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Kevin P. Granata Memorial Lecture -- A swell idea: mechanical and molecular views of muscle’s radial motions and flows

Wednesday, February 5, 2020

2:30pm – 3:45pm

310 Kelly Hall, Virginia Tech Campus

Tom Daniel

Department of Biology

University of Washington


During muscle contraction, a lattice of contractile proteins contain myosin motors anchored on thick filaments which bind to and slide actin thin filaments, generating force and movement.  These molecular motors rely on ATP, supplied at the limits of diffusion, to the interior of the lattice of thick and thin filaments. If the lattice is isovolumetric it must expand (swell) when muscle shortens, altering the binding dynamics of myosin. If the lattice is not isovolumetric then fluid flow must occur between the lattice and surrounding intracellular spaces.  Fluid flow at this spatial scale has not been considered previously.  Here we show that the contractile lattice of muscle is neither isovolumetric, nor constant in radial spacing as suggested by the classic sliding filament model. Instead lattice spacing is time-varying, depends on activation, and can manifest a negative (auxetic) Poisson ratio. This talk will combine computational and experimental analyses of forces, flows and movements at the nm spatial scale in fully intact muscle.   Using a convective-diffusive flow model,  we show that volument changes in the filament lattice creates nm-scale “breathing” which enhances ATP transport, promotes metabolite exchange, and may play a role in the regulation of contraction itself.



Tom’s research and teaching melds neuroscience, engineering, computing, and biomechanics to understand the control and dynamics of movement in biology. He was trained in Biology at Duke and Engineering at Caltech.  He has been on the faculty in the Biology of the University of Washington since 1984 and was its founding chair.  He was MacArthur Fellow, a Guggenheim and AAAS Fellow, and a recipient of the University of Washington Distinguished Teaching Award and the University of Washington Graduate Mentor Award.  He is on the board of reviewing editors for Science Magazine, the Federal Advisory Committee for the NSF Bio Directorate, the Board of Directors for Allen Institute and the Paul G. Allen Family Foundation, and he is the U.S. representative for the Council of Scientists for the Human Frontiers of Science Program.