Tomographic imaging of biological specimens with the cryo transmission X-ray microscope

Using the photoelectric absorption contrast between water and protein at 2. 4 nm wavelength, cryo X-ray microscopy has visualized protein structures do wn to 30 mn size in unstained, unsectioned biological specimens. Due to the large depth of focus of the Fresnel zone plate objectives, computed tomogr aphy based on a tilt series of X-ray microscopic images can be used to reco nstruct the three-dimensional specimen structure. This method has been appl ied to the green alga Chlamydomonas reinhardtii, and to cell nuclei of male Drosophila melanogaster fruit fly cells. (C) 2001 Elsevier Science B.V. Al l rights reserved.