Carbohydrate-carbohydrate interaction provides adhesion force and specificity for cellular recognition and adhesion

Carbohydrates at the cell surface have been proposed as mediators in cell-cell recognition events involved in embryogenesis, metastasis, and other proliferation processes by calcium-dependent carbohydrate to carbohydrate interactions. They are the most prominently exposed structures on the surface of living cells, and with flexible chains and many binding sites are ideal to serve as the major players in initiating these cellular events. However, biological relevance of these type interactions is often questioned because of the very low affinity binding of single carbohydrate molecules and that they manifest themselves only through the contact of a large number of molecules tightly arranged in the membrane. Weak interactions are considerably more difficult to study and only a few biologically significant examples of direct carbohydrate-carbohydrate interactions have been reported, e.g. pioneering work showing glycosphingolipid self-interactions through multivalent interaction of Lewis X epitopes. However, there are no reports on the existence of specific proteoglycan self-interactions through carbohydrate-carbohydrate interactions in cellular recognition system, as it has been done with glycosphingolipids. Here, we used sponges, organisms on which the first proteoglycan-mediated cell-cell recognition in the animal kingdom was demonstrated, as a model system to study carbohydrate-mediated cellular recognition. We show that the interaction between single oligosaccharides from surface proteoglycans is relatively strong and comparable to protein-carbohydrate interactions, highly specific, and dependent on Ca2+-ions. 200 kDa glycans from the core protein of Microciona prolifera cell surface proteoglycans have been previously shown to mediate homotypic Microciona proteoglycan-proteoglycan interactions. Here, 200 kDa glycans from four different sponge species: Microciona prolifera, Halichondria panicea, Suberites fuscus and Cliona celata were purified and investigated for species-specific interactions. Selective recognition of glycans by live cells was studied to confirm the existence of glycan-glycan recognition system in biologically relevant situations. Mature sponge cells have the ability to reaggregate species-specifically and form homogenous aggregates on a shaker at the right shear forces in the presence of physiological 10 mM Ca2+. Live cells were allowed to aggregate with glycan-coated beads similar in size to small sponge cells in the presence of calcium. They specifically recognized beads coated with their own glycans and did not mix but separated from beads coated with glycans isolated from different species. The glycan-glycan recognition assay was developed to mimic species-specific cellcell recognition in sponges. 200 kDa glycans immobilized onto beads similar in size to small sponge cells assembled species-specifically in the presence of physiological calcium, at the same shear forces as in cell-cell aggregation. Glycans coated on beads aggregated with glycans from the same species coated on beads, and separated from glycans from other species. The glycan density necessary for specific live cellcell recognition in sponges is 828 molecules/μm2. In our studies, the glycan density necessary for specific glycan-coated bead was very similar: ~810 molecules/μm2. Mature live cells demonstrated specific recognition of 200 kDa glycans during selective-binding to glycans coated on surfaces in the presence of calcium. They strongly adhered to glycans from their own surface proteoglycans coated onto a solid polystyrene phase, while the binding to glycans from different proteoglycans was 3 - 5 times lower. Moreover, homotypic adhesion to glycan-coated plates enhanced sponge cell differentiation and formation of mineral skeleton (spicules). Larval cells, after settlement and spreading of larvae, can fuse species-specifically in nature. In our studies, live larval cells recognized and adhered specifically to glycans purified from adhesion proteoglycans from their "mother sponge". They showed almost no interaction with glycans from other species. As in cell-glycan adhesion assays, highly species-specific adhesion of 200 kDa glycans to glycan-coated surfaces could be observed in the presence of physiological calcium. Tested glycans bound strongly to glycans from the same species and showed up to a six fold reduction in binding to glycans from other species. Atomic force microscopy (AFM) was performed to measure for the first time adhesion forces between single glycan molecules obtained from different surface proteoglycans. Measurements revealed equally strong adhesion forces in the range of several hundred piconewtons (pN) between glycan molecules as between proteins and glycans measured in another recognition system. Moreover, statistically significant differences (p value < 0.01) were seen between homotypic (glycans from the same species) and heterotypic (glycans from different species) interactions. Moreover, the polyvalent character of binding characterized mainly interactions between glycans from the same species. This indicates that not only the higher adhesion force per binding site as such but also the higher amount of multiple interactions between glycans from the same species versus mixture of glycans from different species guaranteed the specificity of the glycan-mediated recognition. These findings confirm for the first time the existence of specific glycan-glycan recognition system between cell surface proteoglycans. We propose that these cell's outermost surface structures serve as important players in initiating the very first contacts between cells through highly species-specific and flexible carbohydratecarbohydrate interactions

