Physics Commons^™

Extracellular Vimentin Is Sufficient To Promote Cell Attachment, Spreading, And Motility By A Mechanism Involving N-Acetyl Glucosamine-Containing Structures, Robert Bucki, Daniel V. Iwamoto, Xuechen Shi, Katherine E. Kerr, Fitzroy J. Byfield, Lukasz Suprewicz, Karol Sklodowski, Julian Sutaria, Pawel Misiak, Agnieszka Z. Wilczewska, Sekar Ramachandran, Aaron Wolfe, Minh H. Thanh, Eli Whalen, Alison E. Patteson, Paul A. Janmey

Physics - All Scholarship

Vimentin intermediate !laments form part of the cytoskeleton

of mesenchymal cells, but under pathological conditions often

associatedwith in"ammation, vimentin !laments depolymerize as

the result of phosphorylation or citrullination, and vimentin

oligomers are secreted or released into the extracellular environment.

In the extracellular space, vimentin can bind surfaces of cells

and the extracellular matrix, and the interaction between extracellular

vimentin and cells can trigger changes in cellular functions,

such as activation of !broblasts to a !brotic phenotype. The

mechanism by which extracellular vimentin binds external cell

membranes and whether vimentin alone can act as an adhesive

anchor for cells is largely …

A Torsion-Based Rheometer For Measuring Viscoelastic Material Properties, Merrill E. Asp, Elise Jutzeler, Jakub Kochanowski, Katherine Kerr, Dawei Song, Sarthak Gupta, Robert Carroll, Alison E. Patteson

Physics - All Scholarship

Rheology and the study of viscoelastic materials are an integral

part of engineering and the study of biophysical systems. Tissue rheology is even

used in the study of cancer and other diseases. However, the cost of a rheometer is

feasible only for colleges, universities, and research laboratories. Even if a rheometer

can be purchased, it is bulky and delicately calibrated, limiting its usefulness to the

laboratory itself. The design presented here is less than a tenth of the cost of a

professional rheometer. The design is also portable, making it the ideal solution to

introduce viscoelasticity to high school students …

Dynamic Remodeling Of Fiber Networks With Stiff Inclusions Under Compressive Loading, Robert J. Carroll, Minh H. Thanh, Alison E. Patteson

Physics - All Scholarship

The ability of tissues to sustain and withstand mechanical stress is critical to tissue development and healthy tissue maintenance. The mechanical properties of tissues are typically considered to be dominated by the fibrous extracellular matrix (ECM) component of tissues. Fiber network mechanics can capture certain mechanical features of tissues, such as shear strain stiffening, but is insufficient in describing the compressive response of certain tissues and blood clots that are rich in extracellular matrix. To understand the mechanical response of tissues, we employ a contemporary mechanical model, a fibrous network of fibrin embedded with inert bead inclusions that preserve the …

How Green Lakes State Park Got Its Name: The Optics And Appearance Of Fayetteville Green Lakes, Eric A. Schiff

Physics - All Scholarship

The extraordinary and variable appearance of the Fayetteville Green Lakes in the spring, summer, and fall has been the subject of journalistic and scientific attention for more than 150 years. This article addresses the subject in two sections for differing readerships. The first section is a description of the essential science for a general readership. The second section is an abstract of the science for technically knowledgeable readers. The layout of the article is designed for a folded paper flier suitable for distribution to visitors to the lakes.

