Structural Analysis of Cell Membranes by Small Convergence Angle HAADF-STEM Tomography
Abstract: The rapidly-frozen and deeply-etched EM image allows us to find that the cytoplasmic surface of the plasma membrane has a large undulation covered with the networks of caveolae, clathrin-coated pits, and actin-based membrane skeletons. In this paper, we compared the three-dimensional reconstruction of the cellular freeze-replica containing of various focal point distances, between the conventional TEM tomography and the variable convergence-angle STEM tomography, by using of the electron microscope equipped with the three condenser-lens system containing Cs correctors. It was clearly found that the small convergence-angular (0.5mrad) HAADF-STEM tomography could make the best 3D reconstruction with little computational artifacts through the missing wedge during EM observation. This proposed freeze-etch tomography could be expected as a novel tool for the plasma membrane research.
Key words: Cell membrane, clathrin-coated pits, freeze-etch, STEM convergence angle, HAADF-STEM tomography