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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Active Matter II (joint session BP/CPP/DY)

CPP 20.9: Talk

Tuesday, March 19, 2024, 11:45–12:00, H 1028

Physical principles of space allocation in an active biofluid — •Sebastian W. Krauss, Mithun Thampi, Pierre-Yves Gires, and Matthias Weiss — Experimental Physics I, Bayreuth, Germany

Living matter has the remarkable ability to self-organize into distinct cellular entities that ultimately form the building blocks of organisms. The organisation in multi-cellular systems emerges by replicating a single fertilized oocyte as template structure in multiple division cycles. In contrast, recent studies on Xenopus egg extracts have shown that an active biofluid that is devoid of template structures and genetic material can spontaneously self-organize into compartments in an ATP-driven fashion even when protein synthesis is blocked. The emerging compartments (protocells) are distinct, lack a confining membrane envelope, and vanish after all ATP has been consumed. Here, we show that protocell geometry is determined by a random-packing process with a coarse-graining dynamics that is similar to two-dimensional foams [Development 150, dev200851 (2023)]. Protocell sizes are seen to be tunable by altering the dynamics of microtubules while preserving geometric features of the pattern. Confining the self-organizing fluid in ellipsoidal microfluidic cavities, i.e. mimicking natural confinements like those in embryos, pattern formation is seen to adapt to the confinement, exhibiting a surprising similarity to spatial compartmentalization in early embryos. Further, we observe that an increasing aspect ratio of the chamber results in the formation of smaller protocells. Our results indicate that mechanical cues and simple self-organization principles are key ingredients in many developmental processes.

Keywords: Pattern formation; Self-organization; Xenopus egg extract; Confinement; Non-equilibrium