Cytochemical demonstration of lectin binding-sites in the cuticle and tissues of Acanthocheilonema viteae (Filarioidea)

Abstract

The lectin-gold technique was used for the ultrastructural localization of lectin binding sites on thin sections of Lowicryl K4M embedded adult females, infective larvae and SDS-2-mercaptoethanol-insoluble cuticle components of Acanthocheilonema (Dipetalonema) viteae. Helix pomatia lectin (HPL) coupled to 14 nm gold particles, was used for the demonstration of N-acetyl- d-galactosamine-containing glycoconjugates. Triticum vulgaris (wheat germ) agglutinin (WGA) coupled to 10 nm gold particles after cross-linking to BSA or ovomucoid-gold after application of unlabeled WGA, demonstrated WGA binding sites ( N-acetyl- d-glucosamine). With both lectins no surface labelling of the cuticle was observed, but subcuticular layers reacted positively. HPL-gold was bound to cuticular fibers, the matrix and to the electron dense layer within the cortical zone of the cuticle of female worms. WGA-gold complexes were bound mainly to the cuticle matrix and somatic tissues. The results support the hypothesis that tissue-dwelling parasitic nematodes have reduced their surface carbohydrates perhaps as a consequence of their parasitic life.