Cytomechanics of oscillatory contractions. 1. Measuring active mechanical properties of the Physarum polycephalum plasmodial strands

An experimental device with an inexpensive electronic-mechanical measurement system was designed to clarify the role of mechanical tensions in cell activation. This device provides for maintaining a specified kinetics of either the object’s length or applied load to measure its tension force or deformation. The experiments were performed with the plasmodium of Physarum polycephalum , a giant unicellular organism, which is a classical object for studying a nonmuscle motility. Several examples of the longitudinal dynamics of the plasmodial strand and its activation in response to periodic switching at certain phases of the contraction- relaxation cycle are described.