Maackia Amurensis Research Articles

In vitro screening of plant lectins and tropical plant extracts for anthelmintic properties

Lectins are plant secondary metabolites (PSM) found in many forages and which may confer anthelmintic properties to gastrointestinal parasites through disrupting the development of parasitic larvae throughout its life cycle. In experiment 1, the ability of the plant lectins jacalin (JAC), concanavalin A (Con A), phytohemagglutinin E2L2 (PHA-E2L2), phytohemagglutinin L4 (PHA-L4), phytohemagglutinin E3L (PHA-E3L), kidney bean albumin (KBA), Robinia pseudoacacia agglutinin (RPA), Maackia amurensis lectin (MAA), Maclura pomifera agglutinin (MAA), Dolichos biflorus agglutinin (DBA), wheat germ agglutinin (WGA) and Galanthus nivalis agglutinin (GNA) to disrupt the feeding of the first stage larvae (L1) of the sheep gastro-intestinal nematodes (GIN) Teladorsagia circumcincta, Haemonchus contortus and Trichostrongylus colubriformis was investigated using a larval feeding inhibition test (LFIT). Only PHA-E3L, WGA and Con A had a potent effect on disrupting larval feeding of all of the three species of GIN investigated. The lectin concentration required to inhibit feeding in 50% of L1 (IC50) was 7.3±1.2, 8.3±1.4 and 4.3±1.7μg/ml for PHA-E3L; 59.1±32.4, 58.7±11.9 and 8.1±7.0μg/ml for Con A and 78.9±11.2, 69.4±8.1 and 28.0±14.1μg/ml for WGA for T. circumcincta, H. contortus and T. colubriformis larvae, respectively (P=0.006). The addition of the lectin inhibitors fetuin, glucose/mannose or N-acetylglucosamine for PHA-E3L, Con A and WGA, respectively, caused an increase in the proportion of larvae that had fed at all concentrations for PHA-E3L only. In experiment 2, the effect of extracts from the tropical plants Azadiractha indica, Trichanthera gigantea, Morus alba, Gliricidia sepium and Leucaena leucocephala on the feeding behaviour of H. contortus L1, was examined. A. indica, T. gigantea and M. alba failed to inhibit 50% of larvae from feeding at concentrations up to 10mg plant extract per ml. In contrast, both G. sepium and L. leucocephala demonstrated a dose-dependent effect on larval feeding with respective IC50 estimates (mean±s.e.) of 0.015mg/ml±0.001 and 3.465mg/ml±0.144, effects which were partly reversed by the inclusion of either the tannin inhibitor polyethylene glycol or the lectin inhibitor Fetuin. These studies demonstrate that plant lectins can have an inhibitory effect on the feeding behaviour of first stage larvae of ovine GIN in vitro. Moreover they also provide novel evidence that lectins may contribute to the anthelmintic properties of some tropical forage plant extracts, such as G. sepium and L. leucocephala.

Sialic acid and sialyl‐lactose glyco‐conjugates: design, synthesis and binding assays to lectins and swine influenza H1N1 virus

The terminal parts of the influenza hemagglutinin (HA) receptors α2,6- and α2,3-sialyllactoses were conjugated to an artificial carrier, named sequential oligopeptide carrier (SOC(4) ), to formulate human and avian receptor mimics, respectively. SOC(4) , formed by the tripeptide unit Lys-Aib-Gly, adopts a rigid helicoids-type conformation, which enables the conjugation of biomolecules to the Lys-N(ε) H(2) groups. By doing so, it preserves their initial conformations and functionalities of the epitopes. We report that SOC(4) -glyco-conjugate bearing two copies of the α2,6-sialyllactose is specifically recognized by the biotinylated Sambucus nigra (elderberry) bark lectin, which binds preferentially to sialic acid in an α2,6-linkage. SOC(4) -glyco-conjugate bearing two copies of the α2,3-sialyllactose was not recognized by the biotinylated Maackia amurensis lectin, despite its well-known α2,3-sialyl bond specificity. However, preliminary immune blot assays showed that H1N1 virus binds to both the SOC(4) -glyco-conjugates immobilized onto nitrocellulose membrane. It is concluded that Ac-SOC(4) [(Ac)(2) ,(3'SL-Aoa)(2) ]-NH(2) 5 and Ac-SOC(4) [(Ac)(2) ,(6'SL-Aoa)(2) ]-NH(2) 6 mimic the HA receptors. These findings could be useful for easy screening of binding and inhibition assays of virus-receptor interactions.

