MRI: Acquisition of a High-Resolution Electron Tomography System

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

The intermediate voltage (300kV) electron microscope equipped with a tilting sample holder for tomography and a cryostage is serving a longstanding need to provide key imaging technologies to a wide variety of biological and bioengineering research programs on the University of Wisconsin - Madison. Users of this microscope are heavily dependent on high resolution imaging for their work on a wide range of important topics, including membrane and protein trafficking, biomineral and biopolymers, viral replication and virus-host interaction, cytoskeletal organization and cell division, nerve terminal organization and exocytosis, bacterial architecture, imaging of molecular complexes, and neuroengineering. This imaging system enables researchers to collect multiple images of relatively thick samples over a series of tilt angles. All these images are mathematically processed to generate a 3D reconstruction (tomogram) of the original section. The increased acceleration voltage is essential for allowing the electron beam to penetrate the sample without plural or inelastic scattering, especially at high tilt angles where the section thickness doubles or nearly triples Electron tomograms of either plastic sections of biological samples or cryofixed biological specimens or biopolymers results in an axial resolution of 2-10 nm. The new equipment is housed in an existing, highly effective campus microscopy and characterization center, managed by a permanent, full-time PhD expert entirely funded by the center budget, and supervised by a dedicated advisory committee of faculty users. The new tomographic system fosters many collaborations on campus and allows researchers and students from almost every single college/school to apply state-of-the-art high resolution imaging techniques. Hands-on demonstrations on the use and applications of the proposed EM are included in the imaging courses taught by the PI and co-PIs. In addition, annual summer workshops are held to train researchers and students on campus on tomographic approaches. The new microscope has also a very important role in outreach. Three-dimensional tomographic models are visually stunning representations. They convey 3D information of cellular structures in a very effective way to everyone, from highly trained biologists to the general public. The new Wisconsin Institute of Discovery (WID) has a microscope and imaging discovery niche in the Town Center that includes a high resolution display consisting of an array of monitors. Tomographic reconstructions derived from the use of the new microscope, including images of replicating viruses, cytoskeletal arrays during cell division, plant organelles, signal transmission in neurons, are displayed in these monitors. In addition, some tomographic models are printed in a 3D printer for display in the WID and other participating Departments.