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Lectin staining of peritoneal mesothelial cells in vitro.

A survey of lectin-binding specificities present on rodent and human mesothelial cells propagated and maintained in tissue culture was made using fluorescein isothiocynate conjugated (FITC) lectins. Rodent and human cells exhibited cell-associated fluorescence following exposure to the FITC-lectins from C. ensiformis, T. vulgaris, A. hypogaea, E. cristagalli and B. simplicifolia, but not with lectins from G. max and D. biflorus. Rodent cells were also positive for FITC-M. pomifera lectin binding. Human, but not rodent, cells were positive for FITC-T. purpureas lectin binding. Exposure of rabbit mesothelial cells in vitro to FITC-lectins that bound to the cell surface resulted in the appearance of discrete loci of putatively intracellular fluorescence. Exposure of cells to ferritin-labelled T. vulgaris lectin at 37 degrees C for as little as 7.5 minutes resulted in the appearance of ferritin-size particles in intracellular vesicles. These results demonstrate 1. the presence of lectin-binding sites in and on peritoneal mesothelial cells from rodents and humans and 2. a possible role of such sites in mediating the entry of lectin-like endogenous molecules into the vacuolar apparatus of these cells.

Animals↗

Lectin-binding properties of the surfaces of in vitro-transformed Schistosoma mansoni and Echinostoma paraensei sporocysts.

As carbohydrates on the surfaces of sporocysts of digenetic trematodes may be targets of attack by the molluscan internal defense system, the lectin-binding patterns of living, in vitro-transformed sporocysts of Schistosoma mansoni and Echinostoma paraensei were characterized. Schistosoma mansoni sporocysts specifically bound 8 and E. paraensei 6 of 11 lectins examined. Sporocysts of the 2 species responded differently to 7 of the 11 lectins. Lectins inhibitable by mannose, galactose, and N-acetylgalactosamine were bound by both species. Lectins inhibited by fucose and N-acetylglucosamine bound uniquely to S. mansoni, and an N-acetylneuraminic acid (NeuNAc)-inhibitable lectin bound only to E. paraensei. Preincubation of sporocysts of either species in the plasma of the host snail Biomphalaria glabrata for as long as 24 hr only marginally altered the subsequent binding of lectins. Pretreatment of S. mansoni sporocysts with pronase E and trypsin substantially altered subsequent lectin binding, but similar treatment of E. paraensei sporocysts had little effect. A neuraminidase enzyme derived from Clostridium perfringens diminished binding of the NeuNAc-inhibitable lectin to E. paraensei sporocysts. This study indicates that lectin-binding monosaccharides are expressed abundantly on sporocyst surfaces, they vary considerably between 2 species parasitizing the same host, and they are not obscured readily or altered by exposure to host plasma.

Animals↗

[Lectin histochemistry in the kidney and renal tumors].

In recent years histochemical methods using lectins with diverse carbohydrate binding specificities have proved useful tools for studying the distribution pattern of intracellular and pericellular glycoconjugates at the tissue level. Several studies of human kidneys have shown that the binding sites for certain lectins are strictly confined to various parts of the nephron. This allows the use of lectins as markers for the particular segments. The glomeruli exhibit abundant sialoglycoproteins at the free surface coat of the podocytes as detected by PNA after sialidase representing a major component of the filtration barrier; neoplastic podocytes of glomeruloid bodies in nephroblastomas as well revealed an intense lectin binding despite failing any vascularization. The lectin binding pattern of renal carcinomas varies within a wide range depending on their histological growth pattern. Whereas most renal carcinomas of clear and granular cell type rarely displayed a slight reactivity with lectins at the cell surface and at the luminal aspect of tubulopapillary tumors, a sub-group of carcinomas named chromophobe type exhibited a strong cytoplasmic staining with DBA and PNA after sialidase. Comparative evaluation of normal kidneys revealed an identical binding pattern exclusively in the intercalated cells of the collecting ducts probably indicating a histogenetic origin of these tumors from the collecting duct epithelium. This assumption derives further support from the detection of precursor lesions rarely detected in normal and tumor-bearing kidneys exhibiting the same lectin binding pattern. In accordance with recent observations in the literature the disclosure of a similar lectin binding pattern in renal oncocytomas and their precursor lesions exhibiting oncocytic transformation clearly favors the assumption of an identical histogenetic origin. On the other hand, few cases of a carcinoma mimicking collecting duct epithelium exhibited a broader lectin binding pattern revealing evidence of secretory activity; the histochemical similarities between this unusual carcinoma and transitional cell carcinoma confirmed the suggested origin from the ducts of Bellini. In conclusion, lectin histochemistry may be a useful tool for estimating the characteristics of renal tumors and elucidating their histogenesis.