Carbohydrate-carbohydrate interaction provides adhesion force and specificity for cellular recognition and adhesion

Carbohydrates at the cell surface have been proposed as mediators in cell-cell recognition events involved in embryogenesis, metastasis, and other proliferation processes by calcium-dependent carbohydrate to carbohydrate interactions. They are the most prominently exposed structures on the surface of living cells, and with flexible chains and many binding sites are ideal to serve as the major players in initiating these cellular events. However, biological relevance of these type interactions is often questioned because of the very low affinity binding of single carbohydrate molecules and that they manifest themselves only through the contact of a large number of molecules tightly arranged in the membrane. Weak interactions are considerably more difficult to study and only a few biologically significant examples of direct carbohydrate-carbohydrate interactions have been reported, e.g. pioneering work showing glycosphingolipid self-interactions through multivalent interaction of Lewis X epitopes. However, there are no reports on the existence of specific proteoglycan self-interactions through carbohydrate-carbohydrate interactions in cellular recognition system, as it has been done with glycosphingolipids. Here, we used sponges, organisms on which the first proteoglycan-mediated cell-cell recognition in the animal kingdom was demonstrated, as a model system to study carbohydrate-mediated cellular recognition. We show that the interaction between single oligosaccharides from surface proteoglycans is relatively strong and comparable to protein-carbohydrate interactions, highly specific, and dependent on Ca2+-ions. 200 kDa glycans from the core protein of Microciona prolifera cell surface proteoglycans have been previously shown to mediate homotypic Microciona proteoglycan-proteoglycan interactions. Here, 200 kDa glycans from four different sponge species: Microciona prolifera, Halichondria panicea, Suberites fuscus and Cliona celata were purified and investigated for species-specific interactions. Selective recognition of glycans by live cells was studied to confirm the existence of glycan-glycan recognition system in biologically relevant situations. Mature sponge cells have the ability to reaggregate species-specifically and form homogenous aggregates on a shaker at the right shear forces in the presence of physiological 10 mM Ca2+. Live cells were allowed to aggregate with glycan-coated beads similar in size to small sponge cells in the presence of calcium. They specifically recognized beads coated with their own glycans and did not mix but separated from beads coated with glycans isolated from different species. The glycan-glycan recognition assay was developed to mimic species-specific cellcell recognition in sponges. 200 kDa glycans immobilized onto beads similar in size to small sponge cells assembled species-specifically in the presence of physiological calcium, at the same shear forces as in cell-cell aggregation. Glycans coated on beads aggregated with glycans from the same species coated on beads, and separated from glycans from other species. The glycan density necessary for specific live cellcell recognition in sponges is 828 molecules/μm2. In our studies, the glycan density necessary for specific glycan-coated bead was very similar: ~810 molecules/μm2. Mature live cells demonstrated specific recognition of 200 kDa glycans during selective-binding to glycans coated on surfaces in the presence of calcium. They strongly adhered to glycans from their own surface proteoglycans coated onto a solid polystyrene phase, while the binding to glycans from different proteoglycans was 3 - 5 times lower. Moreover, homotypic adhesion to glycan-coated plates enhanced sponge cell differentiation and formation of mineral skeleton (spicules). Larval cells, after settlement and spreading of larvae, can fuse species-specifically in nature. In our studies, live larval cells recognized and adhered specifically to glycans purified from adhesion proteoglycans from their "mother sponge". They showed almost no interaction with glycans from other species. As in cell-glycan adhesion assays, highly species-specific adhesion of 200 kDa glycans to glycan-coated surfaces could be observed in the presence of physiological calcium. Tested glycans bound strongly to glycans from the same species and showed up to a six fold reduction in binding to glycans from other species. Atomic force microscopy (AFM) was performed to measure for the first time adhesion forces between single glycan molecules obtained from different surface proteoglycans. Measurements revealed equally strong adhesion forces in the range of several hundred piconewtons (pN) between glycan molecules as between proteins and glycans measured in another recognition system. Moreover, statistically significant differences (p value < 0.01) were seen between homotypic (glycans from the same species) and heterotypic (glycans from different species) interactions. Moreover, the polyvalent character of binding characterized mainly interactions between glycans from the same species. This indicates that not only the higher adhesion force per binding site as such but also the higher amount of multiple interactions between glycans from the same species versus mixture of glycans from different species guaranteed the specificity of the glycan-mediated recognition. These findings confirm for the first time the existence of specific glycan-glycan recognition system between cell surface proteoglycans. We propose that these cell's outermost surface structures serve as important players in initiating the very first contacts between cells through highly species-specific and flexible carbohydratecarbohydrate interactions

