Inverse Size Scaling of the Nucleolus by a Concentration-dependent Phase Transition
| Date/Time: | Thursday, 05 Feb 2015 from 4:10 pm to 5:00 pm |
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| Location: | Physics 0003 |
| Phone: | 515-294-5441 |
| Channel: | College of Liberal Arts and Sciences |
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Cells exhibit a remarkable degree of spatial organization. In addition to classic membrane-bound organelles, the cytoplasm and nucleoplasm are partitioned into functional compartments that lack a defining membrane. How such structures assemble and stably persist without a membrane holding them together is unclear. Combining mathematical modeling with quantitative imaging of live C. elegans embryos, I characterized the size and assembly of the nucleolus, a non-membrane-bound organelle important for cell size homeostasis. I find that nucleolar components condense into nucleoli only above a threshold concentration and that the final size of the organelle depends linearly on concentration. My results suggest that phase transitions may provide a general mechanism for spatially organizing the cell and generating organelles of appropriate size.
Dr. Stephanie Weber earned bachelor's degrees in Biology and Chemistry from Duke University and a Ph.D. in Biochemistry from Stanford University. As a graduate student, she combined live-cell microscopy and polymer dynamics theory to investigate the anomalous motion of DNA in bacterial cells. This work revealed that the cytoplasm, typically ignored as an inert medium, plays an active role in moving macromolecules around the cell. As a Damon Runyon Postdoctoral Fellow at Princeton University, Steph studies the physical mechanisms governing the size and assembly of the nucleolus, a non-membrane-bound organelle important for cell size homeostasis. She is interested in understanding how living systems establish and dynamically regulate spatial organization across length scales.