Agglutinin

The aim of this study was to establish the normal pattern of some haemato-immunological parameters in the mussel Perna perna to serve as a reference for further studies using this species as a biological indicator of environmental contaminants. We investigated the morphology and cytochemistry of the circulating haemocytes of P. perna , their role in phagocytosis and superoxide anion production, their numbers and composition, the agglutinin concentration in the plasma and the presence of phenoloxidase activity. Two blood cell types, hyalinocytes (HY) and granulocytes (GR), were found in the haemolymph of P. perna . HY were agranular cells with a basophilic cytoplasm, whereas GR contained abundant eosinophilic granules. HY comprised approximately 60% of the blood cell types in the circulation. Both haemocyte types, but especially the GR were actively phagocytic and contained acid phosphatase. After stimulation with zymosan, the blood cells were able to reduce NBT to formazan, suggesting the generation of the superoxide anion. Glycogen was not histochemically detectable in either haemocyte type. The number of cells in circulation (THC) did not significantly vary with sex or size of the mussels (3,145·5 and 3,668·5 cells/mm3in males and females respectively). The mussel plasma had an agglutinating activity against different mammalian erythrocytes. A phenoloxidase activity was not encountered either in the haemocyte fraction or in the mussel plasma, even after induction with the protease trypsin or non-self molecules, such as LPS from Gram-negative bacteria and β-1, 3-glucans from fungi.

A lectin was purified from the leaves of Allium altaicum and corresponding gene was cloned. The lectin namely Allium altaicum agglutinin (AAA) was ~24 kDa homodimeric protein and similar to a typical garlic leaf lectin. It was synthesized as 177 amino acid residues pre-proprotein, which consisted of 28 and 43 amino acid long N and C-terminal signal peptides, respectively. The plant expressed this protein more in scapes and flowers in comparison to the bulbs and leaves. Hemagglutination activity (with rabbit erythrocytes) was 1,428 fold higher as compared to Allium sativum leaf agglutinin (ASAL) although, the insecticidal activity against cotton aphid (Aphis gossypii) was relatively low. Glycan array revealed that AAA had higher affinity towards GlcAb1-3Galb as compared to ASAL. Homology analysis showed 57–94% similarity with other Allium lectins. The mature protein was expressed in E. coli as a fusion with SUMO peptide in soluble and biologically active form. Recombinant protein retained high hemagglutination activity.

With increasing use of lectin genes in crop plants to improve insect resistance, the dietary exposure of humans to lectins will rise and it is necessary to assess whether the presently most favored insecticidal lectin, Galanthus nivalis agglutinin, would be harmful for ...

The effect of expressing the gene encoding snowdrop lectin (Galanthus nivalis agglutinin, GNA) in transgenic potato plants, on parasitism of the phytophagous insect pest Lacanobia oleracea by the gregarious ectoparasitoid Eulophus pennicornis, was investigated in glasshouse trials. Expression of GNA (approx. 1.0% total soluble protein) by transgenic plants significantly reduced the level of pest damage, thus confirming previous studies. Furthermore, the presence of the parasitoid significantly reduced the levels of damage incurred either by the transgenic or control plants when compared to those plants grown in the absence of the parasitoid. For the GNA expressing plants the presence of the parasitoid resulted in further reductions (ca. 21%) in the level of damage caused by the pest species. The ability of the wasp to parasitise and subsequently develop on the pest larvae was not altered by the presence of GNA in the diet of the host. E. pennicornis progeny that developed on L. oleracea reared on GNA expressing plants showed no significant alteration in fecundity when compared with wasps that had developed on hosts fed on control potato plants, although mean size and longevity of female parasitoids was significantly reduced. The number of F 2 progeny produced by parasitoids derived from hosts fed on GNA-expressing plants was not significantly different to those produced by parasitoids from hosts fed control plants. Results from the present study demonstrate that the use of transgenic plants expressing insecticidal proteins can be compatible with the deployment of beneficial insects and that the two factors may interact in a positive manner.

