Introduction

Mycorrhizal plants obtain a considerable proportion of their nutrient ions, as well as some potentially toxic elements, by way of the fungal hyphae. Pathways for solute movement in mycorrhiza are therefore different from those in non-mycorrhizal roots. The structure and physiology of the fungus interacts with that of the root in a poorly understood manner. Identification of sites of localization of elements at the subcellular level, in cell organelles, cytoplasm or cell walls, would help to clarify the process involved in their uptake, transport and deposition or detoxification in mycorrhiza.

METHODS IN MICROBIOLOGY VOLUME 23 ISBN 0-12-521523-1

Copyright © 1991 by Academic Press Limited All rights of reproduction in any form reserved

Electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) are techniques that have recently become available for general use in association with transmission electron microscopy. Theoretically they offer the possibility for localization and identification of all elements at a resolution which is otherwise unattainable. They also simultaneously yield information on the ultrastructure of the specimen.

EELS and ESI are based on the element-specific energy loss (A E) and the deflection of the inelastically scattered electrons of the electron beam passing the inner shells of the atoms in the specimen (Fig. 1). The EELS signal is higher than the X-ray signal by some orders of magnitude and it increases with decreasing atomic number. For the biologically important elements, which are mostly of lower atomic number, EELS therefore has some major advantages for microanalysis in comparison with energy dispersive X-ray analysis (EDXA).

Fig. 1. Electron beam (Eq) passing an atom: electrons are scattered elastically (£0) without energy loss and inelastically (E0- AE) with element-specific energy loss (A E) (after Bauer, 1985).

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Body Detox Made Easy

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