Search

Histochemical, lectin-histochemical, and immunohistochemical analyses were performed on parietal cells of the greater horseshoe bat, Rhinolophus ferrumequinum, to clarify the composition and distribution of oligosaccharide chains in the beta-subunit of the protonic pump H(+),K(+)-ATPase. PAS, Alcian Blue (pH 2.5) and Alcian Blue (pH 1.0) stainings detected only neutral glycoconjugates. Lectin-binding analyses included LTA, UEA-I, ConA, SBA, BSI-B4, AAA, DBA, PNA, and WGA. WGA-and PNA-bindings were also tested after beta-elimination to detect O-linked glycans. Parietal cells were negative for binding to LTA and UEA-I, and to PNA and WGA after beta-elimination, indicating the lack of (1,2) fucosylated residues and of N-linked glycans, respectively. Immunohistochemical tests with anti-alpha- and anti-beta-H(+),K(+)-ATPase were positive. Two alternative patterns of glycoconjugate distribution were found, i.e. a perinuclear and a diffuse one, indicating localization in the intracellular canaliculus and in the tubulovesicular system of the parietal cells, respectively. Both the subunits of the H(+),K(+)-ATPase and the galactosyl/galactosaminyl residues were co-distributed in both the perinuclear and the diffuse patterns, suggesting that the residues are part of the protonic pump. Glycosyl/glycosaminyl and mannosyl groups were concentrated in the tubulovesicular system, and fucosylated residues were found almost exclusively in the intracellular canaliculi; thus they are probably not included in the oligosaccharide chains of beta-H(+),K(+)-ATPase. These findings indicate that the oligosaccharide chains linked to the beta-H(+),K(+)-ATPase subunit in R. ferrumequinum have distinct features compared to the other mammals studied and confirms the taxon specificity of the chains in the proton pump.

In this study, the variety of sugar residues in the gut glycoconjugates of Triturus carnifex (Amphibia, Caudata) are investigated by carbohydrate conventional histochemistry and lectin histochemistry. The oesophageal surface mucous cells contained acidic glycoconjugates, with residues of GalNAc, Gal beta1,3 GalNAc and (GlcNAc beta1,4)(n) oligomers. The gastric surface cells mainly produced neutral glycoproteins with residues of fucose, Gal beta1-3 GalNAc, Gal-alphaGal, and (GlcNAc beta1,4)(n) oligomers in N- and O-linked glycans, as the glandular mucous neck cells, with residues of mannose/glucose, GalNAc, Gal beta1,3 GalNAc, (GlcNAc beta1,4)(n)oligomers and fucose linked alpha1,6 or terminal alpha1,3 or alpha1,4 in O-linked glycans. The oxynticopeptic tubulo-vesicular system contained neutral glycoproteins with N- and O-linked glycans with residues of Gal-alphaGal, Gal beta1-3 GalNAc and (GlcNAc beta1,4)(n)oligomers; Fuc linked alpha1,2 to Gal, alpha1,3 to GlcNAc in (poly)lactosamine chains and alpha1,6 to GlcNAc in N-linked glycans. Most of these glycoproteins probably corresponds to the H(+)K(+)-ATPase beta-subunit. The intestinal goblet cells contained acidic glycoconjugates, with residues of GalNAc, mannose/ glucose, (GlcNAc beta1,4)(n)oligomers and fucose linked alpha1,2 to Gal in O-linked oligosaccharides. The different composition of the mucus in the digestive tracts may be correlated with its different functions. In fact the presence of abundant sulphation of glycoconjugates, mainly in the oesophagus and intestine, probably confers resistance to bacterial enzymatic degradation of the mucus barrier.

