The properties of l-fucose binding agglutinin associated with the cell wall of Rhizoctonia solani

The adherence of Escherichia coli B cells to cell wall associated-agglutinin of the soil borne plant pathogen Rhizoctonia solani, was inhibited by l-fucose, l-galactose, trypsin, SDS, cycloheximide and Na₂-EDTA. The coiling of the biocontrol agent Trichoderma harzianum around Rhizoctonia hyphae was prevented by SDS, cycloheximide, Na₂-EDTA and methyl--l-fucoside — an inhibitor of Rhizoctonia agglutinin not metabolized by both fungi. The possible role of the agglutinin in Trichoderma-Rhizoctonia interaction is discussed.     

Cell surface inCalluna vulgaris L. hair roots

Summary Calluna vulgaris possesses small roots called hair roots, which in natural conditions are colonized by symbiotic mycorrhizal fungi. A specialized cell surface-consisting of the cell wall and the overlaying mucilage-has been hypothesized to be important for the establishment of ericoid mycorrhizae. In this work the cell surface of hair roots of plants growing in sterile conditions has been characterized by using in situ techniques, integrated when possible, by biochemical analysis. The mucilage is abundant around the apex, while it becomes thinner and thinner on the differentiated parts. Sugar residues such as mannose, glucose and galactose are regularly distributed along the whole root length, while N-acetylglucosamine residues are limited to the differentiated part of the hair root. Cellobiohydrolase-gold complex, used to reveal -1, 4-glucans, regularly labels mucilage and cell walls of apical and differentiated regions. Polygalacturonic acids revealed by monoclonal antibodies are found at the surface of the cap cells and on the cell walls of the inner tissues in the differentiated zones, but never at the surface of the epidermal cells.The labeling continuity between mucilage and cell walls demonstrates that some molecules such as -1, 4-glucans are common to the two compartments, but probably have a different status of aggregation. On the contrary, other molecules, such as N-acetylglucosamine or polygalacturonic acid display a precise pattern of localization following root differentiation.Abbreviations FITC fluorescein isothiocyanate - WGA wheat germ agglutinin - Con A concanavalin A - RCA₁₂₀ Ricinus communis agglutinin - UEA Ulex europaeus agglutinin - CBH I cellobiohydrolase I - TEM transmission electron microscopy - MeNH₂ methylamine - PATAg periodic acid-thiocarbohydrazide-silver proteinate reaction - PAS periodic acid-Schiff reaction     

Use of antisera to localize callose,xylan and arabinogalactan in the cell-plate,primary and secondary walls of plant cells

Antibodies to cellobiose, L-arabinopyranose, L-arabinofuranose, D-galactose, oligosaccharides containing 14 xylose, oligosaccharides containing 14 glucose, and oligosaccharides containing 13 glucose have been raised in rabbits. The antisera have been characterized to show the specificity of binding to particular polysaccharides. They have been used for immunocytology using the electron microscope to locate the polymers in dividing and differentiating cells of bean (Phaseolus vulgaris L.) root, bean callus tissue and cells of Zinnia elegans L. in vitro. Arabinogalactans have been shown to be present in the cell-plate and primary walls but not in secondary thickening. Xylan as distinct from xyloglucan was found in the primary walls but not in the cell-plate. It was present in large amounts in the secondary thickening. Callose was found in the cell plate and also in the young growing wall. In the wall it was specifically located at the plasmodesmata. The use of the antibody against L-arabinofuranose enabled a specific organelle to be detected which was membranous and which occurred within the cytoplasm and also within the vacuole of the cells. Membranes carrying polymers containing L-arabinofuranose were also found in layers just under the plasmamembrane.Abbreviations L-Araf L-arabinofuranose - L-Arap L-arabinopyranose - BSA bovine serum albumin - Gal galactose - D-Galp D-galactopyranose - Glc glucose - Xyl xylose     

Characterization of the mucilage sheaths ofLemonniera aquatica by lectin-gold labelling

