Ultrastructural visualization of galactose in the glycoprotein of gastric surface cells with a peanut lectin conjugate

Carbohydrate characterization of quail primordial germ cells during migration and gonadal differentiation

A selection of lectins were used to study changes in the distribution of sugar residues in primordial germ cells (PGCs) during gonadal colonization and differentiation. Although the cytochemical characteristics of PGCs have been described in the chick, little is known about such characteristics in other avian species of interest to experimental biology. Therefore, we studied embryos of Japanese quail (Coturnix coturnix japonica) by light and laser confocal scanning microscopy, using the QH1 antibody as a tool to identify PGCs in both sexes and at all stages. LEA, WGA and RCA-I bound to PGCs in a similar way to QH1. LEA was the best marker for all stages. The presence of acid phosphatase and the intense reaction of LEA, WGA, RCA-I and WFA at the cell surface were shown to be a useful tool in the study of the migratory PGCs of the quail. Quails were sexed histologically in younger embryos than in chick; results were confirmed by PCR. The lectin-binding pattern changed drastically in differentiated gonads. Cell surface reactivity was almost entirely lost. Quail differentiating oogonia showed a characteristic binding pattern to QH1 and to the lectins WGA, RCA-I and WFA. Binding was observed in intense spots in the Golgi complex, and there was a specific PNA reaction. These results suggest that some selective sugar binding sites on the PGCs play a significant role in their migration, colonization and maturation.

Lectin binding and identification of sialic acid acceptor sugars in rabbit oviduct under hormone administration

Localization of individual glycosidic residues and sialic acid acceptor sugars was investigated by conjugated lectins in the rabbit oviduct under physiological hormonal conditions and human chorionic gonadotropin (HCG) administration. Ampulla and isthmus were found to exhibit lectin binding profiles typical of each hormonal stage. Two different sialylated glycomolecules were identified within the epithelial lining; in particular, sialoglycoconjugates characterized by the terminal sequence sialic acid-galactose were visualized in the secretory cells and the sialic acid-N-acetylgalactosamine terminal disaccharides were localized on both ciliated and secretory cells of the entire oviduct. Surface and cytoplasmic sialoglycoconjugates were also found to exhibit a differential behaviour inside the two oviduct tracts examined. Present findings further supported the idea that in ampulla and isthmus, the greatest modifications consequent to hormone treatment take place at different times.

A lectin histochemical study of intrahepatic ducts in patients with hepatolithiasis

A panel of 12 biotinylated lectins was used to investigate the diversity of glycoconjugate on the epithelium of stone-containing intrahepatic bile ducts and compared to controls. Among the 12 lectins, only WGA (wheat germ agglutinin) and Con A (concanavalin agglutinin) stained the epithelium of stone-containing intrahepatic ducts. Con A, a glucose/mannose-specific lectin, bound weakly on the epithelium of the stone-bearing intrahepatic duct in 10 of the 25 specimens, but none of the controls. All stone-containing intrahepatic bile ducts were stained heavily and homogenously by WGA, the N-acetylglucosamine-specific lectin. The high columnar epithelia of both intramural and extramural glands were stained in the supranuclear region, while the serous acini of extramural glands were stained in whole cytoplasm. The epithelium of intrahepatic ducts from the controls was stained weakly by WGA only. The WGA receptors were not abolished by pretreatment of neuraminidase. This led us to conclude that the stone-containing intrahepatic ducts were rich in N-acetylglucosamine and the heavy and homogenous staining with WGA will be indicative of hypersecretion of mucus from stone-bearing intrahepatic bile ducts.

Combined lectin binding and PAS/alcian blue staining in glycol methacrylate sections

Evaluation of cryofixation and paraffin and glycol methacrylate embedding showed that lectin binding was essentially independent of the embedding medium. Fluorescence intensity increased in the following order: glycol methacrylate, paraffin and cryostat sections. The optical resolution increased in the reverse order. Semi-thin glycol methacrylate sections provided satisfactory fluorescence intensities and the best resolution of all embedding techniques applied. Furthermore the lectin treated sections can be stained further using routine histological or specific histochemical methods. The potassium hydroxide/alcian blue/periodic acid-phenylhydrazine-Schiff method was used successfully to demonstrate sulfated and nonsulfated sialomucins. Lectins combined with mucin histochemistry allowed visualization of specific sugar residues in the same glycol methacrylate plastic section.