Epithelium↗

Lectin binding to cystic stages of Taenia taeniaeformis.

Studies of membrane glycoconjugates of Taenia taeniaeformis were initiated by assays of the lectin binding characteristics of 35-day-old cysticerci. Parasites fixed in glutaraldehyde were incubated with one of the following FITC-labelled lectins: Concanavalin A (Con A), Lens culinaris agglutinin (LCA), Ricinus communis agglutinin (RCA), peanut agglutinin (PNA), fucose binding protein (FBP) and wheat germ agglutinin (WGA) and either their specific or a nonspecific sugar. Ultraviolet microscopy revealed that only Con A and LCA bound in large amounts to the surface of cysticerci. This binding was partly inhibited by the specific sugar, but the nonspecific sugar had little effect. The lectin not removed by either of the sugars may have been bound nonspecifically to the charged glycocalyx. Lectins were primarily bound on the anterior third of the parasite around the scolex invagination. Kinetic studies of lectin interactions were carried out with LCA and RCA by spectrophotofluorometric analysis of the amount bound specifically or nonspecifically over a range of lectin concentrations. Lens culinaris lectin binding was found to be specific and involve 2 receptors which showed large differences in their affinity for lectin and prevalence on the surface. Ricinus communis lectin did not bind specifically but nonspecific interactions were observed. Adherence of small numbers of host cells was shown to have no measurable effect on the lectin binding characteristics. The results suggest that the major surface carbohydrates exposed are D-mannose and/or D-glucose residues with the other sugar groups poorly represented. This relatively homogeneous surface may have implications for the antigenicity of the parasite in its host.

Animals↗

Measurement of Sarcophaga peregrina lectin under various physiological conditions by radioimmunoassay.

Lectin induced in the hemolymph of Sarcophaga peregrina (flesh fly) larvae on injury of the body wall or on pupation was studied further by radioimmunoassay, focusing on the interaction between the lectin and hemocytes. It was found that the amount of lectin on the surface of hemocytes prepared from injured larvae increased with time after injury of the body wall. Radioiodinated lectin could bind to hemocytes prepared from injured larvae more effectively than those from normal larvae, indicating a difference in the affinities to lectin of hemocytes from these two sources. The lectin was found to be synthesized in the fat-body and then secreted into the hemolymph both on injury of the body wall and on pupation. A significant level of lectin was maintained in pupae during the entire pupal stage, but it decreased rapidly before emergence, and no lectin was found in newly emerged flies. Since the lectin greatly activated the activity of mouse bone marrow cells to kill Candida parapsilosis cells, the biological significance of humoral lectin in the defense mechanism was discussed from the ontogenic viewpoint.

Animals↗

[Soluble and semisoluble lectins from mollicutes and their possible functions].

When studying mollicute lectins it was established that Acholeplasma laidlawii PG-8 synthesizes two half-soluble lectins one of which is specific to N-acetyl-D-glucosamine, and the other--to D-glucosamine.HCl; phytopathogenic strain A. laidlawii var. granulum 118 produced 4 lectins one of which is soluble and specific in respect to fructose-1.6-diphosphate, the rest three lectins are half-soluble and specific to one of the sugars--D-galactosamine.HCl, rafinose and D-glucosamine.HCl. In Mycoplasma pneumoniae FH all the four lectins found in the culture liquid have been classified as half-soluble, specific to one of carbohydrates--D-galactosamine.HCl, talose, N-acetyl-neuramine acid and D-glucose; M. capricolum Cal. Kid. synthesizes four lectins; two of them being defined as soluble (one of the lectins is, respectively, specific to talose and D-glucosamine.HCl, two others, as half-soluble, specific to one of sugars--rafinose or D-glucose. The results obtained permit a conclusion to be made that the half-soluble lectins of mollicutes, on the one hand, are the factors of adhesion on the corresponding organs of macroorganism and, on the other hand take part in the transport of substances from without into the microorganism cell. Soluble lectins determine pathogenicity of mollicutes and form with half-soluble lectins a single chain to providing the mycoplasma cells with nutrients and to protect them from the action of the macroorganism immune system.