A pre-embedding lectin-gold labelling method was used to characterize the carbohydrate components in the mucilage ofLemonniera aquatica. A specific tissue processing protocol was developed, namely: a) primary fixation in 2% paraformaldehyde and 0.2% glutaraldehyde in PIPES buffer (pH 7.2) for 30 min; b) secondary fixation in 2% glutaraldehyde in the same buffer system for 1 h; c) post-fixation in 1% aqueous OsO₄ for 1h; d) embedment in Möllenhaur's resin. The three gold conjugated lectins used were: concanavalin A, wheat germ agglutinin andLimax flavus agglutinin, allowing detection of their complementary saccharides, namely α-d-mannose/α-d-glucose,N-acetyl-d-glucosamine (GluNAc), andN-acetylneuraminic acid (NANA), respectively.N-Acetyl-d-glucosamine and NANA residues were the major components of germ tube mucilage with only a small amount of α-d-manose/α-d-glucose. However, NANA was restricted to the mucilage in the region of germ tube emergence from the conidial arm. The abundance of GluNAc and NANA residues on hyphae and appressoria was less than that on the germ tube. Conversely, α-d-mannose/α-d-glucose was more abundant in the appressorial mucilage. Variability of mucilage composition was found to exist between different structures of the germinated conidium and also between different regions of the same structure. Further, the conidial cell wall ofL. aquatica is not chitinous, and lacks NANA and α-d-mannose/α-d-gluocse.     

The monoclonal antibody,anti-asialoglycophorin from human erythrocytes,specific forβ-d-Gal-1-3-α-d-GalNAc-chains (Thomsen-Friedenreich receptors)

The monoclonal antibody 22.19 of IgM class obtained after immunization of BALB/c mice with asialoglycophorin of human erythrocyte membranes is described. The specificity of this antibody for -d-Gal-1-3--d-GalNAc- disaccharide chains (Thomsen-Friedenreich receptors) was established by studying its reactivity against various erythrocytes, glycoproteins and oligosaccharides and by comparison with two lectins, peanut agglutinin andVicia graminea lectin, which recognize these disaccharide chains.Abbreviations PNA peanut agglutinin - VgL Vicia graminea lectin - TF Thomsen-Friedenreich - HSA human serum albumin - MoAb monoclonal antibody     

Interactions of galactose-binding lectins with plant protoplasts

Summary Protoplasts isolated from cell suspension cultures of carrot (Daucus carota L.) and leaves of tobacco (Nicotiana tabacum L.) were treated with three lectins specific for galactosyl residues. After incubation with RCA I (Ricinus communis agglutinin, molecular weight 120,000) conjugated to ferritin or fluorescein, freshly isolated protoplasts displayed heavy labeling of their surfaces. Moreover, they agglutinated rapidly when exposed to low concentrations of RCA I. In parallel studies, PNA (peanut agglutinin) also bound extensively to the protoplast plasma membranes whileBandeiraea simplicifolia lectin I attached relatively weakly. When protoplasts were cultured for two days and then incubated with conjugates of RCA I and PNA, additional binding sites were revealed on the regenerating walls.The results indicate that galactosyl residues are distributed densely over the surface of plant protoplasts. They also allow inferences to be made regarding the positions and linkages of the galactose groups being recognized by the lectins. Moreover, they open up the question whether the galactosyl moieties detected in the wall derive from those labeled on the plasma membrane. To conclude, we make comparisons with binding by concanavalin A, and predict that galactose-recognizing lectins will join and in certain respects prove superior to concanavalin A as probes of the plant cell surface.     

Saccharide binding to three Gal/GalNAc specific lectins: Fluorescence,spectroscopic and stopped-flow kinetic studies

Fluorescence and stopped-flow spectrophotometric studies on three plant lectins fromPsophocarpus tetragonolobus (winged bean),Glycine max (soybean) andArtocarpus integrifolia (jack fruit) have been studied usingN-dansylgalactosamine as a fluorescent ligand. The best monosaccharide for the winged bean agglutinin I (WBA I) and soybean (SBA) is Me-GalNAc and for jack fruit agglutinin (JFA) is Me-Gal. Examination of the percentage enhancement and association constants (1.51×10⁶, 6.56×10⁶ and 4.17×10⁵ M^–1 for SBA, WBA I and JFA, respectively) suggests that the combining regions of the lectins SBA and WBA I are apolar whereas that of JFA is polar. Thermodynamic parameters obtained for the binding of several monosaccharides to these lectins are enthalpically favourable. The binding of monosaccharides to these lectins suggests that the-OH groups at C-1, C-2, C-4 and C-6 in thed-galactose configuration are important loci for interaction with these lectins. An important finding is that the JFA binds specifically to Galß1-3GaINAc with much higher affinity than the other disaccharides which are structurally and topographically similar.The results of stopped-flow spectrometry on the binding ofN-dansylgalactosamine to these lectins are consistent with a bimolecular single step mechanism. The association rate constants (2.4×10⁵, 1.3×10⁴, and 11.7×10⁵ M^–1 sec^–1 for SBA, WBA I and JFA, respectively) obtained are several orders of magnitude slower than the ones expected for diffusion controlled reactions. The dissociation rate constants (0.2, 3.2×10^–2, 83.3 sec^–1 for SBA, WBA I and JFA, respectively) obtained for the dissociation ofN-dansylgalactosamine from its lectin complex are slowest for SBA and WBA I when compared with any other lectin-ligand dissociation process.Abbreviations SBA Soybean agglutinin - WBA I Winged bean agglutinin (Basic) - JFA Jack fruit agglutinin - PNA Peanut agglutinin - Con A Concanavalin A - Dansyl (Dns) 5-dimethylaminonaphthalene-I-sulphonyl - 2GaINDns N-dansylgalactosamine - dGal 2-deoxygalactose - l-Ara l-arabinose - d-Fuc d-fucose - l-Rha l-rhamnose - N-acetyllactosamine Galß4GlcNAc - melibiose Gal6Glc     