Ultrastructural distribution of lectin-binding sites on gastric superficial mucus-secreting epithelial cells. The role of Golgi apparatus in the initial glycosylation

Normal human gastric epithelial cells were examined by electron microscopy using each of five biotinylated lectins [Ulex europaeus agglutinin I (UEA-I), peanut agglutinin (PNA), wheat germ agglutinin (WGA), soybean agglutinin (SBA) and Dolichos biflorus agglutinin (DBA)] as a probe. We employed 35 gastric surgical specimens removed from complicated peptic disease. The lectin-binding sites were revealed with streptavidin-colloidal gold complex. All specimens were embedded in Spurr and LR White resins. In superficial foveolar epithelial cells, the lectins used were generally positive in all cell types (mainly UEA-1 and PNA) on the Golgi region and mucus cytoplasmic vacuoles, with many variations among cells in the same case. On the other hand, extracellular mucus was negative for WGA. Labelling with PNA revealed a biphasic pattern (peripheral positivity) on mucous droplets in surface and foveolar cells. The cis side of the Golgi apparatus was labelled with SBA and PNA and rough endoplasmic reticulum with SBA (only five cases). Lectin-binding variability could be related to heterogeneous composition of gastric mucus. Our results with SBA suggest initiation of O-glycosylation at the Golgi apparatus; however a role of the rough endoplasmic reticulum cannot be excluded (N-glycosylation). We propose the following sequence of sugar addition to the carbohydrate side-chains of gastric glycoproteins: (1) GaNAc (Golgi apparatus cis-side), (2) GlcNAc (Golgi apparatus intermediate face), (3) GalNac or Gal, alpha-L-fucose (Golgi apparatus trans-side).

Subcompartment sugar residues of gastric surface mucous cells studied with labeled lectins

We examined the intracellular localization of sugar residues of the rat gastric surface mucous cells in relation to the functional polarity of the cell organellae using preembedding method with several lectins. In the surface mucous cells, the nuclear envelope and rough endoplasmic reticulum (rER) and cis cisternae of the Golgi stacks were intensely stained with Maclura pomifera (MPA), which is specific to alpha-Gal and GalNAc residues. In the Golgi apparatus, one or two cis side cisternae were stained with MPA and Dolichos biflorus (DBA) which is specific to terminal alpha-N-acetylgalactosamine residues, while the intermediate lamellae were intensely labeled with Arachis hypogaea (PNA) which is specific to Gal beta 1,3 GalNAc. Cisternae of the trans Golgi region were also stained with MPA, Ricinus communis I (RCA I) which is specific to beta-Gal and Limax flavus (LFA) which is specific to alpha-NeuAc. Immature mucous granules which are contiguous with the trans Golgi lamellae were weakly stained with RCA I, while LFA stained both immature and mature granules. The differences between each lectin's reactivity in the rough endoplasmic reticulum, in each compartment of the Golgi lamellae and in the secretory granules suggest that there are compositional and structural differences between the glycoconjugates in the respective cell organellae, reflecting the various processes of glycosylation in the gastric surface mucous cells.

Glycoconjugate unique to migrating primordial germ cells differs with genera

Previous cytochemical studies showing that rat primordial germ cells (PGCs) possess a unique surface glycoconjugate containing terminal alpha-N-acetylgalactosamine were extended in this study to determine whether a similar distinctive glycoconjugate coats the surface of PGCs in the mouse. The results showed that mouse PGCs fail to react with peroxidase-conjugated lectins specific for localizing glycoconjugate with terminal N-acetylgalactosamine. All available lectin conjugates with affinity for other terminal sugars or internal sugar linkages also failed to stain mouse PGCs except for the conjugates that bind to alpha-fucose. One fucose-specific lectin conjugate stained only PGCs in the early mouse embryo but stained additional sites in more mature embryos and lost reactivity with PGCs after gestational day 14. Another fucose-specific conjugate stained PGCs until day 15, but with less selectivity, and a third such conjugate bound to several sites, but not to PGCs. The results suggest that the developmental mechanisms mediating cellular interaction, migration, and differentiation may be similar in different genera, but the specific structure of the cell surface glycoconjugate involved in these mechanisms differs.

