu Prakash have found, permitting it to increase and refold with out ending up in a tangled mess. “We figured most of this out by playing with a piece of paper,” says Prakash.

Lacrymaria olor is a single-celled organism, or protist, that lives in recent water and hunts its prey with its terribly extendible neck-like protrusion. Its identify means “tear of a swan”, after its swan-like neck and tear-shaped physique.

Whereas cell membranes are extremely versatile, they aren’t elastic and can’t stretch. So how L. olor extends its neck to such an incredible size has been a thriller because it was first seen beneath a microscope within the sixteenth century. “We compared this to many other organisms, and it’s orders of magnitude larger in this extension,” says Prakash. “That’s the puzzle.”

He and Flaum turned intrigued once they noticed L. olor in samples they collected from a swamp six or seven years in the past, and so they got down to clear up the thriller. Flaum used plenty of completely different methods to picture the outer construction of L. olor and its interior cytoskeleton, made from buildings referred to as microtubules. “We tried many different ways of looking at it to understand what was happening,” she says.

This revealed that the cell membrane of L. olor is folded into 15 pleats, and every pleat spirals across the cell, forming a helical construction. Prakash calls this folding sample “curved crease origami”, or “Lacrigami”.

However how does L. olor unfold and refold this big space of cell membrane with out getting right into a tangle? What Prakash and Flaum labored out is that due to the best way the pleats are stabilised by bands of microtubules linked to them, a whole crease can not unfold abruptly. As an alternative, just one level of a crease can unfold or refold at any time.

As these factors transfer in parallel up every of the 15 creases, the cell membrane unfolds in an orderly method, extending the neck. Reversing the method shortens the neck.

“Instead of randomly folding, like if you were to crumple paper, it has a guiding rail for it to fold back in the same way every time,” says Flaum.

The folding and unfolding is powered by the beating hairs, or cilia, that cowl your complete floor of the cell, says Prakash. It requires vitality to unfold in addition to refold, not like a spring, however wants little or no as a result of cell membranes bend simply.

So far as he is aware of, nobody has found this folding sample earlier than. “When we figured this out, I’d always thought that somebody playing with paper would have discovered this origami,” says Prakash. “It’s quite simple.” Anybody could make it with a chunk of paper and little bit of tape, he says.

“The clever origami design of its neck makes cilia effective for high-speed, long-range hunting,” write Leonardo Gordillo and Enrique Cerda on the College of Santiago in Chile in an accompanying article. “The origami-like protrusion mechanism identified by Flaum and Prakash has the potential to inspire new strategies in soft-matter engineering.”

Certainly, Prakash and Flaum are actually engaged on creating medical robots primarily based on “Lacrigami”. “If you had a small micro-robot in a very small space, and it could suddenly extend, that would be hugely useful in microsurgeries,” he says. “But we did this work because it’s just beautiful and a mystery to solve. We had no thought of it being useful in any way.”