Binding of fluorescent lectins to the surface of germ cells from fetal and early postnatal mouse gonads

Fluorescent lectins were used to study the chemical nature of carbohydrate moieties present on the surface of female and male germ cells isolated from mouse gonads during fetal and early posnatal development. Concanavalin A (ConA), lens culinaris agglutinin (LCA), ricinus communis agglutinin (RCA_I) and wheat germ agglutinin (WGA) bound intensely to the germ cell plasma membrane at all stages studied. Other lectins such as ulex europaeus agglutinin (UEA_I) and agglutinin (SBA) did not bind or bound moderately (SBA to female germ cells only). Distinct developmental-related changes were observed when female germ cells were labeled with fluorescein-conjugated peanut agglutinin (PNA) or dolichos biflorus agglutinin (DBA). DBA and PNA binding was absent or weak in fetal female and male germ cells, but became intensely positive in oocytes in the immediate postnatal period. The percentage of oocytes stained with DBA increased during the first three days after birth, and from day 3–4 onwards all oocytes were strongly labeled. I suggest that these changes in lectin binding reflect changes in biochemical structure of the oocyte surface related to differentiative events occurring in the mouse ovary immediately after birth.     

Flow cytometric analyses of lectin binding to rat alveolar macrophages

The binding characteristics of ten FITC-labeled plant lectins (Con-A, MPA, BPA, PNA, WGA, SBA, UEA-I, DBA, GS-I, GS-II) to lavaged rat alveolar macrophages were assessed by flow cytometry. The alveolar macrophages (AM) were incubated with varying concentrations of each lectin in a pinocytosis-inhibiting buffer. In addition to measuring lectin-associated green fluorescence, the electronic cell volumes and axial light loss characteristics of the AM were also measured flow cytometrically. These latter parameters were found to be good indicators of cell agglutination caused by some of the lectins, and, in conjunction with green fluorescence measurements, usefully serve to determine optimal or nonagglutinating lectin concentrations for flow cytometric studies. With the exception of UEA-I, all of the lectins examined bound to AM, although a wide range of binding was observed among the lectins. At subagglutinating concentrations, Con A, MPA, BPA, PNA, WGA, SBA, and GS-I bound to the AM with unimodal patterns. Histograms of lectin-associated fluorescence intensity obtained with DBA clearly presented a pattern consistent with a more complex, bimodal distribution of labeled AM, suggesting the presence of at least two subset populations. The low-intensity distribution of AM represented congruent to 70% of the cells, while the more strongly labeled subset represented congruent to 15% of the parent AM population. The remaining balance of the AM was identified as another subpopulation by the failure to detectably bind to the DBA. While GS-II bound to all of the AM, this lectin labeled about 5% of the cells much more intensely than the bulk of the population. Thus, two subset populations of AM could be resolved according to their differing avidities for the GS-II lectin.     

Changes in lectin-binding pattern in the digestive tract of Xenopus laevis during metamorphosis. II. Small intestine.

The binding of seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA-I; soybean agglutinin, SBA; Ulex europeus agglutinin, UEA-I; and wheat germ agglutinin, WGA) to the small intestine in metamorphosing Xenopus laevis was studied by the avidin-biotin-peroxidase (ABC) method. The staining pattern of the epithelium with all lectins except for UEA-I and Con A changed gradually during metamorphic climax; the main component of the epithelium, absorptive cells, gradually became positive for DBA, PNA, and SBA and the scattered goblet cells for RCA-I and WGA. On the other hand, the change of the staining pattern in the connective tissue occurred only for Con A, RCA-I, and WGA, and this change took place rapidly at the beginning of climax (stage 60). Increased staining for Con A and WGA at stage 60 was observed only in a group of connective tissue cells close to the epithelium and in the basement membrane. As metamorphosis progressed, this localization of the staining intensity became less clear. At the completion of metamorphosis (stage 66), the absorptive cells were stained with all lectins except for UEA-I, whereas the goblet cells stained only with RCA-I and WGA. These results indicate that lectin histochemistry can distinguish between larval and adult cells of both two epithelial types (absorptive and goblet cells). The technique may also identify a group of connective tissue cells, close to the epithelium, that possibly induce the metamorphic epithelial changes.     