Antioxidant and antiradical properties of polyphenols in the mechanism hepatoprotective actions of preparations Maackia amurensis

For finding-out of a role antioxidant and antiradical properties of poly-phenols in mechanisms hepatoprotective actions of preparations from Maackia amurensis activity of preparations from ядровой wood (Macsar), an extract of cellular culture Maackia amurensis, stilbens. Antiradical properties of preparations measured on ability to cooperate with difenilpikrilgidrazilom (DPPH). It is established, that for Macsar, PKMA, monomeasured and dimeric Stilbenes is absent correlations between antiradical activity of the given preparations from a polyphenolic complex Mauck Amur in modelling system with DPPH and them hepatoprotective effect in vivo. Monomeasured and dimeric stilbenes, possessing the highest antiradical activity appreciated on their ability to restore stable radical DPPH, have not shown expressed hepatoprotective activity at a hepatites.

Phytoestrogens are the correctors of vasomotor and psychoemotional reactions after experimental ovariectomy

The effects of Maackia amurensis extract (200 mg/kg, p.o. during the 14 days) on the vasomotor and psychoemotional reactions in rats after ovariectomy were investigated. The Maackia amurensis extract did not change the blood level of sex hormones, showed anxiolytic activity with the models of anxious disorders, did not influence considerably on the motor activity in «open field» test. Maackia amurensis extract reduced the pathological vasomotor reactions, showing by the change in vessels reactions on vasoactive agents and «hot flushes».

Application of partial-filling capillary electrophoresis using lectins and glycosidases for the characterization of oligosaccharides in a therapeutic antibody

Oligosaccharides in therapeutic recombinant antibodies play important roles in regulation of various biological functions. To monitor the glycosylation profiles of antibody pharmaceuticals in the manufacturing process, a highly sensitive and specific method is required. We extended partial-filling techniques using lectins and exoglycosidases in capillary electrophoresis for the characterization of 8-aminopylene-1,3,6-trisulfonic acid labeled N-linked oligosaccharides derived from the therapeutic antibody rituximab. In the lectin-filling method, Galb1–4GlcNAc-specific Erythrina cristagali agglutinin, a1, 6-linked Fuc-specific Aleuria aurantia lectin and Neu5Aca2–3Gal-specific Maackia amurensis lectin were used. The oligosaccharides migrated through the lectin plug during separation; the changes in separation profiles were observed according to the interaction with the lectins. The glycosidase-filling method allowed rapid digestion as suggested by the electropherograms. Partial-filling CE methods can avoid tedious hands-on procedures such as overnight incubation and optimization reaction condition with lectins and exoglycosidases. Combination of these partial-filling capillary electrophoresis methods makes the characterization of oligosaccharide profiles of therapeutic antibodies easier and faster.

Early Murine T-lymphocyte Activation Is Accompanied by a Switch from N-Glycolyl- to N-Acetyl-neuraminic Acid and Generation of Ligands for Siglec-E

It is well established that murine T-lymphocyte activation is accompanied by major changes in cell-surface sialylation, potentially influencing interactions with sialic acid-binding immunoglobulin-like lectins (siglecs). In the present study, we analyzed early activation of murine CD4+ and CD8+ T-lymphocytes at 24 h. We observed a striking and selective up-regulation in the binding of a recombinant soluble form of siglec-E, an inhibitory siglec, which is expressed on several myeloid cell types including antigen-presenting dendritic cells. In contrast, much lower levels of T cell binding were observed with other siglecs, including sialoadhesin, CD22, and siglec-F and the plant lectins Maackia amurensis leukoagglutinin and Sambucus nigra agglutinin. By mass spectrometry, the sialic acid content of 24-h-activated CD4+ and CD8+ T-lymphocytes exhibited an increased proportion of N-acetyl-neuraminic acid (NeuAc) to N-glycolyl-neuraminic acid (NeuGc) in N-glycans. Reduced levels of NeuGc on the surface of activated T cells were demonstrated using an antibody specific for NeuGc and the expression levels of the gene encoding NeuAc- to NeuGc-converting enzyme, CMP-NeuAc hydroxylase, were also reduced. Siglec-E bound a wide range of sialylated structures in glycan arrays, had a preference for NeuAc versus NeuGc-terminated sequences and could recognize a set of sialoglycoproteins that included CD45, in lysates from activated T-lymphocytes. Collectively, these results show that early in T cell activation, glycan remodelling involves a switch from NeuGc- to NeuAc-terminating oligosaccharides on cell surface glycoproteins. This is associated with a strong up-regulation of siglec-E ligands, which may be important in promoting cellular interactions between early activated T-lymphocytes and myeloid cells expressing this inhibitory receptor.

