Tiny predator owes its shape-shifting ability to “origami-like” cellular architecture

For a tiny hunter of the microbial world that relies on extending its neck up to 30 times its body length to release its deadly attack, intricate origami-like cellular geometry is key. This geometry enables the rapid hyperextensibility of the neck-like protrusion, for single-celled predator Lacrymaria olor, a new study reports. The findings not only explain L. olor’s extreme shape-shifting ability but also hold potential for inspiring innovations in soft-matter engineering or the design of robotic systems. Single-celled protists are well known for their ability to perform dynamic morphological changes in real time, including large transformations in cell architecture. These organisms undergo large strains and strain rates to accomplish such feats. One such protist, L. olor,extends a neck-like protrusion to catch prey at a distance. This tiny, 40-micron single-celled creature can repeatedly stretch this protrusion up to 1200 microns in less than 30 seconds and then retract it just as quickly. However, the underlying mechanisms that produce L. olor’s extreme hyperextensibility remain unknown. To observe these mechanics at the sub-cellular level, Eliott Flaum and Manu Prakash used a combination of live imaging, confocal, and transmission electron microscopy. They discovered that an origami-like layered cortical cytoskeleton and membrane architecture enables L. olor’s rapid extension and contraction. According to the findings, the cell membrane is folded into 15 contagious pleats that, together, form a curved-crease origami that can sequentially unspool for rapid and repeatable hyper-extensions of the neck. This intricate folding scheme is scaffolded on a helicoidal structure of microtubule filaments that guides the membrane creases to ensure fast and efficient unfolding and refolding during shape changes. To better understand the dynamics involved, Flaum and Prakash developed a mechanical paper model that mimics L. olor’s curved crease origami architecture. In a Perspective, Leonardo Gordillo and Enrique Cerda discuss the findings in greater detail.