Trypanosoma rhodesiense bloodstream trypomastigote and culture procyclic cell surface carbohydrates

Bloodstream trypomastigote and culture procyclic (insect midgut) forms of a cloned T. rhodesiense variant (WRAT at 1) were tested for agglutination with the lectins concanavalin A (Con A), phytohemagglutinin P (PP), soybean agglutinin (SBA), fucose binding protein (FBP), wheat germ agglutinin (WGA), and castor bean lectin (RCA). Fluorescence-microscopic localization of lectin binding to both formalin-fixed trypomastigotes and red cells was determined with fluorescein isothiocyanate (FITC)-conjugated Con A, SBA, FBP, WGA, RCA, PNA (peanut agglutinin), DBA (Dolichos bifloris), and UEA (Ulex europaeus) lectins. Electron microscopic localization of lectin binding sites on bloodstream trypomastigotes was accomplished by the Con A-horseradish peroxidase-diamino-benzidine (HRP-DAB) technique, and by a Con A-biotin/avidin-ferritin method. Trypomastigotes, isolated by centrifugation or filtration through DEAE-cellulose or thawed after cryopreservation, were agglutinated by the lectins Con A and PP with agglutination strength scored as Con A greater than PP. No agglutination was observed in control preparations or with the lectins WGA, FBA or SBA. Red cells were agglutinated by all the lectins tested. Formalin-fixed bloodstream trypomastigotes bound FITC-Con A and FITC-RCA but not FITC-WAG, -SBA, -PNA, -UEA or -DBA lectins. All FITC-labeled lectins bound to red cells. Con A receptors, visualized by Con A-HRP-DAB and Con A-biotin/avidin-ferritin techniques, were distributed uniformly on T. rhodesiense bloodstream forms. No lectin receptors were visualized on control preparations. Culture procyclics lacked a cell surface coat and were agglutinated by Con A and WGA but not RCA, SBA, PP and FBP. Procyclics were not agglutinated by lectins in the presence of competing sugar at 0.25 M.(ABSTRACT TRUNCATED AT 250 WORDS)     

138 Molecular Evolution of Glutamine Synthetase In Protists

The binding of fluorescein isothiocyanate (FITC) conjugated lectins to gametes of Aglaothamnion byssoides Itono during the fertilization was studied by the use of confocal microscope. The physiological effects of lectins and carbohydrates on gamete binding were also examined. Three lectins, concanavalin A (ConA), Soybean agglutinin (SBA) and wheat germ agglutinin (WGA) bound to the surface of spermatia, but each lectin labeled different region of the spermatium. SBA bound only to the spermatial appendages but ConA bound to the whole spermatial surface except spermatial appendages. WGA labeled narrow region which connects spermatial body and appendages. During fertilization, ConA and WGA specific substances on the spermatial surface moved towards the area contacting with trichogyne and accumulated on the surface of fertilization canal. Spermatial binding to trichogynes was inhibited by pre-incubation of spermatia with SBA, while trichogyne receptors were blocked by the complementary carbohydrate, N-acetyl-D-galactosamine. WGA and its complementary carbohydrate had little effect on gamete binding. For searching the step of sexual isolation, crossing experiment was performed between Aglaothamnion byssoides and twelve other red algal species. Results showed that the gamete recognition was genus-specific: the gametes bound freely with their partners of the same genus. When two species from same genus were crossed, sexual isolation occurs gradually during the fertilization process. Therefore, sexual isolation in red algae appears to be determined by multi-step process and gamete binding is the initial step.     

Lectin histochemistry of rabbit nephron

In order to investigate the usefulness of lectin histochemistry to detail nephronal segmentation we used 12 different biotinylated lectins (Con-A, DBA, GS-I, LCA, PNA, PWN, RCA-I, RCA-II, SWGA, SBA, UEA-I, and WGA) and Avidin-Biotin-Peroxidase (ABC) system on formalin-fixed and paraffin-embedded rabbit kidney sections. Each lectin, except UEA-I which did not stain any nephron structure, shows a different staining pattern along the nephron. Con-A, LCA, and RCA-I display a diffuse staining, while BS-I, RCA-II, SWGA, PWN, DBA, SBA and PNA are selective markers for specific nephron tracts. Furthermore, it is possible, according to the WGA binding pattern, to differentiate the convoluted part of the proximal tubule into two parts, named Segment A and Segment B. Lectin histochemistry on formalin-fixed and paraffin-embedded rabbit kidney sections displays a specific binding pattern along the rabbit nephron and shows interesting morphofunctional correlations.     