Distribution of sialic acid receptors and influenza A virus of avian and swine origin in experimentally infected pigs

BackgroundPigs are considered susceptible to influenza A virus infections from different host origins because earlier studies have shown that they have receptors for both avian (sialic acid-alpha-2,3-terminal saccharides (SA-alpha-2,3)) and swine/human (SA-alpha-2,6) influenza viruses in the upper respiratory tract. Furthermore, experimental and natural infections in pigs have been reported with influenza A virus from avian and human sources.MethodsThis study investigated the receptor distribution in the entire respiratory tract of pigs using specific lectins Maackia Amurensis (MAA) I, and II, and Sambucus Nigra (SNA). Furthermore, the predilection sites of swine influenza virus (SIV) subtypes H1N1 and H1N2 as well as avian influenza virus (AIV) subtype H4N6 were investigated in the respiratory tract of experimentally infected pigs using immunohistochemical methods.ResultsSIV antigen was widely distributed in bronchi, but was also present in epithelial cells of the nose, trachea, bronchioles, and alveolar type I and II epithelial cells in severely affected animals. AIV was found in the lower respiratory tract, especially in alveolar type II epithelial cells and occasionally in bronchiolar epithelial cells. SA-alpha-2,6 was the predominant receptor in all areas of the respiratory tract with an average of 80-100% lining at the epithelial cells. On the contrary, the SA-alpha-2,3 was not present (0%) at epithelial cells of nose, trachea, and most bronchi, but was found in small amounts in bronchioles, and in alveoli reaching an average of 20-40% at the epithelial cells. Interestingly, the receptor expression of both SA-alpha-2,3 and 2,6 was markedly diminished in influenza infected areas compared to non-infected areas.ConclusionsA difference in predilection sites between SIV and AIV virus was found, and this difference was in accordance with the distribution of the SA-alpha-2,6 and SA-alpha-2,3 receptor, respectively. The results indicated that the distribution of influenza A virus receptors in pigs are similar to that of humans and therefore challenge the theory that the pig acts as a mixing vessel between human and avian influenza viruses. Furthermore, it was shown that AIV prefers to infect alveolar type II epithelial cells in pigs. This corresponds with findings in humans emphasising the resemblance between the two species.

A Sialylated Glycan Microarray Reveals Novel Interactions of Modified Sialic Acids with Proteins and Viruses

Many glycan-binding proteins in animals and pathogens recognize sialic acid or its modified forms, but their molecular recognition is poorly understood. Here we describe studies on sialic acid recognition using a novel sialylated glycan microarray containing modified sialic acids presented on different glycan backbones. Glycans terminating in β-linked galactose at the non-reducing end and with an alkylamine-containing fluorophore at the reducing end were sialylated by a one-pot three-enzyme system to generate α2-3- and α2-6-linked sialyl glycans with 16 modified sialic acids. The resulting 77 sialyl glycans were purified and quantified, characterized by mass spectrometry, covalently printed on activated slides, and interrogated with a number of key sialic acid-binding proteins and viruses. Sialic acid recognition by the sialic acid-binding lectins Sambucus nigra agglutinin and Maackia amurensis lectin-I, which are routinely used for detecting α2-6- and α2-3-linked sialic acids, are affected by sialic acid modifications, and both lectins bind glycans terminating with 2-keto-3-deoxy-D-glycero-D-galactonononic acid (Kdn) and Kdn derivatives stronger than the derivatives of more common N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc). Three human parainfluenza viruses bind to glycans terminating with Neu5Ac or Neu5Gc and some of their derivatives but not to Kdn and its derivatives. Influenza A virus also does not bind glycans terminating in Kdn or Kdn derivatives. An especially novel aspect of human influenza A virus binding is its ability to equivalently recognize glycans terminated with either α2-6-linked Neu5Ac9Lt or α2-6-linked Neu5Ac. Our results demonstrate the utility of this sialylated glycan microarray to investigate the biological importance of modified sialic acids in protein-glycan interactions.

