Regensburg 2025 – scientific programme

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BP: Fachverband Biologische Physik

BP 17: Poster Session II

BP 17.34: Poster

Tuesday, March 18, 2025, 18:00–20:30, P4

Investigating the rheology of intracellular transport by magnetic tweezers — •Katharina Beitzinger, Simon Wieland, and Holger Kress — Biological Physics, University of Bayreuth, Germany

Intracellular transport is an important part of phagocytosis, the cellular internalization of extracellular objects such as bacteria or microplastic particles. After uptake, the phagosome is transported mainly by dyneins along microtubules to the perinuclear region as part of the phagosomal maturation process. However, the kinetics of the recruitment of the motors to the phagosome is largely unknown. In order to investigate the mechanics of the transport, we use magnetic tweezers in combination with paramagnetic particles, internalized by mouse macrophages. By switching the tweezers on and off periodically, we exert alternating forces on the particle during the transport. The changes in the local viscoelastic cell properties are determined by modeling the creep compliance with a power law. First experiments show that the viscosity of the cells around the phagosomes remains almost constant, while the stiffness increases over time. The change in stiffness can be an indicator for a progressive adaption of the cell towards external stress by a recruitment of molecular motors to the phagosome. We expect that a quantification of the local viscoelastic cell properties during phagosomal transport can lead to a better understanding of this fundamental cellular process.

Keywords: Viscoelasticity; Intracellular transport; Magnetic tweezers