Induction and formation ofCochliobolus sativus appressoria

Summary GerminatingCochliobolus sativus spores were induced to form appressoria on a variety of artificial surfaces, including replicas of the barley leaf surface. Evidence was obtained for the involvement of chemical and topographic signals during induction of appressorium formation inC. sativus. Germ tube thigmotropism was also observed in vitro. Ultrastructure relevant to appressorium formation was observed, including the germ tube apex, apical swelling of the germ tube apex prior to appressorium formation, the appressorium with associated septation and the penetration peg. Cytochemical probes applied to germlings at the electron microscope level failed to detect -D-mannan, -D-glucan, -D-galactan, D-glcNAc or D-galNAc polymers in the extracellular mucilage associated with the fungal germlings. The ultrastructure of hyphal apices from germlings grown under different nutritional conditions differed with respect to Spitzenkörper morphology, apex shape and in the quantity of associated extracellular mucilage. Experimental findings are discussed relative to current understanding of appressorium induction in more extensively studied systems.Abbreviations PDA potato dextrose agar - DS dilute salts - Con A concanavalin A - RcA₁₂₀ Ricinus communis agglutinin₁₂₀ - WGA wheat germ agglutinin - HpA Helix pomatia agglutinin - DIC differential interference contrast - UV ultraviolet - TEM transmission electron microscopy - NNF National Nanofabrication Facility     

Immuno-gold localization of α-L-arabinofuranosyl residues in pollen tubes of Nicotiana alata Link et otto

Immuno-gold labelling using a monoclonal antibody (PCBC3) with a primary specificity for -L-arabinofuranosyl residues was used to locate these residues in pollen tubes of Nicotiana alata grown in vivo. The antibody bound to the outer fibrillar layer of the pollen-tube wall: the inner, non-fibrillar wall layer was not labelled. Cytoplasmic vesicles (0.2 m diameter) were also labelled. The antibody may bind to an arabinan in the pollen-tube wall.     

Quantitative estimation of the surface carbohydrates on the infection structures of rust fungi with enzymes and lectins

Lectins of Triticum vulgaris (WGA), Concanavalia ensiformis (ConA), Phaseolus vulgaris (PHA), Lotus tetragonolobus (LTA), Arachis hypogaea (PNA), Ricinus communis (RCA I), Griffonia simplicifolia (GSA II) and the enzymes endo-(13)--D-glucanase, exo-(13)--D-glucanase and laminarinase were tested for binding to the infection structures of Puccinia coronata and Uromyces appendiculatus. The enzymes and lectins were labeled with fluorescein and the fluorescence was measured with a microscope photometer. GSA II and ConA bound to all parts of the two rust fungi to a certain extent. The germ tubes of P. coronata bound at least two times more WGA than did the germ tubes of U. appendiculatus. The appressoria of both rust fungi additionally bound exo-(13)--glucanase, endo-(13)--glucanase and laminarinase. The substomatal vesicle and the infection hypha of both rust fungi mainly bound the glucanases. Furthermore, the substomatal vesicle of U. appendiculatus bound PHA. No obvious binding with LTA, RCA I and PNA was observed. Binding generally could be inhibited by appropriate haptens. Binding to uredospores generally appeared unspecific. The results indicate that the germ tubes have chitin on their outer surfaces, the appressoria chitin and glucans and the substomatal vesicles and infection hyphae mainly glucans. Compared to P. coronata, U. appendiculatus has more terminal linked glucose residues or the glucan has more (13)--linkages. Also, U. appendiculatus has N-acetylgalactosamine or a similar sugar on the surface of the substomatal vesicle.Abbreviations ConA Concanavalia ensiformis agglutinin - FITC fluorescein isothiocyanate - GSA II Griffonia simplicifolic agglutimin II - LTA Lotus tetragonolobus agglutinin - PBS phosphate buffered saline - PNA Peanut agglutinin - RCA I Ricinus communis agglutinin I - PHA Phaseolus vulgaris agglutinin - WGA Wheat germ agglutinin     

