Lectin analysis of surface saccharides during the cell cycle in four dinoflagellate species

The surface glycocalyx of four dinoflagellate species were examined by fluorescent lectins. Cultures were synchronized by darkness for 82 h and changes in DNA content, cell density and surface sugars composition were monitored at 2 h intervals for 52 h in populations of four species: Alexandrium minutum, Gymnodinium catenatum, Prorocentrum micans and Gyrodinium impudicum. Lectin binding properties indicated changes in the glycoconjugate: composition of the cell surface during the cell cycle. Differences in the lectin binding pattern among species were also observed. No detectable alpha -D-N-acetyl-galactosaminyl residues were found in A. minutum and G. catenatum at the cell surface and only small and irregular amounts of alpha -L-fucose were detected. However, large amounts of Lu-mannose, alpha -glucose, (N-acetyl-beta -D-glucosamine)(2) and, N-acetyl-beta -D-glucosaminyl were found during the greater part of the cell cycle of this species. P. micans only showed positive labeling when ConA was used, suggesting the presence of cu-mannosyl and alpha -glucosyl residues. More complex sugars such alpha -L-fuc and alpha -galNAc were never observed or were present in low amounts. All the sugar residues analyzed were present in the cell surface of G. impudicum in significant amounts. Evidence was also obtained for internalization of WGA receptors in P. micans and its binding to the nuclear membrane. (C) 2001 Elsevier Science B.V. All rights reserved.