A histochemical study using lectin methods was performed on myxosporean parasites from vastly different fish hosts from marine and fresh waters. Six biotinylated lectins were used (WGA, SBA, BS-I, Con-А, UEA-I and SNA). The binding paltem of Con-A and WGA revealed the presence of mannose and/or glucose, and N-acetyl-D-glucosamine respectively, in polar capsules and valves of most of the myxosporea assayed. Thus, chitin may be present in polar capsules and/or valves of myxosporean spores. The BS-I binding pattern showed the presence of a-!)-galactose and/or N-acetyl-D-galactosamine residues in polar capsules of Kudoa sp., Zschokkeìla mugilis Sitjà-Bobadilla et Alvarez-Pellitero, 1993 and Leplotheca sp., and in the valves of the latter. Scarce amounts of N-acetyl-D-galactosamine and/or α-D-galactose were demonstrated by SBA binding in Sphaerospora dicentrarchi Sitjà-Bobadilla et Alvarez-Pellitero 1992, Leplotheca sp. and Kudoa sp. valves, and in Leptotheca sp. polar capsules. The UEA-I staining indicated the absence ofa-L-fucose in all the myxosporea assayed except in Leptotheca sp. N-acety!neuraminic acid was detected with SNA in the polar capsules and sporoplasms of Polysporoptasma sparis Sitjà-Bobadilla et-Alvarez-Pellitero, 1995 and in the polar capsules and valves of Kudoa sp. These results indicate that, although Myxosporea may have conserved carbohydrate structures, some of them can show significantly different binding patterns, which may be useful in diagnostic and functional studies.
The presence of terminal carbohydrate residues in Enteromyxum leei (Diamant, Lom et Dyková, 1994) Palenzuela, Redondo et Álvarez-Pellitero, 2002 stages in gilthead seabream intestines was studied at light microscopy (LM) and transmission electron microscopy (TEM) level using lectin histochemical techniques. Abundant mannose and/or glucose residues were demonstrated by the intense staining caused by binding of biotinylated concanavalin A (Con A), at both LM and TEM. A clear positivity was also obtained with Ulex europaeus (UEA I) agglutinin specific for fucose residues. Both lectins stained E. leei proliferative and sporogonic stages, though glycan patterns varied between these developmental stages. Wheat germ agglutinin (WGA) and Bandeiraea simplicifolia lectin I (BSL I) recognised only structures in the sporogonic stages. Faint labelling occurred with Glycine max (SBA) lectin. No staining was obtained with Sambucus nigra (SNA) agglutinin. The TEM studies demonstrated a restricted presence of N‑acetyl-D-galactosamine and α-D-galactose, whereas glucose/mannose and fucose, the dominant structures, were also present at the parasite membranes and host-parasite interface, suggesting a role in host-parasite interaction.