Cortical microtubules mark the mucilage secretion domain of the plasma membrane in Arabidopsis seed coat cells

During their differentiation Arabidopsis thaliana seed coat cells undergo a brief but intense period of secretory activity that leads to dramatic morphological changes. Pectic mucilage is secreted to one domain of the plasma membrane and accumulates under the primary cell wall in a ring-shaped moat around an anticlinal cytoplasmic column. Using cryofixation/transmission electron microscopy and immunofluorescence, the cytoskeletal architecture of seed coat cells was explored, with emphasis on its organization, function and the large amount of pectin secretion at 7 days post-anthesis. The specific domain of the plasma membrane where mucilage secretion is targeted was lined by abundant cortical microtubules while the rest of the cortical cytoplasm contained few microtubules. Actin microfilaments, in contrast, were evenly distributed around the cell. Disruption of the microtubules in the temperature-sensitive mor1-1 mutant affected the eventual release of mucilage from mature seeds but did not appear to alter the targeted secretion of vesicles to the mucilage pocket, the shape of seed coat cells or their secondary cell wall deposition. The concentration of cortical microtubules at the site of high vesicle secretion in the seed coat may utilize the same mechanisms required for the formation of preprophase bands or the bands of microtubules associated with spiral secondary cell wall thickening during protoxylem development.     

Spore Adhesion and Cell Wall Formation in Gelidium Floridanum (Rhodophyta, Gelidiales)

The attachment of spores to a substratum is essential for their germination and, therefore, to the completion of the life cycle of the red algae. In most red algae, spores are liberated without a cell wall, within a sheath of mucilage which is responsible for their primary attachment. Utilizing fluorescent-labeled lectins, we identified carbohydrate residues and their locations in the mucilage and cell walls of spores of Gelidium floridanum. Cell wall formation and mucilage composition were studied with calcofluor, toluidine blue (AT-O), alcian blue (AB) and periodic acid-Schiff (PAS). In the mucilage we identified α-D mannose, α-D glucose, β-D-galactose, N-acetyl-glucosamine and N-acetyl-galactosamine. The first two sugar residues were not found in the cell wall of the germ tube but they were present on the rhizoid’s cell wall indicating their importance to substrate adhesion. A cell wall is produced soon after the spore’s attachment, beginning with a polar deposition of cellulose and its gradual spread around the spore as indicated by calcofluor. The cell wall matrix was positive to AB and metachromatic to AT-O, indicating acidic polysaccharides, while cellulose microfibrills were positive to PAS. A polar disorganization of the cell wall triggers the process of germination. As spores are the natural form of propagation of Gelidium, the understanding of the mechanisms of spore attachment may contribute to the cultivation of this valuable seaweed.     

Structures of the α(1-3)-galactose-containing asparagine-linked glycans of a Lewis lung carcinoma cell subline resistant toAleuria aurantia agglutinin: elucidation by1H-NMR spectroscopy

Four bi-antennary glycan fractions of theN-acetyllactosamine-type, derived from a Lewis lung carcinoma (LL₂) cell subline resistant to theAleuria aurantia agglutinin were studied by 400 MHz¹H-NMR spectroscopy. By this method, their antennae were found to be terminated either by (2-3 or 6)-linkedN-acetylneuraminic acid or (1-3)-linked galactose residues. The primary structure of glycans of these four glycopeptide or derived oligosaccharide-alditols has been determined in full detail.Abbreviations NAc N-acetyl group - NGc N-glycolyl group - GlcNAc N-acetylglucosamine - NeuAc N-acetylneuraminic acid - NeuGc N-glycolylneuraminic acid - Man mannose - Gal galactose - Fuc fucose - Con A concanavalin A - LCA Lens culinaris agglutinin - AAA Aleuria aurantia agglutinin - WGA Wheat germ agglutinin - RCA II Ricinus communis agglutinin II - PBS phosphate buffered saline, 0.01m Na₂HPO₄/0.14m NaCl, pH 7.2 - HPLC high performance liquid chromatography - EMEM Eagle's Minimal Essential Medium - Lec^R lectin resistant - MG -methylglycoside     

