Abstract
Cell nucleus is full of various components, and inside of the nucleus has complicated and heterogeneous structure. Though most functions of nuclear domains have been well studied, nuclear mechanical properties have been scarcely studied. The reason is because it is extremely difficult to construct the experimental system which can measure mechanical properties of the minute nucleus. Additionally, the relation of nuclear configuration and mechanical properties is not clarified. In this study, the experimental system was developed to measure the stiffness of the nucleus of living cell in order to verify the inhomogeneity of the cell nucleus. The system is composed of two devices: one is a glass micro probe sensor which can measure stiffness of cell nucleus, and the other is a rotatable device which can move the cell nucleus to the center position of the microscope and can rotate the nucleus horizontally. The devices are assembled on the stage of an inverted phase contrast microscope. Experimental studies have been carried out using normal human osteoblast. The method has shown capability to detect difference of stiffness on cell nucleus. Comparing the three-dimensional configuration and local stiffness of the cell nucleus, it is found that nucleolus is a high stiffness domain and is involved in the structure of the cell configuration. As mentioned above, mechanical inhomogeneity was confirmed in cell nucleus.
