ALBERT

Description: ABSTRACT The phenotypic modulation of VSMCs is a key cellular event driving neointimal formation and vascular remodeling. As a multifaceted cytokine of cell-mediated immunity, IFN-γ has been shown to play a critical role in the pathogenesis of vascular proliferative diseases. Although the important function of IFN-γ on regulating VSMC activation is well established, the molecular mechanisms by which elicits VSMC responses are poorly defined. Recent studies have identified HMGB1 as a principal effector to mediate IFN-γ-dependent biological functions in multiple cell types. Moreover, SIRT1 has emerged as a critical regulator of cellular processes through deacetylating multiple substrates, including HMGB1. Thus, we examined the role of IFN-γ on HMGB1 release, SIRT1 expression, and VSMC phenotypic modulation as well as the underlying molecular mechanisms. We show that IFN-γ dose-dependently induces HMGB1 cytoplasmic accumulation and its active release from VSMCs, resulting in enhanced HMGB1 in the medium. Conversely, IFN-γ treatment led to a dramatic decrease in SIRT1 expression. Additionally, pretreatment with resveratrol, a selective SIRT1 activator, abrogated IFN-γ-induced HMGB1 translocation and its release. Moreover, IFN-γ stimulates VSMC phenotypic modulation to an activated synthetic state characterized by the repression of SMC differentiation markers such as SM22α and calponin and the increase in cell motility. In contrast, blocking HMGB1 release or activity by resveratrol and HMGB1-neutralizing antibody prevents IFN-γ-induced phenotypic modulation of VSMCs. Overall, this study provides the first evidence showing that HMGB1 plays a critical role in regulating VSMC phenotypic modulation, suggesting that HMGB1 may be a potential therapeutic target to prevent vascular occlusive diseases. This article is protected by copyright. All rights reserved

Description: In this study, we aimed to clarify spatial variations in xylem sap flow, and to determine the impacts of these variations on stand-scale transpiration ( E ) estimates. We examined circumferential and radial variations in sap flow velocity ( F d ) measured at several directions and depths in tree trunks of black locust ( Robinia pseudoacacia ) and native oak ( Quercus liaotungensis ), both of which have ring-porous wood anatomy, in forest stands on the Loess Plateau, China. We evaluated the impacts of circumferential variations in F d on stand-scale transpiration estimates using a simple scaling exercise. We found significant circumferential variations in F d in the outermost xylem in both species (coefficients of variation= 20–45%). For both species, F d measured at the inner xylem was smaller than that of the outermost xylem and the F d at the depth of 〉 10 mm was almost zero. The simple exercises showed that omitting circumferential variations in F d affected the E estimate by 16–21%, which was less than the effects of omitting within-tree radial and tree-to-tree variations in F d in both species. These results suggest that circumferential variations in F d can be a minor source of error for E estimates compared with within-tree radial and tree-to-tree variations in F d , regardless of the significant circumferential variations. Copyright © 2011 John Wiley & Sons, Ltd.

Description: The exotic Spartina alterniflora from North America has been rapidly invading the entire Chinese coast, while the impacts of plant invasion on the gross (GPP) and net primary production (NPP) of the coastal salt marshes were less known. In this study, we investigated the photosynthetic performance, leaf characteristics and primary production of the exotic C 4 grass and the dominant native C 3 grass ( Phragmites australis ) in two marsh mixtures (equipped with eddy covariance systems) in the Yangtze Estuary. The light-saturation photosynthetic rate and annual peak leaf area index ( LAI ) of S . alterniflora was higher than that of P . australis throughout the growing season. The leaf nitrogen content of P . australis declined sharper during the latter growing season than that of S . alterniflora . The leaf-to-canopy production model with species-specific (C 3 and C 4 types) parameterizations could reasonably simulate the daily trends and annual GPP amount against the 3-year flux measurements from 2005 to 2007, and the modeled NPP agreed with biomass measurements from the two species during 2012. The percentage contributions of GPP between the two species were on average 5.82:1 and 2.91:1 in the two mixtures, respectively. The annual NPP amounts from S . alterniflora were higher by approximately 1.6 times than that from P . australis . Our results suggested that higher photosynthesis efficiency, higher LAI and longer growing season resulted in greater GPP and NPP in the exotic species relative to the native species. The rapid expansion rate of S . alterniflora further made it the leading contributor of primary production in the salt marsh.