Late type of daughter cell wall synthesis in one of the Chlorellaceae, <Emphasis Type="Italic">Parachlorella kessleri</Emphasis> (Chlorophyta,Trebouxiophyceae)

Autosporulation is a common mode of propagation for unicellular algae. Autospore-forming species of Chlorellaceae, Chlorella vulgaris Beijerinck, C. sorokiniana Shihira et Krauss, C. lobophora Andreyeva, and Parachlorella kessleri (Fott et Nováková) Krienitz et al. have glucosamine as the main constituent of their rigid cell wall. Recent phylogenetic analyses have showed that the Chlorellaceae divided into two sister groups: the Chlorella-clade and the Parachlorella-clade. We compared the cell wall structure and synthesis of the daughter cell wall in the four species by electron microscopy using rapid freezing and freeze substitution methods. The cell wall of C. vulgaris, C. sorokiniana, and C. lobophora consisted of an electron-dense thin layer with an average thickness of 17–20, 22, and 19 nm, respectively. In these three species, daughter cell wall synthesis occurred on the outer surface of the plasma membrane in the early cell-growth phase. The cell wall of P. kessleri, however, was electron-transparent and 54–59 nm in thickness. Ruthenium red staining of P. kessleri indicated that ruthenium-red-specific polysaccharides accumulated over the outer surface of the plasma membrane. Immunoelectron microscopic observation with an anti--1, 3-glucan antibody and staining with wheat germ agglutinin (WGA) indicated that the cell wall contained -1, 3-glucan and WGA specific N-acetyl--D-glucosamine. In P. kessleri, daughter cell wall synthesis began after successive protoplast division. The daughter cell wall synthesis during autosporulation in the four species of Chlorellaceae can be classified into two types—the early and the late types.     

Cytomorphological characters supporting the taxonomic validity ofCyanothece (Cyanoprokaryota)

The fine structure of the type species of the genusCyanothece Komárek 1976,C. aeruginosa, is described and compared with the main cytological characteristics of morphologically related members of the generaCyanobium, Cyanobacterium andSynechococcus. Several morphological features, such as cell walls with thick outer layers containing a special type of vesicles, position of thylakoids, keritomy (net-like appearance of protoplast caused by arrangement of thylakoids, net-like nucleoids and/or by tendency to form intrathylakoidal spaces) and a special structure of mucilaginous envelopes were found to be characteristic of this genus, supporting its separate position among coccal cyanoprokaryotes (cyanobacteria, cyanophytes). The taxonomic significance of ultrastructural features in all mentioned genera is discussed.     

Analysis of labeling of plant protoplast surface by fluorophore-conjugated lectins

