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X-Ray Microscope Scans Cellular Machinery
This 3-D image, showing a yeast cell during cell division, was created using a high-powered X-ray microscope. X-ray microscopes produce high-fidelity images quickly and can help scientists study protein locations within a cell. (Image by Carolyn Larabell and Mark Le Gros, Lawrence Berkeley National Laboratory and University of California, San Francisco)
At the National Center for X-ray Tomography, scientists have built a transmission X-ray microscope that can produce meticulous 3-D images of cells. Just as CT (computed tomography) scans provide a detailed view within the human body, X-ray tomography can generate high-resolution images of the internal structures of cells.
The X-ray microscope, located at the Lawrence Berkeley National Laboratory in California, uses X-rays created by a synchrotron—a circular particle accelerator that produces X-ray beams many orders of magnitude brighter than those from laboratory X-ray generators. The high intensity allows researchers to collect a complete data set for the 3-D image of a 10-micron-thick cell in a matter of minutes, compared to days or weeks for electron microscopes. This quick turnaround will allow scientists to accumulate a statistically significant volume of data within a relatively short time. Also, the high penetrating power of these bright X-rays, coupled with a near absence of refraction, makes them an ideal probe for determining the locations of labeled proteins in cells.
“A protein can have different functions depending on where it’s spatially located inside a cell,” says cell biologist Carolyn Larabell, the principal investigator for the new center. “Knowing where a protein is located throughout the cell cycle can be very important in determining its role.” The new microscope offers the possibility of generating “tomographic atlases” that chart with high precision the locations of individual proteins at every state in the cell cycle, thus providing unique insights into the architecture and workings of cells.
X-ray tomography helps to bridge the “gap” between light and electron microscopy. Traditional microscopy uses visible light and is preferred by many biologists, because it enables them to examine living cells in their natural state. Resolution, however, is limited to a wavelength of 200 nanometers, slightly shorter than the wavelength of visible light. Electron microscopy provides better resolution but requires dehydration of cells and elaborate preparation and staining—a technique that potentially alters the structure of cells. X-ray tomography is an emerging technology that combines some of the best features of light and electron microscopy by allowing whole-cell visualization at a sharper resolution of nearly 35 nanometers, without the elaborate specimen preparations. Future improvements may eventually sharpen the resolution even further to nearly 15 nanometers.
The National Center for X-ray Tomography was officially dedicated on October 11, 2006, and will undergo further testing in January 2007 before opening to the biomedical community. The center was developed with support from NCRR and the U.S. Department of Energy (DOE). Larabell received initial funding from the Office of Biological & Environmental Research at DOE and the National Institute of General Medical Sciences to develop the X-ray microscope technology.
The National Center for X-ray Tomography is one of 52 NCRR-funded Biomedical Technology Resource Centers around the nation. These centers provide scientists with access to a broad spectrum of technologies, techniques, and methodologies, including computational tools, optical and spectroscopic technologies, and advanced microscopy.
“The National Center for X-ray Tomography is the only resource of its kind in the United States,” says Gerry McDermott, a research biophysicist at the center. “We believe it will offer a completely new way to explore cellular structure and function.”
—Al Staropoli
To Gain Access: The National Center for X-ray Tomography performs research in biological and biomedical imaging and cell biology. It houses the first soft X-ray microscope in the world, designed specifically for biological and biomedical applications. The center is a joint program between the University of California, San Francisco, and Lawrence Berkeley National Laboratory. The National Center for X-ray Tomography is expected to become available to qualified biomedical researchers throughout the nation in Spring 2007. Researchers can gain access to the microscope and other resources by submitting a proposal to the center. To learn more or to submit a proposal, visit The National Center for X-ray Tomography Web site.