Lectin binding to newt epidermis: fluorescent localization and effects on motility

The ability of seven lectins to bind to newt epidermal cells and influence their motility was examined. Of the seven fluoresceinated lectins applied to frozen sections containing intact newt skin and migrating epidermis (wound epithelium), only Con A (concanavalin A), WGA (wheat germ agglutinin), and PNA (peanut agglutinin) produced detectable epidermal fluorescence. Con A and WGA each heavily labeled all layers of intact epidermis, but PNA bound only to the more superficial layers. In contrast to a single population of labeled cells in migrating epidermal sheets after treatment with Con A, there were both labeled and unlabeled cells after exposure to either WGA or PNA. The wound bed was labeled by both Con A and WGA, but not by PNA. DBA (Dolichos bifloris agglutinin), RCA I (Ricinus communis agglutinin), and UEA (Ulex europaeus agglutinin), did not produce significant fluorescence with either migrating or intact epidermis. In general, inhibitory effects on epidermal motility correlated with the binding studies. Thus, Con A, WGA, and PNA, the lectins which clearly bound to the epidermis, all produced a concentration-dependent depression in the rate of epidermal wound closure. RCA was somewhat paradoxical in that it was moderately inhibitory despite showing essentially no binding. The effects of SBA and UEA were equivocal. DBA had no effect. These results indicate that the inhibition of motility produced by Con A that we have described previously is not peculiar to this mannose-binding lectin, but is shared by at least one lectin with an affinity for D-GlcNAc (WGA), and one with an affinity for B-D-Gal(1-3)-D-GalNAc (PNA).(ABSTRACT TRUNCATED AT 250 WORDS)     

Lectin-binding patterns in the developing tooth

The lectin-binding patterns of the cells involved in amelogenesis and dentinogenesis in developing teeth of rats were studied. Undifferentiated odontogenic epithelia exhibited very slight staining with almost all of the lectins examined. The lectin-staining affinities of secretory ameloblasts could be divided into two categories: Concanavalin-A (Con-A), Wheat germ agglutinin (WGA) and Soybean agglutinin (SBA) binding occurred from the middle to apical cytoplasm, whereas Ricinus communis agglutinin-I (RCA-I) and Ulex europeus I (UEA-I) binding predominated in the basal regions. The cells of the stratum intermedium exhibited relatively strange lectin staining, which appeared to be dependent on ameloblastic maturation. The basement membranes in undifferentiated epithelia were markedly positive for lectin binding. Odontoblasts showed moderate Con-A staining on the apical side of the cells, as well as slight-to-moderate reactions with WGA and SBA. Pulp cells and dental papillae showed slight-to-moderate lectin staining, and predentin and dentin were also moderately positive for Con-A and RCA-I binding and slightly so for WGA and SBA. The lectin-binding affinities were enhanced during the formation of enamel and dentin, and appeared to be dependent on the degree of cellular differentiation in ameloblasts and odontoblasts.     

Inhibition of the activation reaction of Xenopus laevis eggs by the lectins WGA and SBA

Ionophore A23187 and electrical activation of dejellied mature eggs of Xenopus laevis are both prevented by the lectins wheat germ agglutinin (WGA) and soya bean agglutinin (SBA). However, this inhibition is not total since one of the events associated with egg activation, the activation potential, still occurs under lectin treatment. After 10 min of incubation in 50 μg/ml WGA or 100 μg/ml SBA, the cortical reaction, cortical contraction, and second polar body emission are totally impaired, whereas the activation potential, although different from the normal one, still proceeds. At the ultrastructural level, the lectin binding sites are localized on the vitelline envelope and on the plasma membrane. The inhibitory effects of these lectins are not detected in jellied eggs. Also, spermatozoa are strongly agglutinated by WGA at concentrations as low as 2.5 μg/ml, but not by SBA. This suggests that inhibition of fertilization in WGA-treated eggs is due to an effect of the lectin on the sperm.     