The galactoside-specific Viscum album L. agglutinin (VAA) is a potent biohazard akin to ricin and a mitogen for immune and tumor cells. These activities depend on cell surface binding to glycans. It is an open question whether the process of ligand binding alters the lectin’s shape. Small angle neutron scattering (SANS) experiments revealed that the carbohydrate ligand lactose induced a decrease of the radius of gyration of dimeric VAA from 54.5 ± 1 to 49.5 ± 1 Å in water. Apparently, VAA in aqueous solution and at the concentrations tested at 3.6 mg/ml and above adopts a compacted structure as response to ligand binding. In contrast to the behavior in aqueous solution, lactose binding in DMSO resulted in an increase of the lectin’s radius of gyration from 49 ± 1 to 55.5 ± 1 Å. Because shape changes may be reflected in the thermostability of the protein, this parameter was examined by activity assays of protein exposed to 60°C and 70°C and by differential scanning calorimetry (DSC). In line with the lactose-induced conformational alterations revealed by the SANS experiments, lactose presence enhanced the thermostability of VAA in water. Thus, binding of the carbohydrate ligand in solution can entail changes in shape and thermostability in the case of the tested plant lectin.

The peptide domain of salivary agglutinin responsible for its interaction with cell surface protein antigen (PAc) of Streptococcus mutans or bovine lactoferrin was found in the same peptide, scavenger receptor cysteine-rich domain peptide 2 (SRCRP2). Inhibition studies suggest that PAc and lactoferrin, of which residues 480 to 492 seem important, competitively bind to the SRCRP2 domain of salivary agglutinin.

A lectin was purified from the leaves of Allium altaicum and corresponding gene was cloned. The lectin namely Allium altaicum agglutinin (AAA) was ~24 kDa homodimeric protein and similar to a typical garlic leaf lectin. It was synthesized as 177 amino acid residues pre-proprotein, which consisted of 28 and 43 amino acid long N and C-terminal signal peptides, respectively. The plant

A lectin was purified from the leaves of Allium altaicum and corresponding gene was cloned. The lectin namely Allium altaicum agglutinin (AAA) was ~24 kDa homodimeric protein and similar to a typical garlic leaf lectin. It was synthesized as 177 amino acid residues pre-proprotein, which consisted of 28 and 43 amino acid long N and C-terminal signal peptides, respectively. The plant

Few papers have been published on tick lectins so far, and therefore more data are needed to complete the mosaic of knowledge of their structural and functional properties. Tissue-specific lectin/haemagglutinin activities of both soft and hard ticks have been investigated. Some tick lectins are proteins with binding affinity for sialic acid, various derivatives of hexosamines and different glycoconjugates. Most tick lectin/haemagglutinin activities are blood meal enhanced, and could serve as molecular factors of self/non-self recognition in defence reactions against bacteria or fungi, as well as in pathogen/parasite transmission. Dorin M, the plasma lectin of Ornithodoros moubata, is the first tick lectin purified so far from tick haemolymph, and the first that has been fully characterized. Partial characterization of other tick lectins/haemagglutinins has been performed mainly with respect to their carbohydrate binding specificities and immunochemical features.

The effect of expressing the gene encoding snowdrop lectin (Galanthus nivalis agglutinin, GNA) in transgenic potato plants, on parasitism of the phytophagous insect pest Lacanobia oleracea by the gregarious ectoparasitoid Eulophus pennicornis, was investigated in glasshouse trials. Expression of GNA (approx. 1.0% total soluble protein) by transgenic plants significantly reduced the level of pest damage, thus confirming previous studies. Furthermore, the presence of the parasitoid significantly reduced the levels of damage incurred either by the transgenic or control plants when compared to those plants grown in the absence of the parasitoid. For the GNA expressing plants the presence of the parasitoid resulted in further reductions (ca. 21%) in the level of damage caused by the pest species. The ability of the wasp to parasitise and subsequently develop on the pest larvae was not altered by the presence of GNA in the diet of the host. E. pennicornis progeny that developed on L. oler...

A lectin was purified from the leaves of Allium altaicum and corresponding gene was cloned. The lectin namely Allium altaicum agglutinin (AAA) was ~24 kDa homodimeric protein and similar to a typical garlic leaf lectin. It was synthesized as 177 amino acid residues pre-proprotein, which consisted of 28 and 43 amino acid long N and C-terminal signal peptides, respectively. The plant expressed this protein more in scapes and flowers in comparison to the bulbs and leaves. Hemagglutination activity (with rabbit erythrocytes) was 1,428 fold higher as compared to Allium sativum leaf agglutinin (ASAL) although, the insecticidal activity against cotton aphid (Aphis gossypii) was relatively low. Glycan array revealed that AAA had higher affinity towards GlcAb1-3Galb as compared to ASAL. Homology analysis showed 57–94% similarity with other Allium lectins. The mature protein was expressed in E. coli as a fusion with SUMO peptide in soluble and biologically active form. Recombinant protein retained high hemagglutination activity.