Ca²⁺ effect on protoplasmic streaming in Nitella internodal cell

Ca²⁺ ion effect on protoplasmic streaming in an internodal cell of Nitella has been investigated for various temperatures. We have found that the protoplasmic streaming at low temperature is remarkably affected by the Ca²⁺ ions in the internodal cell but larger concentrations of the Ca²⁺ ions are needed to suppress the streaming velocity at higher temperatures. These streaming behaviors of the protoplasm, furthermore, have been elucidated on the basis of the reaction equations which take into account ATP hydrolysis due to actin-myosin molecules and inactivity of the molecules due to the Ca²⁺ ions.