137 Gamete Recognition and Sexual Isolation in a Red Alga,Aglaothamnion Byssoides (Rhdophyta)

The binding of fluorescein isothiocyanate (FITC) conjugated lectins to gametes of Aglaothamnion byssoides Itono during the fertilization was studied by the use of confocal microscope. The physiological effects of lectins and carbohydrates on gamete binding were also examined. Three lectins, concanavalin A (ConA), Soybean agglutinin (SBA) and wheat germ agglutinin (WGA) bound to the surface of spermatia, but each lectin labeled different region of the spermatium. SBA bound only to the spermatial appendages but ConA bound to the whole spermatial surface except spermatial appendages. WGA labeled narrow region which connects spermatial body and appendages. During fertilization, ConA and WGA specific substances on the spermatial surface moved towards the area contacting with trichogyne and accumulated on the surface of fertilization canal. Spermatial binding to trichogynes was inhibited by pre‐incubation of spermatia with SBA, while trichogyne receptors were blocked by the complementary carbohydrate, N‐acetyl‐D‐galactosamine. WGA and its complementary carbohydrate had little effect on gamete binding. For searching the step of sexual isolation, crossing experiment was performed between Aglaothamnion byssoides and twelve other red algal species. Results showed that the gamete recognition was genus‐specific: the gametes bound freely with their partners of the same genus. When two species from same genus were crossed, sexual isolation occurs gradually during the fertilization process. Therefore, sexual isolation in red algae appears to be determined by multi‐step process and gamete binding is the initial step.     

Glycoconjugates in normal human kidney. A histochemical study using 13 biotinylated lectins

The avidin-biotin-peroxidase complex technique was used with 13 lectins to study the glycoconjugates of normal human renal tissue. The evaluated lectins included Triticum vulgaris (WGA), Concanavalin ensiformis (ConA), Phaseolus vulgaris leukoagglutinin and erythroagglutinin (PHA-L and PHA-E), Lens culinaris (LCA), Pisum sativum (PSA), Dolichos biflorus (DBA), Glycine max (SBA), Arachis hypogaea (PNA), Sophora japonica (SJA), Bandeiraea simplicifolia I (BSL-I), Ulex europaeus I (UEA-I) and Ricinus communis I (RCA-I). Characteristic and reproducible staining patterns were observed. WGA and ConA stained all tubules; PHA-L, PHA-E, LCA, PSA stained predominantly proximal tubules; DBA, SBA, PNA, SJA and BSL-I stained predominantly distal portions of nephrons. In glomeruli, WGA and PHA-L stained predominantly visceral epithelial cells; ConA stained predominantly basement membranes and UEA-I stained exclusively endothelial cells. UEA-I also stained endothelial cells of other blood vessels and medullary collecting ducts. Sialidase treatment before staining caused marked changes of the binding patterns of several lectins including a focal loss of glomerular and tubular staining by WGA; an acquired staining of endothelium by PNA and SBA; and of glomeruli by PNA, SBA, PHA-E, LCA, PSA and RCA-I. The known saccharide specificities and binding patterns of the lectins employed in this study allowed some conclusions about the nature and the distribution of the sugar residues in the oligosaccharide chains of renal glycoconjugates. The technique used in this report may be applicable to other studies such as evaluation of normal renal maturation, classification of renal cysts and pathogenesis of nephrotic syndrome. The observations herein reported may serve as a reference for these studies.     

