Glycoproteomics of Lubricin-Implication of Important Biological Glyco- and Peptide-Epitopes in Synovial Fluid

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Chinese as a Second Language Pronunciation Teaching Survey

This survey study aims to provide an overview of Chinese as a second language (CSL) pronunciation teaching in the higher educational institutions in the US. 80 respondents participated in and completed an online survey. The survey elicited the participants’ responses in the following constructs: the context of Chinese pronunciation teaching, the status of Chinese pronunciation teaching, the CSL learners’ motivation and goal of Chinese pronunciation teaching, approach of pinyin teaching, difficulties in segments and suprasegmentals, and issues related to the training of Chinese pronunciation teaching. Not only have the findings from the study shed new light on many important issues in Chinese pronunciation teaching, they also have important pedagogical implications for all parties in CSL teaching: learners, instructors, researchers, textbook compilers, and administrators. While this study raises more questions than answers in Chinese pronunciation teaching, the survey highlights some critical issues that entail the joint efforts of the CSL field and points to the direction of further studies on Chinese pronunciation and Chinese pronunciation teaching

Helicobacter suis infection alters glycosylation and decreases the pathogen growth inhibiting effect and binding avidity of gastric mucins

Helicobacter suis is the most prevalent non-Helicobacter pylori Helicobacter species in the human stomach and is associated with chronic gastritis, peptic ulcer disease, and gastric mucosa-associated lymphoid tissue (MALT) lymphoma. H. suis colonizes the gastric mucosa of 60-95% of pigs at slaughter age, and is associated with chronic gastritis, decreased weight gain, and ulcers. Here, we show that experimental H. suis infection changes the mucin composition and glycosylation, decreasing the amount of H. suis-binding glycan structures in the pig gastric mucus niche. Similarly, the H. suis-binding ability of mucins from H. pylori-infected humans is lower than that of noninfected individuals. Furthermore, the H. suis growth-inhibiting effect of mucins from both noninfected humans and pigs is replaced by a growth-enhancing effect by mucins from infected individuals/pigs. Thus, Helicobacter spp. infections impair the mucus barrier by decreasing the H. suis-binding ability of the mucins and by decreasing the antiprolific activity that mucins can have on H. suis. Inhibition of these mucus-based defenses creates a more stable and inhabitable niche for H. suis. This is likely of importance for long-term colonization and outcome of infection, and reversing these impairments may have therapeutic benefits

An integrated natural remanent magnetization acquisition model for the Matuyama-Brunhes reversal recorded by the Chinese loess

Geomagnetic polarity reversal boundaries are key isochronous chronological controls for the long Chinese loess sequences, and further facilitate paleoclimatic correlation between Chinese loess and marine sediments. However, owing to complexity of postdepositional remanent magnetization (pDRM) acquisition processes related to variable dust sedimentary environments on the Chinese Loess Plateau (CLP), there is a long-standing dispute concerning the downward shift of the pDRM recorded in Chinese loess. In this study, after careful stratigraphic correlation of representative climatic tie points and the Matuyama-Brunhes boundaries (MBB) in the Xifeng, Luochuan, and Mangshan loess sections with different pedogenic environments, the downward shift of the pDRM is semiquantitatively estimated and the acquisition model for the loess natural remanent magnetization (NRM) is discussed. The measured MB transition zone has been affected by the surficial mixing layer (SML) and remagnetization. Paleoprecipitation is suggested to be the dominant factor controlling the pDRM acquisition processes. Rainfall-controlled leaching would restrict the efficiency of the characterized remanent magnetization carriers aligning along the ancient geomagnetic field. We conclude that the MBB in the central CLP with moderate paleoprecipitation could be considered as an isochronous chronological control after moderate upward adjustment. A convincing case can then be made to correlate L8/S8 to MIS 18/1

The O-glycomap of lubricin, a novel mucin responsible for joint lubrication, identified by site-specific glycopeptide analysis

