Study of Histriculus cavicola Cyst Wall Using Different Lectins

Abstract

Summary Histriculus cavicola resting cyst walls have been examined with a variety of lectins binding specifically to certain sugar residues. Light and electron microscopic lectin histochemistry shows that the endocyst is the cyst wall layer with a greater and more varied saccharide residue content since it binds to the majority of lectins tested. The mesocyst contains some saccharide residues although these have not been detected in previous cytochemistry studies. The ectocyst is not stained with any of the lectins tested. None of the cyst wall layers were stained with MAA and UEA-I lectins, however we cannot rule out the possibility of the presence of sialic acid residues and/or fucose linked oligosaccharides from other linkages. Lectin blottings of isolated cyst wall proteins show the presence of several glycoproteins with molecular weights of 210-200, 190, 110-105, 95-85, 76, 73-68, 55, 50, 45, 40-36 kDa. The 190 kDa glycoprotein is located in the endocyst since this is the only band stained with PNA and DBA, lectins that bind strongly and only to the endocyst layer. This glycoprotein is the only one in which we have detected complex N and 0 linked glycans. The other glycoproteins present N linked glycans, although some of these may have 0 linked glycans, so far not detected by us.