Enzymatic degradation and quantitative lectin labeling for characterizing glycoconjugates which act as lectin acceptors in cat submandibular gland

Abstract

Sites of binding of eight different lectins (LTA, UEA I, WGA, SBA, DBA, CON A, PNA, RCA I) to cat submandibular gland were studied after exposure of tissue sections to sialidase, alpha-fucosidase, beta-galactosidase, alpha-mannosidase, beta-N-acetylglucosaminidase. All lectins were affected by enzymatic predigestion and the labeling of individual lectins was highly dependent upon the glycosidase used to pretreat the sections. Glycoconjugates of demilunar, acinar and ductal cells exhibited a different composition of terminal sequences. For example, fucose proved to form the disaccharide fucose-galactose in demilunar and acinar cells, whereas it was present with the sequence fucose-N-acetyl-D-glucosamine in striated duct cells. Sialic acid participated both to the terminal sequence sialic acid-galactose and sialic acid-N-acetyl-D-galactosamine either in demilunar or in ductal cells. Lectin labeling combined with glycosidase digestion was also helpful in verifying the influence of neighbouring oligosaccharides on the affinity of lectins for the respective sugars.

A lectin histochemical study of the zygomatic salivary gland of adult dogs

“…The different results obtained with UEA I and LTA, lectins having the same nominal specificity, could be attributed to the presence of fucose in N-glycosidically linked secretory glycoproteins, which are only present in some acinar and tubular cells, while fucose in O-glycans is detectable in all of these cells. Similar data have been reported in human salivary glands (Laden et aL, 1984) and in the salivary glands of other mammalian species, including mice (Schulte and Spicer, 1983), rats , cats (Menghi et al, 1989) and dogs (Pedini et aL, 1994a,b).…”

Localization of glycoconjugates in dog parotid gland by lectin histochemistry

“…This different binding affinity has also been found in the salivary glands of other species Spicer, 1983, 1984a;Menghi et al, 1989). UEA I reactivity can probably be attributed to the presence of fucose in O-glycosidically linked secretory glycoproteins, whereas LTA binds fucose in N-glycosidically linked glycoconjugates (Schulte and Spicer, 1983).…”

“…Recent advances in the characterization of carbohydrate components have been obtained by lectin histochemistry. This method has been widely used to study stored secretory glycoproteins in the major salivary glands of many mammals (Schulte and Spicer, 1983;1984a;Schulte et al, 1985;Menghi et al, 1987Menghi et al, , 1989Menghi et al, , 1992Accili et aL, 1989Accili et aL, , 1992Gargiulo et al, 1993). The dog parotid gland has been the subject of numerous ultrastructural (Nagato and Tandler, 1986) and histochemical investigations (Aureli et al, 1960;Bignardi, 1961;Bignardi et aL, 1962;Reifel and Travill, 1972) that have demonstrated that acinar cells are characterized by a seromucous secretion.…”

Lectin histochemistry of developing submandibular glands of fetal Syrian golden hamsters

“…1989). Furthermore, heterogeneity in lectin-staining intensity is seen within the same cell population (Naito et al 1983;Spicer 1983, 1984;Schulte et al 1985;Menghi et al 1989). In the developing submandibular glands of fetal hamsters, secretory cell products exhibited various degrees of staining, ranging from light to heavy with HPA, MPA, PNA, GSA I-B4 and UEA I.…”

“…1985;Takai etal. 1986;Menghi et al 1989) but changes in lectin binding to the submandibular glands during fetal development have not been studied in any species.…”