Lectin-binding pattern of Senegalese sole Solea senegalensis (Kaup) testis

Abstract

The localization and characterization of oligosaccharide sequences in the testis of Senegalese sole Solea senegalensis was investigated using 12 lectins in combination with KOH saponification and sialidase digestion (K-s). The interstitial compartment contained all the sugar residues investigated, those bearing oligosaccharides terminating with sialic acid (Neu5Ac) α2,3Galß1,4GlcNAc, Neu5AcGalNAcα1,3(LFucß1,2)Galß1,3/4GlcNAcß1 and GalNAcα1,3(LFuc1,2)Galß1,3/4GlcNAcß1 being more abundant in the medullar region than in the cortex. The melano-macrophage centres found in the interstitial compartment displayed glycans terminating with Galß1,3GalNAc. The basal lamina separating the germinal and interstitial compartments exhibited glycans with terminal/internal mannose, internal ßGlcNAc, and terminal Neu5Acα2,6Gal/GalNAc, and Neu5AcGalß1,3GalNAc, Galß1,3GalNAc (PNA), Galß1,4GlcNAc, GalNAc, αGal, and αL-Fuc. In the germinal compartment, the Sertoli cells expressed only glycans terminating with Neu5Acα2,3Galß1,4GlcNAc in the apical and supra-nuclear lateral surface of the spermatonial cysts located in the distal part of the seminiferous lobules. Primary spermatocytes exhibited oligosaccharides terminating with Galß1,3GalNAc and αGalNAc in the cytoplasm and nucleus, respectively. The spermatids contained highly mannosylated glycans terminating with GalNac, αGal, and αL-Fuc. The head of spermatozoa expressed a more complex glycosylation pattern characterized by the additional presence of oligosaccharides terminating with Neu5Acα2,3Galß1,4GlcNAc, Neu5AcGalß1,3GalNAc, Neu5AcGalNAcα1,3(LFucα1,2)Galß1,3/4GlcNAcß1, GalNAcα1,3(LFucα1,2)Galß1,3/4GlcNAcß1. The comparison with previous lectin histochemical studies carried out in other fish species reveals a specific glycosylation pattern of Senegalese sole testicular structures and spermatozoa head