Changes in cell-surface carbohydrates of Trypanosoma cruzi during metacyclogenesis under chemically defined conditions.
Highly purified lectins with specificities for receptor molecules containing sialic acid, N-acetylglucosamine (D-GlcNAc), N-acetylgalactosamine (D-GalNAc), galactose (D-Gal), mannose-like residues (D-Man) or L-fucose (L-Fuc), were used to determine changes in cell-surface carbohydrates of the protozoal parasite Trypanosoma cruzi during metacyclogenesis under chemically defined conditions. Of the D-GalNAc-binding lectins, BS-I selectively agglutinated metacyclic trypomastigotes, MPL was selective for replicating epimastigotes, whereas SBA strongly agglutinated all developmental stages of T. cruzi. WGA (sialic acid and/or D-GlcNAc specific) was also reactive with differentiating epimastigotes and metacyclic trypomastigotes but displayed a higher reactivity with replicating epimastigote forms. A progressive decrease in agglutinating activity was observed for jacaline (specific for D-Gal) during the metacyclogenesis process; conversely, a progressive increase in affinity was observed for RCA-I (D-Gal-specific), although the reactivity of other D-Gal-specific lectins (PNA and AxP) was strong at all developmental stages. All developmental stages of T. cruzi were agglutinated by Con A and Lens culinaris lectins (specific for D-Man-like residues); however, they were unreactive with the L-fucose-binding lectins from Lotus tetragonolobos and Ulex europaeus. These agglutination assays were further confirmed by binding studies using 125I-labelled lectins. Neuraminidase activity was detected in supernatants of cell-free differentiation medium using the PNA hemagglutination test with human A erythrocytes. The most pronounced differences in lectin agglutination activity were observed between replicating and differentiating epimastigotes, suggesting that changes in the composition of accessible cell-surface carbohydrates precede the morphological transformation of epimastigotes into metacyclic trypomastigotes.
de Andrade
A F
AF
Instituto de Microbiologia, UFRJ, Cidade Universitaria, Rio de Janeiro, Brazil.
Esteves
M J
MJ
Angluster
J
J
Gonzales-Perdomo
M
M
Goldenberg
S
S
D000372:Agglutination Tests; D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology / Q000378:metabolism*; D000954:Antigens, Surface / Q000276:immunology / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D037102:Lectins / Q000378:metabolism; D009439:Neuraminidase / Q000378:metabolism; D014349:Trypanosoma cruzi / Q000254:growth & development / Q000276:immunology / Q000378:metabolism*
D000953:Antigens, Protozoan; D000954:Antigens, Surface; D037102:Lectins; D009439:Neuraminidase