Description: River confluences and their associated tributaries are key morphodynamic nodes that play important roles in controlling hydraulic geometry and hyporheic water exchange in fluvial networks. However, the existing knowledge regarding hyporheic water exchange associated with river confluence morphology is relatively scarce. On the 14 th and 15 th of January, 2016, the general hydraulic and morphological characteristics of the confluent meander bend (CMB) between the Juehe River and the Haohe River in the southern region of Xi’an City, Shaanxi Province, China were investigated. The patterns and magnitudes of vertical hyporheic water exchange (VHWE) were estimated based on a one-dimension heat steady-state model while the sediment vertical hydraulic conductivity ( K v ) was calculated via in situ permeameter tests. The results demonstrated that six hydrodynamic zones and their extensions were observed at the CMB during the test period. These zones were likely controlled by the obtuse junction angle and low momentum flux ratio, influencing the sediment grain size distribution of the CMB. The VHWE patterns at the test site during the test period mostly showed upwelling flow dominated by regional groundwater discharging into the river. The occurrence of longitudinal downwelling and upwelling patterns along the meander bend at the CMB was likely subjected to the comprehensive influences of the local sinuosity of the meander bend and regional groundwater discharge, and finally formed regional and local flow paths. Additionally, in dominated upwelling areas, the change in VHWE magnitudes was nearly consistent with that in K v values, and higher values of both variables generally occurred in erosional zones near the thalweg paths of the CMB, which were mostly made up of sand and gravel. This was potentially caused by the erosional and depositional processes subjected to confluence morphology. Furthermore, lower K v values observed in downwelling areas at the CMB were attributed to sediment clogging caused by local downwelling flow. The confluence morphology and sediment K v are thus likely the driving factors which cause local variations in the VHWE of fluvial systems.

Description: The establishment of either forest or grassland on degraded cropland has been proposed as an effective method for climate change mitigation because these land use types can increase soil carbon (C) stocks. This paper synthesized 135 recent publications (844 observations at 181 sites) focused on the conversion from cropland to grassland, shrubland or forest in China, better known as the ‘Grain-for-Green’ Program to determine which factors were driving changes to soil organic carbon (SOC). The results strongly indicate a positive impact of cropland conversion on soil C stocks. The temporal pattern for soil C stock changes in the 0–100 cm soil layer showed an initial decrease in soil C during the early stage (〈 5 years), and then an increase to net C gains (〉 5 years) coincident with vegetation restoration. The rates of soil C change were higher in the surface profile (0–20 cm) than in deeper soil (20–100 cm). Cropland converted to forest (arbor) had the additional benefit of a slower but more persistent C sequestration capacity than shrubland or grassland. Tree species played a significant role in determining the rate of change in soil C stocks (conifer 〈 broadleaf, evergreen 〈 deciduous forests). Restoration age was the main factor, not temperature and precipitation, affecting soil C stock change after cropland conversion with higher initial soil C stock sites having a negative effect on soil C accumulation. Soil C sequestration significantly increased with restoration age over the long term, therefore, the large scale of land use change under the ‘Grain-for-Green’ Program will significantly increase China's C stocks. This article is protected by copyright. All rights reserved.

Description: Based on the bis-triazole ligand 2, 6-bis(1, 2,4-triazole-4-yl)pyridine (L), the triazole-iron(II) complexes [Fe(L) 2 (dca) 2 (H 2 O) 2 ] · 2H 2 O ( 1 ) (Nadca = sodium dicyanamide), {[Fe(μ 2 -L) 2 (H 2 O) 2 ]Cl 2 } n ( 2 ), and {[Fe(μ 2 -L) 2 (H 2 O) 2 ](ClO 4 ) 2 · L · H 2 O} n ( 3 ) were isolated by solvent diffusion methods. When iron(II) salts and Nadca were used, compound 1 was isolated, which contains mononuclear Fe(L) 2 (dca) 2 (H 2 O) 2 units. When FeCl 2 or FeClO 4 were used, one-dimensional (1D) cation iron(II) chains ( 2 ) and two-dimensional (2D) cation iron(II) networks ( 3 ) were isolated indicating anion directing structural diversity. Moreover, variable-temperature magnetic susceptibility data of 1 – 3 were recorded in the temperature range 2–300 K. The magnetic curve of complex 2 was fitted by using the classical spin Heisenberg chain model indicating anti-ferromagnetic interactions ( J = –5.31 cm –1 ). Obviously complexes 1 – 3 show no detectable thermal spin crossover behaviors, the lack of spin-crossover behavior may be correlated with FeN 4 O 2 coordination spheres in 1 – 3 .

Description: Andesitic magmatism and rocks are widespread at convergent plate boundaries. Electrically conductive bodies beneath subduction zone arc volcanoes, such as the Uturuncu Volcano, Bolivia, may correspond to active reservoirs of H 2 O-bearing andesitic magma. Laboratory measurements of electrical conductivity of hydrous andesitic melts are required to constrain the physicochemical conditions of these magma reservoirs in combination with magnetotelluric data. This experimental study investigates electrical conductivity of andesitic melts with 0.01-5.9 wt% of H 2 O at 1164-1573 K and 0.5-1.0 GPa in a piston cylinder apparatus using sweeping-frequency impedance spectroscopy. Electrical conductivity of andesitic melt increases with increasing temperature and H 2 O concentration but decreases with pressure. Across the investigated range of H 2 O concentration, electrical conductivity varies by 1.2-2.4 log units, indicating stronger influence of H 2 O for andesitic melt than for rhyolitic and dacitic melts. Using the Nernst-Einstein equation, the principal charge carrier is inferred to be Na in anhydrous melt but divalent cations in hydrous andesitic melts. The experimental data are regressed into a general electrical conductivity model for andesitic melt accounting for the P-T -H 2 O dependences altogether. Modeling results show that the conductive layer at 〉20 km depths beneath the surface of the Uturuncu Volcano could be interpreted by the presence of less than 20 vol% of H 2 O-rich andesitic melt (with 6-9 wt% H 2 O).