Localization and significance of peanut agglutinin-binding sites on ependymoma cells

It has been suggested that peanut agglutinin (PNA)-binding sites in benign and malignant tissues were quite different. To clarify the difference of PNA-binding sites between benign and malignant ependymoma, PNA-binding sites are investigated on the surface membrane of tissues from benign and malignant ependymomas and cultured ependymoma cells. In four of five malignant ependymoma cases, PNA binding occurred in a diffuse cell membrane fashion or granular intracytoplasmic fashion without neuraminidase treatment. On the other hand, PNA binding was observed without neuraminidase treatment in only two of eight benign ependymoma cases. After neuraminidase treatment, all of our benign and malignant ependymoma cases evidenced PNA binding. PNA binding was clearly evident on the cell membrane of ependymoma cells which were able to express organotypic structures, that is, to form ependymal rosettes after neuraminidase treatment. Normal rat ependymal cells showed PNA binding only after neuraminidase treatment. These findings suggest that the masking of PNA-binding sites of ependymoma cells by sialic acid may be correlated with tumor cell differentiation.

Lectin expression in neoplastic and non-neoplastic lesions of the rectum

The expression of six lectins (Arachis hypogaea, B. simplicifolia I, concanavalin A, Dolichus biflorus, Triticum vulgaris, Lotus tetragonolobus) was studied in 24 adenocarcinomas, 24 adenomas, 20 metaplastic polyps, 17 specimens of mucosal prolapse (solitary ulcer syndrome) and 10 of normal mucosa, all taken from the rectum. Qualitative, quantitative and distributive differences in lectin expression were observed between adenocarcinoma and normal mucosa. These cancer-associated glycoprotein alterations were also observed, though to a lesser extent, in benign neoplastic and non-neoplastic lesions of the rectum. It appears therefore that the glycoprotein modifications associated with malignant transformation are not specific indicators of malignancy. It is suggested that the common denominator is a disturbance in the activities of enzymes, particularly the glycosyl-transferases and glycosidases, involved in the biosynthesis of glycoprotein. This disturbance can occur in situations where cells are less differentiated either through developmental immaturity, rapid cellular division or neoplastic de-differentiation. These changes are therefore more likely to reflect the state of differentiation rather than the malignant nature of the cells. It is shown that the greater the deviation of the lesion from normal the greater the glycoprotein alterations. The potential usefulness of lectin expressions as predictive indicators of biological behaviour of adenocarcinomas of the large bowel needs further studies.

Histochemical characteristics of glycoproteins in the bile duct system of mice immunized with swine serum

The bile duct system of BALB/c and DDY mice, which were immunized with swine serum (SS) or not, was examined histochemically. Biliary epithelial cells of the SS-treated BALB/c mice, which were positively stained with periodic acid-Schiff (PAS) and had binding sites of Dolichos biflorus (DBA), were thought to secrete neutral glycoproteins with terminal N-acetyl-D-galactosamine residues. Those of the SS-treated DDY mice were however negatively or weakly stained with any histochemical stainings. On the other hand, glandular epithelial cells of the SS-treated mice of both strains, which were positively stained with high iron diamine-alcian blue (HID-AB) and had binding sites of DBA, Griffonia simplicifolia-II (GS-II), Ulex europaeus-I (UEA-I), and Triticum vulgaris (WGA), were thought to secrete glycoproteins with terminal sialic acid residues. Biliary and glandular epithelial cells of the normal mice contained only a small amount of glycoproteins showing similar histochemical characteristics to those in the SS-treated BALB/c mice. BALB/c mice immunized with SS were thought to be very useful for the investigation of production and secretion of glycoproteins in the bile duct system as well as being good model of bile duct disease.