Synthesis and Optimization of Lectin Functionalized Nanoprobes for the Selective Recovery of Glycoproteins from Human Body Fluids

Biomedical sciences, and in particular biomarker research, demand efficient glycoprotein enrichment platforms. Herein magnetic nanoprobes (MNP), after being coated with three broad-spectrum lectins-concanavalin A (ConA), wheat germ agglutinin (WGA), and Maackia amurensis lectin (MA)-were utilized to selectively capture glycoproteins from human body fluids. Additionally, a new methodology, based on protection of the lectins with their target sugars prior to coupling with MNPs, was proposed to overcome the nonspecific nature of conjugation. This approach contributed to preserve lectin conformation, increasing by 40% and 90% the affinity of ConA and MA for glycoproteins in relation to synthesis with nonprotected lectins. Optimal operating conditions (temperature, time) and maximum binding capacities were further determined for each lectin by use of fetuin as a reference. The enhanced performance of lectin-based nanoplatforms was demonstrated by comparing MNP@ConA with conventional Sepharose@ConA. These experiments have shown that ConA immobilized on MNP exhibited 5 times higher affinity for fetuin and ovalbumin when compared with Sepharose@ConA with the same amount of immobilized lectin. MNP@Lectins were then applied to human serum, saliva, and urine and the recovered proteins were digested with trypsin and analyzed by nano-HPLC MALDI-TOF/TOF. This allowed the identification of 180 proteins, 90% of which were found to be glycosylated by use of bioinformatics tools, therefore revealing low levels of unspecific binding. Thus, MNP@lectins have proved to be a valuable tool for glycoproteomic studies, particularly when dealing with minute amounts of material.

Identification of Glycan Structure Alterations on Cell Membrane Proteins in Desoxyepothilone B Resistant Leukemia Cells

Resistance to tubulin-binding agents used in cancer is often multifactorial and can include changes in drug accumulation and modified expression of tubulin isotypes. Glycans on cell membrane proteins play important roles in many cellular processes such as recognition and apoptosis, and this study investigated whether changes to the glycan structures on cell membrane proteins occur when cells become resistant to drugs. Specifically, we investigated the alteration of glycan structures on the cell membrane proteins of human T-cell acute lymphoblastic leukemia (CEM) cells that were selected for resistance to desoxyepothilone B (CEM/dEpoB). The glycan profile of the cell membrane glycoproteins was obtained by sequential release of N- and O-glycans from cell membrane fraction dotted onto polyvinylidene difluoride membrane with PNGase F and β-elimination respectively. The released glycan alditols were analyzed by liquid chromatography (graphitized carbon)-electrospray ionization tandem MS. The major N-glycan on CEM cell was the core fucosylated α2-6 monosialo-biantennary structure. Resistant CEM/dEpoB cells had a significant decrease of α2-6 linked sialic acid on N-glycans. The lower α2-6 sialylation was caused by a decrease in activity of β-galactoside α2-6 sialyltransferase (ST6Gal), and decreased expression of the mRNA. It is clear that the membrane glycosylation of leukemia cells changes during acquired resistance to dEpoB drugs and that this change occurs globally on all cell membrane glycoproteins. This is the first identification of a specific glycan modification on the surface of drug resistant cells and the mechanism of this downstream effect on microtubule targeting drugs may offer a route to new interventions to overcome drug resistance.

