Carbohydrate patterns of the pure cholinergic synapse of Torpedo electric organ: a cytochemical and immunocytochemical electron microscopic approach.
Using post-embedding gold staining techniques, we investigated the ultrastructural distribution of terminal sugars and carbohydrate chains located at the pure cholinergic electric organ tissue of Torpedo marmorata. Neither alpha-N-acetylgalactosamine (GalNAc)-specific lectins (DBA, SBA, HPA) nor monoclonal antibodies (MAb) recognizing Tn (Gal-NAc alpha-O-Ser/Thr; MAb Cu-1) and sialyl-Tn epitopes (NeuAc alpha 2,6GalNAc alpha-O-Ser/Thr; MAb B72.3 and OSM-10) were capable of labeling any of the synaptic structures. The absence of gold labeling was likewise noted with UEA-I (L-fucose) and with PNA (T-antigen, Gal beta 1,3GalNAc alpha). After neuraminidase pre-treatment of ultra-thin sections, PNA labeling was rendered evident, indicating the presence of neuraminic acid-masked T-antigen. Certain synaptic vesicles were labeled for neuraminic acid (LFA) and for N-acetyllactosamine (DSA), whereas others were not labeled at all. Gold labeling with LFA, RCA-I (beta-galactose), and DSA in the membrane infoldings of the dorsal face of the electrocyte was visualized. As noted above, the PNA reaction was revealed only after pre-treatment with neuraminidase. Dorsal (non-synaptic) basal lamina were reactive with DSA, whereas the synaptic portion was likewise labeled with LFA and RCA-I. Finally, RCA-I labeling was noted in the Schwann cell nucleus. Comparisons between these results and those described at the neuromuscular junction were made.
Egea
G
G
Laboratori de Neurobiologia Cel.lular i Molecular, Hospital de Bellvitge, Universitat de Barcelona, Spain.
Marsal
J
J
D000606:Amino Sugars / Q000032:analysis; D000818:Animals; D000957:Antigens, Viral, Tumor / Q000032:analysis; D002241:Carbohydrates / Q000032:analysis*; D002799:Cholinergic Fibers / Q000737:chemistry*; D004557:Electric Organ / Q000737:chemistry* / Q000648:ultrastructure; D007150:Immunohistochemistry; D037102:Lectins; D008854:Microscopy, Electron / Q000379:methods; D009438:Neuraminic Acids / Q000032:analysis; D009439:Neuraminidase; D009469:Neuromuscular Junction / Q000737:chemistry*; D019887:Peanut Agglutinin; D013569:Synapses / Q000737:chemistry*; D014101:Torpedo
D000606:Amino Sugars; D000957:Antigens, Viral, Tumor; D002241:Carbohydrates; D037102:Lectins; D009438:Neuraminic Acids; D019887:Peanut Agglutinin; C000458:N-acetyllactosamine; D009439:Neuraminidase