Trypanosoma rhodesiense Bloodstream Trypomastigote and Culture Procyclic Cell Surface Carbohydrates1, 2, 3

Bloodstream trypomastigote and culture procyclic (insect midgut) forms of a cloned T. rhodesiense variant (WRATat 1) were tested for agglutination with the lectins concanavalin A (Con A), phytohemagglutinin P (PP), soybean agglutinin (SBA), fucose binding protein (FBP), wheat germ agglutinin (WGA), and castor bean lectin (RCA). Fluorescence-microscopic localization of lectin binding to both formalin-fixed trypomastigotes and red cells was determined with fluorescein isothiocyanate (FITC)-conjugated Con A, SBA, FBP, WGA, RCA, PNA (peanut agglutinin), DBA (Dolichos bifloris), and UEA (Ulex europaeus) lectins. Electron microscopic localization of lectin binding sites on bloodstream trypomastigotes was accomplished by the Con A-horseradish peroxidase-diaminobenzidine (HRP-DAB) technique, and by a Con A-biotin/avidin-ferritin method. Trypomastigotes, isolated by centrifugation or filtration through DEAE-cellulose or thawed after cryopreservation, were agglutinated by the lectins Con A and PP with agglutination strength scored as Con A < PP. No agglutination was observed in control preparations or with the lectins WGA, FBA or SBA. Red cells were agglutinated by all the lectins tested. Formalin-fixed bloodstream trypomastigotes bound FITC-Con A and FITC-RCA but not FITC-WGA, -SBA, -PNA, -UEA or -DBA lectins. All FITC-labeled lectins bound to red cells. Con A receptors, visualized by Con A-HRP-DAB and Con A-biotin/avidin-ferritin techniques, were distributed uniformly on T. rhodesiense bloodstream forms. No lectin receptors were visualized on control preparations. Culture procyclics lacked a cell surface coat and were agglutinated by Con A and WGA but not RCA, SBA, PP and FBP. Procyclics were not agglutinated by lectins in the presence of competing sugar at 0.25 M. The expression of lectin binding cell surface saccharides of T. rhodesiense WRATat 1 is related to the parasite stage. Sugars resembling α-D-mannose are on the surface of bloodstream trypomastigotes and culture procyclics; n-acetyl-D-galactosamine and D-galactose residues are on bloodstream forms; and n-acetyl-D-glucosamine-like sugars are on procyclic stages.     

Lectin-binding patterns in the developing tooth

Summary The lectin-binding patterns of the cells involved in amelogenesis and dentinogenesis in developing teeth of rats, were studied. Undifferentiated odontogenic epithelia exhibited very slight staining with almost all of the lectins examined. The lectin-staining affinities of secretory ameloblasts could be divided into two categories: Concanavalin-A (Con-A), Wheat germ agglutinin (WGA) and Soybean agglutinin (SBA) binding occurred from the middle to apical cytoplasm, whereas Ricinus communis agglutinin-I (RCA-I) and Ulex europeus I (UEA-I) binding predominated in the basal regions. The cells of the stratum intermedium exhibited relatively stranges lectin staining, which appeared to be dependent on ameloblastic maturation. The basement membranes in undifferentiated epithelia were markedly positive for lectin binding. Odontoblasts showed moderate Con-A staining on the apical side of the cells, as well as slight-to-moderate reactions with WGA and SBA. Pulp cells and dental papillae showed slight-to-moderate lectin staining, and predentin and dentin were also moderately positive for Con-A and RCA-I binding and slightly so for WGA and SBA. The lectin-binding affinities were enhanced during the formation of enamel and dentin, and appeared to be dependent on the degree of cellular differentiation in ameloblasts and odontoblasts.     

Distribution of lectin receptors sites in the zona pellucida of follicular and ovulated rat oocytes.