Summary Fluorescein or rhodamine conjugates of seventeen different lectins were tested for their ability to label the plasma membrane of live plant protoplasts. During the investigation, a strong effect of calcium was observed on the binding of several lectins to protoplasts derived from suspension cultured rose cells (Rosa sp. Paul's Scarlet). The binding of these lectins was increased by elevating the calcium concentration from 1 to 10 mM in the buffer. Other divalent cations had variable, but similar, effects on lectin binding. The mechanism of this effect appeared to involve the protoplast surface rather than the lectins. Although the cell wall-degrading enzymes used to isolate protoplasts had generally no effect on lectin binding, one clear exception was observed. Binding ofArachis hypogaea agglutinin was markedly reduced on protoplasts isolated with Driselase as compared to protoplasts isolated with a combination of Cellulysin and Pectolyase Y-23. Although most of the lectins that labeled protoplasts derived from cultured rose cells or from corn root cortex (Zea mays L. WF9 × Mo17) had specificities for galactose or N-acetylgalactosamine, some differences in protoplast labeling between lectins of the same saccharide specificity were observed. Two different analyses of the interaction betweenRicinus communis agglutinin and rose protoplasts showed that binding was cooperative with an apparent association constant of 7.2 × 10⁵M^–1 or 9.8 × 10⁵M^–1 with a maximum of approximately 10⁸ lectin molecules bound per protoplast. Treatment of protoplasts with glycosidases which hydrolyze either N- or O-glycosidic linkages of glycoproteins slightly enhanced labeling of protoplasts byRicinus communis agglutinin. Interpretation of these results are discussed.Abbreviations MPR medium, minimal organic medium (Nothnagel andLyon 1986) - APA Abrus precatorius agglutinin - CSA Cytisus sessilifolius agglutinin - ECA Erythrina cristagalli agglutinin - GS-I Griffonia simplicifolia agglutinin - LcH Lens culinarus agglutinin - PNA Arachis hypogaea agglutinin - SBA Glycine max agglutinin - VAA Viscum album agglutinin - VFA Vicia faba agglutinin - WGA Triticum vulgaris agglutinin - Con A Canavalia ensiformis agglutinin - HPA Helix pomatia agglutinin - TPA Tetragonolobus purpureas agglutinin - RCA Ricinus communis agglutinin - DBA Dolichos biflorus agglutinin - SJA Sophora japonica agglutinin - BPA Bauhinia purpurea agglutinin - FITC fluorescein isothiocyanate - Ga1NAc N-acetylgalactosamine - FDA fluorescein diacetate - 2-O-Me-D-Fuc 2-O-methyl-D-fucose Parts of the work presented here are also submitted in partial fulfillment of requirements for the Ph.D. degree.     

Glycosylation with thioglycosides activated by dimethyl(methylthio)sulfonium tetrafluoroborate: synthesis of two trisaccharide glycosides corresponding to the blood group A and B determinants

Two trisaccharide glycosides,p-trifluoroacetamidophenylethyl 3-O-(2-acetamido-2-deoxy--d-galactopyranosyl)-2-O-(-l-fucopyranosyl)--d-galactopyranoside andp-trifluoroa-cetamidophenylethyl 2-O-(-l-fucopyranosyl)-3-O-(-d-galactopyranosyl)--d-galactopyranoside, corresponding to the human blood group A and B determinants, were synthesized. A key fucosylgalactosyl disaccharide derivative was glycosylated with galactosaminyl or galactosyl donors, respectively. Dimethyl (thiomethyl)sulfonium tetrafluoroborate was used for thioglycoside activation in coupling reactions.     

Cytochemical identification of arabinogalactan protein in the outer epidermal wall of maize coleoptiles

Artificial carbohydrate antigen (Yariv reagent), fluorescence-labeled -l-fucose-binding lectin, and -D-galactose-binding lectin were used to localize arabinogalactan protein in sections of maize (Zea mays L.) coleoptiles. All three probes bind to cell walls of vascular tissue and the outer epidermis. Intense staining is obtained at the outer and inner faces of the growth-controlling outer epidermal wall. At the inner face of this wall the auxin-inducible osmiophilic particles, hitherto observed only by electron microscope (Kutschera et al. 1987, Planta 170, 168–180), are strongly stained by all three probes and can therefore be identified as deposits of arabinogalactan protein. It is proposed that this proteoglycan acts as an epidermal wallloosening factor in auxin-mediated coleoptile growth.Abbreviation AGP arabinogalactan protein I thank Dr. R. Bergfeld for the electron micrograph of Fig. 13. This work was supported by the Deutsche Forschungsgemeinschaft.     

Binding of concanavalin A and wheat germ agglutinin by murine peritoneal macrophages: ultrastructural and cytophotometric studies

Summary Concanavalin A and wheat germ agglutinin were employed in conjunction with the horseradish peroxidase-diaminobenzidine method for the detection of sugar residues on the surface coat of exudate and resident murine peritoneal macrophages. Electron microscopical and cytophotometric techniques were used for the visualization and quantification of the final reaction product on the surface of cells. After incubation with concanavalin A and wheat germ agglutinin, both exudate and resident macrophages showed readily detectable final reaction product indicating the presence of numerous, easily accessible, -methyl-d-mannosyl andN-acetyl-d-glucosaminyl residues on their surface. The binding of concanavalin A was higher with resident than with exudate macrophages. With wheat germ agglutinin, a different pattern of lectin binding was observed: more electron-dense product was deposited on exudate than on resident macrophage surfaces. The binding of concanavalin A and wheat germ agglutinin to macrophages was inhibited by the competing sugars -methyl-d-mannoside andN-acetyl-d-glucosamine, respectively.