Abstracts of the 53rd Starch Convention 2002 at Detmold

摘要

Atomic Force Microscopy (ARM) allows the 'imaging' of biological samples in a natural, or near natural environmerit, with the minimum of sample preparation. The major requirement is that the samples must be relatively flat: the surface roughness needs to be comparable to, or less than the size of the surface features to be imaged. Starch granules pose an interesting problem because of their large size and shape. Embedding granules in a non-penetrating resin has been shown to produce,samples that can be sectioned and imaged to reveal the internal structure of the granule, without the need for many of the pretreatments used previously in electron or atomic force microscopy of starch. The structural features revealed include growth rings and 'blocklets'. The presently accepted model for the internal structure of starch granules has been developed from Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) studies. With these techniques it is necessary to pre-process the granule by lintnerisation, or enzyme treatment, in order to enhance the crystalline structure. Samples are often embedded, using penetrating resins with harsh setting regimes, and the samples may need to be stained and/or metal coated. The milder embedding and sectioning methods employed in the present studies, has revealed changes in granule structure, induced when granules are embedded in interpenetrating resins such as 'Nanoplast'. Furthermore, the present, more natural AFM images of the growth ring structure within the granule, differs significantly from previous SEM and TEM images of lintnerised, or amylase treated granules. The methodology developed permits comparison of the structures of starch granules from different plant species, and an investigation of the effect of specific genetic mutations in the biosynthetic pathway on granule structure.