Letter to the Glyco-Forum: Effective glycoanalysis with Maackia amurensis lectins requires a clear understanding of their binding specificities

Letter to the Glyco-Forum: Effective glycoanalysis with Maackia amurensis lectins requires a clear understanding of their binding specificities

Sialylation of the Fas Death Receptor by ST6Gal-I Provides Protection against Fas-mediated Apoptosis in Colon Carcinoma Cells

The glycosyltransferase, ST6Gal-I, adds sialic acid in an α2-6 linkage to the N-glycans of membrane and secreted glycoproteins. Up-regulation of ST6Gal-I occurs in many cancers, including colon carcinoma, and correlates with metastasis and poor prognosis. However, mechanisms by which ST6Gal-I facilitates tumor progression remain poorly understood due to limited knowledge of enzyme substrates. Herein we identify the death receptor, Fas (CD95), as an ST6Gal-I substrate, and show that α2-6 sialylation of Fas confers protection against Fas-mediated apoptosis. Intriguingly, differences in ST6Gal-I activity do not affect the function of DR4 or DR5 death receptors upon treatment with TRAIL, implicating a selective effect of ST6Gal-I on the Fas receptor. Using ST6Gal-I knockdown and forced overexpression colon carcinoma cell models, we find that α2-6 sialylation of Fas prevents apoptosis stimulated by FasL as well as the Fas-activating antibody, CH11, as evidenced by decreased activation of caspases 8 and 3. We also show that α2-6 sialylation of Fas does not alter the binding of CH11, but rather inhibits the capacity of Fas to induce apoptosis by blocking the association of FADD with Fas cytoplasmic tails, an event that initiates death-inducing signaling complex formation. Furthermore, α2-6 sialylation of Fas inhibits Fas internalization, which is required for apoptotic signaling. Although dysregulated Fas activity is a well known mechanism through which tumors evade apoptosis, the current study is the first to link Fas insensitivity to the actions of a specific sialyltransferase. This finding establishes a new paradigm by which death receptor function is impaired for the self-protection of tumors against apoptosis.

Effect of polyphenolic complexes wood and cellular culture Maackia amurensis on the MR тomography performance of a liver

Comparative evaluation of hepatoprotective properties of polyphenolic fraction from wood (Maksar) and a polyphenolic complex of cell culture of Maakia amurensis.Therapeutic efficacy of the objects was assessed by their effect on the MR tomographic performance of the liver of rats with experimental СCl4-hepatitis. Hepatoprotective activity of polyphenol complex cell culture Maakia amurensis is not inferior to the original effect of the drug Maksar.

Sialylated and O-glycosidically linked glycans in prion protein deposits in a case of Gerstmann-Sträussler-Scheinker disease

Prion diseases are caused by an abnormal form of the prion protein (PrP(Sc)). We identified, with lectins, post-translational modifications of brain proteins due to glycosylation in a Gerstmann-Sträussler-Scheinker (GSS) patient. The lectin Amaranthus leucocarpus (ALL), specific for mucin type O-glycosylated structures (Galß1,3 GalNAcα1,0 Ser/Thr or GalNAcα1,0 Ser/Thr), and Sambucus nigra agglutinin (SNA), specific for Neu5Acα2,6 Gal/GalNAc, showed positive labeling in all the prion deposits and in the core of the PrP(Sc) deposits, respectively, indicating specific distribution of O-glycosylated and sialylated structures. Lectins from Maackia amurensis (MAA, Neu5Acα2,3), Macrobrachium rosenbergii (MrL, Neu5,9Ac2-specific) and Arachis hypogaea (PNA, Gal-specific) showed low staining of prion deposits. Immunohistochemistry colocalization with prion antibody indicated that all lectins stained prion protein deposits. These results show that specific modifications in the glycosylation pattern are closely related to the hallmark lesions and might be an early event in neuronal degeneration in GSS disease.

