Identification of receptors for epidermal growth factor in the electron microscope by using an epidermal-growth-factor-biotin/avidin-gold procedure [proceedings]

Double-staining methods at the ultrastructural level applying colloidal gold conjugates

Several double gold-labeling methods have been reviewed, and our own results of applying some of these methods have been included. Of the six double-staining methods tested, four gave satisfactory results (indirect double immunogold staining method, two-face protein A-gold staining method, two-face amplified protein A-gold staining method, and formaldehyde blockade protein A-gold staining method). The other two techniques (sequential double protein A-gold staining method and formaldehyde blockade amplified protein A-gold staining method) showed cross-reaction between the first and second staining sequence.

Problems in the production and use of 5 nm avidin-gold colloids

Over the past 5 years we have encountered several problems in the production and use of 5 nm avidin-gold colloids for markers in electron microscopy. These problems include flocculation of colloids during reduction of chloroauric acid, insoluble gold pellets following ultracentrifugation, and non-specific binding of avidin-gold colloids to biological membranes. We are able to avoid these problems by: avoiding the use of crystalline chloroauric acid; succinoylating egg white avidin prior to adsorption on the gold sols; resuspending the pellets following ultracentrifugation in 5 mM phosphate buffer, pH 7.5; and using the avidin-gold colloids within 4 weeks of production.

Electron microscopical localization of nucleic acids by means of nuclease--gold complexes

Nucleic acids can be specifically localized at the electron microscope level by means of enzyme--gold complexes. Two enzymes RNAase A and DNAase I were labelled with colloidal gold, and the enzyme--gold complexes obtained applied on thin sections of glutaraldehyde-fixed and Epon-embedded tissues. Using RNAase--gold, the rough endoplasmic reticulum and the nucleolus of different cells appeared densely labelled. With the DNAase--gold the labelling was present over the euchromatin and the mitochondria. The quantitative evaluation, performed on different cellular compartments of the pancreatic acinar cells, confirmed the qualitative observations and ascertained the specificity of the labelling. The application of this technique, for the demonstration of nucleic acids in different tissues, is illustrated.

Cell surface labelling with gold colloid particulates: the use of avidin and staphylococcal protein A-coated gold in conjunction with biotin and fc-bearing ligands

Procedures for preparing gold colloid particles stabilized with either avidin or protein A are described. Methods of using these general utility tracers for localizing biotinylated and fc bearing immunoglobulins are outlined and, as examples of the way in which these methods can be applied, procedures for identifying epidermal growth factor receptors and surface fibronectin on ovarian granulosa cells are described.