Analysis of monosaccharides, fatty constituents and rare O-acetylated sialic acids from gonads of the starfish Asterias rubens

Abstract A previous study (Bergwerff et al., Biochimie 74 (1992

Galectin-4 and sulfatides in apical membrane trafficking in enterocyte-like cells

We have previously reported that 1-benzyl-2-acetamido-2-deoxy-α-d-galactopyranoside (GalNAcα-O-bn), an inhibitor of glycosylation, perturbed apical biosynthetic trafficking in polarized HT-29 cells suggesting an involvement of a lectin-based mechanism. Here, we have identified galectin-4 as one of the major components of detergent-resistant membranes (DRMs) isolated from HT-29 5M12 cells. Galectin-4 was also found in post-Golgi carrier vesicles. The functional role of galectin-4 in polarized trafficking in HT-29 5M12 cells was studied by using a retrovirus-mediated RNA interference. In galectin-4–depleted HT-29 5M12 cells apical membrane markers accumulated intracellularly. In contrast, basolateral membrane markers were not affected. Moreover, galectin-4 depletion altered the DRM association characteristics of apical proteins. Sulfatides with long chain-hydroxylated fatty acids, which were also enriched in DRMs, were identified as high-affinity ligands for galectin-4. Together, our data propose that interaction between galectin-4 and sulfatides plays a functional role in the clustering of lipid rafts for apical delivery

Four‐dimensional‐STEM analysis of the phyllosilicate‐rich matrix of Ryugu samples

Ryugu asteroid grains brought back to the Earth by the Hayabusa2 space mission are pristine samples containing hydrated minerals and organic compounds. Here, we investigate the mineralogy of their phyllosilicate-rich matrix with four-dimensional scanning transmission electron microscopy (4D-STEM). We have identified and mapped the mineral phases at the nanometer scale (serpentine, smectite, pyrrhotite), observed the presence of Ni-bearing pyrrhotite, and identified the serpentine polymorph as lizardite, in agreement with the reported aqueous alteration history of Ryugu. Furthermore, we have mapped the d-spacings of smectite and observed a broad distribution of values, ranging from 1 to 2 nm, with an average d-spacing of 1.24 nm, indicating significant heterogeneity within the sample. Such d-spacing variability could be the result of either the presence of organic matter trapped in the interlayers or the influence of various geochemical conditions at the submicrometer scale, suggestive of a range of organic compounds and/or changes in smectite crystal chemistry

Utilisation des dérivés heptafluorobutyrates pour l'analyse qualitative et quantitative des constituants des glycoconjugués par chromatographie gazeuse couplée à la spectrométrie de masse

La GC-MS, utilisée pour son potentiel résolutif, sa sensibilité et sa rapidité, impose souvent de dériver leséchantillons afin de les protéger de la thermolyse et de favoriser leur volatilité. Il existe déjà de nombreuses méthodologies permettant cela, mais aucune d'entre elles ne permet d'analyser efficacement l'ensemble des constituants des glycoconjugués. C'est pourquoi, nous avons développé une technique plus universelle de dérivation par des groupements heptafluorobutyrates, qui permet en trois étapes successives, sur un seul et même échantillon sans qu'il ne quitte son contenant, d'analyser qualitativement et quantitativement la quasitotalité des constituants des glycoconjugués. Ainsi, elle permet d'obtenir la composition d'un mélange en monosaccharides (pentoses, hexoses, désoxy-hexoses, hexosamines, acides hexuroniques, etc.), en acides sialiques, en lipides (acides gras, bases sphingoïdes, monoalkylglycérols, plasmalogènes, etc.) et en acides aminés..LILLE1-BU (590092102) / SudocSudocFranceF

Activité lectinique des cytokines humaines (implications dans les voies de transduction lymphocytaires et modélisation de l'interaction cytokine-ligand)

LILLE1-BU (590092102) / SudocSudocFranceF

Natural ligands of porcine olfactory binding proteins

Nagnan-Le Meillour: agent mis à disposition par l'unité INRA 1197.International audienceKnowledge of endogenous ligands of olfactory binding proteins is a prerequisite for studying their role in odor and pheromone transduction. Here, we report the extraction, derivatization, and characterization by gas chromatography-mass spectrometry of the natural ligands of pig, Sus scrofa (L.), Von Ebner’s Gland protein (VEG) and odorant binding protein (OBP). We identified two isoforms (VEG1 and VEG2), which differed only by the linkage of an O-N-acetylglucosamine (O-GlcNac) group on VEG1. The natural ligands of VEG1 were characterized as two isomers of testosterone, whereas ligands of VEG2 and OBP were fatty acids or their derivatives. Our findings suggest that the binding specificity of VEG1 for steroids is governed by the presence of an O-GlcNac moiety on the protein. This specificity was confirmed by the binding of radiolabeled testosterone only by VEG1 in an in-gel binding assay. This is the first evidence for a post-translational modification in the process of odorant discrimination by olfactory binding proteins