Lectin reactivity in human large bowel

The affinity of six lectins (Arachis hypogaea, Concanavalin A, Bandeiraea simplicifolia I. Dolichus biflorus, Triticum vulgaris and Lotus tetragonolobus) was studied in 10 normal human large intestines. The results showed that each lectin had its own characteristic staining pattern. They differed in their affinity for different cellular components, local distribution within crypts and regional distribution between right (ascending colon) and left (rectum) segments of the large bowel. Arachis hypogaea stained predominantly the supranuclear golgi cisternae and Concanavalin A the cytoplasm. Triticum vulgaris stained preferentially the mucin of the well differentiated cells of the upper crypt while Lotus tetragonolobus characteristically stained the glycocalyx and apical portion of the less differentiated basal cells of the lower crypt. Goblet-cell mucin of the ascending colon had greater affinity for Bandeiraea simplicifolia I and that of the rectum for Triticum vulgaris. Lotus tetragonolobus stained more frequently and extensively the goblet-cell mucin of the upper crypts of the ascending colon than that of the rectum. The goblet cell mucins of the upper crypts were consistently stained in both the right and left segments of the large bowel by Dolichus biflorus while the mucins of the less differentiated cells of the lower crypts were less consistently stained in the ascending colon.

Histochemical demonstration of sugar residues by lectin and immunocytochemical techniques for blood group antigens in human colon

Goblet cell mucin in 39 human colons was studied by methods specific for various sugar residues, including staining with three lectins, Dolichos biflorus agglutinin (DBA, specific for blood group A antigen), Griffonia simplicifolia agglutinin-I (GSA-I, B) and peanut agglutinin (PNA, T antigen), and immunostaining for A, B, H and T. Isoantigens A, B or H were found only in the right colon. GSA-I reactive goblet cells occurred in the right colon of both blood group A and B patients and possibly contained isoantigens. However DBA reactive cells were found in all cases. Prior neuraminidase digestion imparted anti-A, GSA-I and DBA reactivities to the cells lining the lower crypts in all cases. This pretreatment also imparted PNA and anti-T reactivities to goblet cells, only the latter reactivity being eliminated by galactose oxidase. Goblet cell mucin in transitional mucosa revealed decreased A and B, and increased H antigens. Enhanced galactose oxidase-Schiff (GOS) and anti-T reactivities were also noted. The present results revealed that some lectin reactions of goblet cells might be related to blood group antigens but others were not, and that different techniques for demonstrating reputedly the same sugar residues produced different results, indicating a need for proper evaluation of their specificity.

Ultrastructural localization of carbohydrates on thin sections of Staphylococcus aureus with silver methenamine and wheat germ agglutinin-gold complex

Postembedding staining of intracellular carbohydrates on thin sections of Staphylococcus aureus was studied by the silver methenamine and the wheat germ agglutinin-gold techniques. Staining of silver grains was observed on both the cell wall and the cross wall. The staining was interpreted to be due to teichoic acid. Labeling by wheat germ agglutinin-gold particles was observed on both the cell wall and the cross wall, and the staining pattern resembled that of silver methenamine staining. Therefore, the labeling was considered to be due to N-acetylglucosamine of teichoic acid. The combination of two types of cytochemical techniques was useful to localize and characterize the carbohydrates of the bacterial cell.

The Golgi apparatus in the acinar cells of the developing embryonic pancreas: II. Localization of lectin-binding sites

The reaction patterns of the Golgi apparatus following staining with the lectins concanavalin A (ConA), Ricinus communis I agglutinin (RCA I), and Helix pomatia lectin (HPA) were studied in the pancreas acinar cells of rat embryos in the course of cell differentiation from day 13 through day 20 of gestation. The binding reactions were localized by means of pre-embedment incubation of 10-microns-thick cryosections of pancreas tissue, prefixed in a mixture of 4% formaldehyde/0.5% glutaraldehyde, using horseradish peroxidase for electron microscope visualization. ConA, which preferentially binds to alpha-D-mannosyl residues, consistently stained the cisternae of the cis Golgi side. The majority of the stacks also showed ConA staining of medial cisternae. The reaction of the trans side was variable; in each stage of development, the cisternae of the trans Golgi side either were devoid of labeling or appeared intensely stained. The reactions obtained with RCA I, which recognizes terminal beta-D-galactosyl residues, changed in the course of cell differentiation; in the protodifferentiated and early differentiated states, the system of "rigid lamellae," located at the trans side of the Golgi stacks, was intensely labeled, but became unreactive after production of secretion granules had started, the reaction then being restricted to the stacked saccules. In regard to the Golgi stacks in each of the developmental stages, RCA I binding sites either were confined to the trans cisternae, or, in addition, were found distributed across elements of the medial and cis compartments.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential binding sites of peroxidase-labelled lectins in the submandibular gland of sucking and adult cats

