Knowledge of the localization of subcellular, diffusible substances at the electron microscope level is very important for understanding of cellular physiology. The technical approaches required to obtain this information, have thus far been applied chiefly to animal cell systems. The lack of such studies of plant tissues is due primarily to difficulties in specimen preparation related to the presence in plant cells and tissues of features such as cell walls, intercellular air spaces, and large vacuoles. For microanalysis it is critical that subcellular elements of interest not be altered in any way (addition, subtraction, movement, masking) by the specimen preparation procedures. Thus, a substantial investment of time and effort is required to develop the necessary technology for application to plant systems. The proposed research will adapt existing animal cell methods and, as necessary, develop additional techniques for the cryofixation, ultrathin sectioning, and analysis of frozen- hydrated plant specimens. If successful, the development of these techniques will permit analysis of elemental composition and localization of elements of physiological importance in plant cells. This fundamental information will be of great importance to the understanding of plant cell biology.