Carbohydrate–carbohydrate interaction provides adhesion force and specificity for cellular recognition

© 2004 Bucior et al. This article is distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License. The definitive version was published in Journal of Cell Biology 165 (2004): 529-537, doi:10.1083/jcb.200309005.The adhesion force and specificity in the first experimental evidence for cell–cell recognition in the animal kingdom were assigned to marine sponge cell surface proteoglycans. However, the question whether the specificity resided in a protein or carbohydrate moiety could not yet be resolved. Here, the strength and species specificity of cell–cell recognition could be assigned to a direct carbohydrate–carbohydrate interaction. Atomic force microscopy measurements revealed equally strong adhesion forces between glycan molecules (190–310 piconewtons) as between proteins in antibody–antigen interactions (244 piconewtons). Quantitative measurements of adhesion forces between glycans from identical species versus glycans from different species confirmed the species specificity of the interaction. Glycan-coated beads aggregated according to their species of origin, i.e., the same way as live sponge cells did. Live cells also demonstrated species selective binding to glycans coated on surfaces. These findings confirm for the first time the existence of relatively strong and species-specific recognition between surface glycans, a process that may have significant implications in cellular recognition.This work was supported by the Friedrich Miescher Institute, branch of the Novartis Research Foundation, the M.E. Müller Foundation, and the Swiss National Research Foundatio

Evaluating macrophytes as indicators of anthropogenic pressures in rivers in Ireland

Publication history: Accepted - 6 January 2021; Published online - 10 February 2021.The ability of macrophytes to indicate pressures in rivers was assessed by comparing metrics for nitrate (NO3), ammonia (NH4), soluble reactive phosphorus (SRP), dissolved oxygen saturation (DO), pH (PH) and siltation (SUBS) with direct estimates of the pressures at 810 sites in the Republic of Ireland, supplemented with General Linear Models (GLMs). The bivariate and rank correlation coefficients using the full data range and the first and fourth quartiles of the river pressures varied between 0.22 and - 0.39 for NO3 and DO; they were smaller or not significant for the other four metrics. The GLMs provided evidence for an independent association between NO3 and the nitrate concentration and SUBS and ammonia, indicating some specificity for these metrics. Discriminating sites in the first and fourth quartiles produced Type II errors between 37 (PH) and 69% (NH4), with a mean of 50. As the pressure-impact relationships are not precise enough (low correlation coefficients) that evidence from a single macrophyte metric is reliable, combining the metric with evidence from other biological groups at one site or from three or more sites may be the most useful approach.Environmental Protection Agency of Ireland - funding of the DETECT Project (2015-W-LS-9) Burnley Borough Council - funding to AB

The autonomy of public sector units in the process of formulating accounting policy : evidence from Poland