The glycosidic residues in the submandibular gland of cat at different ages were studied using a battery of 6 lectins conjugated with horseradish peroxidase as histochemical reagents. The submandibular glands of sucking and adult cats showed diversities in the reaction intensity or in the localization of binding sites. The morphologically distinct secretory tracts appear to produce different types of oligosaccharides in sucking and adult subjects. The sugars that can be defined as growth markers in the cat submandibular gland seem to be alpha-L-fucose, N-acetyl-D-glycosamine and beta-galactose. The data originated from this research have been compared with biochemical data previously obtained by the authors on the cat submandibular gland during growth.

Evidence for glycoconjugate in nociceptive primary sensory neurons and its origin from the Golgi complex

Glycoconjugates with terminal galactose residues were localized in rat spinal cord and spinal ganglia using lectin-HRP conjugates of Griffonia simplicifolia and Glycine max agglutinins. Alternate staining of serial sections with HRP-labelled lectins and an antibody for substance P (SP) showed staining in identical primary sensory neurons with both methods. Similarly, lectin-reactive as well as SP-positive fibers were found in Rexed laminae I and II, Lissauer's tract, the spinal nucleus and tract of the trigeminal nerve, the nucleus commissuralis and a small bundle of fibers just ventral to the central canal. Administration of capsaicin to neonatal rats produced a significant decrease in lectin-reactive fibers of the substantia gelatinosa, and in the number of lectin-reactive sensory neurons. The coexistence of SP with galactose-containing glycoconjugates in spinal ganglion neurons, as well as sensitivity of these cells to capsaicin, provided a basis for classifying the reactive neurons as nociceptive in type. Ligation of dorsal roots resulted in disappearance of lectin reactivity in the spinal cord and caused accumulation of lectin-positive material proximal to the ligature, indicating somatofugal transport of galactose-containing glycoconjugates. Colchicine injection caused an increase in SP reactivity in dorsal ganglion neurons but no change in lectin staining of galactoconjugate. At the ultrastructural level affinity for the lectin conjugates was confined to the Golgi cisternae and the plasmalemma of B-type sensory neurons in the dorsal ganglion. The axolemma of unmyelinated processes stained selectively in dorsal roots and the substantia gelatinosa of the spinal cord. These findings provide evidence for the presence in certain sensory cells of a characteristic galactosylconjugate which may prove to be of significance in nerve function.

Terminal glycosylation in rat hepatic Golgi fractions: heterogeneous locations for sialic acid and galactose acceptors and their transferases

Endogenous acceptors for N-acetylglucosamine (GlcNAc), galactose (Gal) or sialic acid (NeuAc) transfer were labeled to high activities when purified hepatic Golgi fractions were incubated with the corresponding radiolabeled nucleotide sugar in the absence of detergent. The in vitro conditions which were optimal for the endogenous glycosylation of GlcNAc and Gal acceptors (Mn2+, ATP) also promoted fusion within a subset of Golgi membranes. Electron microscope radioautography revealed that the majority of NeuAc acceptors were associated with unfused Golgi membranes, whereas the majority of Gal acceptors were localized to fused membranes. GlcNAc acceptors were approximately equally distributed between fused and unfused membranes. Under conditions in which Golgi membrane fusion was absent (-Mn2+), only NeuAc transfer was active. The majority of endogenous NeuAc acceptors were consequently assigned to the more trans regions of the hepatic Golgi apparatus as concluded from a combination of radioautography (NeuAc transfer) and acid NADPase cytochemistry (reactive medial and trans Golgi saccules). The distribution of NeuAc and Gal transferases was assessed after Percoll gradient centrifugation of disrupted Golgi fractions. The median density of NeuAc transferase was lower than that of Gal transferase. The studies are indicative of distinct Golgi components harboring the majority of acceptors and enzymes for terminal glycosylation.

