Physics Colloquium: Destructive Testing on Cellular Machinery: Probing Mechanics of Cell Division by Laser Ablation

The Department of Physics is pleased to welcome Professor Mary Williard Elting for an in-person colloquium presentation. Professor Elting is an assistant professor in the Department of Physics at North Carolina State University. Her interests lie in the iontersection of physics and biology, and her research is driven by the broad question of how biological function emerges from structure and mechanics.

Abstract:

Inside each eukaryotic cell, the microtubule and actin cytoskeletons impart organization by assembling into diverse architectures whose properties are tuned to their mechanical functions. The cell reuses many of the same building blocks in multiple functions by regulating their assembly over space and time. The mitotic spindle is a cytoskeletal machine that has the critical task of segregating chromosomes when cells divide, ensuring that each new daughter cell receives exactly one copy of its genetic information. To do so, it must generate force for pulling on chromosomes and also, in some cases, to distort and reshape surrounding cellular structures such as the nuclear envelope. Meanwhile, the actin-based contractile ring pulls on the plasma membrane (which delineates the boundary of the cell), changing its topology to transform one cell into two. Accuracy in both processes is essential, since mistakes in cell division lead to birth defects and miscarriage when they occur in development and are associated with cancer. Robustness is also important, as cells divide more than 10 trillion times during human development and more than 10 billion times per day in adults. While many of the molecules essential for cell division have been identified, many gaps remain in our understanding of the mechanics of this process. How is force exerted in the correct locations at the correct times? How does force propagate between structures with different material properties, and how are those properties themselves tuned for different functions? How can complex cellular machinery self-assemble without a “director” telling all the parts where to go?

In part, these gaps in our knowledge persist because of the difficulty of exerting controlled mechanical perturbations inside live cells. By combining live cell confocal imaging, laser ablation, quantitative analysis, and molecular perturbations, our group probes how the cell builds cytoskeletal structures that accomplish the mechanical functions of cell division. We test how and where force is generated, and how cells maintain these forces over both space and time. We examine these questions in a variety of systems, including both fission yeast and mammalian cells. In this talk, I will discuss cellular mechanisms that prevent, detect, and repair damage to cell division machinery, indicating that both the spindle and the contractile ring are active materials that can self-repair. Together, these mechanisms provide mechanical redundancy and isolation well suited to ensuring accurate cell division amidst a dynamic environment within and outside the cell.

This is an in-person colloquium. If you are interested in attending virtually, please contact phyadmin@syr.edu for the Zoom link.