Physics of Life seminars

Cryopreservation constrains manufacturing and clinical delivery of immune cells such as NK and T cells. DMSO protects against freezing but becomes toxic at physiological temperatures; associated infusion morbidity can require washing or divided dosing that diminishes therapeutic effectiveness. This talk presents an alternative in which reversible, cytocompatible hydrogels encapsulate cells before freezing without DMSO. The speaker examines evidence that encapsulation cushions osmotic stress, suppresses kinetic and phase transitions, and reduces injury caused by extracellular ice growth and fusion. The discussion covers recovery efficiency, function after thawing, control of biological stress responses, and the challenges of extending the approach to clinical-scale cell preservation.

Oliver Zier (CfA) presents this Special MPA Cosmology Seminar in Lecture Hall E.0.11 at MPA, Garching. The organizer lists a 30-minute slot, normally comprising a 20-minute presentation and 10 minutes of discussion. This occurrence takes place on Wednesday rather than the series’ usual Tuesday. The published listing supplies the topic and schedule but no separate scientific abstract.

Public lecture by Prof. Didier Queloz, FRS (Jacksonian Professor of Natural Philosophy, Cambridge; Professor of Physics, ETH Zurich), organized by the Swiss Physical Society at EPFL, on how exoplanet discoveries transformed understanding of planet formation and the search for life signatures in planetary atmospheres. Free admission for the general public.

Cells and microorganisms are motile, yet the stationary nature of conventional microscopes impedes comprehensive, long-term behavioral and biomechanical analysis. The limitations are twofold: a narrow focus permits high-resolution imaging but sacrifices the broader context of organism behavior, while a wider focus compromises microscopic detail. This trade-off is especially problematic when investigating rapidly motile ciliates, which often have to be confined to small volumes between coverslips affecting their natural behavior. To address this challenge, we introduce Trackoscope, an 2-axis autonomous tracking microscope designed to follow swimming organisms ranging from 10μm to 2mm across a 325 square centimeter area for extended durations—ranging from hours to days—at high resolution. Utilizing Trackoscope, we captured a diverse array of behaviors, from the air-water swimming locomotion of Amoeba to bacterial hunting dynamics in Actinosphaerium, walking gait in Tardigrada, and binary fission in motile Blepharisma. Trackoscope is a cost-effective solution well-suited for diverse settings, from high school labs to resource-constrained research environments. Its capability to capture diverse behaviors in larger, more realistic ecosystems extends our understanding of the physics of living systems. The low-cost, open architecture democratizes scientific discovery, offering a dynamic window into the lives of previously inaccessible small aquatic organisms.

The emergent dynamics exhibited by collections of living organisms often shows signatures of symmetries that are broken at the single-organism level. At the same time, organism development itself encompasses a well-coordinated sequence of symmetry breaking events that successively transform a single, nearly isotropic cell into an animal with well-defined body axis and various anatomical asymmetries. Combining these key aspects of collective phenomena and embryonic development, we describe here the spontaneous formation of hydrodynamically stabilized active crystals made of hundreds of starfish embryos that gather during early development near fluid surfaces. We describe a minimal hydrodynamic theory that is fully parameterized by experimental measurements of microscopic interactions among embryos. Using this theory, we can quantitatively describe the stability, formation and rotation of crystals and rationalize the emergence of mechanical properties that carry signatures of an odd elastic material. Our work thereby quantitatively connects developmental symmetry breaking events on the single-embryo level with remarkable macroscopic material properties of a novel living chiral crystal system.