Description: In intestinal and pyloric epithelia leucine-rich repeat-containing G protein-coupled receptor 5 ( Lgr5 )-expressing cells represent long-lived adult stem cells which give rise to all epithelial cell types including endocrine cells. Ablation of the Apc gene in Lgr5 -expressing cells leads to intestinal and pyloric adenomas. To assess whether all epithelial tumours of the gastrointestinal tract are derived from LGR5-positive stem cells we crossed Lgr5-EGFP-IRES-creER T2 mice which express EGFP and Cre recombinase driven by the Lgr5 promoter with CEA424-SV40-TAg mice which develop pyloric neuroendocrine carcinomas of epithelial origin. In 19-day-old mice, single SV40 T antigen (TAg)-positive cells were identified preferentially at the the base of pyloric glands close to the stem cell compartment. However, contrary to previous publications describing subpopulations of LGR5-positive cells in gastrointestinal neoplasia we could not detect Lgr5- EGFP-positive tumour cells in malignant lesions. The lack of expression of the Wnt target gene Lgr5 is probably not caused by suppression of Wnt signalling by TAg since β-catenin-mediated Wnt signalling, as measured by the TOPflash assay, was not inhibited. To determine the cellular origin of CEA424-SV40-TAg tumours we performed tracing experiments using Lgr5-EGFP-IRES-creERT2:CEA424-SV40-TAg:ROSA26-tdRFP mice. Following tamoxifen induction it was possible to efficiently trace the progeny of Lgr5 -expressing cells in gastrointestinal tissue via red fluorescent protein (RFP) expression. No RFP-positive tumour cells were detected even when RFP gene activation occurred in 7-day-old mice well before the appearance of TAg-positive tumour cells. Hence we conclude that Lgr5 -expressing stem cells probably do not constitute the cells-of-origin in CEA424-SV40-TAg mice. Consequently, not all epithelial tumours in the pyloric region are initiated by transformation of LGR5-positive stem cells. Thus additional long-lived LGR5-negative stem cells or progenitor cells with low turnover rate might exist in the pyloric region which can give rise to tumours.

Description: Providing enantiomerically pure products is of key importance in the fine chemicals, food, and pharmaceutical industries. A continuous preferential crystallization process is presented that allows the separation of conglomerate forming enantiomers in a stable, robust, and flexible way. This is achieved by coupling two continuous crystallizers by exchanging their clear liquid phases. Each crystallizer is connected to a suspension mill responsible for in situ seed generation through particle breakage. The dynamic and steady-state behavior of this process is extensively analyzed for racemic feed streams through process simulations, and parameter regions, which yield pure enantiomers in both crystallizers, are identified. For enriched feed streams, it is further shown when this novel flow sheet is capable of outperforming an ideal batch process in terms of solvent consumption per unit mass of desired enantiopure product produced. © 2015 American Institute of Chemical Engineers AIChE J , 61: 2810–2823, 2015

Description: Paleosols contain information about the rates of soil organic carbon turnover when the soil was actively forming. However, this temporal information is often difficult to interpret without tight stratigraphic control on the age of the paleosol. Here we apply ramped pyrolysis/oxidation (Ramped PyrOx) 14 C analyses to evaluate age spectra of transgressive early Holocene paleosols from the Mississippi Delta in southeastern Louisiana, U.S.A. We find 14 C age spectra from soil organic matter (SOM) in both paleosols and overlying basal peats that represent variability in age that is close to, or only slightly greater than, analytical uncertainty of 14 C measurements. Such age spectra have not previously been observed in the sedimentary record. Here, they indicate vigorous soil carbon turnover prior to burial, which homogenized 14 C ages within SOM across the entire thermochemical spectrum. The weighted bulk 14 C ages from Ramped PyrOx of paleosols and overlying peats are identical within analytical and process-associated uncertainty, and corroborate 14 C ages from charcoal fragments and plant macrofossils from the overlying peat. The youngest ages from Ramped PyrOx age spectra may also potentially be applied as chronometers for stratigraphic burial ages. Our results suggest rapid turnover (≪300 yr) of carbon in these soils relative to input of allochthonous carbon, indicating that the 14 C age of different soil components is decoupled from thermochemical stability and instead reflects vigorous turnover processes. The concurrence of paleosol and peat 14 C ages also suggests that pedogenic processes were linked with the development of coastal marshes, and that the priming effect potentially masked the signal of allochthonous carbon inputs during sea-level rise. This article is protected by copyright. All rights reserved.

