a Tensegrity Model of Cell by  Donald Ingber    see- The Architecture of Life by D. Ingber

on flexible-puckering surface - rounded nucleus	on rigid surface - flattened nucleus
tissue culture cells above monolayer have rounded nuclei	- monolayer of cells in tissue culture are flattened

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   Ingber's view of the cell as a tensegrity structure may help explain why cells in tissue culture spread out and flatten when grown on rigid glass of plastic petri dishes, but when on a flexible surface the cells contract and become spherical.

 

   Ingber modeled a cell as a tensegrity structure made of six wood dowels and elastic string. The wooden dowels occurred in three pairs, each perpendicular to the other two and bore the compressive stress. Tension bearing elastic string connected to the ends of the dowels, pulling them into a stable, 3-D form. A smaller, spherical tensegrity model, inside the larger one, represented the

cell's nucleus. Stretched elastic strings between the nucleus and dowels mimicked  cytoskeletal connections.

 

   Applying downward force on the tensegrity cell model shapes it into a flattened pile of sticks and string. When the force is removed, the energy stored in the tensed filaments causes the cell model to spring back to its original, roughly spherical shape. The pictures above from Ingber's article's suggest how cells may behave when placed on a rigid or flexible surfaces.

 

   When attached to a taut, stretched piece of cloth the model flattens and spread out. The model's attachment to the flat cloth  is analogous to the adhesion receptors (integrins) which physically connect a cell to an anchoring basement membrane substratum. 

   When the basement cloth is freed from its moorings, thereby making the cell's anchoring surface flexible, the tensegrity model rounds up into its more spherical form, puckering the cloth underneath. The cell's nucleus patterns its shape after that of the tensegrity model in a coordinated fashion. In living cells nuclei spread and flatten out in a similar manner when they adhere to a substrate. Ingber's dowel and elastic string model of a cell, reveals that tensegrity structures may mimic the known behavior of living cells.

Tensegrity Model Structures:  straw models - Camp Elsewhere - Domes
 
References :
Donald E. Ingber - The Architecture of Life, Scientific American, January 1998
Donald E. Ingber et al - Cellular Tensegrity and Mechanochemical Transduction,
                             Annual Reviews of Physiology, 1997, 19:329-339
Donald E. Ingber - Tensegrity: The Architectural Basis of Cellular Mechanotransduction,
                             Annual Review of Physiology, Vol. 59, pages 575--599; 1997.

Donald E. Ingber, M.D. and Ph.D. associate professor of pathology at Harvard Medical School and a research associate departments of surgery Children's Hospital in Boston. Professor Ingber is a founder of Molecular Geodesics, a company which creates advanced materials based upon biologically properties.