Development of a novel method to evaluate sialylation of glycoproteins and analysis of gp96 sialylation in Hela, SW1990 and A549 cell lines

BACKGROUND: Glycoproteins play a critical role in the cellular activities of eukaryotes. Sialic acid is typically the outermost monosaccharide of glycolipids and glycoproteins, and is necessary for normal development. RESULTS: A strategy based on avidin-biotin affinity was established to enrich sialylated glycoproteins from HeLa cervical carcinoma, SW1990 pancreatic adenocarcinoma, and A549 lung adenocarcinoma cells. Using HPLC-MS/MS, western blot, real-time PCR, and enzyme-linked immunosorbent assay, gp96 was identified in all three cell lines. No significant difference in the protein expression of gp96 was detected at the whole cell level, but the amount of bioti-nylated gp96 in SW1990 cells was 30-40 % lower than that in A549 and HeLa cells, and the amount of sialylated gp96 in SW1990 cells was 30 % lower than that in A549 and HeLa cells. Immunoblotting results showed that the expression of sialyltransferase proteins in the total cell lysates from HeLa and A549 cells were higher than that in SW1990 cells. CONCLUSIONS: We established a new method for investigating the expression and sialylation of glycoproteins using metabolic labeling, click chemistry, and avidin-biotin affinity. We successfully used this method to purify sialylated glycoproteins from cancer cell lines. Our results showed that the levels of gp96 sialylation varied across different cancer cell lines, and this may be because of differences in sialyltransferase expression

Rapid and robust spatiotemporal dynamics of the first-order phase transition in crystals of the organic-inorganic perovskite (C12H25NH3)2PbI4

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Contrasting responses of different functional groups stabilize community responses to a dominant shrub under global change

Changes in precipitation regimes and nitrogen deposition levels due to global change are altering terrestrial ecosystems worldwide. Most attempts at understanding how biotic interactions affect plant species and community responses to global change have focused on biotic interactions measured at the community level. However, these approaches ignore that communities include functionally dissimilar species that might respond differently to changes in the effects of dominant neighbours along environmental gradients. We test the hypothesis that plant species with differences in functional traits may exhibit contrasting interactions with a dominant shrub species within a single community, thereby stabilizing community-level responses to the effects of global change. We manipulated water and nitrogen applications in a semi-arid dune community in northern China, quantified the biomass of herbaceous species occurring below the dominant shrub, Artemisia ordosica, and in adjacent open patches (without the shrub), and measured herbaceous species height and leaf dry matter content. The effects of A. ordosica were quantified at the species, group and community levels using the relative interaction index (RII). Redundancy analysis was performed on species traits and the RII values to assess the relationships between functional differences in species and plant–plant interactions. Species were then grouped using a cluster analysis and the RII values were recalculated at the group level. The redundancy analysis showed that species height and leaf dry matter content were significantly correlated to the changes in species' responses to the effect of A. ordosica along treatments. The four groups of species identified by the cluster analysis showed contrasting variations in competitive or facilitative responses depending on species traits and environmental treatments. However, the interactions measured at the group level balanced the community-level responses, as we found no significant changes in the effects of A. ordosica along treatments for community biomass, richness and functional diversity indices. Synthesis. Our findings indicate that species with different functional strategies within a community exhibit contrasting responses to a dominant shrub along environmental gradients. These contrasting changes in plant–plant interactions of functionally different species may balance the responses of community-level metrics. This suggests that functional differences between species groups and the balance of plant–plant interactions stabilize community responses to global change. © 2021 British Ecological Societ

Propylbenzmethylation at Val-1(alpha) markedly increases the tetramer stability of the PEGylated hemoglobin: A comparison with propylation at Val-1(alpha)

Background: Hemoglobin (Hb)-based oxygen carriers (HBOCs) are potential pharmaceutical agents that can be used in surgery or emergency medicine. PEGylation can modulate the vasoactivity of Hb and is a widely used approach to develop HBOCs. However, PEGylation can significantly enhance the tetramer-dimer dissociation of Hb, which may perturb the structure of Hb and increase its observed adverse effect. Thus, it is necessary to increase the tetramer stability of the PEGylated Hb