Acholeplasma laidlawii↗

Differential binding properties of Gal/GalNAc specific lectins available for characterization of glycoreceptors.

Differentiating the binding properties of applied lectins should facilitate the selection of lectins for characterization of glycoreceptors on the cell surface. Based on the binding specificities studied by inhibition assays of lectin-glycan interactions, over twenty Gal and/or GalNAc specific lectins have been divided into eight groups according to their specificity for structural units (lectin determinants), which are the disaccharide as all or part of the determinants and of GalNAc alpha 1-->Ser (Thr) of the peptide chain. A scheme of codes for lectin determinants is illustrated as follows: (1) F (GalNAc alpha 1-->3GalNAc), Forssman specific disaccharide--Dolichos biflorus (DBL), Helix pomatia (HPL) and Wistaria floribunda (WFL) lectins. (2) A (GalNAc alpha 1-->3 Gal), blood group A specific disaccharide--Codium fragile subspecies tomentosoides (CFT), Soy bean (SBL), Vicia villosa-A4 (VVL-A4), and Wistaria floribunda (WFL) lectins. (3) Tn (GalNAc alpha 1-->Ser (Thr) of the protein core)--Vicia villosa B4 (VVL-B4), Salvia sclarea (SSL), Maclura pomifera (MPL), Bauhinia purpurea alba (BPL) and Artocarpus integrifolia (Jacalin, AIL). (4) T (Gal beta 1-->3GalNAc), the mucin type sugar sequences on the human erythrocyte membrane(T alpha), T antigen or the disaccharides at the terminal nonreducing end of gangliosides (T beta)--Peanut (PNA), Bauhinia purpurea alba (BPL), Maclura pomifera (MPL), Sophora japonica (SJL), Artocarpus lakoocha (Artocarpin) lectins and Abrus precatorius agglutinin (APA).(5) I and II (Gal beta 1-->3(4)GlcNAc)--the disaccharide residue at the nonreducing end of the carbohydrate chains derived from either N- or O-glycosidic linkage--Ricinus communis agglutinin (RCA1), Datura stramonium (TAL, Thorn apple), Erythrina cristagalli (ECL, Coral tree), and Geodia cydonium (GCL). (6) B (Gal alpha 1-->3Gal), human blood group B specific disaccharide--Griffonia(Banderiaea) simplicifolia B4 (GSI-B4). (7) E (Gal alpha 1-->4Gal), receptors for pathogenic E. coli agglutinin, Shiga toxin and Mistletoe toxic lectin-I (ML-I) and abrin-a.

Acetylgalactosamine↗

Budding-specific lectin induced in epithelial cells is an extracellular matrix component for stem cell aggregation in tunicates.

We have examined immunocytochemically the expression, localization and in vivo function of a calcium-dependent and galactose-binding 14 x 10(3) Mr lectin purified from the budding tunicate, Polyandrocarpa misakiensis. Lectin granules first appeared in the inner epithelium of a double-walled bud vesicle. Soon after the bud entered the developmental phase, the granules were secreted into the mesenchymal space, where the lectin-positive extracellular matrix (ECM) developed. The lectin was also produced and secreted by granular leucocytes during budding. Hemoblasts, pluripotent stem cells in the blood, were often found in association with the ECM and they aggregated with epithelial cells to form organ rudiments. The lectin showed a high binding affinity for hemoblast precursors. The blockage of epithelial transformation of stem cells by galactose in in vivo bioassy was ineffective in the presence of the lectin. Polyclonal anti-lectin antibody prevented the hemoblasts spreading on the ECM and moving toward the epithelium, but it did not block the cell-cell adhesion of hemoblasts. By three days of bud development, lectin granules and ECM have almost disappeared from the developing bud together with a cessation of hemoblast aggregation. These results show that Polyandrocarpa lectin is a component of the ECM induced specifically in budding and suggest strongly that it plays a role in bud morphogenesis by directing the migration of pluripotent stem cells to the epithelium.

Animals↗

Localization of endogenous lectins in normal human breast, benign breast lesions and mammary carcinomas.