Binding of lectin-fluorescein conjugates to intracellular compartments of growth-plate chondrocytes in situ

In this study, lectin-binding techniques are applied to growth-plate cartilage to analyze the intracellular localization of lectin-binding glycoconjugates of chondrocytes in situ. The binding of ten fluorescein-conjugated lectins is analyzed on 1-micron-thick Epon-embedded, nondecalcified sections of growth plates from Yucatan swine. Comparisons are made to intracellular binding in chondrocytes of tracheal, articular, and auricular cartilage. Ear epithelium, tracheal epithelium, and kidney are used as positive control tissues for the specificity of lectin binding. Only the mannose-binding lectins had affinity for the RER and nuclear envelope. Eight lectins reacted within the Golgi complex with characteristic patterns which ranged from localized fine linear strands to extensive vesicular accumulations. When cartilage slabs were exposed before embedment to the ionophore monensin to disrupt intracellular transport through the Golgi, it was possible to define differential subcompartments of the Golgi complex, based upon sites of sugar addition. Also, it was possible to characterize the cytoplasmic deposits of reserve-zone chondrocytes which were positive with concanavalin A as glycogen, based upon their sensitivity to amylase. This method allows resolution at the light-microscopic level of lectin-binding glycoconjugates with localization to specific organelles. Patterns of intracellular binding were consistent with biochemical data relating to the subcellular localization of processing steps of complex carbohydrates prior to secretion.

Post-embedding localization of glycoconjugates by means of lectins on thin sections of tissues embedded in LR white

A simple post-embedding technique for the electron microscopical detection of lectin-binding sites using thin sections of tissues embedded in the resin LR White is described. With this technique, no prior etching of the sections is necessary. The cellular fine structure is well preserved and permits close correlation of the labelling to distinct cellular compartments. After mild aldehyde fixation (4% formaldehyde and 0.5% glutaraldehyde for 30 min), enterocyte brush border, vesicles and lysosomes as well as goblet cell Golgi apparatus and mucin are intensely stained after 30-60 min. The hydrophilia and penetrability of LR White is shown by the formation of oxidized diaminobenzidine reaction product arising from horseradish peroxidase-conjugated lectins. The precipitate not only covers the surface of the sections but is also formed within the resin, as is revealed on cross-sections through thin and semithin sections. The addition of 0.2 M solutions of the appropriate inhibitory sugars prevented staining, which indicates a specific binding. Examples are given of the binding of gold-, ferritin- and peroxidase-conjugated lectins for the purpose of detecting glycoconjugates in various intracellular compartments.

Evaluation of the specificity of lectin binding to sections of plant tissue

Hand sections of young corn root tips have been used in a study of problems encountered in the binding of fluorescently-labelled lectins to plant tissues. It was found, surprisingly, that with lectins specific for a sugar known to be present (Lotus and Ulex lectins for L-fucose), with a lectin specific for a sugar thought not to be present (wheat-germ agglutinin for N-acetylglucosamine), with non-lectin glycoprotein and protein (gamma-globulin and bovine serum albumin) and with basophilic dyes (alcian blue and toluidine blue), a coincidental binding pattern similar to the pattern of autofluorescence in the same tissue was obtained. Corn root tissues include cell walls composed of complex polysaccharides esterified with ferulic acid residues, as well as mucilages which are highly hydrated and expanded. In such material, neither standard inhibition controls with haptens nor the use of a wide range of lectin concentrations are adequate to distinguish clearly specific and non-specific binding of fluorescently-labelled lectin. Therefore, lectins are not the simple test probes they have been supposed. Before interpreting results obtained in using fluorescently-labelled lectins on any tissue sections, all available information (biochemical as well as histochemical) about the tissue must be considered.

Distribution of lectin binding sites in rabbit oviduct

The carbohydrate histochemistry of the rabbit oviduct has been examined by the use of four lectins conjugated with horseradish peroxidase as histochemical reagents. Each lectin gave a very distinct typical pattern of binding, but for each lectin there was no difference between the distribution of binding sites in ampulla and isthmus. Wheat germ lectin bound exclusively with the connective tissue of the oviduct folds; winged pea lectin was detected only in the ciliated cells; peanut lectin binding sites were visualized in the secretory cells; the binding reactivity of soybean lectin was limited to the basal part of the cilia. Although it is very difficult at present to correlate the distribution of lectin binding sites with the function of the positive cells, some hypotheses have been advanced.