The article describes the three key properties of the lakes’ waters that …

Unique Role Of Vimentin Networks In Compression Stiffening Of Cells And Protection Of Nuclei From Compressive Stress, Katarzyna Pogoda, Fitzroy Byfield, Piotr Deptuła, Mateusz Cieśluk, Łukasz Suprewicz, Karol Skłodowski, Jordan L. Shivers, Anne Van Oosten, Katrina Cruz, Ekaterina Tarasovetc, Ekaterina L. Grishchuk, Fred C. Mackintosh, Robert Bucki, Alison E. Patteson, Paul A. Janmey

Physics - All Scholarship

In this work, we investigate whether stiffening in compression is a feature of single cells and whether the intracellular polymer networks that comprise the cytoskeleton (all of which stiffen with increasing shear strain) stiffen or soften when subjected to compressive strains. We find that individual cells, such as fibroblasts, stiffen at physiologically relevant compressive strains, but genetic ablation of vimentin diminishes this effect. Further, we show that unlike networks of purified F-actin or microtubules, which soften in compression, vimentin intermediate filament networks stiffen in both compression and extension, and we present a theoretical model to explain this response based on …

Spreading Rates Of Bacterial Colonies Depend On Substrate Stiffness And Permeability, Alison Patteson, Merrill Asp, Minh H. Thanh, Danielle A. Germann, Robert J. Carroll, Alana Franceski, Roy D. Welch, Arvind Gopinath

Physics - All Scholarship

The ability of bacteria to colonize and grow on different surfaces is an essential process for biofilm development. Here, we report the use of synthetic hydrogels with tunable stiffness and porosity to assess physical effects of the substrate on biofilm development. Using time-lapse microscopy to track the growth of expanding Serratia marcescens colonies, we find that biofilm colony growth can increase with increasing substrate stiffness, unlike what is found on traditional agar substrates. Using traction force microscopy-based techniques, we find that biofilms exert transient stresses correlated over length scales much larger than a single bacterium, and that the magnitude of …

Materials Science And Mechanosensitivity Of Living Matter, Alison E. Patteson, Merrill E. Asp, Paul A. Janmey

Physics - All Scholarship

Living systems are composed of molecules that are synthesized by cells that use energy sources within their surroundings to create fascinating materials that have mechanical properties optimized for their biological function. Their functionality is a ubiquitous aspect of our lives. We use wood to construct furniture, bacterial colonies to modify the texture of dairy products and other foods, intestines as violin strings, bladders in bagpipes, and so on. The mechanical properties of these biological materials differ from those of other simpler synthetic elastomers, glasses, and crystals. Reproducing their mechanical properties synthetically or from first principles is still often unattainable. The …

Rab11 Endosomes And Pericentrin Coordinate Centrosome Movement During Pre-Abscission In Vivo, Nikhila Krishnan, Maxx Swoger, Lindsay I. Rathbun, Peter J. Fioramonti, Judy Freshour, Michael Bates, Alison E. Patteson, Heidi Hehnly

Physics - All Scholarship

The last stage of cell division involves two daughter cells remaining interconnected by a cytokinetic bridge that is cleaved during abscission. Conserved between the zebrafish embryo and human cells, we found that the oldest centrosome moves in a Rab11-dependent manner towards the cytokinetic bridge sometimes followed by the youngest. Rab11-endosomes are organized in a Rab11-GTP dependent manner at the mother centriole during pre-abscission, with Rab11 endosomes at the oldest centrosome being more mobile compared with the youngest. The GTPase activity of Rab11 is necessary for the centrosome protein, Pericentrin, to be enriched at the centrosome. Reduction in Pericentrin expression or …

Vimentin Intermediate Filaments Mediate Cell Morphology On Viscoelastic Substrates, Maxx Swoger, Sarthak Gupta, Elisabeth E. Charrier, Michael Bates, Heidi Hehnly, Alison E. Patteson

Physics - All Scholarship

The ability of cells to take and change shape is a fundamental feature underlying development, wound repair, and tissue maintenance. Central to this process is physical and signaling interactions between the three cytoskeletal polymeric networks: F-actin, microtubules, and intermediate filaments (IFs). Vimentin is an IF protein that is essential to the mechanical resilience of cells and regulates cross-talk among the cytoskeleton, but its role in how cells sense and respond to the surrounding extracellular matrix is largely unclear. To investigate vimentin’s role in substrate sensing, we designed polyacrylamide hydrogels that mimic the elastic and viscoelastic nature of in vivo tissues. …