Use of pectinases complexed to colloidal gold for the ultrastructural localization of polygalacturonic acids in the cell walls of the fungus Ascocalyx abietina.

Three pectinase--gold complexes were used to localize polygalacturonic acids in the fungus Ascocalyx abietina (Lagerberg) Schlaepfer-Bernhard. With the pectinesterase and pectin lyase--gold complexes, the labelling was uniformly distributed over the fungus walls and did not seem to be significantly influenced by the tissue preparation. With the polygalacturonase--gold complex, differences in the labelling distribution were noted according to the fixation procedure indicating, therefore, that osmication of the tissues could greatly interfere with the localization of the specific enzyme binding sites. These results demonstrate, for the first time, the possibility of detecting polygalacturonic acids by means of different gold-complexed pectinases.