Description: Fjords are disproportionately important for global organic carbon (OC) burial relative to their spatial extent, and may be important in sequestering atmospheric CO2, providing a negative climate feedback. Within fjords, multiple locally variable delivery mechanisms control mineral sediment deposition, which in turn modulates OC burial. Sediment and OC sources in Fiordland, New Zealand include terrigenous input at fjord heads, sediment reworking over fjord-mouth sills, and landslide events from steep fjord walls. Box cores were analyzed for sedimentary texture, sediment accumulation rate, and OC content to evaluate the relative importance of each delivery mechanism. Sediment accumulation was up to 3.4 mm/yr in proximal and distal fjord areas, with lower rates in medial reaches. X-radiograph and 210Pb stratigraphy indicate mass wasting and surface-sediment bioturbation throughout the fjords. Sediment accumulation rates are inversely correlated with %OC. Spatial heterogeneity in sediment depositional processes and rates is important when evaluating OC burial within fjords.

Description: Understanding salt transport and deposition patterns during evaporation from porous media is important in many engineering and hydrological processes such as soil salinization, ecosystem functioning and land-atmosphere interaction. As evaporation proceeds, salt concentration increases until it exceeds solubility limits, locally, and crystals precipitate. The interplay between transport processes, crystallization and evaporation influences where crystallization occurs. During early stages, the precipitated salt creates an evolving porous structure affecting the evaporation kinetics. We conducted a comprehensive series of experiments to investigate how the salt concentration and precipitation influence evaporation dynamics. Our results illustrate the contribution of the evolving salt crust to the evaporative mass losses. High-resolution thermal imaging enabled us to investigate the complex temperature dynamics at the surface of precipitated salt, providing further confirmation of salt crust contribution to the evaporation. We identify different phases of saline water evaporation from porous media with the corresponding dominant mechanisms in each phase and extend the physical understanding of such processes.

Description: Zooplankton from clear alpine lakes is exposed to stressful levels of solar UV radiation (UVR). As these pelagic organisms experience high UVR and large changes in solar radiation conditions between ice-free and ice-cover periods, they have evolved various strategies to minimize UVR exposure and damage. Here, we studied the relation between photoprotection levels (mycosporine-like amino acids, carotenoids), antioxidant capacities, and gene expression of heat shock proteins ( hsps ) as indicator of stress in the copepod Cyclops abyssorum tatricus during the course of a year. Expression of hsp60 , hsp70 , and hsp90 was measured in the field (baseline expression [BE]) and after UVR exposure in the laboratory. The BE differed among genes and seasons ( hsp60 : high during summer, hsp70 and hsp90 : high during the ice-cover period). The gene expression of hsp70 was upregulated after exposure to UVR (up to 5.2-fold change), while hsp60 and hsp90 were only constitutively expressed. A strong seasonal pattern was found in the photoprotective compounds and antioxidant capacities, with highest levels during the ice-free period. The extent of upregulation of hsp70 gene expression increased with decreasing photoprotection levels and peaked 24 h post UVR exposure (9.6-fold change) at the time of lowest photoprotection (February). Our data suggest that hsp70 gene expression is modulated by seasonal plasticity in photoprotection. This ability of adequate stress response is essential for survival in highly variable ecosystems such as alpine lakes.

Description: Author(s): Nikolas Liebster, Jingyi Tang, Daniel Ratner, Wei Liu, Sharon Vetter, Zhirong Huang, and Sergio Carbajo The microbunching instability is known to be detrimental to x-ray free electron laser performance. At the Linear Coherent Light Source, the microbunching instability is suppressed with a laser heater, which increases the uncorrelated energy spread of e-beam in the injector. While the current system ... [Phys. Rev. Accel. Beams 21, 090701] Published Tue Sep 11, 2018

Description: Author(s): J. F. Haase, P. J. Vetter, T. Unden, A. Smirne, J. Rosskopf, B. Naydenov, A. Stacey, F. Jelezko, M. B. Plenio, and S. F. Huelga We present a flexible scheme to realize non-Markovian dynamics of an electronic spin qubit, using a nitrogen-vacancy center in diamond where the inherent nitrogen spin serves as a regulator of the dynamics. By changing the population of the nitrogen spin, we show that we can smoothly tune the non-Ma... [Phys. Rev. Lett. 121, 060401] Published Thu Aug 09, 2018

Description: Vibrio harveyi β- N -acetylglucosaminidase ( Vh GlcNAcase) is a new member of the GH20 glycoside hydrolase family responsible for the complete degradation of chitin fragments, with N -acetylglucosamine (GlcNAc) monomers as the final products. In this study, the crystallization and preliminary crystallographic data of wild-type Vh GlcNAcase and its catalytically inactive mutant D437A in the absence and the presence of substrate are reported. Crystals of wild-type Vh GlcNAcase were grown in 0.1  M sodium acetate pH 4.6, 1.4  M sodium malonate, while crystals of the D437A mutant were obtained in 0.1  M bis-tris pH 7.5, 0.1  M sodium acetate, 20% PEG 3350. X-ray data from the wild-type and the mutant crystals were collected at a synchrotron-radiation light source and were complete to a resolution of 2.5 Å. All crystals were composed of the same type of dimer, with the substrate N , N ′-diacetylglucosamine (GlcNAc 2 or diNAG) used for soaking was cleaved by the active enzyme, leaving only a single GlcNAc molecule bound to the protein.