Biophysical Society Bulletin | January 2025

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Know the Editor Paul Janmey

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University of Pennsylvania Editor, Cell Biophysics Biophysical Journal

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Rupture

Paul Janmey

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What are you currently working on that excites you? The mechanical properties of the nucleus, which is something I never expected to work on but was motivated by previous experiments of Fitzroy Byfield and Alison Patteson in our lab. The nucleus is usually considered the stiffest organelle in the cell, but it can be deformed by surprisingly small forces if they are applied slowly and over a large surface of the nucleus. The soft deformation appears to require nuclear motor proteins, and we are trying to understand how this happens. What have you read lately that you found really interesting or stimulating? During the pandemic, I worked on an article about how cells sense each other’s presence at a distance. This process is important for wound healing and normal development. There are great experiments from a century ago in which small tissue pieces or severed nerves were planted in diluted blood plasma clots, and people noticed that when two of these explants were placed near each other, cells migrated out from the explant not at random, but in a straight line to the other cell explant. The distance over which this sensing occurred was over a millimeter, or hundreds of times large than a single cell. The hypotheses for this sensing included chemical, electrical, or mechanical stimuli. The first two were ruled out, and mechanical effects, including forces on the clot matrix, alignment of fibers in the clot, or stiffness changes appeared most likely. Similar studies constitute current mechanobiolo gy research, but with fancier tools and a century of molecular biology.

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Biophysical Reports Engineering stress as a motivation for filamentous virus morphology Andrew McMahon, Swetha Vijayakrishnan, Hafez El Sayyed, Danielle Groves, Michaela J. Conley, Edward Hutchison, and Nicole C. Robb “Many viruses form particles that vary in size and shape, including small spheres or long filamentous structures that can reach many microns in length. While virion structure is of interest not only in the context of virus assembly but also because pleomorphic variations may correlate with infectiv ity and pathogenicity, filament formation is not well under stood, and viral filaments are relatively understudied. Here, the authors used a pressure vessel model and microscopy to investigate the relationship between virion dimensions and engineering stress and concluded that viral filaments offer an optimal shape that allows viruses to have a larger volume than they could in any alternative geometry, thus offering new insight into viral filament formation.”

Version of Record Published September 6, 2024 DOI: https:/doi.org/10.1016/j.bpr.2024.100181

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January 2025

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