The lubricative, heavily glycosylated mucin-like synovial glycoprotein lubricin has previously been observed to contain glycosylation changes related to rheumatoid and osteoarthritis. Thus, a site-specific investigation of the glycosylation of lubricin was undertaken, in order to further understand the pathological mechanisms involved in these diseases. Lubricin contains an serine/threonine/proline (STP)-rich domain composed of imperfect tandem repeats (EPAPTTPK), the target for O-glycosylation. In this study, using a liquid chromatography–tandem mass spectrometry approach, employing both collision-induced and electron-transfer dissociation fragmentation methods, we identified 185 O-glycopeptides within the STP-rich domain of human synovial lubricin. This showed that adjacent threonine residues within the central STP-rich region could be simultaneously and/or individually glycosylated. In addition to core 1 structures responsible for biolubrication, core 2 O-glycopeptides were also identified, indicating that lubricin glycosylation may have other roles. Investigation of the expression of polypeptide N-acetylgalactosaminyltransferase genes was carried out using cultured primary fibroblast-like synoviocytes, a cell type that expresses lubricin in vivo. This analysis showed high mRNA expression levels of the less understood polypeptide N-acetylgalactosaminyltransferase 15 and 5 in addition to the ubiquitously expressed polypeptide N-acetylgalactosaminyltransferase 1 and 2 genes. This suggests that there is a unique combination of transferase genes important for the O-glycosylation of lubricin. The site-specific glycopeptide analysis covered 82% of the protein sequence and showed that lubricin glycosylation displays both micro- and macroheterogeneity. The density of glycosylation was shown to be high: 168 sites of O-glycosylation, predominately sialylated, were identified. These glycosylation sites were focused in the central STP-rich region, giving the domain a negative charge. The more positively charged lysine and arginine residues in the N and C termini suggest that synovial lubricin exists as an amphoteric molecule. The identification of these unique properties of lubricin may provide insight into the important low-friction lubricating functions of lubricin during natural joint movement

Nucleotide and Nucleotide Sugar Analysis by Liquid Chromatography-Electrospray Ionization-Mass Spectrometry on Surface-Conditioned Porous Graphitic Carbon

We examined the analysis of nucleotides and nucleotide sugars by chromatography on porous graphitic carbon with mass spectrometric detection, a method that evades contamination of the MS instrument with ion pairing reagent. At first, adenosine triphosphate (ATP) and other triphosphate nucleotides exhibited very poor chromatographic behavior on new columns and could hardly be eluted from columns previously cleaned with trifluoroacetic acid. Satisfactory performance of both new and older columns could, however, be achieved by treatment with reducing agent and, unexpectedly, hydrochloric acid. Over 40 nucleotides could be detected in cell extracts including many isobaric compounds such as ATP, deoxyguanosine diphosphate (dGTP), and phospho-adenosine-5′-phosphosulfate or 3′,5′-cyclic adenosine 5'-monophosphate (AMP) and its much more abundant isomer 2′,3′-cylic AMP. A fast sample preparation procedure based on solid-phase extraction on carbon allowed detection of very short-lived analytes such as cytidine 5'-monophosphate (CMP)-2-keto-deoxy-octulosonic acid. In animal cells and plant tissues, about 35 nucleotide sugars were detected, among them rarely considered metabolites such as uridine 5'-diphosphate (UDP)-l-arabinopyranose, UDP-l-arabinofuranose, guanosine 5'-diphosphate (GDP)-l-galactofuranose, UDP-l-rhamnose, and adenosine diphosphate (ADP)-sugars. Surprisingly, UDP-arabinopyranose was also found in Chinese hamster ovary (CHO) cells. Due to the unique structural selectivity of graphitic carbon, the method described herein distinguishes more nucleotides and nucleotide sugars than previously reported approaches

BabA-mediated adherence of pediatric ulcerogenic H. pylori strains to gastric mucins at neutral and acidic pH

Funding This work was supported by the Familjen Erling-Perssons Stiftelse;Fundação para a Ciência e a Tecnologia [FCTPTDC/BIM-MEC/1051/2012];Swedish research council [521-2011-2370];Swedish research council [621-2014-4361]; Swedish cancer society;Åke Wibergs ;Ragnar Söderbergs stiftelse;Stiftelserna Wilhelm och Martina Lundgrens;Svenska Forskningsrådet Formas [221-2013-590];Svenska Forskningsrådet Formas [221-2011-1036].Helicobacter pylori infection can result in non-ulcer dyspepsia (NUD), peptic ulcer disease (PUD), adenocarcinoma, and gastric lymphoma. H. pylori reside within the gastric mucus layer, mainly composed of mucins carrying an array of glycan structures that can serve as bacterial adhesion epitopes. The aim of the present study was to characterize the binding ability, adhesion modes, and growth of H. pylori strains from pediatric patients with NUD and PUD to gastric mucins. Our results showed an increased adhesion capacity of pediatric PUD H. pylori strains to human and rhesus monkey gastric mucins compared to the NUD strains both at neutral and acidic pH, regardless if the mucins were positive for Lewis b (Leb), Sialyl-Lewis x (SLex) or LacdiNAc. In addition to babA positive strains being more common among PUD associated strains, H. pylori babA positive strains bound more avidly to gastric mucins than NUD babA positive strains at acidic pH. Binding to Leb was higher among babA positive PUD H. pylori strains compared to NUD strains at neutral, but not acidic, pH. PUD derived babA-knockout mutants had attenuated binding to mucins and Leb at acidic and neutral pH, and to SLex and DNA at acidic pH. The results highlight the role of BabA-mediated adherence of pediatric ulcerogenic H. pylori strains, and points to a role for BabA in adhesion to charged structures at acidic pH, separate from its specific blood group binding activity.publishersversionpublishe