Hydrogen bond activated glycosylation under mild conditions

Herein, we report a new glycosylation system for the highly efficient and stereoselective formation of glycosidic bonds using glycosyl N-phenyl trifluoroacetimidate (PTFAI) donors and a charged thiourea hydrogen-bond-donor catalyst. The glycosylation protocol features broad substrate scope, controllable stereoselectivity, good to excellent yields and exceptionally mild catalysis conditions. Benefitting from the mild reaction conditions, this new hydrogen bond-mediated glycosylation system in combination with a hydrogen bond-mediated aglycon delivery system provides a reliable method for the synthesis of challenging phenolic glycosides. In addition, a chemoselective glycosylation procedure was developed using different imidate donors (trichloroacetimidates, N-phenyl trifluoroacetimidates, N-4-nitrophenyl trifluoroacetimidates, benzoxazolyl imidates and 6-nitro-benzothiazolyl imidates) and it was applied for a trisaccharide synthesis through a novel one-pot single catalyst strategy.Bio-organic Synthesi

FAM46B is a prokaryotic-like cytoplasmic poly(A) polymerase essential in human embryonic stem cells

Family with sequence similarity (FAM46) proteins are newly identified metazoan-specific poly(A) polymerases (PAPs). Although predicted as Gld-2-like eukaryotic non-canonical PAPs, the detailed architecture of FAM46 proteins is still unclear. Exact biological functions for most of FAM46 proteins also remain largely unknown. Here, we report the first crystal structure of a FAM46 protein, FAM46B. FAM46B is composed of a prominently larger N-terminal catalytic domain as compared to known eukaryotic PAPs, and a C-terminal helical domain. FAM46B resembles prokaryotic PAP/CCA-adding enzymes in overall folding as well as certain inter-domain connections, which distinguishes FAM46B from other eukaryotic non-canonical PAPs. Biochemical analysis reveals that FAM46B is an active PAP, and prefers adenosine-rich substrate RNAs. FAM46B is uniquely and highly expressed in human pre-implantation embryos and pluripotent stem cells, but sharply down-regulated following differentiation. FAM46B is localized to both cell nucleus and cytosol, and is indispensable for the viability of human embryonic stem cells. Knock-out of FAM46B is lethal. Knock-down of FAM46B induces apoptosis and restricts protein synthesis. The identification of the bacterial-like FAM46B, as a pluripotent stem cell-specific PAP involved in the maintenance of translational efficiency, provides important clues for further functional studies of this PAP in the early embryonic development of high eukaryotes

A new species of Cistopus (Cephalopoda: Octopodidae) from Taiwan and morphology of mucous pouches

Cistopus taiwanicus n. sp. is a medium to large benthic octopus. The primary diagnostic character for the genus Cistopus is the possession of eight mucous pouches set in the oral surface of the webs between each of the arm bases. This study describes the morphological characters of C. taiwanicus from Taiwanese waters and the histology of the mucous pouches. Cistopus taiwanicus can be distinguished from Cistopus indicus by enlarged suckers in mature males and lower sucker counts on normal arms and hectocotylized arm. The inner walls of the mucous pouches are composed of columnar epithelial cells and mucus is secreted from the epithelial cells. Cistopus taiwanicus shows sexual dimorphism in the openings of the mucous pouches; males possess radial white stripes around the mucous pores and significantly larger pore diameters

Synthesis, photocatalytic activities and degradation mechanism of Bi2WO6 toward crystal violet dye

Nanocrystalline Bi2WO6 (BWO) with square-plates morphology was prepared by the hydrothermal synthesis in autoclave. Bi(NO3) (3)center dot 5H(2)O with (NH4)(10)W12O41 center dot 5H(2)O was reacted in pH 9 solution at 160 degrees C for 24 h, 48 h and 72 h to yield the resulting Bi2WO6 as a white precipitate. Bi2WO6 was characterized by the field emission scanning electron microscopy with the energy dispersive X-ray spectrometer (FE-SEM -EDS), the X-ray diffractrommeter (XRD), and the high resolution X-ray photoelectron spectroscopy (HR-XPS). The XPS spectra showed a binding energy shift of Bi element, suggesting that the Bi((+3-x)) formal oxidation state could be the substoichiometric forms of Bi within the Bi2O2 layer. The photocatalytic activities of the prepared BWO samples were evaluated by the photodegradation of crystal violet (CV) dye under UV-light irradiation (365 nm). The intermediates were separated and characterized by HPLC-PDA-ESI/MS techniques and the results indicate that the N-de-methylation with oxidative degradation of the crystal violet dye took place. Based on these intermediates, we propose and discuss the degradation pathways. (C) 2011 Elsevier B.V. All rights reserved

Upregulation of Yy1 Suppresses Dilated Cardiomyopathy caused by Ttn insufficiency

10.1038/s41598-019-52796-0Scientific Reports911633

Magnetism signals in a stalagmite from Southern China and reconstruction of paleorainfall during the interglacial‐glacial transition

Precipitation variations deduced from speleothem stable oxygen isotopes (δ18O) have long been debated in monsoonal China. The magnetic property in speleothems is interpreted to be related to regional precipitation and can therefore offer reliable information of regional precipitation variations. Here we present a speleothem from southern China to explore the magnetic signals in speleothems, and to reconstruct regional precipitation. Saturation magnetization (Ms), which represents the magnetic mineral concentrations, is used as an indicator of effective rainfall variations. The precipitation inferred from Ms varies increased sharply in the period prior to 80.3 ka BP, followed by a drop to precipitation anomaly afterwards, indicating that regional precipitation varied greatly during the hominin‐occupied interval in southern China. Power spectrum analysis of Ms values shows significant 205‐, ~90‐, ~77‐, and ~64‐yrs periodicities, suggesting that the solar activity may play an important role in precipitation variations in southern China during the MIS5a/4 transition