Carbohydrate electron microscopy

Therefore, while X-ray diffraction studies allowed the to detect the presence of 5 carbohydrates, electron microscopy diffraction studies allowed us to obtain information concerning the distance between the neighboring atoms within one carbohydrate residue. 

Antibodies against sugars (carbohydrate residues) can be difficult to obtain and lectins are a solution to these problems. Lectins are naturally occurring plant and animal proteins or glycoproteins that selectively bind noncovalently to carbohydrate residues. Lectins can be labeled directly or secondary antibodies against lectins enables the use of other immuno techniques (30) including electron microscopy (31). 

HIV is a typical member of the retrovirus family, in that it is an enveloped virus that carries RNA as its genetic information. The structure of HIV (Fig. 2) has been determined by electron microscopy. The viral membrane is acquired from the infected cell as the virus buds through the cell membrane. Inserted into the viral membrane are protein molecules coupled to carbohydrates (glycoproteins) which are essential for viral infectivity and probably also play a role in the... 

Fiebrig, L, Harding, S.E., Rowe, A.J., Hyman, S.C., and Davis, S.S., Transmission electron microscopy studies on pig gastric mucin and its interactions with chitosan, Carbohydr. Polym., 28 239-244 (1995). 

A hindrance to the elucidation of membrane structure is, of course, the material itself. Membranes are rather intractable lipoprotein systems. Their lipid, protein, and carbohydrate contents are variable both quantitatively and qualitatively since they cannot be crystallized, a detailed analysis by x-ray diffraction is impossible, and since they do not form solutions, the use of hydrodynamic or light-scattering techniques is quite limited. Electron microscopy has been the major physical method, but it is becoming increasingly clear that the electron microscope, at least at present, is incapable by itself of clarifying membrane structure on the molecular level (47). Despite an extensive literature, there is no general... 

The eukaryotic cell cytoplasm consists of the cytosol, which is the matrix that presents no visible structure even when observed by electron microscopy. Organelles and inclusion bodies are immersed in the cytosol. The organelles are responsible for intense metabolic activity and include the mitochondria, Golgi complex, lysosome, and endoplasmic reticulum Figure 2.1). Inclusion bodies are less frequent and consist of lipid, carbohydrate, and pigment-storing structures. 

The adhesion protein FimH mediates the attachment of uropathogenic E. coli strains with the host cell glycocalyx and specifically recognizes mannosylated structures. In 2002, Lin et al. first demonstrated that the glyco-AuNP can be used as a probe for staining the binding protein on the cell surface through carbohydrate-receptor interactions [67], Man-AuNPs were used to visualize the FimH adhesins on the type I pili of E. coli via transmission electron microscopy. 

The main carbohydrate components of isolated bakers yeast cell-walls are glucan (29%) and mannan (31%). The proportions vary with the strains and culture conditions for example, a marked decrease of mannan content occurs in inositol-starved cells. The structure of the cell wall is not known with certainty, but electron microscopy reveals two distinct layers, and it is believed that the outside surface consists of a charged, phosphorylated mannan layer (see the article by Northcote and references therein). 

This review covers the formation, composition, structure, function and properties of the acquired pellicle. Specifically, the formation of pellicle is considered in terms of thermodynamic and kinetic aspects. The composition of the pellicle is reviewed in terms of the proteins, carbohydrates and lipids that have been identified using a range of analytical techniques. The ultrastructure of the pellicle is described in some detail from studies involving enamel slabs carried in the mouth, in which the subsequent pellicle was analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). The function of the pellicle is outlined in terms of its lubrication properties, its ability to act as a semi-permeable membrane and its overall protection of the underlying enamel surfaces. Since pellicle is formed at the interface between the enamel surface and the oral environment, the important process of bacterial attachment to the pellicle surface is described and the specific bacterial binding sites found in the pellicle are summarised. The influence of diet and nutrition on the pellicle layer is considered. The formation of extrinsic stain is discussed in particular, the role that chlorhexidine... 

Sonju T, Christensen TB, Komstad L, Rolla G Electron microscopy, carbohydrate analyses and biological activities of the proteins adsorbed in two hours to tooth surfaces in vivo. Caries Res 1974 8 113-122. 

---