Influence of fixation on the lectin binding sites in the rabbit salivary glands

In order to verify the influence of fixative on the formation of any nonspecific lectin bindings, the authors have carried out an investigation on rabbit salivary glands. The results obtained applying peanut, soybean, wheat germ, and winged pea lectins to unfixed samples of rabbit submandibular and sublingual glands agreed almost completely with the results of our previous research effected on the same samples fixed with aldehydes. The most important differences between the fixed samples and the unfixed ones consisted in the lack of reactivity of the material inside the secretion lumina to all the lectins used, and in the lack of peanut binding to the submandibular gland. No significant differences in intensity and location were found for soybean, wheat germ, and winged pea lectins.

Glycoconjugate cytochemistry of the rat fundic gland using lectin/colloidal-gold conjugates and Lowicryl K4M. Helix pomatia lectin is a specific marker for mucous neck cells in fundic glands of the rat gastric mucosa

The fundic gland of the rat stomach was studied using the low-temperature embedding resin Lowicryl K4M and postembedding staining with lectin/colloidal-gold (CG) conjugates. Intense labeling with Ricinus communis agglutinin I was observed not only in mucous-producing cells but also in parietal cells. In contrast, Helix pomatia agglutinin (HPA) only labeled mucous neck cells and intermediate cells between mucous neck cells and chief cells. The other epithelial cells present in the rat fundic gland showed virtually no reaction with this lectin. Our results indicate that HPA might be a marker lectin of mucous neck cells and their derivatives. The combination of embedding in the hydrophilic resin Lowicryl K4M and postembedding staining with lectin-CG conjugates provided satisfactory staining results, and made it possible to visualize the precise distribution of terminal glycoconjugates in intracellular components as well as on the plasma membrane.

Comparative study of procedures for histological detection of lectin binding by use of Griffonia simplicifolia agglutinin I and gastrointestinal mucosa of the rat

The histological localisation of alpha-D-galactopyranosyl residues in glycoconjugates of rat stomach and duodenal mucosae was studied by use of Griffonia simplicifolia agglutinin I, i.e. the isolectin mixture (A + B) and the isolectin B4 (B4). Cryostat sections which were either unfixed or acetone fixed and paraffin sections from both ethanol-acetic acid and formaldehyde fixed tissue blocks were compared. Cellular details were better preserved in paraffin than in cryostat sections. Reactivity of cells binding GS I was less sensitive after formaldehyde than after ethanol-acetic acid fixation inasmuch as higher concentrations of lectins were needed. This drawback could be overcome by trypsinisation of the sections. The binding pattern of GS I (A + B) corresponded with that of GS I (B4) in either cryostat or paraffin sections. GS I was detected in the cytoplasm of parietal cells and in Brunner's gland cells. In duodenal crypts and villi, lectin was bound to supranuclear regions in the cytoplasm of columnar and goblet cells. The staining efficiency of fluorescein (FITC), horseradish peroxidase (HRP) and colloidal gold particle (CGP) labels in both direct and indirect lectin stainings was compared. Under all experimental conditions, indirect methods required lower concentrations of lectins than direct ones; indirect procedures increased sensitivity about 5-10 fold. CGP labels were always of highest sensitivity when gold particles were further developed by a silver precipitation method. HRP was not as efficient in lectin localisation as CGP, but cytochemical staining was more convenient in routine work. Direct FITC labellings proved to be of lowest sensitivity.

