Cell and Tissue Structure
The following are imaging and characterization techniques that can be used to study cell and tissue structure.
Cryo-Electron Microscopy and Tomography
Using electrons, cryo-electron microscopy (cryo-EM) and cryo-electron tomography (cryo-ET) techniques provide images of biological materials that are frozen in their native state, ranging from proteins to very large biological assemblies and complexes, at variable resolutions that stretch to the atomic level. Studies are done in two- and three dimensions and do not require crystalline materials.
- Cryo-EM/ET Overview
- Facility: Center for Structural Molecular Biology at ORNL
- Facility: Laboratory for Biomolecular Structure (LBMS) at Brookhaven National Laboratory
- Facility: Pacific Northwest National Laboratory Environmental Molecular Sciences Laboratory
- Facility: Stanford-SLAC Cryo-EM Center at SLAC National Accelerator Laboratory
Neutron imaging includes neutron radiography and computed tomography. Taking advantage of H/D contrast, and the high penetrating power and the nondestructive nature of neutrons, it is possible to study structures of a wide range of hierarchical and complex materials of biological relevance at a resolution of ~50 µm. Examples include transport and interactions of fluids in porous media, plant-plant and plant-fungal interactions, pore structure and voids in soil under environmentally relevant conditions, and cavitation and gas embolism in plant-soil-groundwater systems.
Soft X-Ray Tomography
There are several variants of X-ray imaging, including 2D and 3D (tomography), that use both soft and hard X-rays. Soft X-ray tomography can be used to image the 3D structural organization of whole, hydrated biological cells in the native state down to a resolution of about 35 nm. Hard X-ray tomography can provide 2D and 3D information on more strongly absorbing and less radiation sensitive biological materials with a resolution of 30 nm or less. A variant of X-ray imaging, called spectromicroscopy, provides spatially resolved information about metal distribution and chemical speciation in materials of biological and medical relevance, including tissues with resolutions typically from submicrons to millimeters.