Description: Sediment cores from the Northwind Ridge north of the Arctic Chukchi-Alaskan margin were analyzed for a suite of stratigraphic and provenance proxies. Based on the correlation to previously studied regional records, cores under study present sedimentary environments of Marine Isotope Stages (MIS) 1e11 (~0.4 Ma) on millennial time scales. Contrasting glacial-interglacial conditions and provenance were characterized by means of clay-mineral and geochemical (elemental and isotopic) proxies along with grain size. Interglacial environments are interpreted as sea-ice dominated, with pre-Holocene sediment transported mostly from the East Siberian to Chukchi-Alaskan margin. In comparison with the recent conditions, this pattern suggests a stronger Transpolar Drift expanding into the Canada Basin at the expense of the Beaufort Gyre, or stronger along-shelf currents. Glacial intervals prior to MIS4 have a predominantly North American signature with carbonaceous or terrigenous source rocks. Carbonaceous inputs marked by Ca peaks are tracked to the western Canadian Arctic Archipelago eroded by the Laurentide Ice Sheet (LIS). Terrigenous sources (Zr peaks) are likely related to areas impacted by the Innuitian Ice Sheet and/or the LIS Mackenzie ice stream. MIS 4 and 2 intervals have a different composition with the Siberian/Chukchi rather than North American provenance. A stronger winnowing indicated by grain size in the glacial intervals suggests a stronger mid-depth circulation. Study results provide new boundary conditions for modeling paleocirculation and glaciations in the western Arctic Ocean.

Description: Background: Dysregulation of glycoproteins is closely related with many diseases. Quantitative proteomics methods are powerful tools for the detection of glycoprotein alterations. However, in almost all quantitative glycoproteomics studies, trypsin is used as the only protease to digest proteins. This conventional method is unable to quantify N-glycosites in very short or long tryptic peptides and so comprehensive glycoproteomics analysis cannot be achieved. Methods: In this study, a comprehensive analysis of the difference of N-glycoproteome between hepatocellular carcinoma (HCC) and normal human liver tissues was performed by an integrated workflow combining the multiple protease digestion and solid phase based labeling. The quantified N-glycoproteins were analyzed by GoMiner to obtain a comparative view of cellular component, biological process and molecular function.Results/conclusions: An integrated workflow was developed which enabled the processes of glycoprotein coupling, protease digestion and stable isotope labeling to be performed in one reaction vessel. This workflow was firstly evaluated by analyzing two aliquots of the same protein extract from normal human liver tissue. It was demonstrated that the multiple protease digestion improved the glycoproteome coverage and the quantification accuracy. This workflow was further applied to the differential analysis of N-glycoproteome of normal human liver tissue and that with hepatocellular carcinoma. A total of 2,329 N-glycosites on 1,052 N-glycoproteins were quantified. Among them, 858 N-glycosites were quantified from more than one digestion strategy with over 99% confidence and 1,104 N-glycosites were quantified from only one digestion strategy with over 95% confidence. By comparing the GoMiner results of the N-glycoproteins with and without significant changes, the percentage of membrane and secreted proteins and their featured biological processes were found to be significant different revealing that protein glycosylation may play the vital role in the development of HCC.

Description: 2-Alkylindoles are prepared regiospecifically in a gold-catalyzed bimolecular process under exceedingly mild reaction conditions. Yanzhao Wang, Longwu Ye, Liming Zhang ( from Chem. Commun.) Yanzhao Wang, Chem. Commun., 2011, DOI: 10.1039/C1CC12212F To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry