Investigating biological materials at the mesoscale
Louise Jawerth, PhD, Max-Planck-Institute for the Physics of Complex Systems, Dresden, Germany
Leuchs-Russell Auditorium, A.1.500, Staudtstraße 2
My interest is in uncovering the microscopic processes and the physical principles that give rise to complex biological phenomena. For many biological and medically relevant processes we strive to build an understanding that bridges the molecular scale to the macroscopic scale; this often requires measuring and testing properties on the mesoscale – the scale that connects the molecular and macroscopic. In this talk, I will describe the tools and conceptual framework we have developed to investigate two important biological materials. In the first example, I will discuss my work in understanding the origins of the unusual material properties exhibited by blood clots. Fundamentally, one function of a blood clot is to provide a mechanical plug that stems the flow of blood in response to injury. We used atomic force microscopy, image processing and further tools in novel ways to directly measure mesoscale properties of the largest structural component of a blood clot that of a network of fibrin fibers. We uncovered how the mechanical behavior of a fibrin network is not related in a simple way to the elastic properties of an individual fiber but, rather, depended on the architecture of the network in an unexpected way. We furthermore added small blood cells called platelets and observed how they altered clot structure and, thus, the material properties of the resulting clot. In the second example, I will discuss our work in understanding droplets of proteins that have phase separated out of solution to form distinct liquid phases much the way oil phase separates from water. These so-called protein condensates have recently been recognized as a ubiquitous strategy utilized by biology to control a plethora of phenomena ranging from healthy functions such as RNA splicing as well as unhealthy ones in which the condensates with prion-like sequences grow solid fibers. I will present our efforts to measure the properties of the condensates on the mesoscale. I will then present some interesting resulting discoveries including that protein condensates can undergo glass-like aging to form solid-like structures and the importance of the droplet surface for pathological fiber formation.