Lectin--peroxidase conjugates in histopathology of gastrointestinal mucosa

Peroxidase (HRP) conjugates of Dolichos biflorus agglutinin (DBA), Arachis hypogaea agglutinin (PNA) and Ulex europaeus agglutinin I (UEA I) were used as specific molecular probes in order to describe histological patterns of carbohydrate moieties in glycoconjugates of gastric mucosa. Specimens of normal mucosa, metaplasias and carcinomas were fixed, embedded in paraffin and stained with lectins by a postembedding technique. In normal mucosa, DBA reacted with surface epithelial, parietal and antral gland cells; neck cells did not react. In single goblet cell metaplasia, with few exceptions, goblet cells showed DBA binding. In contrast, mainly negative goblet cells were seen in intestinal metaplasia. In gastric carcinomas of intestinal or diffuse types, heterogeneous staining patterns were observed. Large numbers of mucus-producing surface epithelial, neck and antral gland cells stained with PNA-HRP conjugates. Parietal cells did not react. Among the chief cells only few showed PNA binding. In single goblet cell metaplasia, equal numbers of goblet cells were positive or negative, whereas goblet cells in intestinal metaplasia were mainly unstained. Carcinomas contained both PNA-positive and PNA-negative cells; PNA-positive cells occurred preferentially in the tumor periphery. UEA I - HRP conjugates stained the bulk of surface epithelial and neck cells; chief cells and antral gland cells were mainly positive, too. Parietal cells did not react. In single goblet cell metaplasia and intestinal metaplasia, UEA I-positive as well as UEA-negative goblet cells occurred. Striated cells exhibited a great variety of lectin reactivity. Carcinomas also showed a heterogeneous staining pattern. Under both normal conditions and in carcinoma development, qualitative and quantitative differences in the composition of glycoconjugates must be expected.

Immunohistochemical localization of peanut lectin binding sites on human brain tumors as determined by peroxidase-antiperoxidase technique in paraffin sections

Peroxidase-antiperoxidase (PAP) technique was selected for visualizing the binding of peanut lectin (PNL) to the most frequent human brain tumors. The randomly selected material included neoplasms of neuroectodermal and mesenchymal origin. We employed 1--5 micrometers of routinely processed and paraffin-embedded tissues. PNL receptors were detected to a variable extent on the cell surface of astrocytoma, glioblastoma multiforme, oligodendroglioma, ependymoma, meningotheliomatous meningeoma, and plexus papilloma. In gliomas as increase in malignancy seems to be associated with a decrease in PNL binding. Except for the plexus papillomas, neuraminidase pretreatment had neither a qualitative nor a quantitative influence on the binding behavior of PNL. Intracellular PNL receptors could be detected in "granular cells" and in the perinuclear region of malignant gliomas.

Ultrastructural visualization of galactosyl residues in various alimentary epithelial cells with the peanut lectin-horseradish peroxidase procedure

A conjugate of peanut lectin with horseradish peroxidase (PL-HRP) has been employed for ultrastructural localization of glycoprotein with presumed terminal galactose residues in mouse alimentary epithelial cells. The PL-HRP conjugate imparted electron opacity in sites that stain at the light microscopic level, as for example, Golgi cisternae in surface epithelial cells of the stomach and in superficial and deep crypt cells and goblet cells of the large intestine. Ultrastructural staining revealed that Golgi cisternae intermediate between the trans and cis faces stained selectively in these sites. Secretion stored in secretory granules or Golgi vesicles in the cells lacked affinity for PL-HRP conjugate, however. Selective staining of intermediate Golgi cisternae in cells with unreactive secretory product is interpreted as indicating the site of galactosyl transferase activity and a location where galactose occurs transitorily as the terminal sugar in the glycoprotein side chains. The luminal aspect of the surface epithelial cells in the stomach and columnar cells in the colon also stained, but with some variability. Staining of these surfaces was considered possibly attributable to PL affinity of some of the secretory glycoprotein which, after absorbing to the cell surface, lost terminal sialic acid through action of luminal enzyme. PL-HRP conjugate stained granules in pancreatic zymogen cells near the block surface but not in other cells, presumably because of limited penetration of reagent. Secretion on the surface of pancreatic acinar cells or in the lumen also exhibited affinity for PL-HRP complex as did the luminal surface of gastric chief cells. Staining of secretion in the pancreatic zymogen cells and gastric chief cells for galactose appeared inconsistent with lack of evidence for presence of glycoprotein in these sites which failed to stain with the periodic acid-Schiff or periodic acid-thiocarbohydrazide-silver proteinate methods for demonstrating glycoprotein at the light and electron microscopic levels. This discrepancy points to possible selective binding of PL-HRP conjugate to a moiety other than terminal galactose of glycoprotein in a few histologic sites. These results demonstrate the applicability of the PL-HRP technique at the ultrastructural level and provide information concerning the chemical structure of epithelial cell glycoproteins and their biosynthesis.