Image processing approaches to biological three-dimensional electron microscopy

Electron microscopy is a powerful technique for imaging complex biological macromolecules in order to further the understanding of their functions. Wh en combined with sufficiently careful sample preparation procedures that pr eserve the native structure of the macromolecules and with sophisticated im age processing procedures, electron microscopy can lead to very informative estimates of the three-dimensional (3D) structures of the specimens under study. 3D reconstruction from electron microscopic data is achieving high g oals and exceeding expectations unthinkable only a few years ago. However. there are still some areas where either not enough work has been invested o r the work has not as yet been fruitful. We describe image processing appro aches that shed further light on some of these difficult areas. (C) 2000 Jo hn Wiley & Sons, Inc.