Meiosis

Why should a biologist care about rheology? Actually, biologists used to care a lot more about rheology than they have lately. A prominent physiology text from the 1950s (An outline of general physiology by L. Heilbrunn) stated that “In any attempt to interpret the machinery of a living cell, it is essential to know something about the mechanical properties of the protoplasm in the cell that is being investigated.” This point of view was largely eclipsed by the emphasis and power of chemical and genetic regulation of cell function. But cells are mechanical as well as chemical and electrical devices, and understanding their biology requires knowledge of all these aspects. Numerous recent studies show that application of external forces or challenging a cell’s internal force generation by adhesion to substrates of different stiffnesses generates signals that can augment or override chemical stimuli. Understanding how forces affect cell growth, division, differentiation and activation requires defining the rheological properties of cells in the same way that understanding chemical signaling requires knowledge of rate constants and affinity constants and signal transduction pathways.