Alteration of the sialylation pattern and memory deficits by injection of Aβ(25–35) into the hippocampus of rats

Sialic acid in glycoconjugates participates in important cellular functions associated with normal development, growth, and communication. Therefore we evaluated the sialylation pattern and memory deficits caused by the injection of Aβ(25–35) into the hippocampus (Hp) of rats. The eight-arm maze spatial-learning and memory test indicated that the injection of Aβ(25–35) into subfield CA1 of the Hp impaired both learning and memory. The sialylation pattern was examined using sialic acid-specific lectins. Our results showed that Maackia amurensis agglutinin (MAA, specific for Neu5Acα2,3Gal) showed reactivity in the CA1 and dentate gyrus (DG) subfields of the Hp mainly in the group injected with vehicle, whereas Macrobrachium rosenbergii lectin (MRL, specific for Neu5,9,7Ac) and Sambucus nigra agglutinin (SNA, specific for Neu5Acα2,6Gal-GalNAc) had increased reactivity in the CA1 and DG subfields of the Hp in the Aβ(25–35)-injected group. The staining pattern of the antibody specific for polysialic acid (a linear homopolymer of α-2,8-linked sialic acid) increased in the CA1 and DG subfields of the Hp of the Aβ(25–35) group compared to the control group. Our results suggest that injection of Aβ(25–35) causes impairment in spatial memory and alters the sialylation pattern in response to compensatory reorganization and-or sprouting of dendrites and axons of the surviving neurons.

Lectin typing of Campylobacter jejuni using a novel quartz crystal microbalance technique

Seven Campylobacter jejuni strains were characterised by a lectin typing assay. The typing system was based on a quartz crystal microbalance technique (QCM) with four commercially available lectins (wheat germ agglutinin, Maackia amurensis lectin, Lens culinaris agglutinin, and Concanavalin A), which were chosen for their differing carbohydrate specificities. Initially, the gold surfaces of the quartz crystals were modified with 11-mercaptoundecanoic acid followed by lectin immobilisation using a conventional amine-coupling technique. Bacterial cells were applied for lectin typing without preliminary treatment, and resonant frequency and dissipation responses were recorded. The adhesion of microorganisms on lectin surfaces was confirmed by atomic force microscopy. Scanning was performed in the tapping mode and the presence of bacteria on lectin-coated surfaces was successfully demonstrated. A significant difference in the dissipation response was observed for different C. jejuni strains which made it possible to use this parameter for discriminating between bacterial strains. In summary, the QCM technique proved a powerful tool for the recognition and discrimination of C. jejuni strains. The approach may also prove applicable to strain discrimination of other bacterial species, particularly pathogens.

Differential expression of the α2,3-sialic acid residues in breast cancer is associated with metastatic potential

Aberrant sialylation is closely associated with the malignant phenotype of cancer cells and metastatic potential. However, the precise nature of the molecules in breast cancers has not been unveiled. In this study, we investigated the expression levels of α2,3-sialic acid residues of 50 primary tumor cases, 50 pair-matched lymph node metastasis tumor samples and in the MDA-MB-231, T-47D and MCF-7 breast cancer cell lines with different metastatic potential. The expression of α2,3-sialic acid residues was analyzed by histochemistry, cytochemistry and flow cytometry with Maackia amurensis lectin (MAL). The invasion and migration abilities of cells were examined using cell adhesion and transwell in vitro assays. Pair-matched lymph node metastasis tumor samples exhibited higher levels of expression of α2,3-sialic acid residues compared to that of primary tumors (P=0.0432). Furthermore, of 38 tumors cases in T1/T2 stages, 31 (81.58%) had weak staining for MAL, which specifically binds to α2,3-sialic acid residues, whereas of 12 tumor cases in T3/T4 stages, only 1 (8.33%) had weak reactions for MAL. The highly metastatic breast cancer cell line MDA-MB-231 exhibited the strongest binding to MAL and the highest expression levels of α2,3-sialic acid residues among the selected cell lines, depending on mRNA expression levels of α2,3-sialyltransferase gene. The adhesion, invasion and migration activities confirmed that MDA-MB-231 exhibited the greater cell adhesion to, migration toward and invasion to Matrigel. Taken together, the high expression of α2,3-sialic acid residues in breast cancer was associated with metastatic potential. This property may be important for developing new therapeutic approaches for breast cancer.

