Conical Tomography: A Method for the Study of Macromolecular Assemblies

We have developed conical tomography for the transmission electron microscope to study a wide range of structures at molecular resolution. Unlike the other related types of tomography (single and double-axis tilt), conical tomography has a higher throughput and more importantly, produces reconstructions that are isotropic in the x-y plane with a resolution of 2-3nm [1]. Using a custom made tilting and rotating stage, we have been able to collect complete conical series from a variety of sources, including thin sections and freeze-fractured replicas of chemical synapses from the rat somato-sensory cortex , isolated synaptic vesicle anti-SV2 complexes. INTRODUCTION We have developed conical tomography for the transmission electron microscope to study the structure of macromolecular assemblies and organelles in their native cellular environment. Unlike the other related types of tomography (single and double-axis tilt), conical tomography has a higher throughput and more importantly, produces reconstructions that are isotropic in the x-y plane with a resolution of 2-3nm [1]. Figure 1. Geometrical representation of the imaged area in A. single-axis tilt, B. double-axis tilt, and C. conical tilt. Since the projection planes are evenly spaced, the resolution is isotropic in the x-y plane. NSTI-Nanotech 2005, www.nsti.org, ISBN 0-9767985-0-6 Vol. 1, 2005 59 Using a custom made tilting and rotating stage, we have been able to collect complete conical series from a variety of sources, including thin sections and freeze-fractured replicas of chemical synapses from the rat somato-sensory cortex (Figure 4), isolated synaptic vesicle anti-SV2 complexes (Figures 7, 8, 9 10).