Grants Will Expand X-Ray Microscope Research

BERKELEY, Calif., March 31 -- Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at San Francisco (UCSF) have been awarded $2.5 million from the National Institutes of Health and the US Department of Energy to build and operate a first-of-its-kind x-ray microscope for Berkeley Lab's Advanced Light Source (ALS) division. The grant will also be used to establish a Biomedical Technology Resource Center at the ALS.

This x-ray tomography image of a yeast cell, taken at the ALS with XM-1, is an example of what could be done with the proposed XM-2. Internal organelles are color-coded according to x-ray absorption. Shown in red are the nucleus (smaller sphere) and large vacuole. Lipid droplets are white, and cytoplasmic structures are orange or green.

"X-ray microscopy is an emerging new technology that will expand the existing imaging toolbox for cell and molecular biologists, and we would like to make this technology available to the greater biological community," said cell biologist and microscopy expert Carolyn Larabell, principle investigator, who has a joint appointment with UCSF’s Anatomy Department and with Berkeley Lab’s Physical Biosciences Division. Berkeley Lab physicist Mark Le Gros is the co-principle investigator.

The researchers have proposed a transmission x-ray microscope (TXM) off a bend magnet beamline at the ALS, an electron-based synchrotron/storage ring capable of generating x-ray beams a hundred million times brighter than those from the best x-ray tubes. The new TXM will be able to image whole, hydrated cells at resolutions of about 35 nanometers and specific structural elements within the cell at a resolution of at least 25 nanometers. Future improvements could put the resolution of this microscope as fine as 10 nanometers, about the size of a protein. Imaging data will be collected at breathtaking speed compared with the time-consuming procedures required to collect data via electron microscopy, the researchers said.

Larabell and Le Gros have been using an existing TXM at the ALS to demonstrate the potential of using this technology in cell and molecular biology studies. The existing TXM, called XM-1 -- the only one of its kind in the US -- was designed and is operated by the Center for X-ray Optics primarily for the study of materials. They said the new TXM, called XM-2, will be optimized for biology and will therefore have several advantages, including improved zone plates, the optic devices composed of nanometer-scale concentric metal rings that are used to focus x-rays for imaging purposes.

XM-2 is expected to be operating at the ALS in 2006.

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