Mucins in the gastrointestinal tract of Rhinolophus ferrumequinum were investigated by histochemistry and lectin histochemistry to evaluate morphofunctional variations of different regions and their possible physiological and evolutionary implications. Histochemical methods included periodic acid-Schiff (PAS), Alcian blue (AB) at pH 2.5 and 1.0 and high-iron-diamine AB pH 2.5. Binding of lectins Con A, DBA, WGA, LTA, LFA, PNA and SBA; LFA, PNA and SBA with prior sialidase treatment; and paradoxical Con A were evaluated. The oesophagus lacked glands. The stomach was divided into a short cardias, a wide fundus and a brief pylorus. The surface muciparous cells secreted sulpho- and sialomucins with N-acetylgalactosamine (GalNAc) residues, N-acetyllactosamine and (beta1,4 N-acetylglucosamine)(n) chains. Towards the pylorus, N-acetylgalactosamine residues disappeared and acidity decreased. Cardiac glands, neck cells in the fundic glands, pyloric and duodenal Brunner's glands all shared neutral, stable class-III mucins, mainly with N-acetylgalactosamine sequences. The intestine was divided into a duodenum, a jejuno-ileum and a short rectum. The goblet cells produced sulpho- and sialomucins with sialylated N-acetylgalactosamine sequences, (beta1,4 N-acetylglucosamine)(n) and N-acetyllactosamine, whose sialylation increased towards the rectum. The main features of the mucins are probably associated with the requirements of fast absorption and food passage and in protection against mechanical and pathogenic injuries.

Mucous cells and enteroendocrine cells of the pyloric region of the ruin lizard (Podarcis sicula campestris De Betta) have been examined by lectin histochemical and immunohistochemical methods. Binding to five plant lectins (Canavalia ensiformis, Con A; Triticum vulgare, wheat germ, WGL; Lotus tetragonolobus, winged pea, WPL; Glycine max, soybean, SBL; Arachis hypogaea, peanut, PNL) was performed to characterize glycoconjugates in the secretory products of superficial and glandular mucous cells. Lectin histochemistry revealed the presence of N-acetyl-D-galactosamine, D-galactose and N-acetyl-D-glucosamine in the pyloric superficial cells. Mucous glandular cells mainly contained neutral glycoproteins with terminal residues of galactose, N-acetyl-D-glucosamine and N-acetyl-D-galactosamine. These cells did not react with Con A after periodate oxidation-sodium borohydride reduction (Paradoxical Con A staining). In the pyloric glands three different types of endocrine cells were identified immunohistochemically: gastrin-, serotonin- and somatostatin-immunoreactive cells; VIP-, bombesin- or cholecystokinin-immunoreactive cells have not been found in the pyloric mucosa.

Secretory cell glycoconjugates of the alimentary canal of the ruin lizard (Podarcis sicula campestris De Betta) were characterized by traditional staining methods and by lectin histochemistry. The goblet cells of the upper esophagus produced sialo- and sulfomucins, while those of the lower esophagus mainly contained sulfomucins. Lectin histochemistry demonstrated the presence of N-acetyl-D-glucosamine and terminal sialic acid. The epithelial mucous cells lining the surface of the stomach and the gastric pits contained neutral glycoproteins with glycosidic residues of N-acetyl-D-galactosamine, D-glucose, D-mannose, D-galactose, and N-acetyl-D-glucosamine. The mucous cells of the gastric glands produced neutral glycoproteins that contained stable class-III mucosubstances, as revealed by Paradoxical Con A staining, with terminal residues of L-fucose and D-galactose. They can be similar to the true neck cells of the gastric pits of other vertebrates. The goblet cells of the small intestine produced acidic glycoproteins with glycosidic residues of N-acetyl-D-glucosamine, sulfated esters on internal residues and terminal sialic acid. In the large intestine, there is a predominance of sulfated mucosubstances with D-galactose, N-acetyl-D-glucosamine, and N-acetyl-D-galactosamine. The microheterogeneity of mucins of the digestive tract, as proved by lectin histochemistry, is probably connected to their different functions.

Histochemical study by traditional staining methods (AB, PAS, HID) and by the use of five peroxidase-labelled lectins (ConA, WGL, WPL, SBL, PNL) were carried out to characterize glycoconjugates in the secretory cells of the nasal mucosa of the Lacertid lizard Podarcis sicula campestris De Betta. The mucus covering the nasal epithelium is produced by the supporting cells and the Bowman glands in the olfactory area, and by typical goblet cells and, probably, a second type of secretory cell, in the non-sensory area. Neutral glycoconjugates containing N-acetyl-D-glucosamine and terminal N-acetyl-D-galactosamine, D-mannose and D-glucose residues were present in the secretory product of the Bowman glands. L-fucose and D-galactose were absent. In the supporting cells the secretory product consisted mainly of sulfated glycoproteins containing D-galactose, N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, D-mannose, D-glucose, but not L-fucose. Glycoconjugates containing terminal sialic acid and penultimate D-galactose were present in typical goblet cells as was N-acetyl-D-glucosamine.