Carbohydrates of the zona pellucida (ZP) in mammals are believed to have a role in sperm-egg interaction. We have characterized the biochemical nature and distribution of the carbohydrate residues of rat ZP at the light (LM) and electron microscope (EM) levels, using lectins as probes. Immature female rats were induced to superovulate and cumulus-oocyte complexes were isolated from the oviduct, fixed with glutaraldehyde, and embedded in araldite for LM and LR-Gold for EM histochemistry. For examination of follicular oocytes, rat ovaries were fixed with glutaraldehyde and embedded in paraffin. The araldite or paraffin sections were deresined or deparaffinized, respectively, labeled with biotin-tagged lectins as probes, and avidin-biotin-peroxidase complex as visualant. For EM examination, thin LR-Gold sections were labeled with RCA-I colloidal gold complex (RCA/G) and stained with uranyl acetate. LM analyses indicate that in ovulated oocytes the ZP intensely binds peanut agglutinin (PNA); succinylated wheat germ agglutinin, (S-WGA), Griffonia simplisifolia agglutinin-I (GS-I) and soybean agglutinin (SBA), and to a lesser extent, lectins from Ricinus communis (RCA-I), Concanavaia ensiformis (Con A), Ulex europoeus (UEA-I), and wheat germ agglutinin (WGA). The neighboring cumulus cells are considerably less reactive and exhibit membrane staining only with Con A, WGA, and PNA. EM analysis of RCA/G binding revealed intensive binding to the inner layer region of the ZP and moderate binding to cytoplasmic vesicles of the cumulus cells. The ZP of follicular oocytes exhibits a different lectin binding pattern, expressed in staining strongly with PNA and S-WGA, and in a tendency of the lectin receptors to occur in the outer portion of the ZP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Early events of secretory granule formation in the rat parotid acinar cell under the influence of isoproterenol. An ultrastructural and lectin cytochemical study

The events involved in the maturation process of acinar secretory granules of rat parotid gland were investigated ultrastructurally and cytochemically by using a battery of four lectins [Triticum vulgaris agglutinin (WGA), Ulex europaeus agglutinin I (UEA-I), Glycine max agglutinin (SBA), Arachys hypogaea agglutinin (PNA)]. In order to facilitate the study, parotid glands were chronically stimulated with isoproterenol to induce secretion. Specimens were embedded in the Lowicryl K4M resin. The trans-Golgi network (TGN) derived secretory granules, which we refer to as immature secretory granules, were found to be intermediate structures in the biogenesis process of the secretory granules in the rat parotid acinar cell. These early structures do not seem to be the immediate precursor of the mature secretory granules: in fact, a subsequent interaction process between these early immature granule forms and TGN elements seems to occur, leading, finally, to the mature granules. These findings could explain the origin of the polymorphic subpopulations of the secretory granules in the normal acinar cells of the rat parotid gland. The lectin staining patterns were characteristic of each lectin. Immature and mature secretory granules were labelled with WGA, SBA, PNA, and lightly with UEA-I. Cis and intermediate cisternae of the Golgi apparatus were labelled with WGA, and trans cisternae with WGA and SBA.     

Lectin binding to neural crest cells. Changes of the cell surface during differentiation in vitro

To examine possible changes in cell surface carbohydrates, fluorescent lectins were applied at various times during differentiation of neural crest cells in vitro. The pattern and intensity of binding of several lectins changed as the crest cells developed into melanocytes and adrenergic cells. Considerable amounts of concanavalin A (Con A) and wheat germ agglutinin (WGA) bound to all unpigmented cells throughout the culture period. Melanocytes, however, bound much less of these lectins. Soy bean agglutinin (SBA), unlike Con A and WGA, only bound later in development to unpigmented cells at about the time when catecholamines were detected histochemically. Binding of SBA could be induced in younger cultures by pretreating the cells with neuraminidase. Melanocytes, however, did not bind detectable amounts of SBA even if treated with neuraminidase. The SBA-binding sites were often concentrated on cytoplasmic extensions and on contact points between neighboring cells, even when receptor mobility was restricted by prefixation of the cells or adsorption of lectin at 0 degrees C. All three lectins bound to cell processes resembling nerve fibers in particularly high amounts.     

Lectin cytochemistry in the gastrointestinal tract with special reference to glycosylation in the Golgi apparatus of Brunner's gland cells.

Two hydrophilic, low temperature-embedding resins, Lowicryl K4M and LR White, were compared in lectin cytochemistry. Post-embedding staining of colloidal gold-labeled Griffonia symplicifolia agglutinin II (GSA-II) resulted in staining of the Golgi apparatus and mucous granules of mucous neck cells in the gastric fundic gland, pylorocytes, and Brunner's gland cells embedded in either resin, although it was much easier to make ultra-thin sections with LR White-embedded material than with the other. Post-fixation with uranyl acetate followed by LR White embedding improved general ultrastructure so that lectin binding sites were identified precisely. All examined lectins, soybean agglutinin (SBA), Maclura pomifera agglutinin (MPA), GSA-II, and Ulex europaeus agglutinin I (UEA-I), stained mucous granules and the Golgi apparatus, in which the staining pattern was characteristic of each lectin: cis cisternae were labeled with SBA and MPA, intermediate cisternae with GSA-II, and trans cisternae and mucous granules with SBA, GSA-II, UEA-I, and lightly with MPA. No labeling was observed in the rough endoplasmic reticulum with any lectin. These findings suggest that the Golgi apparatus is the site of O-linked glycosylation and can be divided into at least three distinct compartments with regard to the glycosylation.     

