Intracellular lectin-binding sites in symbiont-bearing Crithidia species.
Crithidia oncopelti, C. deanei, and C. desouzai are flagellates of the Trypanosomatidae family that present bacterium-like endosymbionts in their cytoplasm. Direct and indirect lectin-gold labeling techniques were used at the electron microscopic level in Lowicryl K4M-embedded cells to demonstrate the presence of intracellular lectin-binding sites. We used the lectins Ulex europaeus I, Griffonia simplicifolia II, Ricinus communis I, Arachis hypogaea, G. simplicifolia I, Wistaria floribunda, Limulus polyphemus, and Canavalia ensiformis, which recognize alpha-L-fucose, alpha- and beta-N-acetylglucosamine, beta-galactose and beta-N-acetylgalactosamine, beta-galactose, alpha-galactose, beta-N-acetylgalactosamine, sialic acid and alpha-D-mannose, and alpha-D-glucose residues, respectively. The nucleus was the cellular structure most frequently labeled by the lectins. The Golgi complex was seldom labeled, whereas the endoplasmic reticulum and the flagellar pocket presented a large number of binding sites. Symbionts had their two unit membranes weakly labeled by the different lectins but displayed no labeling of the space between the membranes.
Motta
M C
MC
Departamento de Parasitologia e Biofisica Celular, Universidade Federal do Rio de Janeiro, Brazil.
Soares
M J
MJ
de Souza
W
W
D000606:Amino Sugars / Q000378:metabolism; D000818:Animals; D002467:Cell Nucleus / Q000737:chemistry / Q000648:ultrastructure; D003421:Crithidia / Q000737:chemistry* / Q000382:microbiology / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000648:ultrastructure; D005407:Flagella / Q000737:chemistry / Q000648:ultrastructure; D006651:Histocytochemistry; D037102:Lectins / Q000378:metabolism; D008854:Microscopy, Electron; D009005:Monosaccharides / Q000378:metabolism; D011975:Receptors, Mitogen / Q000302:isolation & purification*; D013559:Symbiosis
D000606:Amino Sugars; D037102:Lectins; D009005:Monosaccharides; D011975:Receptors, Mitogen