Lectin receptors

Mining for salt-tolerant genes from halophyte Zoysia matrella using FOX system and functional analysis of ZmGnTL

Zoysia matrella is a salt-tolerant turfgrass grown in areas with high soil salinity irrigated with effluent water. Previous studies focused on explaining the regulatory mechanism of Z. matrella salt-tolerance at phenotypic and physiological levels. However, the molecular mechanism associated with salt tolerance of Z. matrella remained unclear. In this study, a high-efficient method named FOX (full-length cDNA overexpression) hunting system was used to search for salt-tolerant genes in Z. matrella. Eleven candidate genes, including several known or novel salt-tolerant genes involved in different metabolism pathways, were identified. These genes exhibited inducible expression under salt stress condition. Furthermore, a novel salt-inducible candidate gene ZmGnTL was transformed into Arabidopsis for functional analysis. ZmGnTL improved salt-tolerance through regulating ion homeostasis, reactive oxygen species scavenging, and osmotic adjustment. In summary, we demonstrated that FOX is a reliable system for discovering novel genes relevant to salt tolerance and several candidate genes were identified from Z. matrella that can assist molecular breeding for plant salt-tolerance improvement.

Glycohistochemistry: the why and how of detection and localization of endogenous lectins

The central dogma of molecular biology limits the downstream flow of genetic information to proteins. Progress from the last two decades of research on cellular glycoconjugates justifies adding the enzymatic production of glycan antennae with information-bearing determinants to this famous and basic pathway. An impressive variety of regulatory processes including cell growth and apoptosis, folding and routing of glycoproteins and cell adhesion/migration have been unravelled and found to be mediated or modulated by specific protein (lectin)-carbohydrate interactions. The conclusion has emerged that it would have meant missing manifold opportunities not to recruit the sugar code to cellular information transfer. Currently, the potential for medical applications in anti-adhesion therapy or drug targeting is one of the major driving forces fuelling progress in glycosciences. In histochemistry, this concept has prompted the introduction of carrier-immobilized carbohydrate ligands (neoglycoconjugates) to visualize the cells' capacity to be engaged in oligosaccharide recognition. After their isolation these tissue lectins will be tested for ligand analysis. Since fine specificities of different lectins can differ despite identical monosaccharide binding, the tissue lectins will eventually replace plant agglutinins to move from glycan profiling and localization to functional considerations. Namely, these two marker types, i.e. neoglycoconjugates and tissue lectins, track down accessible binding sites with relevance for involvement in interactions in situ. The documented interplay of synthetic organic chemistry and biochemistry with cyto- and histochemistry nourishes the optimism that the application of this set of innovative custom-prepared tools will provide important insights into the ways in which glycans can act as hardware in transmitting information during normal tissue development and pathological situations.

Lectin binding patterns of porcine oviduct mucosa and endometrium during the oestrous cycle

Important functions of the oviduct during reproduction include the provision of an optimal environment for gametes and zygotes and nutrition of the early embryo. These functions are ensured by the secretion of an oviductal fluid which is known to contain organ-specific glycoproteins. Glycoconjugates of the apical glycocalyx are considered to play a major role in cell recognition and interaction processes. In the present investigation, binding patterns of Con A, HPA, LTA, RCA I, UEA I, and WGA were studied in defined segments of the oviduct (infundibulum, ampulla, isthmus) and in the uterus during the oestrous cycle. The carbohydrate distribution showed regional as well as time dependent differences. LTA, HPA and WGA reacted strongly with Golgi regions and secretory granules in the oviduct epithelium during the follicular phase, indicating high secretory activity. LTA, HPA, and UEA I also revealed a varying carbohydrate composition of the glycocalyx during the oestrous cycle. Prominent regional differences in glycoconjugate expression were shown in oviductal segments by LTA and HPA binding: during the follicular phase, LTA binding sites were only present on epithelial cells of the isthmic segment, the ampulla and infundibulum being unreactive. D-N-acetyl-galactosamine residues were demonstrated on ciliated epithelial cells of the ampulla and infundibulum exclusively during oestrus. The glycocalyx of uterine epithelial cells was clearly defined by HPA, WGA, LTA, RCA I and UEA I; LTA binding was restricted to the secretory phase. The observation of regional and time dependent variability in glycoconjugate distribution strongly indicates their specific physiological functions in reproductive processes.

The distribution of type-2 chain histo-blood group antigens in normal cycling human endometrium

The blood group ABO(H) determinants are major allogenic antigens in both erythrocytes and tissue of man. These antigens and related carbohydrates are markers of cellular maturation and differentiation in many epithelial tissues and have recently attracted great interest as tumor-associated antigens. Previous studies of endometrial tissues have indicated that glycosylation in this tissue may be related to hormonal stimulation. We have investigated the immunohistochemical distribution of type-2 chain histo-blood group-related carbohydrates in specimens of normal, cycling endometria obtained from hysterectomies on women with known ABO/Lewis erythrocyte type and saliva secretor status. N-acetyllactosamine and Le(x) were demonstrated to be uninfluenced by the genetic background. A and Ale(y) antigens were exclusively demonstrated in endometria from blood group A individuals, while Le(y) was expressed in endometria from blood group 0 individuals mainly. The precursor N-acetyllactosamine as well as the terminal H, A, and ALe(y) antigens were shown in only a few cells. In contrast, N-acetyllactosamine substituted by sialic acid and/or fucose residues (Le(x), sialosyl-Le(x), Le(y)) were demonstrated in epithelial cells of normal, cycling endometrium, but with both quantitative and qualitative differences in staining relating to the menstrual cycle, indicating that type-2 chain antigens are expressed under both genetic and hormonal influence in human cycling endometrium.