Amt xr41 digital

Samples (3.5 µL) with different polymerization methods were applied to pre-hydrophilized carbon grids and negatively stained with 1.5% uranyl acetate. The specimens were examined in an H-7100 electron microscope (Hitachi) operating at 75 kV. EM images were recorded by AMT XR41 digital CCD camera (Advanced Microscopy Techniques). MT lengths and angles of branches were measured by ImageJ using EM images taken at a nominal magnification of 30kx. To evaluate the straightness of MTs, EM images were taken at a nominal magnification of 20kx. A homemade ImageJ macro was used to obtain the coordinates of start and end points of one MT, and segmented length of the same MT at the same time. The end-to-end distances of MTs were calculated and the ratio with the segmented lengths of corresponding MTs were obtained. To analyze the proportions of the MT types, EM images were taken at a nominal magnification of 30kx. Visual inspection was performed to categorize MT types. For both measurement of straightness and analysis of proportions of MT types, MTs with at least 500-nm long were used.