Specific antisera against three mammalian beta-galactoside-specific lectins of apparent molecular weights 14.5 kDa, 18 kDa and 29 kDa have been used to localize these lectins in normal breast, and in benign and malignant mammary lesions. In normal breast tissue discrete localization of two lectins (Mrs 14.5 kDa and 18 kDa) was demonstrated in fibroblasts, smooth muscle cells, myoepithelial cells and capillary endothelium. Extracellular localization of one lectin (Mr 14.5 kDa) in collagen was apparent. The third lectin (Mr 29 kDa) labelled preferentially luminal cells and their secretory product. Two benign tumours (an analyzed fibroadenoma and a papilloma) revealed strong staining with two lectins (Mrs 18 kDa and 29 kDa). Of the 24 mammary carcinomas examined, the lectin (Mr 14.5 kDa) was expressed by only occasional tumour cells, the lectin (Mr 18 kDa) occurred in many tumour cells and the lectin (Mr 29 kDa) labelled tumour cells in nearly all cases. The expression of these beta-galactoside-specific endogenous lectins therefore appears to be regulated differently in normal breast compared with mammary tumours.

Breast↗

Isolation and some properties of mammalian hepatic membrane lectins.

Membrane lectins were isolated from sheep, goat, and buffalo liver by chromatography on an asialofetuin (ASF)-Sepharose 4B column. The lectins moved as a single protein band in SDS-PAGE with molecular masses of 42, 54 and 50 kDa, respectively, for sheep, goat and buffalo lectins. The molecular masses remained unchanged in 0.2 M 2-mercaptoethanol. As judged from the inhibition of binding of the lectin to ASF gel, the three lectins were beta-galactoside-specific. Sheep, goat and buffalo lectins were found to be sialoglycoproteins containing 18.6, 27 and 38.8 mol/mol lectin of neutral hexose, respectively; the corresponding values for the sialic acid content being 5.3, 8.7 and 11.8 mol/mol lectin. Thus goat and buffalo lectins are physico-chemically different from many mammalian hepatic lectins described so far.

Animals↗

Isolation and characterization of a receptor lectin specific for galactose/N-acetylgalactosamine from macrophages.

Rat-peritoneal macrophages are shown to be able to take up glycoproteins terminated by galactose as well as those by mannose and/or N-acetylglucosamine. A lectin responsible for the uptake of galactose-terminated glycoproteins was isolated by affinity chromatography on a column of Sepharose 4B-asialoorosomucoid. The macrophage lectin isolated shared many properties in common with the well-established hepatic lectin specific for galactose/N-acetylgalactosamine. Thus, the lectin bound to asialoglycoproteins specifically, and the binding was inhibited by galactose and N-acetylgalactosamine. The lectin had a single major component of mol. wt. 42,000 as well as two minor components of 60,000 and 65,000, and required calcium for binding. In addition, the macrophage lectin was immunologically crossreactive with the hepatic lectin. Despite these similarities, however, the macrophage lectin was differentiated from the hepatic lectin in molecular size, relative preponderance of minor components, and titration profile with the antibodies raised against the hepatic galactose/N-acetylgalactosamine-specific lectin.

Acetylgalactosamine↗

Hepatocyte adhesion to carbohydrate-derivatized surfaces. I. Surface topography of the rat hepatic lectin.

The rat hepatic lectins, galactose- and N-acetylgalactosamine-binding proteins found on the hepatocyte cell surface, mediate adhesion of isolated primary rat hepatocytes to artificial galactose-derivatized polyacrylamide gels. Biochemical and immunohistochemical techniques were used to examine the topographical redistribution of the rat hepatic lectins in response to galactose-mediated cell adhesion. Hepatocytes isolated from rat liver by collagenase perfusion had an average of 7 x 10(5) cell surface lectin molecules per cell, representing 30-50% of the total lectin molecules per cell, the remainder residing in intracellular pools. Hepatocytes incubated on galactose-derivatized surfaces, whether at 0-4 degrees C or 37 degrees C, rapidly lost greater than 80% of their accessible cell surface lectin binding sites into an adhesive patch of characteristic morphology. The kinetics of rat hepatic lectin disappearance were used to estimate a lateral diffusion coefficient greater than 9 x 10(-9) cm2/s at 37 degrees C, suggesting rapid and unimpeded lectin diffusion in the plane of the membrane. Indirect immunofluorescence labeling of adherent cells using antihepatic lectin antibody revealed a structured ring of receptors surrounding an area of exclusion (patch) of reproducible size and shape which represented approximately 8% of the hepatocyte cell surface. Notably, adherent cells, which had lost greater than 80% of their accessible surface binding sites, still endocytosed soluble galactose-terminated radioligand at greater than 50% of the rate of nonadherent control cells. No net movement of rat hepatic lectin from intracellular pools to the cell surface was found on cells recovered after adhesion to galactose-derivatized surfaces at 37 degrees C, suggesting that the physical size and/or lectin density of the patch was restricted by kinetic or topological constraints.

