Author: T. G. Frey
This page links you to Quicktime Movies demonstrating the process of electron tomography and the results from three-dimensional reconstruction of a mitochondrion. Click on the icon depicting the movie you would like to see, or scroll down and view the movies in succession in order to view the steps in making a three-dimensional model of a mitochondrion.
Ref: Perkins, G., Renken, C., Martone, M.E., Young, S.J., Ellisman, M., and Frey, T. "Electron Tomography of Neuronal Mitochondria: THree-Dimensional Structure and Organization of Cristae and Membrane Contacts" Journal of Structural Biology 119, 260-272 (1997).
Tilt Series of a Mitochondrion
The first step is to collect a tilt series from a semi-thick section.
Click on the image below to download a Quicktime movie of the tilt series.
The tilt series shows the three-dimensional structure viewed from many different angles in projection onto two-dimensional images; this is the information that it needed to calculate its structure in three-dimensions. The three-dimensional structure or "Tomogram" can be calculated from these images.
Electron Tomogram of a Mitochondrion
A tomogram is a thee-dimensional picture.
The movie shows sections of the tomogram one right after the other
Click on the image below to download the Quicktime Movie.
This is a three-dimensional reconstruction of a dendritic mitochondrion from chick cerebellum reconstructed tomographically from a tilt series of a 0.5 micron section. This Quicktime Movie steps through every fourth section of the three dimensional tomogram.
In order to create a three-dimensional model, the individual sections of the tomogram are segmented by separately tracing different membrane components; in this case the outer membrane is traced in dark blue, the inner boundary membrane in light blue, and the cristae membrane in yellow. Note, however, the cristae membrane and the inner boundary membrane are one continuous surface. The tracings from all sections are modeled as three-dimensional surfaces and displayed as a three-dimensional model by the program Synu developed at the National Center for Microscopy and Imaging Research at UCSD.
The tomogram was segmented by manually contouring into regions bounded by the outer, inner boundary, and cristal membranes shown in dark blue, light blue, and yellow respectively. Only the initial frame shows the outer membrane; in subsequent frames the inner boundary membrane is displayed as translucent so that the cristal membrane can be viewed through it. Note that the inner boundary membrane and the cristal membrane are components of the inner mitochondrial membrane and are one continuous surface joined at 30 nm diameter tubular connections or crista junctions.
In this case only four crista are displayed in separate colors to demonstrate the different morphologies observed in this mitochondrion. These range from the red crista at upper right which is a single tubule through somewhat more complex cristae with several tubular crista junctions to the inner boundary membrane to the large yellow crista consisting of a large lamellar compartment with many crista junctions. Two segments of the endoplasmic reticulum adjacent to the mitochondrion are shown in light brown and green.
Changes in Mitochondrial Structure During Apoptosis
Other Mitochondria Sites