Phylogenetic polymorphism on lectin binding to junctional and non-junctional basal lamina at the vertebrate neuromuscular junction

The histochemical binding of seven fluoreceinated lectins was comparatively studied in muscular tissue from twenty three different animal species including mammalians, amphibians, avians and fishes. Special interest was taken in the exploration of the differential lectin-binding properties at the neuromuscular synapse. Binding to synaptic sites was demonstrated using lectins that recognizes N-acetylgalactosamine and among of them, Dolichus biflorus agglutinin (DBA), was the most specific. Nevertheless, DBA fails to stain endplates in the muscle from most of the avians and the fishes (including the Torpedo electric organ) indicating that a polymorphic distribution of glycoconjugates exist at the vertebrate neuromuscular junction. Other lectins such as Concanavalin A (ConA) or Wheat germ agglutinin (WGA), share a similar staining properties in all animals that we examined making an intense label over the complete muscle surface. Although the species-related polymorphism on lectin binding does not reveal a clear relationship with the evolutionary tree, they give an evidence on the chemical heterogeneity of molecules specifically concentrated at the neuromuscular junction.