Lectin inhibition assays for the analysis of bioactive milk sialoglycoconjugates

Assay systems were developed to determine bioactive sialylated structures in complex and crude mixtures as they occur in milk fractionation processes. The sialic acid-binding proteins Maackia amurensis lectin and Sambucus nigra agglutinin as well as Siglec-2 and Siglec-4 were used in inhibition assays. The complementary linkage specificities of these lectins allow the determination of α2,3- and α2,6-linked sialic acids even in the presence of high lactose concentrations that are common in milk products. The functionality and linkage specificity of the assays have been evaluated using oligosaccharides from human and bovine milk. Furthermore, the presence of bioactive sialoglycoconjugates has been determined in fractions from a bovine milk fractionation process like sweet buttermilk, lactose-reduced serum, skim milk proteins, caseins and glycomacropeptides.

Fucose and sialic acid expressions in human seminal fibronectin and α{1} -acid glycoprotein associated with leukocytospermia of infertile men.

Introduction: The aim of this study was to compare fucose and sialic acid residue expression on fibronectin and α1-acid glycoprotein in the seminal plasma of men suspected of infertility and suffering from leukocytospermia. Subjects and methods: Seminal ejaculates were collected from 27 leukocytospermic and 18 healthy, normozoospermic men. The relative degree of fucosylation and sialylation of fibronectin and α1-acid glycoprotein was estimated by ELISA using fucose and sialic acid specific lectins from Aleuria aurantia, Lotus tetragonolobus, and Ulex europaeus as well as Maackia amurensis and Sambucus nigra, respectively. Results: Leukocytospermic seminal fibronectin, in comparison with fibronectin of normal fertile group, showed lower relative reactivity with AAL, LTA and UEA, and higher reactivity with MAA and SNA, while the AGP of the leukocytospermic group was less reactive with AAL, and the relative reactivity with LTA and MAA was significantly higher. Fibronectin and α1-acid glycoprotein reactivity with UEA and MAA showed high positive correlations. Discussion: Leukocytospermia was associated with the alterations of terminal monosaccharide expression in human seminal fibronectin and α1-acid glycoprotein. The increase of sialyl-Lewisx antigen in α1-acid glycoprotein can be used as a marker of genital tract inflammation manifested by leukocytospermia.

Sialic acid profiles in the respiratory tracts of selected species of raptors: evidence for potential binding sites for human and avian influenza A viruses

Context The ability of influenza A viruses to recognise and bind to cell surface receptors such as sialic acid linked to galactose by an α2,3 linkage (SAα2,3-gal) and sialic acid linked to galactose by an α2,6 linkage (SAα2,6-gal) is a major determinant of influenza A virus infection. Although the epidemiological surveys of influenza A virus infection in raptors suggest that some raptor species are susceptible to influenza A viruses under natural conditions, the sialic acid profiles in the respiratory and intestinal tracts of raptors are unknown. Aims To examine the sialic acid receptor profiles in the respiratory tracts of the selected raptor species and assess the potential susceptibility of raptors to avian and human influenza viruses and the role of raptors in the epidemiology and evolution of influenza A viruses. Methods The lectin immunohistochemistry staining method was used to examine the sialic acid profiles in the respiratory tracts of eight different species of raptors. Key results A strong staining with Maackia amurensis agglutinin (MAA), specific for sialic acid linked to galactose by an α2,3 linkage (SAα2,3-gal), was observed in the epithelial cells of the respiratory tract of Accipiter nisus and Falco tinnunculus. However, a positive staining for both MAA and Sambucus nigra agglutinin (SNA), specific for sialic acid linked to galactose by an α2,6 linkage (SAα2,6-gal), was detected in the epithelial cells of the upper respiratory tract of Accipiter gularis, Buteo buteo, Otus sunia, Bubo bubo and Asio otus, and in the epithelial cells of the alveoli of Buteo buteo, Falco peregrinus, Otus sunia and Bubo bubo. Conclusions Both avian and human influenza A virus receptors are expressed in six species of raptors examined. There are some variations in the type and distribution of sialic acid receptor expression among different raptor species. No correlation between phylogeny of birds and their sialic acid receptor distributions was observed. Implications Since SAα2,3-gal and SAα2,6-gal are often considered as the primary receptors for avian influenza A viruses and human influenza A viruses, respectively, our data suggest that raptors could be a potential host for avian and human influenza A viruses.