Acrylic Resins↗

Differentiated microdomains on the luminal surface of capillary endothelium: distribution of lectin receptors.

Lectins conjugated with either peroxidase or ferritin were used to detect specific monosaccharide residues on the luminal front of he fenestrated endothelium in the capillaries of murine pancreas and intestinal mucosa. The lectins tested recognize, if accessible, the following residues: alpha-N-acetylgalactosaminyl (soybean lectin), beta-D-galactosyl (peanut agglutinin [PA] and Ricinus communis agglutinin-120 [RCA]), beta-N-acetylglucosaminyl and sialyl residues (wheat germ agglutinin [WGA]), alpha-L-fucosyl (lotus tetragonolobus lectin), and alpha-D-glucosyl and beta-D-mannosyl (concanavalin A [ConA]). Thi labeled lectins were introduced by perfusion in situ after thoroughly flushing with phosphate-buffered saline the microvascular beds under investigation. Specimens were fixed by perfusion, and subsequently processed for peroxidase detection and electron microscopy. Control experiments included perfusion with: (a) unlabeled lectin before lectin conjugate; (b) labeled lectin together with the cognate hapten sugar, and (c) horseradish peroxidase or ferritin alone. Binding sites were found to be relatively homogeneously distributed on the plasmalemma proper, except for Lotus tetragonolobus lectin and Con A, which frequently bound in patches. Plasmalemmal vesicles, transendothelial channels, and their associated diaphragms were particularly rich in residues recognized by RCA and PA (beta-D-galactosyl residues) and by WGA (beta-N-acetylglucosaminyl residues). Receptors for all lectins tested appeared to be absent or considerably less concentrated on fenestral diaphragms. The results reported here extend and complement previous findings on the existence of microdomains generated by the preferential distribution of chemically different anionic sites (Simionescu et al., 1981, J. Cell Biol., 9:605-613 and 614-621).

Animals↗

Comparative cross-linking activities of lactose-specific plant and animal lectins and a natural lactose-binding immunoglobulin G fraction from human serum with asialofetuin.

Plant and animal lectins bind and cross-link certain multiantennary oligosaccharides, glycopeptides, and glycoproteins. This can lead to the formation of homogeneous cross-linked complexes, which may differ in their stoichiometry depending on the nature of the sugar receptor involved. As a precisely defined ligand, we have employed bovine asialofetuin (ASF), a glycoprotein that possesses three asparagine-linked triantennary complex carbohydrate chains with terminal LacNAc residues. In the present study, we have compared the carbohydrate cross-linking properties of two Lac-specific plant lectins, an animal lectin and a naturally occurring Lac-binding polyclonal immunoglobulin G subfraction from human serum with the ligand. Quantitative precipitation studies of the Lac-specific plant lectins, Viscum album agglutinin and Ricinus communis agglutinin, and the Lac-specific 16 kDa dimeric galectin from chicken liver demonstrate that these lectins form specific, stoichiometric cross-linked complexes with ASF. At low concentrations of ASF, 1:9 ASF/lectin (monomer) complexes formed with both plant lectins and the chicken lectin. With increasing concentrations of ASF, 1:3 ASF/lectin (monomer) complexes formed with the lectins irrespective of their source or size. The naturally occurring polyclonal antibodies, however, revealed a different cross-linking behavior. They show the formation of 1:3 ASF/antibody (per Fab moiety) cross-linked complexes at all concentrations of ASF. These studies demonstrate that Lac-specific plant and animal lectins as well as the Lac-binding immunoglobulin subfraction from specific stoichiometric cross-linked complexes with ASF. These results are discussed in terms of the structure-function properties of multivalent lectins and antibodies.

Animals↗

Purification and Characterization of Griffonia simplicifolia Leaf Lectins.