PURPOSE: To examine the autonomy of public sector entity in the development and application of accounting policy, understood as a mandatory element of the accounting system, and the perception of such independence on the part of the persons responsible for accounting in these units.DESIGN/METHODOLOGY/APPROACH: The article adopts a qualitative research approach, in accordance with the case study and survey method. The analysis incorporated data collected during a case study carried out in two Polish budgetary units (basic form of public finance sector units in Poland), the survey was completed by 35 intentionally selected entities.FINDINGS: The authors found that the entities surveyed show independence in the creation and development of accounting policy and practice, however, this independence is significantly limited by the interference of supervisors. At the same time, the survey shows that the persons responsible for accounting in these entities consider it desirable to increase their freedom in accounting policy development.PRACTICAL IMPLICATIONS: In their opinion, this will provide an opportunity to make the accounting system a tool that is more useful in management.ORIGINALITY/VALUE: Examination of public-entity accounting policy is rare in general, and virtually absent with respect to Polish entities. Thus, this work is a step to fill this research gap. The article contributes to the literature on the subject by exploring the issue.peer-reviewe

Effectiveness and safety of betrixaban extended prophylaxis for venous thromboembolism compared with standard-duration prophylaxis intervention in acute medically ill patients : a systematic literature review and network meta-analysis

Aims: To determine the clinical effectiveness and safety of venous thromboembolism (VTE) prophylaxis using US- and Europe-approved anticoagulants relative to extended-duration VTE prophylaxis with betrixaban. Low molecular weight heparins (LMWHs), unfractionated heparin (UFH), fondaparinux sodium and placebo were each compared to betrixaban, as standard-duration VTE prophylaxis for hospitalized, non-surgical patients with acute medical illness at risk of VTE. Materials and methods: A systematic literature review was conducted up to June 2019 to identify randomized controlled trials (RCTs) of VTE prophylaxis in hospitalized, non-surgical patients with acute medical illness at risk of VTE. Studies that reported the occurrence of VTE events (including death) and, where possible, major bleeding, from treatment initiation to 20–50 days thereafter were retrieved and extracted. A Bayesian fixed effect network meta-analysis was used to estimate efficacy and safety of betrixaban compared with standard-duration VTE prophylaxis. Results: Seven RCTs were analyzed which compared betrixaban, LMWHs, UFH, fondaparinux sodium, or placebo. There were significantly higher odds (median odds [95% credible interval]) of VTE with LMWHs (1.38 [1.12–1.70]), UFH (1.60 [1.05–2.46]), and placebo (2.37 [1.55–3.66]) compared with betrixaban. There were significantly higher odds of VTE-related death with placebo (7.76 [2.14–34.40]) compared with betrixaban. No significant differences were observed for the odds of major bleeding with all comparators, VTE-related death with any active standard-duration VTE prophylaxis, or of VTE with fondaparinux sodium, compared with betrixaban. Limitations and conclusions: In this indirect comparison, betrixaban was shown to be an effective regimen with relative benefits compared with LMWHs and UFH. This indicates that betrixaban could reduce the burden of VTE in at-risk hospitalized patients with acute medical illness who need extended prophylaxis, though without direct comparative evidence, stronger conclusions cannot be drawn

Machine learning using host/guest energy histograms to predict adsorption in metal–organic frameworks: Application to short alkanes and Xe/Kr mixtures

A machine learning (ML) methodology that uses a histogram of interaction energies has been applied to predict gas adsorption in metal–organic frameworks (MOFs) using results from atomistic grand canonical Monte Carlo (GCMC) simulations as training and test data. In this work, the method is first extended to binary mixtures of spherical species, in particular, Xe and Kr. In addition, it is shown that single-component adsorption of ethane and propane can be predicted in good agreement with GCMC simulation using a histogram of the adsorption energies felt by a methyl probe in conjunction with the random forest ML method. The results for propane can be improved by including a small number of MOF textural properties as descriptors. We also discuss the most significant features, which provides physical insight into the most beneficial adsorption energy sites for a given application