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The importance of water flux and hydraulic resistance in animal cell migrationYizeng Li, PhD Friday, September 10, 2021 Our knowledge of animal cell mechanics has been centered on the contribution of the cytoskeleton. This includes how we understand cell migration, which has mostly been studied on flat two-dimensional surfaces or in three-dimensional matrices. Forces induced by actin polymerization and focal adhesion are considered the dominant, if not the only, mechanism for cell migration. In addition to being on a surface or in a matrix, cells in vivo can also be physically confined and face high hydraulic resistance such as cells in a tumor. In addition, water, the most abundant molecule in cells, moves across the cell membrane and influences cell mechanics. Indeed, recent experimental studies have suggested the importance of water flux and hydraulic resistance in confined cell migration. In this talk, I will review the canonical picture of actin-driven cell migration, followed by some recent experimental discoveries on the impact of water. Afterward, I will present a mathematical framework of cell migration where both actin and water are equally treated. I will then introduce how physical environments such as hydraulic resistance enter into the model. At the end of the talk, I will discuss non-intuitive model predictions and their implications on cell biology. |
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Theory of epithelial-mesenchymal plasticity and its importance for cancer metastasisHerbert Levine, PhD Friday, September 24, 2021 Until very recently most cancer biologists operated with the assumption that the most common route to metastasis involved cells of the primary tumor transforming to a motile single-cell phenotype via complete EMT (the epithelial-mesenchymal transition). This change allowed them to migrate individually to distant organs, eventually leading to clonal growths in other locations. But, a new more nuanced picture has been emerging, based on advanced measurements and on computational systems biology approaches. It has now been realized that cells can readily adopt states with hybrid properties, use these properties to move collectively and cooperatively, and reach distant niches as highly metastatic clusters. This talk will focus on the accumulating evidence for this revised perspective, the role of biological physics theory in instigating this whole line of investigation, and on open questions currently under investigation. |
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Physico-chemical properties of nuclear waste glass simulants and the effects of gamma-ray irradiation: A collaborative investigation between AU and SRNLJosé A. Jiménez, PhD Friday, November 5, 2021 Borosilicate glass has been adopted internationally for the treatment of nuclear waste with the object of long-term stabilization through vitrification. Still, the effects of self-radiation on glass composition following radioactive element decay over thousands of years can only be simulated. In this context, the work carried out as part of the Visiting Faculty Program at the Savannah River National Laboratory (SRNL) was undertaken to gain insights into the effects of gamma radiation on various properties of borosilicate glass simulants. The International Simple Glass (ISG) system agreed upon by the international community as representative glass was employed in the study. The original ISG containing Fe2+/Fe3+ impurities, as well as two ISG ‘iron-free’ analogs recently synthesized by Corning, were evaluated as part of the investigation aiming to clarify the influence of metal impurities. All three glasses have been preliminarily subjected to gamma ray irradiation (e.g. 1 MGy). Various characterizations were then intended for the glasses before and after gamma irradiation in the comparative evaluation: X-ray diffraction and vibrational spectroscopy (structural properties); dilatometry and calorimetry measurements (thermal properties); and optical absorption and photoluminescence spectroscopy (optical properties). Further assessed is the chemical durability through corrosion tests as part of the comprehensive evaluation. This seminar will thus present preliminary results from the ongoing collaborative investigation between AU and with SRNL, as well as conclusions to date and outlook as appropriate. |
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Seminar series sponsored by: Augusta University Research Institute, College of Science and Mathematics, Department of Chemistry and Physics