Leaves from mature Griffonia simplicifolia plants were examined for the presence of leaf lectins possessing sugar binding specificities similar to the four known seed lectins (GS-I, GS-II, GS-III, GS-IV). Three (GS-I, -II, -IV) of the four known G. simplicifolia seed lectins were present in the leaves. Leaf G. simplicifolia lectins I and IV were similar to the respective seed lectins. Leaf GS-II, however, was composed of two types of subunits (M(r) = 33,000 and 19,000), whereas the seed lectin consists of only one type of subunit (M(r) 32,500). Seed and leaf GS-II lectins also had different isoelectric points. All leaf and seed lectins were similar with respect to their hemagglutination and glycoconjugate precipitation properties and all subunits contained covalently bound carbohydrate. Leaf GS-IV appeared slightly under-glycosylated compared to seed GS-IV.The fate of GS-I and GS-II seed lectins in aging cotyledons was investigated. GS-I isolectins usually contain isolectin subtypes associated with each main isolectin. Upon inbibition and germination, these GS-I isolectin subtypes disappeared. Over time, GS-II lectin did not change its disc gel electrophoretic properties.

Journal Article↗

Properties of Lectins in the Root and Seed of Lotononis bainesii.

A lectin was purified from the root of Lotononis bainesii Baker by affinity chromatography on Sepharose-blood group substance A + H. The molecular weight of the lectin was estimated by gel filtration to be 118,000. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the lectin was a tetramer composed of two slightly different subunits with respective molecular weights of 32,000 and 35,000. The lectin had a hexose content of 12% (w/w) and contained the sugars fucose, glucosamine, mannose, and xylose. Root lectin hemagglutination was preferentially inhibited by disaccharides with terminal nonreducing galactose residues. Antigens capable of cross-reaction with root lectin antibody were not detected in the seed of L. bainesii.A lectin from the seed of L. bainesii was partially purified by adsorption to pronase-treated rabbit erythrocytes. The lectin preparation had a molecular weight of approximately 200,000. Galactose and galactono-1,4-lactone inhibited seed lectin hemagglutination but lactose was ineffective. There was no evidence that the root of L. bainesii contained material antigenically related to the seed lectin.

Journal Article↗

Host recognition in the Rhizobium-soybean symbiosis : evidence for the involvement of lectin in nodulation.

Rhizobium japonicum mutant strain HS111 was previously shown to be defective in the rate of initiation of infection leading to subsequent nodule formation (1984 Plant Physiol 74: 84-89). Mutant strain HS111's defect in nodulation can be phenotypically reversed to wild type levels by pretreatment with root exudates from all soybean varieties that have been tested. The data indicate that lectin-Rhizobium interaction is necessary for the phenotypic reversal of the nodulation characteristics of mutant strain HS111. Pretreatment of strain HS111 with soybean seed lectin mimics the effect of root exudate pretreatment. In addition, the presence of 30 millimolar d-galactose, a hapten of soybean seed lectin, in the root exudate or soybean seed lectin pretreatment solution prevents enhancement of nodulation of strain HS111. Pretreatment of mutant strain HS111 in soybean root exudate which has had galactose-specific lectin(s) removed by affinity chromatography (affinity eluate) results in no enhancement of nodulation by strain HS111. Lectin(s) subsequently removed from the affinity column possesses 100% of the stimulatory activity originally found in the root exudate. Pretreatment of strain HS111 in root exudate from a soybean seed line (T102) known to lack seed lectin due to an insertion in the structural gene results in the reversal of the defective nodulation phenotype. This latter result indicates that the lectin found in soybean root exudate is genetically distinct from the seed lectin. It is apparently this root lectin that is involved in nodulation.

Journal Article↗

Production of a Lectin in Tissue Cultures of Dolichos biflorus.

Callus cultures have been produced from the epicotyl and leaves, hypocotyl, and roots of germinating Dolichos biflorus seeds. These cultures were initiated on media containing 2,4-dichlorophenoxyacetic acid and kinetin, transferred to media with increased amounts of these hormones, and then maintained on hormone-free media. Extracts of these cultures were examined by radioimmunoassays specific for the lectin from the seeds of this plant and for a lectin that is present only in the stems and leaves of the intact plant. Although the seed lectin was not detected in any cultures, the stem and leaf lectin was produced in those cultures grown on the hormone free media. Lectin isolated from these cultures had subunits identical in electrophoretic mobilities to the subunits from the lectin isolated from intact stems and leaves. Levels of this lectin decreased when the cells were transferred back to media containing hormones and increased again upon transfer to the hormone-free media. The absence of exogenous hormones and the production of lectin were also correlated with the rapid growth and greening of the cells. Immunofluorescence and immunocytochemical studies on sections of cultured cells indicated that the stem and leaf lectin is associated with the cytoplasm as well as the cell wall as has been found in previous studies on the subcellular localization of this lectin in the intact plant.

Journal Article↗