Characterization of Carbohydrates on the Surface of Second-stage Juveniles of Meloidogyne spp.

Fluorescent conjugates of the lectins soybean agglutinin (SBA), Concanavalin A (Con A), wheat germ agglutinin (WGA), Lotus tetragonolobus agglutinin (LOT), and Limulus polyphemus agglutinin (LPA) bound primarily to amphidial openings and amphidial secretions of viable, preinfective second-stage juveniles (J2) of Meloidogyne incognita races 1 and 3 (Mil, Mi3) and M. javanica (Mj). No substantial difference in fluorescent lectin binding was observed among the populations examined. Binding of only LOT and LPA were inhibited in the presence of 0.1 M competitive sugar. Structural differences in amphidial carbohydrate complexes among populations of Mi 1, Mi3, and Mj were revealed by glycohydrolase treatment of preinfective J2 and subsequent labeling with fluorescent lectins. A quantitative microfiltration enzyme-linked lectin assay revealed previously undetected differences in lectin binding to nonglycohydrolase-treated J2. Freinfective J2 of Mj bound the greatest amount of SBA, LOT, and WGA, whereas J2 of Mil bound the most LPA.     

Distribution of lectin receptors in postimplantation mouse embryos at 6-8 days gestation

We have examined the pattern of binding of eleven lectins--BSL-II, WGA, LPA, Con A, DBA, SBA, LTA, UEA-I, MPA, PNA, and RCA-I, with specificity for a range of saccharides, to postimplantation mouse embryos from 6 to 8 days of gestation. The lectins were used to stain sections of ethanol-fixed paraffin-embedded and formaldehyde-fixed gelatin-embedded embryonic material. Our observations reveal a complex pattern of lectin binding to both cell surfaces and cytoplasm. Many of the lectins bind particularly to the outer surface of visceral endoderm (e.g., DBA, WGA, SBA, and RCA-I) and to the surface of the proamniotic cavity (e.g., RCA-I, PNA, and WGA). In the newly formed mesenchyme of primitive-streak-stage embryos, galactose and N-Ac-neuraminic acid are present but lectins with specificity for other sugars either did not bind to the cells or bound only in small amounts.     

Changes in lectin-binding pattern in the digestive tract of Xenopus laevis during metamorphosis. I. Gastric region.

The distribution of structural and secretory glycoconjugates in the gastric region of metamorphosing Xenopus laevis was studied by the avidin-biotin-peroxidase (ABC) histochemical staining method using seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA-I; soybean agglutinin, SBA; Ulex europeus agglutinin I, UEA-I; and wheat germ agglutinin, WGA). Throughout the larval period to stage 60, the epithelium consisting of surface cells and gland cells was stained in various patterns with all lectins examined, whereas the thin layer of connective tissue was positive only for RCA-I. At the beginning of metamorphic climax, the connective tissue became stained with Con A, SBA, and WGA, and its staining pattern varied with different lectins. The region just beneath the surface cells was strongly stained only with RCA-I. With the progression of development, both the epithelium and the connective tissue gradually changed their staining patterns. The surface cells, the gland cells, and the connective tissue conspicuously changed their staining patterns, respectively, for Con A and WGA; for Con A, PNA, RCA-I, SBA, and WGA; and for Con A, RCA-I, and WGA. At the completion of metamorphosis (stage 66), mucous neck cells became clearly identifiable in the epithelium, and their cytoplasm was strongly stained with DBA, PNA, RCA-I, and SBA. These results indicate that lectin histochemistry can provide good criteria for distinguishing among three epithelial cell types, namely, surface cells, gland cells, and mucous neck cells, and between adult and larval cells of each type.